Lee, Jung Ho; Li, Fang; Grishaev, Alexander; Bax, Ad
2015-02-04
Three-bond (3)J(C'C') and (3)J(HNHα) couplings in peptides and proteins are functions of the intervening backbone torsion angle ϕ. In well-ordered regions, (3)J(HNHα) is tightly correlated with (3)J(C'C'), but the presence of large ϕ angle fluctuations differentially affects the two types of couplings. Assuming the ϕ angles follow a Gaussian distribution, the width of this distribution can be extracted from (3)J(C'C') and (3)J(HNHα), as demonstrated for the folded proteins ubiquitin and GB3. In intrinsically disordered proteins, slow transverse relaxation permits measurement of (3)J(C'C') and (3)J(HNH) couplings at very high precision, and impact of factors other than the intervening torsion angle on (3)J will be minimal, making these couplings exceptionally valuable structural reporters. Analysis of α-synuclein yields rather homogeneous widths of 69 ± 6° for the ϕ angle distributions and (3)J(C'C') values that agree well with those of a recent maximum entropy analysis of chemical shifts, J couplings, and (1)H-(1)H NOEs. Data are consistent with a modest (≤30%) population of the polyproline II region.
Nonminimally coupled scalar field and Ashtekar variables
Capovilla, R. )
1992-08-15
The nonminimal coupling of a scalar field is considered in the framework of Ashtekar's new variables formulation of gravity. A first-order action functional for this system is derived in which the field variables are a tetrad field, and an SL(2,{ital C}) connection, together with the scalar field. The tetrad field and the SL(2,{ital C}) connection are related to the Ashtekar variables for the vacuum case by a conformal transformation. A canonical analysis shows that for this coupling the equations of Ashtekar's formulation of canonical gravity are nonpolynomial in the scalar field.
Scalar field, nonminimal coupling, and cosmology
Demianski, M. International Center for Relativistic Astrophysics, Dipartimento di Fisica, Universita di Roma La Sapienza,'' Rome ); de Ritis, R.; Marmo, G.; Platania, G.; Rubano, C.; Scudellaro, P.; Stornaiolo, C. Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Mostra d'Oltremare, pad. 19, 80125 Napoli )
1991-11-15
We study the dynamics of a flat Friedmann-Robertson-Walker universe filled with a self-interacting scalar field nonminimally coupled to the gravitational field. Dynamical equations for the system can be derived from a pointlike Lagrangian. For this system an additional Noether symmetry exists provided that the coupling constant {xi} is equal to 0 or 1/6. When {xi}=1/6 the scalar potential has to be constant. In this case we obtain an exact solution. We also analyze the behavior of the scalar field when {xi}{ne}0, 1/6. Most of the considered solutions are unphysical but there exists a very interesting case in which the effective cosmological constant is rapidly changing, which might lead to inflation.
Kundt spacetimes minimally coupled to scalar field
NASA Astrophysics Data System (ADS)
Tahamtan, T.; Svítek, O.
2017-06-01
We derive an exact solution belonging to the Kundt class of spacetimes both with and without a cosmological constant that are minimally coupled to a free massless scalar field. We show the algebraic type of these solutions and give interpretation of the results. Subsequently, we look for solutions additionally containing an electromagnetic field satisfying nonlinear field equations.
Atomic precision tests and light scalar couplings
Brax, Philippe; Burrage, Clare
2011-02-01
We calculate the shift in the atomic energy levels induced by the presence of a scalar field which couples to matter and photons. We find that a combination of atomic measurements can be used to probe both these couplings independently. A new and stringent bound on the matter coupling springs from the precise measurement of the 1s to 2s energy level difference in the hydrogen atom, while the coupling to photons is essentially constrained by the Lamb shift. For a range of masses these constraints are not as stringent as those from fifth force experiments or optical astrophysical and laboratory measurements. However, they have the advantage that they are universal, applying to all scalars, even those that hide their effects dynamically from fifth force searches, such as the chameleon and Galileon models. Combining these constraints with current particle physics bounds we find that the contribution of a scalar field to the recently claimed discrepancy in the proton radius measured using electronic and muonic atoms is negligible.
Noncommutative Scalar Field Minimally Coupled to Gravity
NASA Astrophysics Data System (ADS)
Bertolami, Orfeu
A model for noncommutative scalar fields coupled to gravity based on the generalization of the Moyal product is proposed. Solutions compatible with homogeneous and isotropic flat Robertson-Walker spaces to first non-trivial order in the perturbation of the star-product are presented. It is shown that in the context of a typical chaotic inflationary scenario, at least in the slow-roll regime, noncommutativity yields no observable effect.
RNA structure and scalar coupling constants
Tinoco, I. Jr.; Cai, Z.; Hines, J.V.; Landry, S.M.; SantaLucia, J. Jr.; Shen, L.X.; Varani, G.
1994-12-01
Signs and magnitudes of scalar coupling constants-spin-spin splittings-comprise a very large amount of data that can be used to establish the conformations of RNA molecules. Proton-proton and proton-phosphorus splittings have been used the most, but the availability of {sup 13}C-and {sup 15}N-labeled molecules allow many more coupling constants to be used for determining conformation. We will systematically consider the torsion angles that characterize a nucleotide unit and the coupling constants that depend on the values of these torsion angles. Karplus-type equations have been established relating many three-bond coupling constants to torsion angles. However, one- and two-bond coupling constants can also depend on conformation. Serianni and coworkers measured carbon-proton coupling constants in ribonucleosides and have calculated their values as a function of conformation. The signs of two-bond coupling can be very useful because it is easier to measure a sign than an accurate magnitude.
LIPSS results for photons coupling to light neutral scalar bosons
Andrei Afanasev; Oliver K. Baker; Kevin Beard; George Biallas; James Boyce; Minarni Minarni; Roopchan Ramdon; Michelle D. Shinn; Penny Slocum
2008-06-01
The LIPSS search for a light neutral scalar boson coupling to optical photons is reported. The search covers a region of parameter space of approximately 1.0 meV and coupling strength greater than 10^-6 GeV^-1. The LIPSS results show no evidence for scalar coupling in this region of parameter space.
CAL3JHH: a Java program to calculate the vicinal coupling constants (3 J H,H) of organic molecules
NASA Astrophysics Data System (ADS)
Aguirre-Valderrama, Alonso; Dobado, José A.
2008-12-01
Here, we present a free web-accessible application, developed in the JAVA programming language for the calculation of vicinal coupling constant (3 J H,H) of organic molecules with the H-Csp3-Csp3-H fragment. This JAVA applet is oriented to assist chemists in structural and conformational analyses, allowing the user to calculate the averaged 3 J H,H values among conformers, according to its Boltzmann populations. Thus, the CAL3JHH program uses the Haasnoot-Leeuw-Altona equation, and, by reading the molecule geometry from a protein data bank (PDB) file format or from multiple pdb files, automatically detects all the coupled hydrogens, evaluating the data needed for this equation. Moreover, a "Graphical viewer" menu allows the display of the results on the 3D molecule structure, as well as the plotting of the Newman projection for the couplings.
CAL3JHH: a Java program to calculate the vicinal coupling constants (3J H,H) of organic molecules.
Aguirre-Valderrama, Alonso; Dobado, José A
2008-12-01
Here, we present a free web-accessible application, developed in the JAVA programming language for the calculation of vicinal coupling constant (3J(H,H)) of organic molecules with the H-Csp3-Csp3-H fragment. This JAVA applet is oriented to assist chemists in structural and conformational analyses, allowing the user to calculate the averaged 3J(H,H) values among conformers, according to its Boltzmann populations. Thus, the CAL3JHH program uses the Haasnoot-Leeuw-Altona equation, and, by reading the molecule geometry from a protein data bank (PDB) file format or from multiple pdb files, automatically detects all the coupled hydrogens, evaluating the data needed for this equation. Moreover, a "Graphical viewer" menu allows the display of the results on the 3D molecule structure, as well as the plotting of the Newman projection for the couplings.
Transverse relaxation of scalar-coupled protons.
Segawa, Takuya F; Baishya, Bikash; Bodenhausen, Geoffrey
2010-10-25
In a preliminary communication (B. Baishya, T. F. Segawa, G. Bodenhausen, J. Am. Chem. Soc. 2009, 131, 17538-17539), we recently demonstrated that it is possible to obtain clean echo decays of protons in biomolecules despite the presence of homonuclear scalar couplings. These unmodulated decays allow one to determine apparent transverse relaxation rates R(2) (app) of individual protons. Herein, we report the observation of R(2) (app) for three methyl protons, four amide H(N) protons, and all 11 backbone H(α) protons in cyclosporin A. If the proton resonances overlap, their R(2) (app) rates can be measured by transferring their magnetization to neighboring (13)C nuclei, which are less prone to overlap. The R(2) (app) rates of protons attached to (13)C are faster than those attached to (12)C because of (13)C-(1)H dipolar interactions. The differences of these rates allow the determination of local correlation functions. Backbone H(N) and H(α) protons that have fast decay rates R(2) (app) also feature fast longitudinal relaxation rates R(1) and intense NOESY cross peaks that are typical of crowded environments. Variations of R(2) (app) rates of backbone H(α) protons in similar amino acids reflect differences in local environments.
Noncommutative scalar field minimally coupled to nonsymmetric gravity
Kouadik, S.; Sefai, D.
2012-06-27
We construct a non-commutative non symmetric gravity minimally coupled model (the star product only couples matter). We introduce the action for the system considered namely a non-commutative scalar field propagating in a nontrivial gravitational background. We expand the action in powers of the anti-symmetric field and the graviton to second order adopting the assumption that the scalar is weekly coupled to the graviton. We compute the one loop radiative corrections to the self-energy of a scalar particle.
Relativistic stars in scalar-tensor theories with disformal coupling
NASA Astrophysics Data System (ADS)
Silva, Hector O.; Minamitsuji, Masato
2017-01-01
We discuss a general formulation to study the structure of slowly-rotating relativistic stars in a broad class of scalar-tensor theories including disformal coupling to matter. Our approach includes as particular cases theories with generalized kinetic terms and generic scalar field potentials, and contains theories with conformal coupling as particular limits. We propose a minimal model to investigate the role of the disformal coupling on the non-perturbative effect known as spontaneous scalarization, which causes relativistic star solutions in certain classes of scalar-tensor theories to differ dramatically from their general relativistic counterparts. Moreover, we show that the moment of inertia and compactness of stars are equation of state independent, which can potentially be used to constrain the model observationally.
Scalar-tensor gravity with scalar-matter direct coupling and its cosmological probe
NASA Astrophysics Data System (ADS)
Kim, Jik-Su; Kim, Chol-Jun
2017-08-01
Making use of the SNIa data set, Nesseris and Perivolaropoulos [Phys. Rev. D 73, 103511 (2006), 10.1103/PhysRevD.73.103511] have found the gravitation constant to evolve in accordance with scalar-tensor gravity. On the other hand, Majerotto et al. [arXiv:astro-ph/0410543] and Guo et al. [Phys. Rev. D 76, 023508 (2007), 10.1103/PhysRevD.76.023508] have found a definite signature of dark energy-dark matter coupling in Einstein tensor gravity background. However, the results of the above works are quite contradictory, so we cannot be sure which of these results should be accepted because both models use different background gravitation. We construct a more inclusive model with scalar-background space-time and scalar-matter couplings. Making use of SNIa(Union) and baryon acoustic oscillation data sets, we made likelihood analyses; the results show that the background gravitation has the tensor characteristics within a confidence level of 68% and the scalar-matter coupling has a rather large positive value δ =±1.01 . As Guo et al. showed, however, inclusion of the cosmic microwave background (CMB) data set in the likelihood analysis significantly reduces the allowed region of the coupling compared to the case without CMB data. Therefore, the value of scalar-matter coupling in this paper could have been estimated too large and the inclusion of CMB data in the next work is expected to yield a more realistic result.
Scalar-tensor theory of gravitation with negative coupling constant
NASA Technical Reports Server (NTRS)
Smalley, L. L.; Eby, P. B.
1976-01-01
The possibility of a Brans-Dicke scalar-tensor gravitation theory with a negative coupling constant is considered. The admissibility of a negative-coupling theory is investigated, and a simplified cosmological solution is obtained which allows a negative derivative of the gravitation constant. It is concluded that a Brans-Dicke theory with a negative coupling constant can be a viable alternative to general relativity and that a large negative value for the coupling constant seems to bring the original scalar-tensor theory into close agreement with perihelion-precession results in view of recent observations of small solar oblateness.
Scalar-tensor theory of gravitation with negative coupling constant
NASA Technical Reports Server (NTRS)
Smalley, L. L.; Eby, P. B.
1976-01-01
The possibility of a Brans-Dicke scalar-tensor gravitation theory with a negative coupling constant is considered. The admissibility of a negative-coupling theory is investigated, and a simplified cosmological solution is obtained which allows a negative derivative of the gravitation constant. It is concluded that a Brans-Dicke theory with a negative coupling constant can be a viable alternative to general relativity and that a large negative value for the coupling constant seems to bring the original scalar-tensor theory into close agreement with perihelion-precession results in view of recent observations of small solar oblateness.
N-body simulations for coupled scalar-field cosmology
Li Baojiu; Barrow, John D.
2011-01-15
We describe in detail the general methodology and numerical implementation of consistent N-body simulations for coupled-scalar-field models, including background cosmology and the generation of initial conditions (with the different couplings to different matter species taken into account). We perform fully consistent simulations for a class of coupled-scalar-field models with an inverse power-law potential and negative coupling constant, for which the chameleon mechanism does not work. We find that in such cosmological models the scalar-field potential plays a negligible role except in the background expansion, and the fifth force that is produced is proportional to gravity in magnitude, justifying the use of a rescaled gravitational constant G in some earlier N-body simulation works for similar models. We then study the effects of the scalar coupling on the nonlinear matter power spectra and compare with linear perturbation calculations to see the agreement and places where the nonlinear treatment deviates from the linear approximation. We also propose an algorithm to identify gravitationally virialized matter halos, trying to take account of the fact that the virialization itself is also modified by the scalar-field coupling. We use the algorithm to measure the mass function and study the properties of dark-matter halos. We find that the net effect of the scalar coupling helps produce more heavy halos in our simulation boxes and suppresses the inner (but not the outer) density profile of halos compared with the {Lambda}CDM prediction, while the suppression weakens as the coupling between the scalar field and dark-matter particles increases in strength.
Gravitating monopole-antimonopole systems at large scalar coupling
Kunz, Jutta; Neemann, Ulrike; Shnir, Yasha
2007-06-15
We discuss static axially symmetric solutions of SU(2) Einstein-Yang-Mills-Higgs theory for large scalar coupling {lambda}. These regular asymptotically flat solutions represent monopole-antimonopole chain and vortex ring solutions, as well as new configurations, present only for larger values of {lambda}. When gravity is coupled to the Yang-Mills-Higgs system, branches of gravitating solutions emerge from the flat-space solutions, and extend up to critical values of the gravitational coupling constant. For small scalar coupling only two branches of gravitating solutions exist, where the second branch connects to a generalized Bartnik-McKinnon solution. For large scalar coupling, however, a plethora of gravitating branches can be present and indicate the emergence of new flat-space branches.
Scalar field conformally coupled to a charged BTZ black hole
NASA Astrophysics Data System (ADS)
Valtancoli, P.
2016-06-01
We study the Klein-Gordon equation of a scalar field conformally coupled to a charged BTZ black hole. The background metric is obtained by coupling a non-linear and conformal invariant Maxwell field to (2 + 1) gravity. We show that the radial part is generally solved by a Heun function and, in the pure gravity limit, by a hypergeometric function.
Top and bottom tensor couplings from a color octet scalar
NASA Astrophysics Data System (ADS)
Martinez, Roberto; Valencia, German
2017-02-01
We compute the one-loop contributions from a color octet scalar to the tensor anomalous couplings of top and bottom quarks to gluons, photons and W bosons. We use known constraints on the parameters of the model to compare the predicted size of these couplings with existing phenomenological constraints.
Supernova constraints on massive (pseudo)scalar coupling to neutrinos
NASA Astrophysics Data System (ADS)
Heurtier, Lucien; Zhang, Yongchao
2017-02-01
In this paper we derive constraints on the emission of a massive (pseudo)scalar S from annihilation of neutrinos in the core of supernovae through the dimension-4 coupling νν S, as well as the effective dimension-5 operator 1/Λ(νν)(SS). While most of earlier studies have focused on massless or ultralight scalars, our analysis involves scalar with masses of order eV–GeV which can be copiously produced during {the explosion of supernovae, whose core temperature is} generally of order T~ Script OO(10) MeV. From the luminosity and deleptonization arguments regarding the observation of SN1987A, we exclude a large range of couplings 10‑12 lesssim |gαβ|lesssim 10‑5 for the dimension-4 case, depending on the neutrino flavours involved and the scalar mass. In the case of dimension-5 operator, for a scalar mass from MeV to 100 MeV the coupling hαβ get constrained from 10‑6 to 10‑2, with the cutoff scale explicitly set Λ = 1 TeV. We finally show that if the neutrino burst of a nearby supernova explosion is detected by Super-Kamiokande and IceCube, the constraints will be largely reinforced.
Scalar decay constant and Yukawa coupling in walking gauge theories
Hashimoto, Michio
2011-05-01
We propose an approach for the calculation of the Yukawa coupling through the scalar decay constant and the chiral condensate in the context of the extended technicolor . We perform the nonperturbative computation of the Yukawa coupling based on the improved ladder Schwinger-Dyson equation. It turns out that the Yukawa coupling can be larger or smaller than the standard model value, depending on the number N{sub D} of the weak doublets for each technicolor (TC) index. It is thus nontrivial whether or not the huge enhancement of the production of the scalar via the gluon fusion takes place even for a walking TC model with a colored techni-fermion. For the typical one-family TC model near conformality, it is found that the Yukawa coupling is slightly larger than the standard model one, where the expected mass of the scalar bound state is around 500 GeV. In this case, the production cross section via the gluon fusion is considerably enhanced, as naively expected, and hence such a scalar can be discovered/excluded at the early stage of the LHC.
Accretion of nonminimally coupled scalar fields into black holes
Rodrigues, Manuela G.; Saa, Alberto
2009-11-15
By using a quasistationary approach, we consider the mass evolution of Schwarzschild black holes in the presence of a nonminimally coupled cosmological scalar field. The mass evolution equation is analytically solved for generic coupling, revealing a qualitatively distinct behavior from the minimal coupling case. In particular, for black hole masses smaller than a certain critical value, the accretion of the scalar field can lead to mass decreasing even if no phantom energy is involved. The physical validity of the adopted quasistationary approach and some implications of our result for the evolution of primordial and astrophysical black holes are discussed. More precisely, we argue that black hole observational data could be used to place constraints on the nonminimally coupled energy content of the Universe.
Minisuperspaces with conformally and minimally coupled scalar fields
NASA Astrophysics Data System (ADS)
Page, Don N.
1991-12-01
One may perform a local field redefinition to transform between gravity minimally coupled to a free scalar field and gravity conformally coupled. However, the allowed field values differ in the two cases. For a minisuperspace consisting of a Friedman-Robertson-Walker geometry and a homogeneous scalar field, the conformal coupling allows a more general class of solutions of the Wheeler-DeWitt equation than does the minimal coupling. Nevertheless, there is a one-to-one correspondence between the bounded solutions in the two cases for k=1. This correspondence exploits an isomorphism between harmonic oscillator wavefunctions and solutions of the massive Klein-Gordon equation in the 1+1 dimensional Rindler wedge.
Effective Hamiltonian for non-minimally coupled scalar fields
NASA Astrophysics Data System (ADS)
Meşe, Emine; Pirinççiog˜Lu, Nurettin; Açıkgöz, Irfan; Binbay, Figen
2009-01-01
In the post Newtonian limit, a non-relativistic Hamiltonian is derived for scalar fields with quartic self-interaction and non-minimal coupling to the curvature scalar of the background spacetime. These effects are found to contribute to the non-relativistic Hamiltonian by adding nonlinearities and by modifying the gravitational Darwin term. As we discuss briefly in the text, the impact of these novel structures can be sizable in dense media like neutron star core, and can have observable signatures in phase transitions, for example.
Brane models with a Ricci-coupled scalar field
Bogdanos, C.; Dimitriadis, A.; Tamvakis, K.
2006-08-15
We consider the problem of a scalar field, nonminimally coupled to gravity through a -{xi}{phi}{sup 2}R term, in the presence of a brane. Exact solutions, for a wide range of values of the coupling parameter {xi}, for both {phi}-dependent and {phi}-independent brane tension, are derived and their behavior is studied. In the case of a Randall-Sundrum geometry, a class of the resulting scalar field solutions exhibits a folded-kink profile. We go beyond the Randall-Sundrum geometry studying general warp factor solutions in the presence of a kink scalar. Analytic and numerical results are provided for the case of a brane or for smooth geometries, where the scalar field acts as a thick brane. It is shown that finite geometries with warp factors that asymptotically decrease exponentially are realizable for a wide range of parameter values. We also study graviton localization in our setup and find that the localizing potential for gravitons with the characteristic volcanolike profile develops a local maximum located at the origin for high values of the coupling {xi}.
Minimally coupled scalar field cosmology in anisotropic cosmological model
NASA Astrophysics Data System (ADS)
Singh, C. P.; Srivastava, Milan
2017-02-01
We study a spatially homogeneous and anisotropic cosmological model in the Einstein gravitational theory with a minimally coupled scalar field. We consider a non-interacting combination of scalar field and perfect fluid as the source of matter components which are separately conserved. The dynamics of cosmic scalar fields with a zero rest mass and an exponential potential are studied, respectively. We find that both assumptions of potential along with the average scale factor as an exponential function of scalar field lead to the logarithmic form of scalar field in each case which further gives power-law form of the average scale factor. Using these forms of the average scale factor, exact solutions of the field equations are obtained to the metric functions which represent a power-law and a hybrid expansion, respectively. We find that the zero-rest-mass model expands with decelerated rate and behaves like a stiff matter. In the case of exponential potential function, the model decelerates, accelerates or shows the transition depending on the parameters. The isotropization is observed at late-time evolution of the Universe in the exponential potential model.
Quantum entanglement in three accelerating qubits coupled to scalar fields
NASA Astrophysics Data System (ADS)
Dai, Yue; Shen, Zhejun; Shi, Yu
2016-07-01
We consider quantum entanglement of three accelerating qubits, each of which is locally coupled with a real scalar field, without causal influence among the qubits or among the fields. The initial states are assumed to be the GHZ and W states, which are the two representative three-partite entangled states. For each initial state, we study how various kinds of entanglement depend on the accelerations of the three qubits. All kinds of entanglement eventually suddenly die if at least two of three qubits have large enough accelerations. This result implies the eventual sudden death of all kinds of entanglement among three particles coupled with scalar fields when they are sufficiently close to the horizon of a black hole.
Coupled channel model of the scalar isovector meson photoproduction
NASA Astrophysics Data System (ADS)
Bibrzycki, Ł.; Kamiński, R.
2017-03-01
We present the coupled channel model of the scalar isovector resonance photoproduction including the πη, KK̅ and πη' channels and calculate resulting mass distribution and the cross section in the πη channel. We show that the shape of this mass distribution, is strongly affected by the phase of background amplitude. We also discuss the effect of inclusion the πη' channel on the overall isovector photoproduction process.
NASA Astrophysics Data System (ADS)
Anderson, David; Yunes, Nicolás
2017-09-01
Scalar-tensor theories of gravity modify general relativity by introducing a scalar field that couples nonminimally to the metric tensor, while satisfying the weak-equivalence principle. These theories are interesting because they have the potential to simultaneously suppress modifications to Einstein's theory on Solar System scales, while introducing large deviations in the strong field of neutron stars. Scalar-tensor theories can be classified through the choice of conformal factor, a scalar that regulates the coupling between matter and the metric in the Einstein frame. The class defined by a Gaussian conformal factor with a negative exponent has been studied the most because it leads to spontaneous scalarization (i.e. the sudden activation of the scalar field in neutron stars), which consequently leads to large deviations from general relativity in the strong field. This class, however, has recently been shown to be in conflict with Solar System observations when accounting for the cosmological evolution of the scalar field. We here study whether this remains the case when the exponent of the conformal factor is positive, as well as in another class of theories defined by a hyperbolic conformal factor. We find that in both of these scalar-tensor theories, Solar System tests are passed only in a very small subset of coupling parameter space, for a large set of initial conditions compatible with big bang nucleosynthesis. However, while we find that it is possible for neutron stars to scalarize, one must carefully select the coupling parameter to do so, and even then, the scalar charge is typically 2 orders of magnitude smaller than in the negative-exponent case. Our study suggests that future work on scalar-tensor gravity, for example in the context of tests of general relativity with gravitational waves from neutron star binaries, should be carried out within the positive coupling parameter class.
Higher-dimensional solitons and black holes with a nonminimally coupled scalar field
Hosler, Dominic; Winstanley, Elizabeth
2009-11-15
We study higher-dimensional soliton and hairy black hole solutions of the Einstein equations nonminimally coupled to a scalar field. The scalar field has no self-interaction potential but a cosmological constant is included. Nontrivial solutions exist only when the cosmological constant is negative and the constant governing the coupling of the scalar field to the Ricci scalar curvature is positive. At least some of these solutions are stable when this coupling constant is not too large.
Averaged energy inequalities for the nonminimally coupled classical scalar field
Fewster, Christopher J.; Osterbrink, Lutz W.
2006-08-15
The stress-energy tensor for the classical nonminimally coupled scalar field is known not to satisfy the pointwise energy conditions of general relativity. In this paper we show, however, that local averages of the classical stress-energy tensor satisfy certain inequalities. We give bounds for averages along causal geodesics and show, e.g., that in Ricci-flat background spacetimes, ANEC and AWEC are satisfied. Furthermore we use our result to show that in the classical situation we have an analogue to the phenomenon of quantum interest. These results lay the foundations for analogous energy inequalities for the quantized nonminimally coupled fields, which will be discussed elsewhere.
Probing scalar coupling differences via long-lived singlet states
NASA Astrophysics Data System (ADS)
DeVience, Stephen J.; Walsworth, Ronald L.; Rosen, Matthew S.
2016-01-01
We probe small scalar coupling differences via the coherent interactions between two nuclear spin singlet states in organic molecules. We show that the spin-lock induced crossing (SLIC) technique enables the coherent transfer of singlet order between one spin pair and another. The transfer is mediated by the difference in syn and anti vicinal or long-range J couplings among the spins. By measuring the transfer rate, we calculate a J coupling difference of 8 ± 2 mHz in phenylalanine-glycine-glycine and 2.57 ± 0.04 Hz in glutamate. We also characterize a coherence between two singlet states in glutamate, which may enable the creation of a long-lived quantum memory.
No nonminimally coupled massless scalar hair for spherically symmetric neutral reflecting stars
NASA Astrophysics Data System (ADS)
Hod, Shahar
2017-07-01
It has recently been proved that horizonless compact stars with reflecting boundary conditions cannot support spatially regular matter configurations made of minimally coupled scalar fields, vector fields, and tensor fields. In the present paper we extend this intriguing no-hair property to the physically interesting regime of scalar fields with nonminimal coupling to gravity. In particular, we prove that static spherically symmetric configurations made of nonminimally coupled massless scalar fields cannot be supported by compact reflecting stars.
Spinning Kerr black holes with stationary massive scalar clouds: the large-coupling regime
NASA Astrophysics Data System (ADS)
Hod, Shahar
2017-01-01
We study analytically the Klein-Gordon wave equation for stationary massive scalar fields linearly coupled to spinning Kerr black holes. In particular, using the WKB approximation, we derive a compact formula for the discrete spectrum of scalar field masses which characterize the stationary composed Kerr-black-hole-massive-scalar-field configurations in the large-coupling regime M μ ≫ 1 (here M and μ are respectively the mass of the central black hole and the proper mass of the scalar field). We confirm our analytically derived formula for the Kerr-scalar-field mass spectrum with numerical data that recently appeared in the literature.
Neutron Star Structure in the Presence of Conformally Coupled Scalar Fields
NASA Technical Reports Server (NTRS)
Sultana, Joseph; Bose, Benjamin; Kazanas, Demosthenes
2014-01-01
Neutron star models are studied in the context of scalar-tensor theories of gravity in the presence of a conformally coupled scalar field, using two different numerical equations of state (EoS) representing different degrees of stiffness. In both cases we obtain a complete solution by matching the interior numerical solution of the coupled Einstein-scalar field hydrostatic equations, with an exact metric on the surface of the star. These are then used to find the effect of the scalar field and its coupling to geometry, on the neutron star structure, particularly the maximum neutron star mass and radius. We show that in the presence of a conformally coupled scalar field, neutron stars are less dense and have smaller masses and radii than their counterparts in the minimally coupled case, and the effect increases with the magnitude of the scalar field at the center of the star.
Improved Measurement of 3J(H αi, N i+1 ) Coupling Constants in H 2O Dissolved Proteins
NASA Astrophysics Data System (ADS)
Löhr, Frank; Schmidt, Jürgen M.; Maurer, Steffen; Rüterjans, Heinz
2001-11-01
A modification to the recently proposed α/β-HN(CO)CA-J TROSY pulse sequence (P. Permi et al., J. Magn. Reson.146, 255-259 (2000)) makes it possible to determine 3J(Hαi, Ni+1) coupling constants from a single E.COSY-type cross-peak pattern rather than from two 1Hα spin-state-edited subspectra. Advantages are increased 15N resolution, critical to extracting accurate 1Hα-15N coupling constants, and minimized differential relaxation due to nested 13Cα and 15N evolution periods. Application of the improved pulse sequence to Desulfovibrio vulgaris flavodoxin results in 3J(Hαi, Ni+1) values being systematically larger than those obtained with the original scheme. Parametrization of the coupling dependence on the protein backbone torsion angle ψ yields the Karplus relation 3J(Hαi, Ni+1)=-1.00 cos2(ψ-120°)+0.65 cos(ψ-120°)-0.15 Hz, with a residual root-mean-square difference of 0.13 Hz between measured and back-calculated coupling constants. The curve compares with data derived from ubiquitin (A. C. Wang and A. Bax, J. Am. Chem. Soc.117, 1810-1813 (1995)), although spanning a slightly larger range of J values in flavodoxin. The orientation of the Ala39/Ser40 peptide link, forming a type-II β-turn in flavodoxin, is twisted against X-ray-derived torsions by approximately 10° in the NMR structure as evident from the analysis of φ- and ψ-related 3J coupling constants. The remaining deviation of some experimental values from the prediction is likely to be due to strong hydrogen bonding, substituent effects, or the additional dependence on the adjacent torsions φ.
Cosmology and stability in scalar tensor bigravity with non-minimal kinetic coupling gravity
Darabi, F.; Mousavi, M. E-mail: mousavi@azaruniv.edu
2015-08-01
We generalize the scalar tensor bigravity models to the non-minimal kinetic coupling scalar tensor bigravity models with two scalar fields whose kinetic terms are non-minimally coupled to two Einstein tensors constructed by two metrics. We show that a broad class of expanding universes can be explained by some solutions of this model. Then, we study the stability issue of the solutions by means of imposing homogeneous perturbation on the equations of motion and extract the stable solutions.
Einstein CARTAN theory for a non-minimally coupled scalar field
NASA Astrophysics Data System (ADS)
de Ritis, Ruggero; Platania, G.; Scudellaro, P.; Stornaiolo, Cosimo
The Einstein equations for a free scalar field nonminimally coupled with the curvature scalar have been extended to a Riemann-Cartan space-time in the absence of matter and radiation and with a cosmological constant. The resulting Cartan equation shows that the source for torsion is given by the scalar field four-gradient. This relation between torsion and the scalar field is used to discuss the initial singularity problem and the possible asymptotic behavior in a Friedmann-Robertson-Walker cosmology.
Scalar-tensor black holes coupled to Born-Infeld nonlinear electrodynamics
Stefanov, Ivan Zh.; Yazadjiev, Stoytcho S.; Todorov, Michail D.
2007-04-15
The nonexistence of asymptotically flat, neutral black holes and asymptotically flat, charged black holes in the Maxwell electrodynamics, with a nontrivial scalar field has been proved for a large class of scalar-tensor theories. The no-scalar-hair theorems, however, do not apply in the case of nonlinear electrodynamics. In the present work numerical solutions describing charged black holes coupled to Born-Infeld type nonlinear electrodynamics in scalar-tensor theories of gravity with massless scalar field are found. The causal structure and properties of the solutions are studied, and a comparison between these solutions and the corresponding solutions in the general relativity is made. The presence of the scalar field leads to a much more simple causal structure. The present class of black holes has a single, nondegenerate horizon, i.e., its causal structure resembles that of the Schwarzschild black hole.
Slow-roll suppression of adiabatic instabilities in coupled scalar field-dark matter models
Corasaniti, Pier Stefano
2008-10-15
We study the evolution of linear density perturbations in the context of interacting scalar field-dark matter cosmologies, where the presence of the coupling acts as a stabilization mechanism for the runaway behavior of the scalar self-interaction potential as in the case of the chameleon model. We show that, in the 'adiabatic' background regime of the system, the rise of unstable growing modes of the perturbations is suppressed by the slow-roll dynamics of the field. Furthermore, the coupled system behaves as an inhomogeneous adiabatic fluid. In contrast, instabilities may develop for large values of the coupling constant, or along nonadiabatic solutions, characterized by a period of high-frequency dumped oscillations of the scalar field. In the latter case, the dynamical instabilities of the field fluctuations, which are typical of oscillatory scalar field regimes, are amplified and transmitted by the coupling to dark matter perturbations.
Quasinormal modes of black holes in scalar-tensor theories with nonminimal derivative couplings
NASA Astrophysics Data System (ADS)
Dong, Ruifeng; Sakstein, Jeremy; Stojkovic, Dejan
2017-09-01
We study the quasinormal modes of asymptotically anti-de Sitter black holes in a class of shift-symmetric Horndeski theories where a gravitational scalar is derivatively coupled to the Einstein tensor. The spacetime differs from exact Schwarzschild-anti-de Sitter, resulting in a different effective potential for the quasinormal modes and a different spectrum. We numerically compute this spectrum for a massless test scalar coupled both minimally to the metric, and nonminimally to the gravitational scalar. We find interesting differences from the Schwarzschild-anti-de Sitter black hole found in general relativity.
NASA Astrophysics Data System (ADS)
Antunes, V.; Novello, M.
2017-04-01
In the present work we revisit a model consisting of a scalar field with a quartic self-interaction potential non-minimally (conformally) coupled to gravity (Novello in Phys Lett 90A:347 1980). When the scalar field vacuum is in a broken symmetry state, an effective gravitational constant emerges which, in certain regimes, can lead to gravitational repulsive effects when only ordinary radiation is coupled to gravity. In this case, a bouncing universe is shown to be the only cosmological solution admissible by the field equations when the scalar field is in such broken symmetry state.
Boundary conditions for conformally coupled scalar in AdS4
NASA Astrophysics Data System (ADS)
Oh, Jae-Hyuk
2015-06-01
We consider conformally coupled scalar with ɸ4 coupling in AdS4 and study its various boundary conditions on AdS boundary. We have obtained perturbative solutions of equation of motion of the conformally coupled scalar with power expansion order by order in ɸ4 coupling λ up to λ2 order. In its dual CFT, we get 2, 4 and 6 point functions by using this solution with Dirichlet and Neumann boundary conditions via AdS/CFT dictionary. We also consider marginal deformation on AdS boundary and get its on-shell and boundary effective actions.
Bean, J.W.; Briand, J.; Burgess, J.L.; Callahan, J.F.
1994-12-01
The conformations of two diazocine turn mimics, which were later incorporated into GPIIb/IIIa peptide antagonists, were investigated using nuclear magnetic resonance techniques. The two compounds, methyl (2,5-dioxo-3-(S)-(3-{omega}-tosylguanidino-propyl)-4-methyl-octahydro-1,4-dazocin-1-yl)acetate (1) and methyl (2,5-dioxo-3-(S)-(3-{omega}-tosyl-guanidino-propyl)-octahydro-1,5-diazocin-1-yl)acetate (2), differ only in their substituent at the diazocine position 4 nitrogen, yet this substitution results in a marked difference in the affinity of the resulting analogs for the GPIIb/IIIa receptor. It was of interest to determine if the difference observed in the antagonistic potency between these analogs was related to constitutional or, perhaps, conformational differences. The backbone conformations of these two molecules can be determined by measuring vicinal coupling constants along the trimethylene portion of the C8 ring backbone and by measuring interproton NOE intensities between the diazocine methine proton and the protons of the trimethylene group. For compound 1, {sup 3}J{sub HH} values measured from a P.E.COSY spectrum and interproton distances calculated from ROESY buildup curves indicated the presence of a single C8 ring backbone conformation where the trimethylene bridge adopted a staggered conformation and the H{alpha}1 and H{gamma}1 protons of the trimethylene group were 2.2 A from the methine proton. For compound 2, however, partial overlap of the central H{beta}1 and H{beta}2 protons made it impossible to measure {sup 3}J{sub HH} values from the P.E.COSY spectrum. We therefore used a {sup 13}C-filtered TOCSY experiment to measure the {sup 3}J{sub CH} values in both compounds 1 and 2. These heteronuclear vicinal coupling constants measured with {sup 13}C in natural abundance in conjunction with measured interproton NOE intensities indicate that these compounds share a common C8 ring backbone conformation.
Building a holographic superconductor with a scalar field coupled kinematically to Einstein tensor
NASA Astrophysics Data System (ADS)
Kuang, Xiao-Mei; Papantonopoulos, Eleftherios
2016-08-01
We study the holographic dual description of a superconductor in which the gravity sector consists of a Maxwell field and a charged scalar field which except its minimal coupling to gravity it is also coupled kinematically to Einstein tensor. As the strength of the new coupling is increased, the critical temperature below which the scalar field condenses is lowering, the condensation gap decreases faster than the temperature, the width of the condensation gap is not proportional to the size of the condensate and at low temperatures the condensation gap tends to zero for the strong coupling. These effects which are the result of the presence of the coupling of the scalar field to the Einstein tensor in the gravity bulk, provide a dual description of impurities concentration in a superconducting state on the boundary.
Non-minimally coupled scalar field cosmology on the phase plane
Hrycyna, Orest; Szydlowski, Marek E-mail: uoszydlo@cyf-kr.edu.pl
2009-04-15
In this publication we investigate dynamics of a flat FRW cosmological model with a non-minimally coupled scalar field with the coupling term {xi}R{psi}{sup 2} in the scalar field action. The quadratic potential function V({psi}) {proportional_to} {psi}{sup 2} is assumed. All the evolutional paths are visualized and classified in the phase plane, at which the parameter of non-minimal coupling {xi} plays the role of a control parameter. The fragility of global dynamics with respect to changes of the coupling constant is studied in details. We find that the future big rip singularity appearing in the phantom scalar field cosmological models can be avoided due to non-minimal coupling constant effects. We have shown the existence of a finite scale factor singular point (future or past) where the Hubble function as well as its first cosmological time derivative diverge.
Cosmological three-coupled scalar theory for the dS/LCFT correspondence
NASA Astrophysics Data System (ADS)
Myung, Yun Soo; Moon, Taeyoon
2015-01-01
We investigate cosmological perturbations generated during de Sitter inflation in the three-coupled scalar theory. This theory is composed of three coupled scalars phip,p=1,2,3) to give a sixth-order derivative scalar theory for phi3, in addition to tensor. Recovering the power spectra between scalars from the LCFT correlators in momentum space indicates that the de Sitter/logarithmic conformal field theory (dS/LCFT) correspondence works in the superhorizon limit. We use LCFT correlators derived from the dS/LCFT differentiate dictionary to compare cosmological correlators (power spectra) and find also LCFT correlators by making use of extrapolate dictionary. This is because the former approach is more conventional than the latter. A bulk version dual to the truncation process to find a unitary CFT in the LCFT corresponds to selecting a physical field phi2 with positive norm propagating on the dS spacetime.
Cosmological three-coupled scalar theory for the dS/LCFT correspondence
Myung, Yun Soo; Moon, Taeyoon E-mail: tymoon@inje.ac.kr
2015-01-01
We investigate cosmological perturbations generated during de Sitter inflation in the three-coupled scalar theory. This theory is composed of three coupled scalars φ{sub p},p=1,2,3) to give a sixth-order derivative scalar theory for φ{sub 3}, in addition to tensor. Recovering the power spectra between scalars from the LCFT correlators in momentum space indicates that the de Sitter/logarithmic conformal field theory (dS/LCFT) correspondence works in the superhorizon limit. We use LCFT correlators derived from the dS/LCFT differentiate dictionary to compare cosmological correlators (power spectra) and find also LCFT correlators by making use of extrapolate dictionary. This is because the former approach is more conventional than the latter. A bulk version dual to the truncation process to find a unitary CFT in the LCFT corresponds to selecting a physical field φ{sub 2} with positive norm propagating on the dS spacetime.
Farakos, K.; Koutsoumbas, G.; Pasipoularides, P.
2007-09-15
Brane world models with a nonminimally coupled bulk scalar field have been studied recently. In this paper we consider metric fluctuations around an arbitrary gravity-scalar background solution, and we show that the corresponding spectrum includes a localized zero mode which strongly depends on the profile of the background scalar field. For a special class of solutions, with a warp factor of the RS form, we solve the linearized Einstein equations, for a pointlike mass source on the brane, by using the brane bending formalism. We see that general relativity on the brane is recovered only if we impose restrictions on the parameter space of the models under consideration.
NASA Astrophysics Data System (ADS)
Panotopoulos, Grigoris; Rincón, Ángel
2017-07-01
We analyze in detail the propagation of a minimally coupled massless scalar field in the gravitational background of a four-dimensional Einstein-Born-Infeld dilaton charged black hole. We obtain analytical expressions for the absorption cross section as well as the decay rate for the scalar field in the aforementioned spacetime, and we graphically show its behavior for different values of the free parameters of the theory.
Stationary states of fermions in a sign potential with a mixed vector–scalar coupling
Castilho, W.M. Castro, A.S. de
2014-01-15
The scattering of a fermion in the background of a sign potential is considered with a general mixing of vector and scalar Lorentz structures with the scalar coupling stronger than or equal to the vector coupling under the Sturm–Liouville perspective. When the vector coupling and the scalar coupling have different magnitudes, an isolated solution shows that the fermion under a strong potential can be trapped in a highly localized region without manifestation of Klein’s paradox. It is also shown that the lonely bound-state solution disappears asymptotically as one approaches the conditions for the realization of spin and pseudospin symmetries. -- Highlights: •Scattering of fermions in a sign potential assessed under a Sturm–Liouville perspective. •An isolated bounded solution. •No pair production despite the high localization. •No bounded solution under exact spin and pseudospin symmetries.
Gravitational collapse of a homogeneous scalar field coupled kinematically to Einstein tensor
NASA Astrophysics Data System (ADS)
Koutsoumbas, George; Ntrekis, Konstantinos; Papantonopoulos, Eleftherios; Tsoukalas, Minas
2017-02-01
We study the gravitational collapse of a homogeneous time-dependent scalar field that, besides its coupling to curvature, is also kinematically coupled to the Einstein tensor. This coupling is a part of the Horndeski theory and we investigate its effect on the collapsing process. We find that the time required for the scalar field to collapse depends on the value of the derivative coupling and the singularity is protected by a horizon. Matching the internal solution with an external Schwarzschild-anti-de Sitter metric we show that a black hole is formed, while the weak energy condition is satisfied during the collapsing process. The scalar field takes on a finite value at the singularity.
Group field theory for quantum gravity minimally coupled to a scalar field
NASA Astrophysics Data System (ADS)
Li, Yang; Oriti, Daniele; Zhang, Mingyi
2017-10-01
We construct a group field theory model for quantum gravity minimally coupled to relativistic scalar fields, defining as well a corresponding discrete gravity path integral (and, implicitly, a coupled spin foam model) in its Feynman expansion. We also analyze a number of variations of the same model, the corresponding discrete gravity path integrals, its generalization to the coupling of multiple scalar fields and discuss its possible applications to the extraction of effective cosmological dynamics from the full quantum gravity formalism, in the context of group field theory condensate cosmology.
Search for strongly coupled Chameleon scalar field with neutron interferometry
NASA Astrophysics Data System (ADS)
Li, K.; Arif, M.; Cory, D.; Haun, R.; Heacock, B.; Huber, M.; Nsofini, J.; Pushin, D. A.; Saggu, P.; Sarenac, D.; Shahi, C.; Skavysh, V.; Snow, M.; Young, A.
2015-04-01
The dark energy proposed to explain the observed accelerated expansion of the universe is not understood. A chameleon scalar field proposed as a dark energy candidate can explain the accelerated expansion and evade all current gravity experimental bounds. It features an effective range of the chameleon scalar field that depends on the local mass density. Hence a perfect crystal neutron interferometer, that measures relative phase shift between two paths, is a prefect tool to search for the chameleon field. We are preparing a two-chamber helium gas cell for the neutron interferometer. We can lower the pressure in one cell so low that the chameleon field range expands into the cell and causes a measurable neutron phase shift while keeping the pressure difference constant. We expect to set a new upper limit of the Chameleon field by at least one order of magnitude. This work is supported by NSF Grant 1205977, DOE Grant DE-FG02-97ER41042, Canadian Excellence Research Chairs program, Natural Sciences and Engineering Research Council of Canada and Collaborative Research and Training Experience Program
Born-Infeld Black Holes Coupled to a Massive Scalar Field
NASA Astrophysics Data System (ADS)
Georgieva, Daniela A.; Stefanov, Ivan Zh.; Yazadjiev, Stoytcho S.; Todorov, Michail D.
Born-Infeld black holes in the scalar-tensor theories of gravity with massless scalar field have been recently obtained [I. Stefanov, S. Yazadjiev and M. Todorov, Phys. Rev. D 75 (2007) 084036; Mod. Phys. Lett. A. 23(34) (2008) 2915; Class. Quantum Gravity 26 (2009) 015006]. The aim of the current paper is to study the effect of the inclusion of a potential for the scalar field in the theory, through a combination of analytical techniques and numerical methods. The black holes coupled to a massive scalar field have richer causal structure in comparison to the massless scalar field case. In the former case, the black holes may have a second, inner horizon. The presence of potential for the scalar field allows the existence of extremal black holes for certain values of the mass of the scalar field and the magnetic (electric) charge of the black hole. The solutions are stable against spherically symmetric perturbations. Arguments in favor of the general stability of the solutions coming from the application of the "turning point" method are also presented.
Asymptotic behavior and Hamiltonian analysis of anti-de Sitter gravity coupled to scalar fields
Henneaux, Marc; Martinez, Cristian; Troncoso, Ricardo; Zanelli, Jorge . E-mail: jz@cecs.cl
2007-04-15
We examine anti-de Sitter gravity minimally coupled to a self-interacting scalar field in D>=4 dimensions when the mass of the scalar field is in the range m{sub *}{sup 2}=
Non-minimally coupled bulk scalar fields in sine-Gordon braneworld models
NASA Astrophysics Data System (ADS)
Moazzen, Masoumeh; Ghalenovi, Zahra
2017-10-01
In this paper, we investigate localization of bulk scalar fields in two types of five-dimensional braneworld models given by sine-Gordon potentials (SG). The sine-Gordon and Double sine-Gordon (DSG) branes are employed to produce different thick brane setups. In both scenarios, we include the bulk mass and non-minimally coupled terms in the global action and obtain some implications on the volcano-like potentials of the Kaluza-Klein modes associated to the corresponding Schrödinger-like equations. Also, we find that minimally and non-minimally coupled massive bulk scalar fields can be localized on SG and DSG branes if their bulk mass obeys an upper bound. Furthermore, it is shown that at the critical value of the non-minimal coupling constant the bulk scalar field cannot be localized on the branes.
Non-minimally coupled scalar fields, Holst action and black hole mechanics
NASA Astrophysics Data System (ADS)
Chatterjee, Ayan
2011-02-01
The paper deals with the extension of the Weak Isolated Horizon (WIH) formulation of black hole horizons to the non-minimally coupled scalar fields. In the early part of the paper, we introduce an appropriate Holst type action to incorporate scalar fields non-minimally coupled to gravity and construct the covariant phase space of the theory. Using this phase space, we proceed to prove the laws of black hole mechanics. Further, we show that with a gauge fixing, the symplectic structure on the horizon reduces to that of a U(1) Chern-Simons theory. The level of the Chern-Simons theory is shown to depend on the non-minimally coupled scalar field.
NASA Astrophysics Data System (ADS)
Dutta, Sourav; Panja, Madan Mohan; Chakraborty, Subenoy
2016-06-01
Non-minimally coupled scalar field cosmology has been studied in this work within the framework of Einstein gravity. In the background of homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime non-minimally coupled scalar field having self-interacting potential is taken as the source of the matter content. The constraint of imposing Noether symmetry on the Lagrangian of the system not only determines the infinitesimal generator (the symmetry vector) but also the coupling function and the self-interacting potential for the scalar field. By choosing appropriately a point transformation in the augmented space, one of the transformed variables is cyclic for the Lagrangian. Finally, using constants of motion, the solutions are analyzed.
NASA Astrophysics Data System (ADS)
Pozdeeva, Ekaterina O.; Skugoreva, Maria A.; Toporensky, Alexey V.; Vernov, Sergey Yu.
2016-12-01
We explore dynamics of cosmological models with bounce solutions evolving on a spatially flat Friedmann-Lemaître-Robertson-Walker background. We consider cosmological models that contain the Hilbert-Einstein curvature term, the induced gravity term with a negative coupled constant, and even polynomial potentials of the scalar field. Bounce solutions with non-monotonic Hubble parameters have been obtained and analyzed. The case when the scalar field has the conformal coupling and the Higgs-like potential with an opposite sign is studied in detail. In this model the evolution of the Hubble parameter of the bounce solution essentially depends on the sign of the cosmological constant.
Boson stars in a theory of complex scalar field coupled to gravity
NASA Astrophysics Data System (ADS)
Kumar, Sanjeev; Kulshreshtha, Usha; Kulshreshtha, Daya Shankar
2015-07-01
We study boson stars in a theory of complex scalar field coupled to Einstein gravity with the potential: (where and are positive constant parameters). This could be considered either as a theory of massive complex scalar field coupled to gravity in a conical potential or as a theory in the presence of a potential which is an overlap of a parabolic and a conical potential. We study our theory with positive as well as negative values of the cosmological constant . Boson stars are found to come in two types, having either ball-like or shell-like charge density. We have studied the properties of these solutions and have also determined their domains of existence for some specific values of the parameters of the theory. Similar solutions have also been obtained by Hartmann, Kleihaus, Kunz, and Schaffer, in a V-shaped scalar potential.
No nonminimally coupled massless scalar hair for spherically symmetric neutral black holes
NASA Astrophysics Data System (ADS)
Hod, Shahar
2017-08-01
We provide a remarkably compact proof that spherically symmetric neutral black holes cannot support static nonminimally coupled massless scalar fields. The theorem is based on causality restrictions imposed on the energy-momentum tensor of the fields near the regular black-hole horizon.
NASA Astrophysics Data System (ADS)
Zeng, Qing; Lin, Liangjie; Chen, Jinyong; Lin, Yanqin; Barker, Peter B.; Chen, Zhong
2017-09-01
Proton-proton scalar coupling plays an important role in molecular structure elucidation. Many methods have been proposed for revealing scalar coupling networks involving chosen protons. However, determining all JHH values within a fully coupled network remains as a tedious process. Here, we propose a method termed as simultaneous multi-slice selective J-resolved spectroscopy (SMS-SEJRES) for simultaneously measuring JHH values out of all coupling networks in a sample within one experiment. In this work, gradient-encoded selective refocusing, PSYCHE decoupling and echo planar spectroscopic imaging (EPSI) detection module are adopted, resulting in different selective J-edited spectra extracted from different spatial positions. The proposed pulse sequence can facilitate the analysis of molecular structures. Therefore, it will interest scientists who would like to efficiently address the structural analysis of molecules.
Spectrum structure of a fermion on Bloch branes with two scalar-fermion couplings
NASA Astrophysics Data System (ADS)
Xie, Qun-Ying; Guo, Heng; Zhao, Zhen-Hua; Du, Yun-Zhi; Zhang, Yu-Peng
2017-03-01
It is known that the Bloch brane is generated by an odd scalar field ϕ and an even one χ. In order to localize a bulk fermion on the Bloch brane, the coupling between the fermion and scalars should be introduced. There are two localization mechanisms in the literature, the Yukawa coupling -η \\bar{\\Psi}{{F}1}≤ft(φ,χ \\right) \\Psi and non-Yukawa coupling λ \\bar{\\Psi}{ΓM}{{\\partial}M}{{F}2}≤ft(φ,χ \\right){γ5} \\Psi . The Yukawa coupling has been considered. In this paper, we consider both couplings between the fermion and the scalars with {{F}1}={χm}{φ2p+1} and {{F}2}={χn}{φ2q} , and investigate the localization and spectrum structure of the fermion on the Bloch brane. It is found that the left-handed fermion zero mode can be localized on the Bloch brane under some conditions, and the effective potentials have rich structure and may be volcano-like, finite square well-like, and infinite potentials. As a result, the spectrum consists of a series of resonant Kaluza-Klein fermions, finite or infinite numbers of bound Kaluza-Klein fermions. Especially, we find a new feature of the introduction of both couplings: the spectrum for the case of finite square well-like potentials contains discrete quasi-localized and localized massive KK modes simultaneously.
Scalar Relativistic Equation-Of Coupled Cluster Calculations of Core-Ionized States
NASA Astrophysics Data System (ADS)
Cheng, Lan
2017-06-01
Scalar relativistic equation-of-motion coupled cluster (EOMCC) calculations of core ionization/excitation energies for a set of benchmark molecules are reported. The Arnoldi algorithm as well as the core-valence-separation (CVS) scheme have been used to expedite the convergence of the wave function for the core-ionized/excited states. Scalar relativistic effects have been accounted for using the spin-free exact two-component theory in its one-electron variant (SFX2C-1e) and their importance are assessed. Preliminary calculations of ligand core excitation spectra of transition-metal containing compounds are also presented.
Nath, Nilamoni; Lokesh; Suryaprakash, Nagarajarao
2012-02-01
The use of long-range heteronuclear couplings, in association with (1)H-(1)H scalar couplings and NOE restraints, has acquired growing importance for the determination of the relative stereochemistry, and structural and conformational information of organic and biological molecules. However, the routine use of such couplings is hindered by the inherent difficulties in their measurement. Prior to the advancement in experimental techniques, both long-range homo- and heteronuclear scalar couplings were not easily accessible, especially for very large molecules. The development of a large number of multidimensional NMR experimental methodologies has alleviated the complications associated with the measurement of couplings of smaller strengths. Subsequent application of these methods and the utilization of determined J-couplings for structure calculations have revolutionized this area of research. Problems in organic, inorganic and biophysical chemistry have also been solved by utilizing the short- and long-range heteronuclear couplings. In this minireview, we discuss the advantages and limitations of a number of experimental techniques reported in recent times for the measurement of long-range heteronuclear couplings and a few selected applications of such couplings. This includes the study of medium- to larger-sized molecules in a variety of applications, especially in the study of hydrogen bonding in biological systems. The utilization of these couplings in conjunction with theoretical calculations to arrive at conclusions on the hyperconjugation, configurational analysis and the effect of the electronegativity of the substituents is also discussed.
Cosmological effects of scalar-photon couplings: dark energy and varying-α Models
Avgoustidis, A.; Martins, C.J.A.P.; Monteiro, A.M.R.V.L.; Vielzeuf, P.E.; Luzzi, G. E-mail: Carlos.Martins@astro.up.pt E-mail: up110370652@alunos.fc.up.pt
2014-06-01
We study cosmological models involving scalar fields coupled to radiation and discuss their effect on the redshift evolution of the cosmic microwave background temperature, focusing on links with varying fundamental constants and dynamical dark energy. We quantify how allowing for the coupling of scalar fields to photons, and its important effect on luminosity distances, weakens current and future constraints on cosmological parameters. In particular, for evolving dark energy models, joint constraints on the dark energy equation of state combining BAO radial distance and SN luminosity distance determinations, will be strongly dominated by BAO. Thus, to fully exploit future SN data one must also independently constrain photon number non-conservation arising from the possible coupling of SN photons to the dark energy scalar field. We discuss how observational determinations of the background temperature at different redshifts can, in combination with distance measures data, set tight constraints on interactions between scalar fields and photons, thus breaking this degeneracy. We also discuss prospects for future improvements, particularly in the context of Euclid and the E-ELT and show that Euclid can, even on its own, provide useful dark energy constraints while allowing for photon number non-conservation.
Possible Statistics of Two Coupled Random Fields: Application to Passive Scalar
NASA Technical Reports Server (NTRS)
Dubrulle, B.; He, Guo-Wei; Bushnell, Dennis M. (Technical Monitor)
2000-01-01
We use the relativity postulate of scale invariance to derive the similarity transformations between two coupled scale-invariant random elds at different scales. We nd the equations leading to the scaling exponents. This formulation is applied to the case of passive scalars advected i) by a random Gaussian velocity field; and ii) by a turbulent velocity field. In the Gaussian case, we show that the passive scalar increments follow a log-Levy distribution generalizing Kraichnan's solution and, in an appropriate limit, a log-normal distribution. In the turbulent case, we show that when the velocity increments follow a log-Poisson statistics, the passive scalar increments follow a statistics close to log-Poisson. This result explains the experimental observations of Ruiz et al. about the temperature increments.
NASA Astrophysics Data System (ADS)
Murphy, Christopher W.
2017-08-01
The apparent breakdown of unitarity in low order perturbation theory is often is used to place bounds on the parameters of a theory. In this work we give an algorithm for approximately computing the next-to-leading order (NLO) perturbativity bounds on the quartic couplings of a renormalizable theory whose scalar sector is ϕ4-like. By this we mean theories where either there are no cubic scalar interactions, or the cubic couplings are related to the quartic couplings through spontaneous symmetry breaking. The quantity that tests where perturbation theory breaks down itself can be written as a perturbative series, and having the NLO terms allows one to test how well the series converges. We also present a simple example to illustrate the effect of considering these bounds at different orders in perturbation theory. For example, there is a noticeable difference in the viable parameter when the square of the NLO piece is included versus when it is not.
Heavy photophilic scalar at the LHC from a varying electromagnetic coupling
NASA Astrophysics Data System (ADS)
Danielsson, Ulf; Enberg, Rikard; Ingelman, Gunnar; Mandal, Tanumoy
2017-06-01
We investigate the phenomenology of a heavy scalar ϕ of the type involved in Bekenstein's framework for varying electromagnetic coupling theories, with the difference that the scalar in our model has a large mass. The model has only two free parameters, the mass Mϕ of the scalar and the scale Λ of new physics. The scalar is dominantly produced through photon-photon fusion at the LHC and leads to a diphoton final state. It can also be produced by quark-antiquark fusion in association with a photon or a fermion pair. Its dominating decay is to diphotons, but it also has a large three-body branching to a fermion pair and a photon, which can provide an interesting search channel with a dilepton-photon resonance. We derive exclusion limits on the Mϕ - Λ plane from the latest 13 TeV LHC diphoton resonance search data. For a benchmark mass of Mϕ ∼ 1 TeV, we find a lower limit on Λ of 18 TeV. We discuss the more complex possibility of varying couplings in the full electroweak theory and comment on the possibility that the new physics is related to extra dimensions or string theory.
NASA Astrophysics Data System (ADS)
Suroso, Agus; Zen, Freddy P.; Hikmawan, Getbogi
2015-09-01
The energy conditions is a set of linear equations of energy density ρ and pressure p which ensure the the field(s) that we used in our model is physically "reasonable". We study the energy conditions for four dimensional nonminimal derivative coupling of scalar field and curvature tensor. Considering the scalar field as a perfect fluid, we find some constraint for the coupling constant ξ in order the energy conditions is satisfied or violated. We find that strong energy conditions (SEC) is violated if -1/9H2 ≤ ξ < 1/18H2. For de Sitter solution a ∝ eH0t for some constant H0, we find that while null, weak, and dominant energy conditions violated when ξ <-[12 H02(2 +9 H02) ] -1 . The accelerating universe is exist for the power law solution (a ∝ tp for constant p) if ξ < 0.
Scale-invariant scalar spectrum from the nonminimal derivative coupling with fourth-order term
NASA Astrophysics Data System (ADS)
Myung, Yun Soo; Moon, Taeyoon
2015-08-01
In this paper, an exactly scale-invariant spectrum of scalar perturbation generated during de Sitter spacetime is found from the gravity model of the nonminimal derivative coupling with fourth-order term. The nonminimal derivative coupling term generates a healthy (ghost-free) fourth-order derivative term, while the fourth-order term provides an unhealthy (ghost) fourth-order derivative term. The Harrison-Zel’dovich spectrum obtained from Fourier transforming the fourth-order propagator in de Sitter space is recovered by computing the power spectrum in its momentum space directly. It shows that this model provides a truly scale-invariant spectrum, in addition to the Lee-Wick scalar theory.
False vacuum bubble nucleation due to a nonminimally coupled scalar field
Lee, Wonwoo; Park, Chanyong; Lee, Bum-Hoon; Lee, Chul H.
2006-12-15
We study the possibility of forming the false vacuum bubble nucleated within the true vacuum background via the true-to-false vacuum phase transition in curved spacetime. We consider a semiclassical Euclidean bubble in the Einstein theory of gravity with a nonminimally coupled scalar field. In this paper we present the numerical computations as well as the approximate analytical computations. We mention the evolution of the false vacuum bubble after nucleation.
Initial data for gravity coupled to scalar, electromagnetic, and Yang-Mills fields
NASA Astrophysics Data System (ADS)
Husain, Viqar
1999-02-01
We give Ansätze for solving classically the initial value constraints of general relativity minimally coupled to a scalar field, electromagnetism, or Yang-Mills theory. The results include both time-symmetric and asymmetric data. The time-asymmetric examples are used to test Penrose's cosmic censorship inequality. We find that the inequality can be violated if only the weak energy condition holds.
Luy, B; Glaser, S J
2001-01-01
The superposition of scalar and residual dipolar couplings gives rise to so-called cylindrical mixing Hamiltonians in dipolar coupling spectroscopy. General analytical polarization and coherence transfer functions are presented for three cylindrically coupled spins 12 under energy-matched conditions. In addition, the transfer efficiency is analyzed as a function of the relative coupling constants for characteristic special cases.
Kakita, Veera Mohana Rao; Kupče, Eriks; Bharatam, Jagadeesh
2015-02-01
Unambiguous measurement of homonuclear scalar couplings (J) in multi-spin scalar network systems is not straightforward. Further, the direct measurement of J-couplings is obscured in solid-state samples due to the dipolar and chemical shift anisotropy (CSA)-dominated line broadening, even under the magic angle spinning (MAS). We present a new multiple frequency selective spin-echo method based on Hadamard matrix encoding, for simultaneous measurement of multiple homonuclear scalar couplings (J) in the solid-state. In contrast to the Hadamard encoded selective excitation schemes known for the solution-state, herein the selectivity is achieved during refocusing period. The Hadamard encoded refocusing scheme concurrently allows to create the spin-spin commutation property between number of spin-pairs of choice in uniformly labelled molecules, which, therefore avoids (1) the repetition of the double selective refocusing experiments for each spin-pair and (2) the synthesis of expensive selective labelled molecules. The experimental scheme is exemplified for determining (1)JCC and (3)JCC values in (13)C6l-Histidine.HCl molecule, which are found to be in excellent agreement with those measured in conventional double frequency selective refocusing mode as well as in the solution-state. This method can be simply extended to 2D/3D pulse schemes and be applied to small bio-molecular solids.
Constraints on tensor and scalar couplings from [Formula: see text] and [Formula: see text].
Beaujean, Frederik; Bobeth, Christoph; Jahn, Stephan
The angular distribution of [Formula: see text] ([Formula: see text]) depends on two parameters, the lepton forward-backward asymmetry, [Formula: see text], and the flat term, [Formula: see text]. Both are strongly suppressed in the standard model and constitute sensitive probes of tensor and scalar contributions. We use the latest experimental results for [Formula: see text] in combination with the branching ratio of [Formula: see text] to derive the strongest model-independent bounds on tensor and scalar effective couplings to date. The measurement of [Formula: see text] provides a complementary constraint to that of the branching ratio of [Formula: see text] and allows us - for the first time - to constrain all complex-valued (pseudo-)scalar couplings and their chirality-flipped counterparts in one fit. Based on Bayesian fits of various scenarios, we find that our bounds even become tighter when vector couplings are allowed to deviate from the standard model and that specific combinations of angular observables in [Formula: see text] are still allowed to be up to two orders of magnitude larger than in the standard model, which would place them in the region of LHCb's sensitivity.
Weakly dynamic dark energy via metric-scalar couplings with torsion
NASA Astrophysics Data System (ADS)
Sur, Sourav; Singh Bhatia, Arshdeep
2017-07-01
We study the dynamical aspects of dark energy in the context of a non-minimally coupled scalar field with curvature and torsion. Whereas the scalar field acts as the source of the trace mode of torsion, a suitable constraint on the torsion pseudo-trace provides a mass term for the scalar field in the effective action. In the equivalent scalar-tensor framework, we find explicit cosmological solutions representing dark energy in both Einstein and Jordan frames. We demand the dynamical evolution of the dark energy to be weak enough, so that the present-day values of the cosmological parameters could be estimated keeping them within the confidence limits set for the standard LCDM model from recent observations. For such estimates, we examine the variations of the effective matter density and the dark energy equation of state parameters over different redshift ranges. In spite of being weakly dynamic, the dark energy component differs significantly from the cosmological constant, both in characteristics and features, for e.g. it interacts with the cosmological (dust) fluid in the Einstein frame, and crosses the phantom barrier in the Jordan frame. We also obtain the upper bounds on the torsion mode parameters and the lower bound on the effective Brans-Dicke parameter. The latter turns out to be fairly large, and in agreement with the local gravity constraints, which therefore come in support of our analysis.
Directly Measuring the Tensor Structure of the Scalar Coupling to Gauge Bosons
Stolarski, Daniel; Vega-Morales, Roberto
2012-12-01
Kinematic distributions in the decays of the newly discovered resonance to four leptons can provide a direct measurement of the tensor structure of the particle's couplings to gauge bosons. Even if the particle is shown to be a parity even scalar, measuring this tensor structure is a necessary step in determining if this particle is responsible for giving mass to the Z. We consider a Standard Model like coupling as well as coupling via a dimension five operator to either ZZ or Z\\gamma. We show that using full kinematic information from each event allows discrimination between renormalizable and higher dimensional coupling to ZZ at the 95% confidence level with O(50) signal events, and coupling to Z\\gamma can be distinguished with as few as 20 signal events. This shows that these measurements can be useful even with this year's LHC data.
Asymptotically free scalar curvature-ghost coupling in quantum Einstein gravity
Eichhorn, Astrid; Gies, Holger; Scherer, Michael M.
2009-11-15
We consider the asymptotic-safety scenario for quantum gravity which constructs a nonperturbatively renormalizable quantum gravity theory with the help of the functional renormalization group (RG). We verify the existence of a non-Gaussian fixed point and include a running curvature-ghost coupling as a first step towards the flow of the ghost sector of the theory. We find that the scalar curvature-ghost coupling is asymptotically free and RG relevant in the ultraviolet. Most importantly, the property of asymptotic safety discovered so far within the Einstein-Hilbert truncation and beyond remains stable under the inclusion of the ghost flow.
The Hamiltonian formalism for scalar fields coupled to gravity in a cosmological background
NASA Astrophysics Data System (ADS)
Bernardini, A. E.; Bertolami, O.
2013-11-01
A novel routine to investigate the scalar fields in a cosmological context is discussed in the framework of the Hamiltonian formalism. Starting from the Einstein-Hilbert action coupled to a Lagrangian density that contains two components-one corresponding to a scalar field Lagrangian, Lϕ, and another that depends on the scale parameter, La-one can identify a generalized Hamiltonian density from which first-order dynamical equations can be obtained. This set up corresponds to the dynamics of Friedmann-Robertson-Walker models in the presence of homogeneous fields embedded into a generalized cosmological background fluid in a system that evolves all together isentropically. Once the generalized Hamiltonian density is properly defined, the constraints on the gravity-matter-field system are straightforwardly obtained through the first-order Hamilton equations. The procedure is illustrated for three examples of cosmological interest for studies of the dark sector: real scalar fields, tachyonic fields and generalized Born-Infeld tachyonic fields. The inclusion of some isentropic fluid component into the Friedmann equation allows for identifying an exact correspondence between the dark sector underlying scalar field and an ordinary real scalar field dynamics. As a final issue, the Hamiltonian formulation is used to set the first-order dynamical equations through which one obtains the exact analytical description of the cosmological evolution of a generalized Chaplygin gas (GCG) with dustlike matter, radiation or curvature contributions. Model stability in terms of the square of the sound velocity, cs2, cosmic acceleration, q, and conditions for inflation are discussed.
NASA Astrophysics Data System (ADS)
Mackrory, Jonathan B.; Bhattacharya, Tanmoy; Steck, Daniel A.
2016-10-01
We present a worldline method for the calculation of Casimir energies for scalar fields coupled to magnetodielectric media. The scalar model we consider may be applied in arbitrary geometries, and it corresponds exactly to one polarization of the electromagnetic field in planar layered media. Starting from the field theory for electromagnetism, we work with the two decoupled polarizations in planar media and develop worldline path integrals, which represent the two polarizations separately, for computing both Casimir and Casimir-Polder potentials. We then show analytically that the path integrals for the transverse-electric polarization coupled to a dielectric medium converge to the proper solutions in certain special cases, including the Casimir-Polder potential of an atom near a planar interface, and the Casimir energy due to two planar interfaces. We also evaluate the path integrals numerically via Monte Carlo path-averaging for these cases, studying the convergence and performance of the resulting computational techniques. While these scalar methods are only exact in particular geometries, they may serve as an approximation for Casimir energies for the vector electromagnetic field in other geometries.
Limits on variations in protein backbone dynamics from precise measurements of scalar couplings.
Vögeli, Beat; Ying, Jinfa; Grishaev, Alexander; Bax, Ad
2007-08-01
3JHN,Halpha, 3JHN,Cbeta, and 3JHN,C' couplings, all related to the backbone torsion angle phi, were measured for the third immunoglobulin binding domain of protein G, or GB3. Measurements were carried out using both previously published methods and novel sequences based on the multiple-quantum principle, which limit attenuation of experimental couplings caused by finite lifetimes of the spin states of passive spins. High reproducibility between the multiple-quantum and conventional approaches confirms the accuracy of the measurements. With few exceptions, close agreement between 3JHN,Halpha, 3JHN,Cbeta, and 3JHN,C' and values predicted by their respective Karplus equations is observed. For the three types of couplings, up to 20% better agreement is obtained when fitting the experimental couplings to a dynamic ensemble NMR structure, which has a phi angle root-mean-square spread of 9 +/- 4 degrees and was previously calculated on the basis of a very extensive set of residual dipolar couplings, than for any single static NMR structure. Fits of 3J couplings to a 1.1-A X-ray structure, with hydrogens added in idealized positions, are 40-90% worse. Approximately half of the improvement when fitting to the NMR structures relates to the amide proton deviating from its idealized, in-peptide-plane position, indicating that the positioning of hydrogens relative to the backbone atoms is one of the factors limiting the accuracy at which the backbone torsion angle phi can be extracted from 3J couplings. Introducing an additional, residue-specific variable for the amplitude of phi angle fluctuations does not yield a statistically significant improvement when fitting to a set of dynamic Karplus curves, pointing to a homogeneous behavior of these amplitudes.
Camci, Ugur; Kucukakca, Yusuf
2007-10-15
We consider some scalar-coupled theories of gravity, including induced gravity, and study the Noether symmetries of Bianchi I, Bianchi III, and Kantowski-Sachs cosmological models for this theory. For various forms of coupling of the scalar field with gravity, some potentials are found in these cosmological models under the assumption that the Lagrangian admits Noether symmetry. The solutions of the field equations for the considered models are presented by using the results obtained from the Noether symmetry. We also find the explicit form of the scalar field in terms of the conformal time for Bianchi I, III, and Kantowski-Sachs models.
The universe dominated by oscillating scalar with non-minimal derivative coupling to gravity
Jinno, Ryusuke; Mukaida, Kyohei; Nakayama, Kazunori E-mail: mukaida@hep-th.phys.s.u-tokyo.ac.jp
2014-01-01
We study the expansion law of the universe dominated by the oscillating scalar field with non-minimal derivative coupling to gravity as G{sup μν}∂{sub μ}φ∂{sub ν}φ. In this system the Hubble parameter oscillates with a frequency of the effective mass of the scalar field, which formerly caused a difficulty in analyzing how the universe expands. We find an analytical solution for power law potentials and interpret the solution in an intuitive way by using a new invariant of the system. As a result, we find marginally accelerated expansion for the quadratic potential and no accelerated expansion for the potential with higher power.
Static black hole solutions with a self-interacting conformally coupled scalar field
Dotti, Gustavo; Gleiser, Reinaldo J.; Martinez, Cristian
2008-05-15
We study static, spherically symmetric black hole solutions of the Einstein equations with a positive cosmological constant and a conformally coupled self-interacting scalar field. Exact solutions for this model found by Martinez, Troncoso, and Zanelli were subsequently shown to be unstable under linear gravitational perturbations, with modes that diverge arbitrarily fast. We find that the moduli space of static, spherically symmetric solutions that have a regular horizon--and satisfy the weak and dominant energy conditions outside the horizon--is a singular subset of a two-dimensional space parametrized by the horizon radius and the value of the scalar field at the horizon. The singularity of this space of solutions provides an explanation for the instability of the Martinez, Troncoso, and Zanelli spacetimes and leads to the conclusion that, if we include stability as a criterion, there are no physically acceptable black hole solutions for this system that contain a cosmological horizon in the exterior of its event horizon.
Backreaction for Einstein-Rosen waves coupled to a massless scalar field
NASA Astrophysics Data System (ADS)
Szybka, Sebastian J.; Wyrebowski, Michał J.
2016-07-01
We present a one-parameter family of exact solutions to Einstein's equations that may be used to study the nature of the Green-Wald backreaction framework. Our explicit example is a family of Einstein-Rosen waves coupled to a massless scalar field. This solution may be reinterpreted as a generalized three-torus polarized Gowdy cosmology with scalar and gravitational waves. We use it to illustrate essential properties of the Green-Wald approach. Among other things we show that within our model the Green-Wald framework uniquely determines backreaction for finite-size inhomogeneities on a predefined background. The results agree with those calculated in the Charach-Malin approach. In the vacuum limit, the Green-Wald, the Charach-Malin and the Isaacson methods imply identical backreaction, as expected.
Greybody factors for a nonminimally coupled scalar field in BTZ black hole background
NASA Astrophysics Data System (ADS)
Panotopoulos, Grigoris; Rincón, Ángel
2017-09-01
In the present work we study the propagation of a probe nonminimally coupled scalar field in BTZ black hole background. We find analytical expressions for the reflection coefficient, the absorption cross-section, and the decay rate in the strong coupling case, where the nonminimal coupling is larger than its conformal value ξc = 1 / 6. Our main results are summarized in several figures, in which we show how the behavior of the aforementioned quantities depends on the parameters of the theory. Our findings show that i) the reflection coefficient tends to zero only for a nonminimal coupling ξ ≥ 0.25, and ii) in the zero angular-momentum case the greybody factor in the low energy regime tends to a finite constant that generically does not coincide with the area of the horizon of the black hole. There is, however, a special case in which this holds.
Inflation from non-minimally coupled scalar field in loop quantum cosmology
Artymowski, Michał; Dapor, Andrea; Pawłowski, Tomasz E-mail: adapor@fuw.edu.pl
2013-06-01
The FRW model with non-minimally coupled massive scalar field has been investigated in LQC framework. Considered form of the potential and coupling allows applications to Higgs driven inflation. Out of two frames used in the literature to describe such systems: Jordan and Einstein frame, the latter one is applied. Specifically, we explore the idea of the Einstein frame being the natural 'environment' for quantization and the Jordan picture having an emergent nature. The resulting dynamics qualitatively modifies the standard bounce paradigm in LQC in two ways: (i) the bounce point is no longer marked by critical matter energy density, (ii) the Planck scale physics features the ''mexican hat'' trajectory with two consecutive bounces and rapid expansion and recollapse between them. Furthermore, for physically viable coupling strength and initial data the subsequent inflation exceeds 60 e-foldings.
NASA Astrophysics Data System (ADS)
Bertone, G.; Cerdeño, D. G.; Collar, J. I.; Odom, B.
2007-10-01
We study the prospects for detecting weakly interacting massive particles (WIMPs) in a number of phenomenological scenarios, with a detector composed of a target simultaneously sensitive to both spin-dependent and spin-independent couplings, as is the case of COUPP (Chicagoland Observatory for Underground Particle Physics). First, we show that sensitivity to both couplings optimizes chances of initial WIMP detection. Second, we demonstrate that, in case of detection, a comparison of the signal on two complementary targets, such as in COUPP CF3I and C4F10 bubble chambers, allows a significantly more precise determination of the dark matter axial and scalar couplings. This strategy would provide crucial information on the nature of the WIMPs and possibly allow discrimination between neutralino and Kaluza-Klein dark matter.
Murphy, Christopher W.
2017-08-17
The apparent breakdown of unitarity in low order perturbation theory is often is used to place bounds on the parameters of a theory. In this work we give an algorithm for approximately computing the next-to-leading order (NLO) perturbativity bounds on the quartic couplings of a renormalizable theory whose scalar sector is Φ 4 -like. And by this we mean theories where either there are no cubic scalar interactions, or the cubic couplings are related to the quartic couplings through spontaneous symmetry breaking. Furthermore, the quantity that tests where perturbation theory breaks down itself can be written as a perturbative series,more » and having the NLO terms allows one to test how well the series converges. We also present a simple example to illustrate the effect of considering these bounds at different orders in perturbation theory. For example, there is a noticeable difference in the viable parameter when the square of the NLO piece is included versus when it is not.« less
Exact Quantization of Einstein-Rosen Waves Coupled to Massless Scalar Matter
NASA Astrophysics Data System (ADS)
Barbero G., J. Fernando; Garay, Iñaki; Villaseñor, Eduardo J.
2005-07-01
We show in this Letter that gravity coupled to a massless scalar field with full cylindrical symmetry can be exactly quantized by an extension of the techniques used in the quantization of Einstein-Rosen waves. This system provides a useful test bed to discuss a number of issues in quantum general relativity, such as the emergence of the classical metric, microcausality, and large quantum gravity effects. It may also provide an appropriate framework to study gravitational critical phenomena from a quantum point of view, issues related to black hole evaporation, and the consistent definition of test fields and particles in quantum gravity.
Mota, David F.; Shaw, Douglas J.
2007-03-15
We show that, as a result of nonlinear self-interactions, it is feasible, at least in light of the bounds coming from terrestrial tests of gravity, measurements of the Casimir force and those constraints imposed by the physics of compact objects, big-bang nucleosynthesis and measurements of the cosmic microwave background, for there to exist, in our Universe, one or more scalar fields that couple to matter much more strongly than gravity does. These scalar fields behave like chameleons: changing their properties to fit their surroundings. As a result these scalar fields can be not only very strongly coupled to matter, but also remain relatively light over solar-system scales. These fields could also be detected by a number of future experiments provided they are properly designed to do so. These results open up an altogether new window, which might lead to a completely different view of the role played by light scalar fields in particle physics and cosmology.
Kuo, M C; Gibbons, W A
1979-12-25
We report for the decapeptide tyrocidine A: (a) H alpha and H beta chemical shifts and scalar coupling constants for most residues of tyrocidine A in methanol-d4 and dimethyl-d6 sulfoxide (Me2so-d6) and the H alpha and H beta chemical shifts for other residues; (b) scalar coupling constants 3J alpha beta for nine side chains in methanol-d4 but only seven side chains in Me2SO-d6, due to chemical shift degeneracy; the Gln9 and Tyr10 side chains in methanol-d4 were only approximately analyzed; (c) a total spin-spin analysis of Pro5 in Me2SO-d6 and, partly by comparison, also in methanol-d4; (d) conversion of 3J alpha beta values to side-chain conformations for all residues in methanol-d4; comparisons, where possible, led to the conclusion that side-chain conformations are similar in methanol-d4 and Me2SO-d6; (e) an absolute conformational analysis of Pro5 from 3J values and a method of assigning all pro-R,S protons; Pro5 has a Ramachandran B, C2-Cexo-Cendo conformation; (f) chi 1, chi 2 conformations of several aromatic residues based upon proton-chromophore distance measurement from anomalous chemical shifts and Johnson-Bovey diagrams; (g) pro-R and pro-S assignments of H beta's from anomalous chemical shifts, high-temperature dependence of anomalous chemical shifts, and backbone side-chain nuclear Overhauser effects; (h) most tertiary conformations of the whole tyrocidine A molecule possessing residues 4--8 and 10 in highly preferred (ca. 90%) chi 1 conformations, but residues 1--3 and 9 having at least two chi 1 rotamers; (2) description of three topographical regions of the molecule--a hydrophobic region, a flat hydrophilic surface on the other side of the molecule, and a hydrophilic region consisting of two peptide backbone units and the side chains of Asn8, Gln9, and Tyr10; (j) proposed side chain, beta-turn, and beta-pleated sheet conformations that readily account for all "normal" and anomalous chemical shifts.
Randall-Sundrum cosmological model with nonminimal derivative coupling of scalar field
Widiyani, Agustina Suroso, Agus Zen, Freddy P.
2015-04-16
Nonminimal derivative coupling (NMDC) of scalar field in time-dependent Randall-Sundrum model is investigated. Firstly, we take a simple relation between the scale factor on the brane, a(t), and the scale factor of the extradimension, b(t), as b = a{sup γ} where γ is a constant. Then, we derive the Einstein equation and find its cosmological solution for a special case of static extra dimension, γ = 0. As the result, we find that de Sitter solution is a typical solution of our model. We also find that the brane tension which is related to cosmological constant on the brane is related to the coupling constant of the model.
Abraham, Raymond J; Leonard, Paul; Tormena, Cláudio F
2012-04-01
The (1) H chemical shifts of selected three-membered ring compounds in CDCl(3) solvent were obtained. This allowed the determination of the substituent chemical shifts of the substituents in the three-membered rings and the long-range effect of these rings on the distant protons. The substituent chemical shifts of common substituents in the cyclopropane ring differ considerably from the same substituents in acyclic fragments and in cyclohexane and were modelled in terms of a three-bond (γ)-effect. For long-range protons (more than three bonds removed), the substituent effects of the cyclopropane ring were analysed in terms of the cyclopropane magnetic anisotropy and steric effect. The cyclopropane magnetic anisotropy (ring current) shift was modelled by (a) a single equivalent dipole perpendicular to and at the centre of the cyclopropane ring and (b) by three identical equivalent dipoles perpendicular to the ring placed at each carbon atom. Model (b) gave a more accurate description of the (1) H chemical shifts and was the selected model. After parameterization, the overall root mean square error for the dataset of 289 entries was 0.068 ppm. The anisotropic effects are significant for the cyclopropane protons (ca 1 ppm) but decrease rapidly with distance. The heterocyclic rings of oxirane, thiirane and aziridine do not possess a ring current. (3) J(HH) couplings of the epoxy ring proton with side-chain protons were obtained and shown to be dependent on both the H-C-C-H and H-C-C-O orientations. Both density functional theory calculations and a simple Karplus-type equation gave general agreement with the observed couplings (root mean square error 0.5 Hz over a 10-Hz range).
Vögeli, Beat; Olsson, Simon; Riek, Roland; Güntert, Peter
2015-12-01
We compiled an NMR data set consisting of exact nuclear Overhauser enhancement (eNOE) distance limits, residual dipolar couplings (RDCs) and scalar (J) couplings for GB3, which forms one of the largest and most diverse data set for structural characterization of a protein to date. All data have small experimental errors, which are carefully estimated. We use the data in the research article Vogeli et al., 2015, Complementarity and congruence between exact NOEs and traditional NMR probes for spatial decoding of protein dynamics, J. Struct. Biol., 191, 3, 306-317, doi:10.1016/j.jsb.2015.07.008 [1] for cross-validation in multiple-state structural ensemble calculation. We advocate this set to be an ideal test case for molecular dynamics simulations and structure calculations.
Measurement of 2J(H,C)- and 3J(H,C)-coupling constants by alpha/beta selective HC(C)H-TOCSY.
Duchardt, E; Richter, C; Reif, B; Glaser, S J; Engels, J W; Griesinger, C; Schwalbe, H
2001-10-01
A new heteronuclear NMR pulse sequence for the measurement of nJ(C,H) coupling constants, the alpha/beta selective HC(C)H-TOCSY, is described. It is shown that the S3E element (Meissner et al., 1997a,b) can be used to obtain spin state selective coherence transfer in molecules, in which adjacent CH moieties are labeled with 13C. Application of the alpha/beta selective HC(C)H-TOCSY to a 10 nt RNA tetraloop 5'-CGCUUUUGCG-3', in which the four uridine residues are 13C labeled in the sugar moiety, allowed measurement of two bond and three bond J(C,H) coupling constants, which provide additional restraints to characterize the sugar ring conformation of RNA in cases of conformational averaging.
Scalar correlator, Higgs decay into quarks, and scheme variations of the QCD coupling
NASA Astrophysics Data System (ADS)
Jamin, Matthias; Miravitllas, Ramon
2016-10-01
In this work, the perturbative QCD series of the scalar correlation function Ψ( s) is investigated. Besides ImΨ( s), which is relevant for Higgs decay into quarks, two other physical correlators, Ψ'' ( s) and D L ( s), have been employed in QCD applications like quark mass determinations or hadronic τ decays. D L ( s) suffers from large higher-order corrections and, by resorting to the large- β 0 approximation, it is shown that this is related to a spurious renormalon ambiguity at u = 1. Hence, this correlator should be avoided in phenomenological analyses. Moreover, it turns out advantageous to express the quark mass factor, introduced to make the scalar current renormalisation group invariant, in terms of the renormalisation invariant quark mass {widehat{m}}_q .To further study the behaviour of the perturbative expansion, we introduce a QCD coupling {widehat{α}}_s , whose running is explicitly renormalisation scheme independent. The scheme dependence of {widehat{α}}_s is parametrised by a single parameter C, being related to transformations of the QCD scale parameter Λ. It is demonstrated that appropriate choices of C lead to a substantial improvement in the behaviour of the perturbative series for Ψ'' ( s) and ImΨ( s).
Dark energy, scalar-curvature couplings and a critical acceleration scale
Navarro, Ignacio
2008-02-15
We study the effects of coupling a cosmologically rolling scalar field to higher-order curvature terms. We show that when the strong coupling scale of the theory is on the 10{sup -3}-10{sup -1} eV range, the model passes all experimental bounds on the existence of fifth forces even if the field has a mass of the order of the Hubble scale in vacuum and non-suppressed couplings to SM fields. The reason is that the coupling to a certain curvature invariant acts as an effective mass that grows in regions of large curvature. This prevents the field from rolling down its potential near sources and makes its effects on fifth-force search experiments performed in the laboratory to be observable only at the submillimeter scale. We obtain the static spherically symmetric solutions of the theory and show that a long-range force appears but it is turned on only below a fixed Newtonian acceleration scale of the order of the Hubble constant. We comment on the possibility of using this feature of the model to alleviate the cold dark matter (CDM) small-scale crisis and on its possible relation to MOND.
C-metric solution for conformal gravity with a conformally coupled scalar field
NASA Astrophysics Data System (ADS)
Meng, Kun; Zhao, Liu
2017-02-01
The C-metric solution of conformal gravity with a conformally coupled scalar field is presented. The solution belongs to the class of Petrov type D spacetimes and is conformal to the standard AdS C-metric appeared in vacuum Einstein gravity. For all parameter ranges, we identify some of the physically interesting static regions and the corresponding coordinate ranges. The solution may contain a black hole event horizon, an acceleration horizon, either of which may be cut by the conformal infinity or be hidden behind the conformal infinity. Since the model is conformally invariant, we also discussed the possible effects of the conformal gauge choices on the structure of the spacetime.
Late-time quantum backreaction of a very light nonminimally coupled scalar
NASA Astrophysics Data System (ADS)
Glavan, Dražen; Prokopec, Tomislav; Takahashi, Tomo
2016-10-01
We investigate the backreaction of the quantum fluctuations of a very light (m ≲Htoday) nonminimally coupled spectator scalar field on the expansion dynamics of the Universe. The one-loop expectation value of the energy-momentum tensor of these fluctuations, as a measure of the backreaction, is computed throughout the expansion history from the early inflationary universe until the onset of recent acceleration today. We show that, when the nonminimal coupling ξ to Ricci curvature is negative (ξc=1 /6 corresponding to conformal coupling), the quantum backreaction grows exponentially during inflation, such that it can grow large enough rather quickly (within a few hundred e -foldings) to survive until late time and constitute a contribution of the cosmological constant type of the right magnitude to appreciably alter the expansion dynamics. The unique feature of this model is in that, under rather generic assumptions, inflation provides a natural explanation for the initial conditions needed to explain the late-time accelerated expansion of the Universe, making it a particularly attractive model of dark energy.
Cosmological dynamics with non-minimally coupled scalar field and a constant potential function
Hrycyna, Orest; Szydłowski, Marek E-mail: marek.szydlowski@uj.edu.pl
2015-11-01
Dynamical systems methods are used to investigate global behaviour of the spatially flat Friedmann-Robertson-Walker cosmological model in gravitational theory with a non-minimally coupled scalar field and a constant potential function. We show that the system can be reduced to an autonomous three-dimensional dynamical system and additionally is equipped with an invariant manifold corresponding to an accelerated expansion of the universe. Using this invariant manifold we find an exact solution of the reduced dynamics. We investigate all solutions for all admissible initial conditions using theory of dynamical systems to obtain a classification of all evolutional paths. The right-hand sides of the dynamical system depend crucially on the value of the non-minimal coupling constant therefore we study bifurcation values of this parameter under which the structure of the phase space changes qualitatively. We found a special bifurcation value of the non-minimal coupling constant which is distinguished by dynamics of the model and may suggest some additional symmetry in matter sector of the theory.
Chattopadhyay, Abhijnan; Esadze, Alexandre; Roy, Sourav; Iwahara, Junji
2016-10-10
NMR scalar couplings across hydrogen bonds represent direct evidence for the partial covalent nature of hydrogen bonds and provide structural and dynamic information on hydrogen bonding. In this article, we report heteronuclear (15)N-(31)P and (1)H-(31)P scalar couplings across the intermolecular hydrogen bonds between protein histidine (His) imidazole and DNA phosphate groups. These hydrogen-bond scalar couplings were observed for the Egr-1 zinc-finger-DNA complex. Although His side-chain NH protons are typically undetectable in heteronuclear (1)H-(15)N correlation spectra due to rapid hydrogen exchange, this complex exhibited two His side-chain NH signals around (1)H 14.3 ppm and (15)N 178 ppm at 35 °C. Through various heteronuclear multidimensional NMR experiments, these signals were assigned to two zinc-coordinating His side chains in contact with DNA phosphate groups. The data show that the Nδ1 atoms of these His side chains are protonated and exhibit the (1)H-(15)N cross-peaks. Using heteronuclear (1)H, (15)N, and (31)P NMR experiments, we observed the hydrogen-bond scalar couplings between the His (15)Nδ1/(1)Hδ1 and DNA phosphate (31)P nuclei. These results demonstrate the direct involvement of the zinc-coordinating His side chains in the recognition of DNA by the Cys2His2-class zinc fingers in solution.
Results from a strong-coupling expansion for a lattice Yukawa model with a real scalar field
Abada, A.; Shrock, R.E. )
1991-01-15
Results are presented from a strong bare Yukawa coupling expansion for a lattice Yukawa theory with a real scalar field. It is found that the effective action involves competing interactions, consistent with the existence of a ferrimagnetic phase at intermediate Yukawa coupling {ital y}. We also give evidence that the (bosonic) continuum theory defined at the ferromagnetic-paramagnetic phase boundary at large {ital y} is free.
Non-minimal derivative coupling scalar field and bulk viscous dark energy
NASA Astrophysics Data System (ADS)
Mostaghel, Behrang; Moshafi, Hossein; Movahed, S. M. S.
2017-08-01
Inspired by thermodynamical dissipative phenomena, we consider bulk viscosity for dark fluid in a spatially flat two-component Universe. Our viscous dark energy model represents phantom-crossing which avoids big-rip singularity. We propose a non-minimal derivative coupling scalar field with zero potential leading to accelerated expansion of the Universe in the framework of bulk viscous dark energy model. In this approach, the coupling constant, κ , is related to viscosity coefficient, γ , and the present dark energy density, \\varOmega _DE^0. This coupling is bounded as κ \\in [-1/9H_0^2(1-\\varOmega _DE^0), 0]. We implement recent observational data sets including a joint light-curve analysis (JLA) for SNIa, gamma ray bursts (GRBs) for most luminous astrophysical objects at high redshifts, baryon acoustic oscillations (BAO) from different surveys, Hubble parameter from HST project, Planck CMB power spectrum and lensing to constrain model free parameters. The joint analysis of JLA + GRBs + BAO + HST shows that \\varOmega _DE^0=0.696± 0.010, γ =0.1404± 0.0014 and H_0=68.1± 1.3. Planck TT observation provides γ =0.32^{+0.31}_{-0.26} in the 68% confidence limit for the viscosity coefficient. The cosmographic distance ratio indicates that current observed data prefer to increase bulk viscosity. The competition between phantom and quintessence behavior of the viscous dark energy model can accommodate cosmological old objects reported as a sign of age crisis in the \\varLambda CDM model. Finally, tension in the Hubble parameter is alleviated in this model.
Quantum bound on the specific entropy in strongly coupled scalar field theory
Aparicio Alcalde, M.; Menezes, G.; Svaiter, N. F.
2008-06-15
We discuss the (g{sub 0}{phi}{sup p}){sub d} self-interacting scalar field theory, in the strong-coupling regime. We assume the presence of macroscopic boundaries confining the field in a hypercube of side L. We also consider that the system is in thermal equilibrium at temperature {beta}{sup -1}. For spatially bounded free fields, the Bekenstein bound states that the specific entropy satisfies the inequality (S/E)<2{pi}R, where R stands for the radius of the smallest sphere that circumscribes the system. Employing the strong-coupling perturbative expansion, we obtain the renormalized mean energy E and entropy S for the system up to the order (g{sub 0}){sup -(2/p)}, presenting an analytical proof that the specific entropy also satisfies in some situations a quantum bound. Defining {epsilon}{sub d}{sup (r)} as the renormalized zero-point energy for the free theory per unit length, the dimensionless quantity {xi}=({beta}/L) and h{sub 1}(d) and h{sub 2}(d) as positive analytic functions of d, for the case of high temperature, we get that the specific entropy satisfies (S/E)<2{pi}R(h{sub 1}(d)/h{sub 2}(d)){xi}. When considering the low-temperature behavior of the specific entropy, we have (S/E)<2{pi}R(h{sub 1}(d)/{epsilon}{sub d}{sup (r)}){xi}{sup 1-d}. Therefore the sign of the renormalized zero-point energy can invalidate this quantum bound. If the renormalized zero-point energy is a positive quantity, at intermediate temperatures and in the low-temperature limit, there is a quantum bound.
Navarro-Vázquez, Armando; Santamaría-Fernández, Raquel; Sardina, Francisco Javier
2017-09-26
MSpin-JCoupling is a modular program for the prediction of scalar couplings using a large variety of Karplus relationships. The program was specially designed for small molecule analysis and can be run in graphical or command-line mode. The architecture of the program is highly modular and new equations can be rapidly implemented, through a complete C++ programming interface, and deployed as run-time loadable plugins. This article is protected by copyright. All rights reserved.
Zandarashvili, Levani; Esadze, Alexandre; Kemme, Catherine A; Chattopadhyay, Abhijnan; Nguyen, Dan; Iwahara, Junji
2016-03-03
The residence times of molecular complexes in solution are important for understanding biomolecular functions and drug actions. We show that NMR data of intermolecular hydrogen-bond scalar couplings can yield information on the residence times of molecular complexes in solution. The molecular exchange of binding partners via the breakage and reformation of a complex causes self-decoupling of intermolecular hydrogen-bond scalar couplings, and this self-decoupling effect depends on the residence time of the complex. For protein-DNA complexes, we investigated the salt concentration dependence of intermolecular hydrogen-bond scalar couplings between the protein side-chain (15)N and DNA phosphate (31)P nuclei, from which the residence times were analyzed. The results were consistent with those obtained by (15)Nz-exchange spectroscopy. This self-decoupling-based kinetic analysis is unique in that it does not require any different signatures for the states involved in the exchange, whereas such conditions are crucial for kinetic analyses by typical NMR and other methods.
NASA Technical Reports Server (NTRS)
Ransom, Jonathan B.
2002-01-01
A multifunctional interface method with capabilities for variable-fidelity modeling and multiple method analysis is presented. The methodology provides an effective capability by which domains with diverse idealizations can be modeled independently to exploit the advantages of one approach over another. The multifunctional method is used to couple independently discretized subdomains, and it is used to couple the finite element and the finite difference methods. The method is based on a weighted residual variational method and is presented for two-dimensional scalar-field problems. A verification test problem and a benchmark application are presented, and the computational implications are discussed.
Boson stars in a theory of complex scalar fields coupled to the U(1) gauge field and gravity
NASA Astrophysics Data System (ADS)
Kumar, Sanjeev; Kulshreshtha, Usha; Shankar Kulshreshtha, Daya
2014-08-01
We study boson shells and boson stars in a theory of a complex scalar field coupled to the U(1) gauge field {{A}_{\\mu }} and Einstein gravity with the potential V(|\\Phi |)\\;:=\\frac{1}{2}{{m}^{2}}{{\\left( |\\Phi |+a \\right)}^{2}}. This could be considered either as a theory of a massive complex scalar field coupled to an electromagnetic field and gravity in a conical potential, or as a theory in the presence of a potential that is an overlap of a parabolic and conical potential. Our theory has a positive cosmological constant (\\Lambda :=4\\pi G{{m}^{2}}{{a}^{2}}). Boson stars are found to come in two types, having either ball-like or shell-like charge density. We studied the properties of these solutions and also determined their domains of existence for some specific values of the parameters of the theory. Similar solutions have also been obtained by Kleihaus, Kunz, Laemmerzahl and List, in a V-shaped scalar potential.
Cadoni, Mariano; Serra, Matteo; Mignemi, Salvatore
2011-10-15
We propose a general method for solving exactly the static field equations of Einstein and Einstein-Maxwell gravity minimally coupled to a scalar field. Our method starts from an ansatz for the scalar field profile, and determines, together with the metric functions, the corresponding form of the scalar self-interaction potential. Using this method we prove a new no-hair theorem about the existence of hairy black-hole and black-brane solutions and derive broad classes of static solutions with radial symmetry of the theory, which may play an important role in applications of the AdS/CFT correspondence to condensed matter and strongly coupled QFTs. These solutions include: (1) four- or generic (d+2)-dimensional solutions with planar, spherical or hyperbolic horizon topology; (2) solutions with anti-de Sitter, domain wall and Lifshitz asymptotics; (3) solutions interpolating between an anti-de Sitter spacetime in the asymptotic region and a domain wall or conformal Lifshitz spacetime in the near-horizon region.
NASA Astrophysics Data System (ADS)
Carlomagno, T.; Schwalbe, H.; Rexroth, A.; Sørensen, O. W.; Griesinger, C.
1998-11-01
New two- and three-dimensional NMR methods are proposed for the measurement of3J(H, H) coupling constants between two adjacent methylene moieties. The new experiment, which is based on a combination of the E.COSY principle and double/zero quantum heteronuclear spectroscopy, has been applied to diaceton-glucose and to the protein rhodniin. The coupling constants of CH-CH2groups have been compared with those obtained from a HCCH-E.COSY experiment to check the reliability of the results. An analysis of the coupling constants derived by comparison between experimental and simulated spectra is presented. Simulations were done with the program wtest considering fully correlated dipolar relaxation. Side-chain conformations in amino acids with adjacent methylene groups can be determined by the new experiment.
Superradiance of a charged scalar field coupled to the Einstein-Maxwell equations
NASA Astrophysics Data System (ADS)
Baake, Olaf; Rinne, Oliver
2016-12-01
We consider the Einstein-Maxwell-Klein-Gordon equations for a spherically symmetric scalar field scattering off a Reissner-Nordström black hole in asymptotically flat spacetime. The equations are solved numerically using a hyperboloidal evolution scheme. For suitable frequencies of the initial data, superradiance is observed, leading to a substantial decrease of mass and charge of the black hole. We also derive a Bondi mass loss formula using the Kodama vector field and investigate the late-time decay of the scalar field.
An Exact Solution of Einstein-Maxwell Gravity Coupled to a Scalar Field
NASA Technical Reports Server (NTRS)
Turyshev, S. G.
1995-01-01
The general solution to low-energy string theory representing static spherically symmetric solution of the Einstein-Maxwell gravity with a massless scalar field has been found. Some of the partial cases appear to coincide with known solutions to black holes, naked singularities, and gravity and electromagnetic fields.
An Exact Solution of Einstein-Maxwell Gravity Coupled to a Scalar Field
NASA Technical Reports Server (NTRS)
Turyshev, S. G.
1995-01-01
The general solution to low-energy string theory representing static spherically symmetric solution of the Einstein-Maxwell gravity with a massless scalar field has been found. Some of the partial cases appear to coincide with known solutions to black holes, naked singularities, and gravity and electromagnetic fields.
NASA Astrophysics Data System (ADS)
Grillo, Nicola
2001-02-01
Quantum gravity coupled to scalar massive matter fields is investigated in the framework of causal perturbation theory using the Epstein-Glaser regularization/renormalization scheme. Detailed one-loop calculations include the matter loop graviton self-energy and the matter self-energy. The condition of perturbative operator gauge invariance to second order implies the usual Slavnov-Ward identities for the graviton two-point connected Green function in the loop graph sector and generates the correct quartic graviton-matter interaction in the tree graph sector. The mass zero case is also discussed.
Graceful exit from inflation for minimally coupled Bianchi A scalar field models
NASA Astrophysics Data System (ADS)
Beyer, F.; Escobar, L.
2013-10-01
We consider the dynamics of Bianchi A scalar field models which undergo inflation. The main question is under which conditions does inflation come to an end and is succeeded by a decelerated epoch. This so-called ‘graceful exit’ from inflation is an important ingredient in the standard model of cosmology, but is, at this stage, only understood for restricted classes of solutions. We present new results obtained by a combination of analytical and numerical techniques.
NASA Astrophysics Data System (ADS)
Herrera-Aguilar, Alfredo; Malagón-Morejón, Dagoberto; Rigel Mora-Luna, Refugio; Quiros, Israel
2012-02-01
We consider warped five-dimensional thick braneworlds with four-dimensional Poincaré invariance originated from bulk scalar matter non-minimally coupled to gravity plus a Gauss-Bonnet term. The background field equations as well as the perturbed equations are investigated. A relationship between 4D and 5D Planck masses is studied in general terms. By imposing finiteness of the 4D Planck mass and regularity of the geometry, the localization properties of the tensor modes of the perturbed geometry are analysed to first order, for a wide class of solutions. In order to explore the gravity localization properties for this model, the normalizability condition for the lowest level of the tensor fluctuations is analysed. It is found that for the examined class of solutions, gravity in four dimensions is recovered if the curvature invariants are regular and the 4D Planck mass is finite. It turns out that both the addition of the Gauss-Bonnet term and the non-minimal coupling between the scalar field and gravity reduce the value of the 4D Planck mass compared to its value when the scalar field and gravity are minimally coupled and the Gauss-Bonnet term is absent. The above discussed analysis depends on the explicit form of the scalar field (through its non-minimal coupling to gravity), making necessary the construction of explicit solutions in order to obtain results in closed form, and is illustrated with some examples which constitute smooth generalizations of the so-called Randall-Sundrum braneworld model. These solutions were obtained by making use of a detailed singular perturbation theory procedure with respect to the non-minimal coupling parameter between the scalar field and gravity, a difficult task that we managed to perform in such a way that all the physically meaningful conditions for the localization of gravity are fully satisfied. From the obtained explicit solutions, we found an interesting effect: when we consider a non-minimally coupled scalar
Dimensional reduction of the Standard Model coupled to a new singlet scalar field
NASA Astrophysics Data System (ADS)
Brauner, Tomáš; Tenkanen, Tuomas V. I.; Tranberg, Anders; Vuorinen, Aleksi; Weir, David J.
2017-03-01
We derive an effective dimensionally reduced theory for the Standard Model augmented by a real singlet scalar. We treat the singlet as a superheavy field and integrate it out, leaving an effective theory involving only the Higgs and SU(2) L × U(1) Y gauge fields, identical to the one studied previously for the Standard Model. This opens up the possibility of efficiently computing the order and strength of the electroweak phase transition, numerically and nonperturbatively, in this extension of the Standard Model. Understanding the phase diagram is crucial for models of electroweak baryogenesis and for studying the production of gravitational waves at thermal phase transitions.
NASA Astrophysics Data System (ADS)
Eshuis, Nan; Aspers, Ruud L. E. G.; van Weerdenburg, Bram J. A.; Feiters, Martin C.; Rutjes, Floris P. J. T.; Wijmenga, Sybren S.; Tessari, Marco
2016-04-01
SABRE (Signal Amplification By Reversible Exchange) nuclear spin hyperpolarization method can provide strongly enhanced NMR signals as a result of the reversible association of small molecules with para-hydrogen (p-H2) at an iridium metal complex. The conversion of p-H2 singlet order to enhanced substrate proton magnetization within such complex is driven by the scalar coupling interactions between the p-H2 derived hydrides and substrate nuclear spins. In the present study these long-range homonuclear couplings are experimentally determined for several SABRE substrates using an NMR pulse sequence for coherent hyperpolarization transfer at high magnetic field. Pyridine and pyrazine derivatives appear to have a similar ∼1.2 Hz 4J coupling to p-H2 derived hydrides for their ortho protons, and a much lower 5J coupling for their meta protons. Interestingly, the 4J hydride-substrate coupling for five-membered N-heterocyclic substrates is well below 1 Hz.
Eshuis, Nan; Aspers, Ruud L E G; van Weerdenburg, Bram J A; Feiters, Martin C; Rutjes, Floris P J T; Wijmenga, Sybren S; Tessari, Marco
2016-04-01
SABRE (Signal Amplification By Reversible Exchange) nuclear spin hyperpolarization method can provide strongly enhanced NMR signals as a result of the reversible association of small molecules with para-hydrogen (p-H2) at an iridium metal complex. The conversion of p-H2 singlet order to enhanced substrate proton magnetization within such complex is driven by the scalar coupling interactions between the p-H2 derived hydrides and substrate nuclear spins. In the present study these long-range homonuclear couplings are experimentally determined for several SABRE substrates using an NMR pulse sequence for coherent hyperpolarization transfer at high magnetic field. Pyridine and pyrazine derivatives appear to have a similar ∼1.2 Hz (4)J coupling to p-H2 derived hydrides for their ortho protons, and a much lower (5)J coupling for their meta protons. Interestingly, the (4)J hydride-substrate coupling for five-membered N-heterocyclic substrates is well below 1 Hz.
Kakita, Veera Mohana Rao; Rachineni, Kavitha; Hosur, Ramakrishna V
2017-07-21
The present manuscript focuses on fast and simultaneous determination of (1) H-(1) H and (1) H-(19) F scalar couplings in fluorinated complex steroid molecules. Incorporation of broadband PSYCHE homonuclear decoupling in the indirect dimension of zero-quantum filtered diagonal experiments (F1-PSYCHE-DIAG) suppresses (1) H-(1) H scalar couplings; however, it retains (1) H-(19) F scalar couplings (along F1 dimension) for the (19) F coupled protons while preserving the pure-shift nature for (1) H resonances uncoupled to (19) F. In such cases, along the direct dimensions, (1) H-(1) H scalar coupling multiplets deconvolute and they appear as duplicated multiplets for the (19) F coupled protons, which facilitates unambiguous discrimination of (19) F coupled (1) H chemical sites from the others. Further, as an added advantage, data acquisition has been accelerated by invoking the known ideas of spectral aliasing in the F1-PSYCHE-DIAG scheme and experiments demand only ~10 min of spectrometer times. Copyright © 2017 John Wiley & Sons, Ltd.
Conformally coupled scalar black holes admit a flat horizon due to axionic charge
NASA Astrophysics Data System (ADS)
Bardoux, Yannis; Caldarelli, Marco M.; Charmousis, Christos
2012-09-01
Static, charged black holes in the presence of a negative cosmological constant and with a planar horizon are found in four dimensions. The solutions have scalar secondary hair. We claim that these constitute the planar version of the Martínez-Troncoso-Zanelli black holes, only known up to now for a curved event horizon in four dimensions. Their planar version is rendered possible due to the presence of two, equal and homogeneously distributed, axionic charges dressing the flat horizon. The solutions are presented in the conformal and minimal frame and their basic properties and thermodynamics analysed. Entertaining recent applications to holographic superconductors, we expose two branches of solutions: the undressed axionic Reissner-Nordström-AdS black hole, and the novel black hole carrying secondary hair. We show that there is a critical temperature at which the (bald) axionic Reissner-Nordström-AdS black hole undergoes a second order phase transition to the hairy black hole spontaneously acquiring scalar hair.
3j Symbols: To Normalize or Not to Normalize?
ERIC Educational Resources Information Center
van Veenendaal, Michel
2011-01-01
The systematic use of alternative normalization constants for 3j symbols can lead to a more natural expression of quantities, such as vector products and spherical tensor operators. The redefined coupling constants directly equate tensor products to the inner and outer products without any additional square roots. The approach is extended to…
3j Symbols: To Normalize or Not to Normalize?
ERIC Educational Resources Information Center
van Veenendaal, Michel
2011-01-01
The systematic use of alternative normalization constants for 3j symbols can lead to a more natural expression of quantities, such as vector products and spherical tensor operators. The redefined coupling constants directly equate tensor products to the inner and outer products without any additional square roots. The approach is extended to…
NASA Astrophysics Data System (ADS)
Boran, Sibel; Kahya, Emre Onur; Park, Sohyun
2017-07-01
The present work is the second part of a series of computations for the self-mass-squared of the conformally coupled (CC) scalar interacting with gravitons. This work includes the kinetic-kinetic and kinetic-conformal parts, and thus completes the full scalar self-mass-squared at one loop order in de Sitter background when combined with the conformal-conformal part previously evaluated. We use dimensional regularization and renormalize the results by subtracting appropriate counterterms. The self-mass squared is finally ready to quantum-correct the CC scalar field equation so that one can study the effect of inflationary produced gravitons on the CC scalar and its observational consequences.
Chu, Yi-Zen
2014-09-15
Motivated by the desire to understand the causal structure of physical signals produced in curved spacetimes – particularly around black holes – we show how, for certain classes of geometries, one might obtain its retarded or advanced minimally coupled massless scalar Green's function by using the corresponding Green's functions in the higher dimensional Minkowski spacetime where it is embedded. Analogous statements hold for certain classes of curved Riemannian spaces, with positive definite metrics, which may be embedded in higher dimensional Euclidean spaces. The general formula is applied to (d ≥ 2)-dimensional de Sitter spacetime, and the scalar Green's function is demonstrated to be sourced by a line emanating infinitesimally close to the origin of the ambient (d + 1)-dimensional Minkowski spacetime and piercing orthogonally through the de Sitter hyperboloids of all finite sizes. This method does not require solving the de Sitter wave equation directly. Only the zero mode solution to an ordinary differential equation, the “wave equation” perpendicular to the hyperboloid – followed by a one-dimensional integral – needs to be evaluated. A topological obstruction to the general construction is also discussed by utilizing it to derive a generalized Green's function of the Laplacian on the (d ≥ 2)-dimensional sphere.
NASA Astrophysics Data System (ADS)
Kamiński, Robert; Bibrzycki, Łukasz
2017-03-01
The low energy (below 2 GeV) πη channel interaction amplitude becomes an object of interest mainly because of the search for exotic mesons in just beginning to collect data detector GlueX in JLab. Finding and interpretation of expected weak signals from these states require a comparison with a very accurate amplitude containing standard (qq¯) states i.e. a0(980) and a0(1450). The main problem in the determination of such amplitude is a total absence of data about the phases and inelasticities in the elastic and inelastic region. In addition, it is necessary to take into account the next two coupled higher channels - KK¯ and πη'. Presented here amplitude is based on separable potential model (working very well for the scalar-isoscalar ππ interactions) with only 9 free parameters. To determine such 3-coupled channel amplitude, the following information has been taken into account: experimental branching ratios and positions of both a0 resonances, theoretical couplings, scattering length from ChPT and value of squared radius of the πη form factor. Phase shifts, inelasticities and cross sections in all single and crossed channels are presented.
NASA Astrophysics Data System (ADS)
Hashino, Katsuya; Kakizaki, Mitsuru; Kanemura, Shinya; Ko, Pyungwon; Matsui, Toshinori
2017-03-01
We calculate the spectrum of gravitational waves originated from strongly first order electroweak phase transition in the extended Higgs model with a real singlet scalar field. In order to calculate the bubble nucleation rate, we perform a two-field analysis and evaluate bounce solutions connecting the true and the false vacua using the one-loop effective potential at finite temperatures. Imposing the Sakharov condition of the departure from thermal equilibrium for baryogenesis, we survey allowed regions of parameters of the model. We then investigate the gravitational waves produced at electroweak bubble collisions in the early Universe, such as the sound wave, the bubble wall collision and the plasma turbulence. We find that the strength at the peak frequency can be large enough to be detected at future space-based gravitational interferometers such as eLISA, DECIGO and BBO. Predicted deviations in the various Higgs boson couplings are also evaluated at the zero temperature, and are shown to be large enough too. Therefore, in this model strongly first order electroweak phase transition can be tested by the combination of the precision study of various Higgs boson couplings at the LHC, the measurement of the triple Higgs boson coupling at future lepton colliders and the shape of the spectrum of gravitational wave detectable at future gravitational interferometers.
NASA Astrophysics Data System (ADS)
Segawa, Takuya F.; Bodenhausen, Geoffrey
2013-12-01
Homogeneous line-widths that arise from transverse relaxation tend to be masked by B0 field inhomogeneity and by multiplets due to homonuclear J-couplings. Besides well-known spin-locking sequences that lead to signals that decay with a rate R1ρ without any modulations, alternative experiments allow one to determine the transverse relaxation rates R2 in systems with scalar-coupled spins. We evaluate three recent strategies by experiment and simulation: (i) moderate-amplitude SITCOM-CPMG sequences (Dittmer and Bodenhausen, 2006 [2]), (ii) multiple-quantum filtered (MQF) sequences (Barrère et al., 2011 [4]) and (iii) PROJECT sequences (Aguilar et al., 2012 [5]). Experiments where the J-evolution is suppressed by spin-locking measure the pure relaxation rate R2(Ix) of an in-phase component. Experiments based on J-refocusing yield a mixture of in-phase rates R2(Ix) and antiphase rates R2(2IySz), where the latter are usually faster than the former. Moderate-amplitude SITCOM-CPMG and PROJECT methods can be applied to systems with many coupled spins, but applications of MQF sequences are limited to two-spin systems since modulations in larger systems can only partly be suppressed.
NASA Astrophysics Data System (ADS)
Cisterna, Adolfo; Cruz, Miguel; Delsate, Térence; Saavedra, Joel
2015-11-01
We derive the odd-parity perturbation equation for the nonminimal kinetic coupling sector of the general Horndeski theory, where the kinetic term is coupled to the metric and the Einstein tensor. We derive the potential of the perturbation, by identifying a master function and switching to tortoise coordinates. We then prove the mode stability under linear odd-parity perturbations of hairy black holes in this sector of Horndeski theory, when a cosmological constant term in the action is included. Finally, we comment on the existence of slowly rotating black hole solutions in this setup and discuss their implications on the physics of compact object configurations, such as neutron stars.
NASA Astrophysics Data System (ADS)
Ghosh, Kaushik
2016-01-01
In this article, we will discuss a Lorentzian sector calculation of the entropy of a minimally coupled scalar field in the Schwarzschild black hole background using the brick wall model of 't Hooft. In the original article, the Wentzel-Kramers-Brillouin (WKB) approximation was used for the modes that are globally stationary. In a previous article, we found that the WKB quantization rule together with a proper counting of the states, leads to a new expression of the scalar field entropy which is not proportional to the area of the horizon. The expression of the entropy is logarithmically divergent in the brick wall cut-off parameter in contrast to an inverse power divergence obtained earlier. In this article, we will consider the entropy for a thin shell of matter field of a given thickness surrounding the black hole horizon. The thickness is chosen to be large compared with the Planck length and is of the order of the atomic scale. We will discuss the corresponding boundary conditions and the appropriateness of the WKB approximation using the Regge-Wheeler tortoise coordinates. When expressed in terms of a covariant cut-off parameter, the entropy of a thin shell of matter field of a given thickness and surrounding the horizon in the Schwarzschild black hole background is given by an expression proportional to the area of the black hole horizon. This leading order divergent term in the cut-off parameter remains to be logarithmically divergent. The logarithmic divergence is expected from the nature of the near-horizon geometry and is discussed in detail at the end of Sect. 2. We will find that these discussions are significant in the context of the continuation to the Euclidean sector and the corresponding regularization schemes used to evaluate the thermodynamical properties of matter fields in curved spaces. These are related with to geometric aspects of curved spaces.
Higgs couplings and new signals from Flavon-Higgs mixing effects within multi-scalar models
NASA Astrophysics Data System (ADS)
Diaz-Cruz, J. Lorenzo; Saldaña-Salazar, Ulises J.
2016-12-01
Testing the properties of the Higgs particle discovered at the LHC and searching for new physics signals, are some of the most important tasks of Particle Physics today. Current measurements of the Higgs couplings to fermions and gauge bosons, seem consistent with the Standard Model, and when taken as a function of the particle mass, should lay on a single line. However, in models with an extended Higgs sector the diagonal Higgs couplings to up-quarks, down-quarks and charged leptons, could lay on different lines, while non-diagonal flavor-violating Higgs couplings could appear too. We describe these possibilities within the context of multi-Higgs doublet models that employ the Froggatt-Nielsen (FN) mechanism to generate the Yukawa hierarchies. Furthermore, one of the doublets can be chosen to be of the inert type, which provides a viable dark matter candidate. The mixing of the Higgs doublets with the flavon field, can provide plenty of interesting signals, including: i) small corrections to the couplings of the SM-like Higgs, ii) exotic signals from the flavon fields, iii) new signatures from the heavy Higgs bosons. These aspects are studied within a specific model with 3 + 1 Higgs doublets and a singlet FN field. Constraints on the model are derived from the study of K and D mixing and the Higgs search at the LHC. For last, the implications from the latter aforementioned constraints to the FCNC top decay t → ch are presented too.
NASA Astrophysics Data System (ADS)
Kim, Sang Pyo; Page, Don N.
1992-05-01
The expansion of the wave function of a quantum Friedmann-Robertson-Walker cosmology minimally coupled to a scalar field with a power-law potential by its scalar-field part decouples the gravitational-field part into an infinite system of linear homogeneous differential equations (equivalent to a matrix equation). The solutions for the gravitational-field part are found in the product integral formulation. It is shown that there exists a spectrum of the wave functions exponentially damped for large three-geometries under the condition that the cosmological constant should vanish. These are interpeted as the Hawking-Page wormholes.
Improved validation of IDP ensembles by one-bond Cα-Hα scalar couplings.
Gapsys, Vytautas; Narayanan, Raghavendran L; Xiang, ShengQi; de Groot, Bert L; Zweckstetter, Markus
2015-11-01
Intrinsically disordered proteins (IDPs) are best described by ensembles of conformations and a variety of approaches have been developed to determine IDP ensembles. Because of the large number of conformations, however, cross-validation of the determined ensembles by independent experimental data is crucial. The (1)JCαHα coupling constant is particularly suited for cross-validation, because it has a large magnitude and mostly depends on the often less accessible dihedral angle ψ. Here, we reinvestigated the connection between (1)JCαHα values and protein backbone dihedral angles. We show that accurate amino-acid specific random coil values of the (1)JCαHα coupling constant, in combination with a reparameterized empirical Karplus-type equation, allow for reliable cross-validation of molecular ensembles of IDPs.
Pseudo-scalar pi N coupling and relativistic proton-nucleus scattering
NASA Technical Reports Server (NTRS)
Gross, Franz; Maung, Khin Maung; Tjon, J. A.; Townsend, L. W.; Wallace, S. J.
1988-01-01
Relativistic p-Ca-40 elastic scattering observables are calculated using relativistic NN amplitudes obtained from the solution of a two-body relativistic equation in which one particle is kept on its mass-shell. Results at 200 MeV are presented for two sets of NN amplitudes, one with pure pseudo-vector coupling for the pion and another with a 25 percent admixture of pseudo-scaling coupling. Both give a very good fit to the positive energy on-shell NN data. Differences between the predictions of these two models (which are shown to be due only to the differences in their corresponding negative energy amplitudes) provide a measure of the uncertainty in contructing Dirac optical potentials from NN amplitudes.
Collection of NMR Scalar and Residual Dipolar Couplings Using a Single Experiment.
Gil-Silva, Leandro F; Santamaría-Fernández, Raquel; Navarro-Vázquez, Armando; Gil, Roberto R
2016-01-11
A new DMSO-compatible aligning gel based on cross-linked poly(2-hydroxylethyl methacrylate) (poly-HEMA) has been developed. Due to a significant difference in bulk magnetic susceptibility between the DMSO inside and outside the gel, it is possible to simultaneously collect isotropic and anisotropic NMR data, such as residual dipolar couplings (RDC), in the same NMR tube. RDC-assisted structural analysis of menthol and the alkaloid retrorsine is reported as proof of concept.
Crossing w = -1 by a single scalar field coupling with matter and the observational constraints
NASA Astrophysics Data System (ADS)
Tong, M. L.; Zhang, Y.; Fu, Z. W.
2011-03-01
Motivated by the Yang-Mills dark energy model, we propose a new model by introducing a logarithmic correction. We find that this model can avoid the coincidence problem naturally and gives an equation of state w smoothly crossing -1 if an interaction between dark energy and dark matter exists. It has a stable tracker solution as well. To confront with observations based on the combined data of SN Ia, BAO, CMB and Hubble parameter, we obtain the best-fit values of the parameters with 1σ, 2σ, 3σ errors for the non-coupled model: Ωm = 0.276 ± 0.008 + 0.016 + 0.024- 0.015 - 0.022, h = 0.699 ± 0.003 ± 0.006 ± 0.008, and for the coupled model with a decaying rate γ = 0.2: Ωm = 0.291 ± 0.004+0.008 + 0.012- 0.007 - 0.011, h = 0.701 ± 0.002 ± 0.005 ± 0.007. In particular, it is found that the non-coupled model has a dynamic evolution almost indistinguishable to ΛCDM at the late-time Universe.
Measurement of small scalar and dipolar couplings in purine and pyrimidine bases.
Zídek, L; Wu, H; Feigon, J; Sklenár, V
2001-10-01
A suite of spin-state-selective excitation (S3E) NMR experiments for the measurements of small one-bond (13C-13C, 15N-13C) and two-bond (1H-13C, 1H-15N) coupling constants in 13C,15N labeled purine and pyrimidine bases is presented. The incorporation of band-selective shaped pulses, elimination of the cross talk between alpha and beta sub-spectra, and accuracy and precision of the proposed approach are discussed. Merits of using S3E rather than alpha/beta-half-filter are demonstrated using results obtained on isotopically labeled DNA oligonucleotides.
3j symbols : to normalize or not to normalize.
van Veenendaal, M.
2011-07-01
The systematic use of alternative normalization constants for 3j symbols can lead to a more natural expression of quantities, such as vector products and spherical tensor operators. The redefined coupling constants directly equate tensor products to the inner and outer products without any additional square roots. The approach is extended to tesseral harmonics. The methodology developed here leads to a significantly clearer presentation, which is of interest, not only for textbooks but also for researchers using spherical tensors.
Kramer, Frank; Glaser, Steffen J
2002-03-01
In the presence of scalar (J) and residual dipolar (D) couplings, the transfer efficiency of homonuclear Hartmann-Hahn and COSY-type mixing depends on the ratio D/J and on the mixing sequence. This dependence is analyzed theoretically and the results are confirmed experimentally. At least two different mixing sequences are required to yield good transfer efficiencies for all ratios D/J. In contrast to COSY-type experiments, homonuclear Hartmann-Hahn sequences can provide efficient transfer even if the sum of D and J is zero, i.e., if the coupling vanishes in the weak coupling limit.
Near-horizon geometry and the entropy of a minimally coupled scalar field in the Kerr black hole
NASA Astrophysics Data System (ADS)
Ghosh, Kaushik
2016-09-01
In this article we will discuss a Lorentzian sector calculation of the entropy of a minimally coupled scalar field in a Kerr black hole background. We will use the brick wall model of 't Hooft. In a Kerr black hole, complications arise due to the absence of a global timelike Killing field and the presence of the ergosphere. Nevertheless, it is possible to calculate the entropy of a thin shell of matter field in the near-horizon region using the brick wall model. The corresponding leading-order entropy of the nonsuperradiant modes is found to be proportional to the area of the horizon and is logarithmically divergent. Thus, the entropy of a three-dimensional system in the near-horizon region is proportional to the boundary surface. This aspect is also valid in the Schwarzschild black holes and is similar to that of the black hole entropy itself. The corresponding internal energy remains finite if the entropy is chosen to be of the order of the black hole entropy itself. For a fixed value of the brick wall cut-off, the leading order entropy in a Kerr black hole is found to be half of the corresponding term in a Schwarzschild black hole. This is due to rotation and is consistent with the preferential emission of particles in a Kerr black hole with azimuthal angular momentum in the same direction as that of the black hole itself. However, we can obtain the Schwarzschild case expression by including a subleading term and taking the appropriate slow rotation limit.
Denisenko, S.N.; Chervin, I.I.; Kostyanovskii, R.G.; Shustov, G.V.
1986-04-01
Stereospecificity of the /sup 3/JC,N,C,H spin-spin coupling constants (/sup 3/ /SUB J/ trans > /SUB J/ gauche) in the /sup 13/C NMR spectra of 1,5-diaza- and 1,3,5-triazabicyclo (3.1.0)hexanes was observed. Proceeding from this, the preferred conformations of the d,/ZETA/ and meso isomers of 2,4,6-trialkyl-1,3,5-triazabicyclo (3.1.0) hexanes were established, and a mechanism for the interconversion of these isomers via openings of the five-membered ring and an imino-enamine equilibrium was proposed. It is also shown that the stereochemical result of the Schmitz reaction is determined in the step involving cyclization of the iminium intermediate.
NASA Astrophysics Data System (ADS)
Li, Hui-Ling; Yang, Shu-Zheng; Zu, Xiao-Tao
2017-01-01
In the framework of holography, we survey the phase structure for a higher dimensional hairy black hole including the effects of the scalar field hair. It is worth emphasizing that, not only black hole entropy, but also entanglement entropy and two point correlation function exhibit the Van der Waals-like phase transition in a fixed scalar charge ensemble. Furthermore, by making use of numerical computation, we show that the Maxwell's equal area law is valid for the first order phase transition. In addition, we also discuss how the hair parameter affects the black hole's phase transition.
Liu, H; Banville, D L; Basus, V J; James, T L
1995-04-01
A method (termed CARNIVAL) for accurately determining distances from proton homonuclear rotating-frame Overhauser effect spectroscopy (ROESY) is described. The method entails an iterative calculation of the relaxation matrix using methodology introduced with the MARDIGRAS algorithm for analysis of two-dimensional nuclear Overhauser effect spectra (B. A. Borgias and T. L. James, J. Magn. Reson. 87, 475, 1990). The situation is complicated in the case of ROESY as spectral peak intensities are influenced by resonance offset and contributions from homonuclear Hartmann-Hahn (HOHAHA) transfer if the nuclear spins are related by scalar coupling. The effects of spin-locking field strength on distance determinations and the ensuing distance errors incurred when HOHAHA corrections are made with limited knowledge of scalar (J) coupling information have been evaluated using simulated ROESY intensities with a model peptide structure. It has been demonstrated that accurate distances can be obtained with little or no explicit knowledge of the homonuclear coupling constants over a moderate range of spin-locking field strengths. The CARNIVAL algorithm has been utilized to determine distances in a decapeptide using experimental ROESY data without measured coupling constants.
NASA Astrophysics Data System (ADS)
Liu, H.; Banville, D. L.; Basus, V. J.; James, T. L.
A method (termed CARNIVAL) for accurately determining distances from proton homonuclear rotating-frame Overhauser effect spectroscopy (ROESY) is described. The method entails an iterative calculation of the relaxation matrix using methodology introduced with the MARDIGRAS algorithm for analysis of two-dimensional nuclear Overhauser effect spectra (B. A. Borgias and T. L. James, J. Magn. Reson.87, 475, 1990). The situation is complicated in the case of ROESY as spectral peak intensities are influenced by resonance offset and contributions from homonuclear Hartmann-Hahn (HOHAHA) transfer if the nuclear spins are related by scalar coupling. The effects of spin-locking field strength on distance determinations and the ensuing distance errors incurred when HOHAHA corrections are made with limited knowledge of scalar ( J) coupling information have been evaluated using simulated ROESY intensities with a model peptide structure. It has been demonstrated that accurate distances can be obtained with little or no explicit knowledge of the homonuclear coupling constants over a moderate range of spin-locking field strengths. The CARNIVAL algorithm has been utilized to determine distances in a decapeptide using experimental ROESY data without measured coupling constants.
Chiavazza, Enrico; Kubala, Eugen; Gringeri, Concetta V; Düwel, Stephan; Durst, Markus; Schulte, Rolf F; Menzel, Marion I
2013-02-01
Scalar coupling relaxation, which is usually only associated with closely resonant nuclei (e.g., (79)Br-(13)C), can be a very effective relaxation mechanism. While working on hyperpolarized [5-(13)C]glutamine, fast liquid-state polarization decay during transfer to the MRI scanner was observed. This behavior could hypothetically be explained by substantial T(1) shortening due to a scalar coupling contribution (type II) to the relaxation caused by the fast-relaxing quadrupolar (14)N adjacent to the (13)C nucleus in the amide group. This contribution is only effective in low magnetic fields (i.e., less than 800 μT) and prevents the use of molecules bearing the (13)C-amide group as hyperpolarized MRS/MRI probes. In the present work, this hypothesis is explored both theoretically and experimentally. The results show that high hyperpolarization levels can be retained using either a (15)N-labeled amide or by applying a magnetic field during transfer of the sample from the polarizer to the MRI scanner. Copyright © 2012 Elsevier Inc. All rights reserved.
NASA Astrophysics Data System (ADS)
Chiavazza, Enrico; Kubala, Eugen; Gringeri, Concetta V.; Düwel, Stephan; Durst, Markus; Schulte, Rolf F.; Menzel, Marion I.
2013-02-01
Scalar coupling relaxation, which is usually only associated with closely resonant nuclei (e.g., 79Br-13C), can be a very effective relaxation mechanism. While working on hyperpolarized [5-13C]glutamine, fast liquid-state polarization decay during transfer to the MRI scanner was observed. This behavior could hypothetically be explained by substantial T1 shortening due to a scalar coupling contribution (type II) to the relaxation caused by the fast-relaxing quadrupolar 14N adjacent to the 13C nucleus in the amide group. This contribution is only effective in low magnetic fields (i.e., less than 800 μT) and prevents the use of molecules bearing the 13C-amide group as hyperpolarized MRS/MRI probes. In the present work, this hypothesis is explored both theoretically and experimentally. The results show that high hyperpolarization levels can be retained using either a 15N-labeled amide or by applying a magnetic field during transfer of the sample from the polarizer to the MRI scanner.
Cadars, Sylvian; Brouwer, Darren H; Chmelka, Bradley F
2009-03-21
Subtle structural details of siliceous zeolites are probed by using two-bond scalar (J) coupling constants to characterize covalently bonded 29Si-O-29Si site pairs and local framework order. Solid-state two-dimensional (2D) 29Si{29Si} NMR measurements and first-principles calculations of 2J(29Si-O-29Si) couplings shed insights on both the local structures of siliceous zeolites Sigma-2 and ZSM-12, as well as the sensitivity of J couplings for detailed characterization analyses. DFT calculations on a model linear silicate dimer show that 2J(Si-O-Si) couplings have complicated multiple angular dependencies that make semi-empirical treatments impractical, but which are amenable to cluster approaches for accurate J-coupling calculations in zeolites. DFT calculations of 2J(29Si-O-29Si) couplings of the siliceous zeolite Sigma-2, whose framework structure is known to high accuracy from single-crystal X-ray diffraction studies, yield excellent agreement between calculated and experimentally measured 2J(Si-O-Si) couplings. For the siliceous zeolite ZSM-12, calculated 2J(29Si-O-29Si) couplings based on less-certain powder X-ray diffraction analyses deviate significantly from experimental values, while a refined structure based on 29Si chemical-shift-tensor analyses shows substantially improved agreement. 29Si J-coupling interactions can be used as sensitive probes of local structures of zeolitic frameworks and offer new opportunities for refining and solving complicated structures, in combination with complementary scattering, modeling, and other nuclear spin interactions.
Geometric scalar theory of gravity
Novello, M.; Bittencourt, E.; Goulart, E.; Salim, J.M.; Toniato, J.D.; Moschella, U. E-mail: eduhsb@cbpf.br E-mail: egoulart@cbpf.br E-mail: toniato@cbpf.br
2013-06-01
We present a geometric scalar theory of gravity. Our proposal will be described using the ''background field method'' introduced by Gupta, Feynman, Deser and others as a field theory formulation of general relativity. We analyze previous criticisms against scalar gravity and show how the present proposal avoids these difficulties. This concerns not only the theoretical complaints but also those related to observations. In particular, we show that the widespread belief of the conjecture that the source of scalar gravity must be the trace of the energy-momentum tensor — which is one of the main difficulties to couple gravity with electromagnetic phenomenon in previous models — does not apply to our geometric scalar theory. From the very beginning this is not a special relativistic scalar gravity. The adjective ''geometric'' pinpoints its similarity with general relativity: this is a metric theory of gravity. Some consequences of this new scalar theory are explored.
Barfield, Michael
2007-08-01
A study is presented of the structural dependencies for scalar, interproton J-coupling across two bonds in a series of substituted methanes. The coupled perturbed, density functional theory method with a B3PW91 functional and aug-cc-pVTZ-J basis sets is used to examine coupling between geminal protons (2)J(H,H') in methane and a series of substituted compounds CH(3)X (X = CH3, CH(2)CH(3), CH=CH2, CH=O, and NH2) as functions of the dihedral angle phi measured about the C1-X2 bonds. All four contributions are obtained but all conformational effects are dominated by the Fermi contact term. Simple linear combination of atomic orbitals (LCAO)-molecular orbital (MO) sum-over-states methods are used to examine the relationships of the coupling constants with dihedral angles as well as internal H-C-H and H-C1-X2 angles. This study explores some novel aspects of geminal H-H coupling including an analysis of the asymmetry in the conformational dependencies arising from non-next-nearest neighbor interactions. For each of the substituted methanes, explicit trigonometric/exponential expressions are given and these accurately reproduce the (2)J(H,H') structural dependencies with standard deviations usually less than 0.03 Hz. The molecular structures for representative bicyclic molecules were fully optimized, and DFT results for (2)J(H,H') reproduce all the trends in the experimental data. A discussion is given on the applicability of the equations for H--H coupling in the substituted methanes to coupling in the bicyclic molecules.
NASA Astrophysics Data System (ADS)
Solanke, D. T.; Karade, T. M.
2017-06-01
In f(R, T) theory of gravity, we have studied the interacting scalar and electromagnetic fields in Bianchi type I space-time, by considering the general cases f(R, T) = f 1(R) + λf 2(T), f( {R,T} ) = f1 ( R )f2 ( T ) and f(R) theory and its particular cases f(R, T) = R + λT, f( {R,T} ) = RT , f(R) = R. It is observed that, even though the cases of f(R, T) are distinct, the convergent and isotropic solution of metric functions can be evolved in each case along with the components of vector potential, corresponding to suitable integrable function in particular cases.
Massaro, A; Tasco, V; Todaro, M T; Cingolani, R; De Vittorio, M; Passaseo, A
2008-09-15
We present in this work the scalar potential formulation of second harmonic generation process in chi((2)) nonlinear analysis. This approach is intrinsically well suited to the applications of the concept of circuit analysis and synthesis to nonlinear optical problems, and represents a novel alternative method in the analysis of nonlinear optical waveguide, by providing a good convergent numerical solution. The time domain modeling is applied to nonlinear GaAs asymmetrical waveguide with dielectric discontinuities in the hypothesis of quasi phase matching condition in order to evaluate the efficiency conversion of the second harmonic signal. The accuracy of the modeling is validated by the good agreement with the published experimental results. The effective dielectric constant method allows to extend the analysis also to 3D optical waveguides.
Electroweak Baryogenesis and Colored Scalars
Cohen, Timothy; Pierce, Aaron; /Michigan U., MCTP
2012-02-15
We consider the 2-loop finite temperature effective potential for a Standard Model-like Higgs boson, allowing Higgs boson couplings to additional scalars. If the scalars transform under color, they contribute 2-loop diagrams to the effective potential that include gluons. These 2-loop effects are perhaps stronger than previously appreciated. For a Higgs boson mass of 115 GeV, they can increase the strength of the phase transition by as much as a factor of 3.5. It is this effect that is responsible for the survival of the tenuous electroweak baryogenesis window of the Minimal Supersymmetric Standard Model. We further illuminate the importance of these 2-loop diagrams by contrasting models with colored scalars to models with singlet scalars. We conclude that baryogenesis favors models with light colored scalars. This motivates searches for pair-produced di-jet resonances or jet(s) + = E{sub T}.
NASA Astrophysics Data System (ADS)
Miao, Yan-Gang; Xu, Zhen-Ming
2017-06-01
We investigate the P{-}V criticality and the Maxwell equal area law for a five-dimensional spherically symmetric AdS black hole with a scalar hair in the absence of and in the presence of a Maxwell field, respectively. Especially in the charged case, we give the exact P{-}V critical values. More importantly, we analyze the validity and invalidity of the Maxwell equal area law for the AdS hairy black hole in the scenarios without and with charges, respectively. Within the scope of validity of the Maxwell equal area law, we point out that there exists a representative van der Waals-type oscillation in the P{-}V diagram. This oscillating part, which indicates the phase transition from a small black hole to a large one, can be replaced by an isobar. The small and large black holes have the same Gibbs free energy. We also give the distribution of the critical points in the parameter space both without and with charges, and we obtain for the uncharged case the fitting formula of the co-existence curve. Meanwhile, the latent heat is calculated, which gives the energy released or absorbed between the small and large black hole phases in the isothermal-isobaric procedure.
NASA Astrophysics Data System (ADS)
Huang, Zhiming; Situ, Haozhen
2017-02-01
In this article, the dynamics of quantum correlation and coherence for two atoms interacting with a bath of fluctuating massless scalar field in the Minkowski vacuum is investigated. We firstly derive the master equation that describes the system evolution with initial Bell-diagonal state. Then we discuss the system evolution for three cases of different initial states: non-zero correlation separable state, maximally entangled state and zero correlation state. For non-zero correlation initial separable state, quantum correlation and coherence can be protected from vacuum fluctuations during long time evolution when the separation between the two atoms is relatively small. For maximally entangled initial state, quantum correlation and coherence overall decrease with evolution time. However, for the zero correlation initial state, quantum correlation and coherence are firstly generated and then drop with evolution time; when separation is sufficiently small, they can survive from vacuum fluctuations. For three cases, quantum correlation and coherence first undergo decline and then fluctuate to relatively stable values with the increasing distance between the two atoms. Specially, for the case of zero correlation initial state, quantum correlation and coherence occur periodically revival at fixed zero points and revival amplitude declines gradually with increasing separation of two atoms.
Conformal scalar field wormholes
NASA Technical Reports Server (NTRS)
Halliwell, Jonathan J.; Laflamme, Raymond
1989-01-01
The Euclidian Einstein equations with a cosmological constant and a conformally coupled scalar field are solved, taking the metric to be of the Robertson-Walker type. In the case Lambda = 0, solutions are found which represent a wormhole connecting two asymptotically flat Euclidian regions. In the case Lambda greater than 0, the solutions represent tunneling from a small Tolman-like universe to a large Robertson-Walker universe.
Conformal scalar field wormholes
NASA Technical Reports Server (NTRS)
Halliwell, Jonathan J.; Laflamme, Raymond
1989-01-01
The Euclidian Einstein equations with a cosmological constant and a conformally coupled scalar field are solved, taking the metric to be of the Robertson-Walker type. In the case Lambda = 0, solutions are found which represent a wormhole connecting two asymptotically flat Euclidian regions. In the case Lambda greater than 0, the solutions represent tunneling from a small Tolman-like universe to a large Robertson-Walker universe.
Noncommutativity and scalar field cosmology
Guzman, W.; Sabido, M.; Socorro, J.
2007-10-15
In this work we extend and apply a previous proposal to study noncommutative cosmology to the Friedmann-Robertson-Walker cosmological background coupled to a scalar field. This is done in classical and quantum scenarios. In both cases noncommutativity is introduced in the gravitational field as well as in the scalar field through a deformation of minisuperspace, and we are able to find exact solutions. Finally, the effects of noncommutativity on the classical evolution are analyzed.
Mou, Yun; Chao, John Chin Hao; Chan, Jerry C C
2006-06-01
We demonstrate that an efficient C' <--> C alpha polarization transfer based on J-coupling can be realized under fast magic-angle spinning (MAS) condition without 1H decoupling. Experimental results are presented for model crystalline compounds as well as a non-crystalline 17-residue polypeptide MB(i + 4)EK. Measurements on MB(i + 4)EK demonstrate that 53% of the initial C' polarization was transferred to the cross peaks at 7.05 T under 25 kHz MAS spinning.
Universal effective coupling constant ratios of 3D scalar ϕ4 field theory and pseudo-ɛ expansion
NASA Astrophysics Data System (ADS)
Sokolov, A. I.; Nikitina, M. A.; Kudlis, A.
2016-10-01
The ratios R2k = g2k/gk - 14 of renormalized coupling constants g2k entering the small-field equation of state approach universal values R*2k at criticality. They are calculated for the three-dimensional λϕ4 field theory within the pseudo-ɛ expansion approach. Pseudo-ɛ expansions for R*6, R*8, R*10 are derived in the five-loop approximation, numerical estimates are obtained with a help of the Padé-Borel-Leroy resummation technique. Its use gives R*6 = 1.6488, the number which perfectly agrees with the most recent lattice result R*6 = 1.649. For the octic coupling the pseudo-ɛ expansion is less favorable numerically. Nevertheless the Padé-Borel-Leroy resummation leads to the estimate R*8 = 0.890 close to the values R*8 = 0.87, R*8 = 0.857 extracted from the lattice and field-theoretical calculations. The pseudo-ɛ expansion for R*10 turns out to have big and rapidly increasing coefficients. This makes correspondent estimates strongly dependent on the Borel-Leroy shift parameter b and prevents proper evaluation of R*10
NASA Astrophysics Data System (ADS)
Di Bari, Lorenzo; Kowalewski, Jozef; Bodenhausen, Geoffrey
1990-12-01
Longitudinal nuclear magnetic relaxation in coupled two-spin systems is discussed in terms of magnetization transfer modes, a generalization of the magnetization modes commonly used in the discussion of one-dimensional NMR relaxation experiments. The symmetry properties of the transfer modes and their relationship to the elements of the usual Redfield relaxation matrix are discussed. Experimental strategies for measuring the amplitudes of the transfer modes are discussed and various selective two-dimensional exchange (``soft-NOESY'') methods are proposed. Experimental data are presented for Exifone, a small organic molecule, and the auto- and cross-correlation spectral densities, the magnitudes of the proton chemical shift anisotropies, and the strengths of the dipolar interaction are derived from the spectra.
Roberts, M.D.
1996-09-01
Static spherically symmetric uncoupled scalar space{endash}times have no event horizon and a divergent Kretschmann singularity at the origin of the coordinates. The singularity is always present so that nonstatic solutions have been sought to see if the singularities can develop from an initially singular free space{endash}time. In flat space{endash}time the Klein{endash}Gordon equation {D`Alembertian}{var_phi}=0 has the nonstatic spherically symmetric solution {var_phi}={sigma}({ital v})/{ital r}, where {sigma}({ital v}) is a once differentiable function of the null coordinate {ital v}. In particular, the function {sigma}({ital v}) can be taken to be initially zero and then grow, thus producing a singularity in the scalar field. A similar situation occurs when the scalar field is coupled to gravity via Einstein{close_quote}s equations; the solution also develops a divergent Kretschmann invariant singularity, but it has no overall energy. To overcome this, Bekenstein{close_quote}s theorems are applied to give two corresponding conformally coupled solutions. One of these has positive ADM mass and has the following properties: (i) it develops a Kretschmann invariant singularity, (ii) it has no event horizon, (iii) it has a well-defined source, (iv) it has well-defined junction condition to Minkowski space{endash}time, and (v) it is asymptotically flat with positive overall energy. This paper presents this solution and several other nonstatic scalar solutions. The properties of these solutions which are studied are limited to the following three: (i) whether the solution can be joined to Minkowski space{endash}time, (ii) whether the solution is asymptotically flat, (iii) and, if so, what the solutions{close_quote} Bondi and ADM masses are. {copyright} {ital 1996 American Institute of Physics.}
NASA Astrophysics Data System (ADS)
Michauk, Christine; Gauss, Jürgen
2007-07-01
An analytic scheme for the computation of scalar-relativistic corrections to nuclear forces is presented. Relativistic corrections are included via a perturbative treatment involving the mass-velocity and the one-electron and two-electron Darwin terms. Such a scheme requires mixed second derivatives of the nonrelativistic energy with respect to the relativistic perturbation and the nuclear coordinates and can be implemented using available second-derivative techniques. Our implementation for Hartree-Fock self-consistent field, second-order Møller-Plesset perturbation theory, as well as the coupled-cluster level is used to investigate the relativistic effects on the geometrical parameters and harmonic vibrational frequencies for a set of molecules containing light elements (HX, X =F, Cl, Br; H2X, X =O, S; HXY, X =O, S and Y =F, Cl, Br). The focus of our calculations is the basis-set dependence of the corresponding relativistic effects, additivity of electron correlation and relativistic effects, and the importance of core correlation on relativistic effects.
Michauk, Christine; Gauss, Jürgen
2007-07-28
An analytic scheme for the computation of scalar-relativistic corrections to nuclear forces is presented. Relativistic corrections are included via a perturbative treatment involving the mass-velocity and the one-electron and two-electron Darwin terms. Such a scheme requires mixed second derivatives of the nonrelativistic energy with respect to the relativistic perturbation and the nuclear coordinates and can be implemented using available second-derivative techniques. Our implementation for Hartree-Fock self-consistent field, second-order Moller-Plesset perturbation theory, as well as the coupled-cluster level is used to investigate the relativistic effects on the geometrical parameters and harmonic vibrational frequencies for a set of molecules containing light elements (HX, X=F, Cl, Br; H2X, X=O, S; HXY, X=O, S and Y=F, Cl, Br). The focus of our calculations is the basis-set dependence of the corresponding relativistic effects, additivity of electron correlation and relativistic effects, and the importance of core correlation on relativistic effects.
Cheng, Lan
2015-08-14
Quantum-chemical computations of nuclear quadrupole-coupling parameters for 24 open-shell states of small molecules based on non-relativistic and spin-free exact two-component (SFX2C) relativistic equation-of-motion coupled-cluster (EOM-CC) as well as spin-orbital-based restricted open-shell Hartree-Fock coupled-cluster (ROHF-CC) methods are reported. Relativistic effects, the performance of the EOM-CC and ROHF-CC methods for treating electron correlation, as well as basis-set convergence have been carefully analyzed. Consideration of relativistic effects is necessary for accurate calculations on systems containing third-row (K-Kr) and heavier elements, as expected, and the SFX2C approach is shown to be a useful cost-effective option here. Further, it is demonstrated that the EOM-CC methods constitute flexible and accurate alternatives to the ROHF-CC methods in the calculations of nuclear quadrupole-coupling parameters for open-shell states.
2016-01-01
In addition to its well-known roles as an electrophile and general acid, the side chain of histidine often serves as a hydrogen bond (H-bond) acceptor. These H-bonds provide a convenient pH-dependent switch for local structure and functional motifs. In hundreds of instances, a histidine caps the N-terminus of α- and 310-helices by forming a backbone NH···Nδ1 H-bond. To characterize the resilience and dynamics of the histidine cap, we measured the trans H-bond scalar coupling constant, 2hJNN, in several forms of Group 1 truncated hemoglobins and cytochrome b5. The set of 19 measured 2hJNN values were between 4.0 and 5.4 Hz, generally smaller than in nucleic acids (∼6–10 Hz) and indicative of longer, weaker bonds in the studied proteins. A positive linear correlation between 2hJNN and the difference in imidazole ring 15N chemical shift (Δ15N = |δ15Nδ1 – δ15Nε2|) was found to be consistent with variable H-bond length and variable cap population related to the ionization of histidine in the capping and noncapping states. The relative ease of 2hJNN detection suggests that this parameter can become part of the standard arsenal for describing histidines in helix caps and other key structural and catalytic elements involving NH···N H-bonds. The combined nucleic acid and protein data extend the utility of 2hJNN as a sensitive marker of local structural, dynamic, and thermodynamic properties in biomolecules. PMID:26523621
Cheng, Lan; Gauss, Jürgen; Ruscic, Branko; ...
2017-01-12
Benchmark scalar-relativistic coupled-cluster calculations for dissociation energies of the 20 diatomic molecules containing 3d transition metals in the 3dMLBE20 database ( J. Chem. Theory Comput. 2015, 11, 2036) are reported in this paper. Electron correlation and basis set effects are systematically studied. The agreement between theory and experiment is in general satisfactory. For a subset of 16 molecules, the standard deviation between computational and experimental values is 9 kJ/mol with the maximum deviation being 15 kJ/mol. The discrepancies between theory and experiment remain substantial (more than 20 kJ/mol) for VH, CrH, CoH, and FeH. To explore the source of themore » latter discrepancies, the analysis used to determine the experimental dissociation energies for VH and CrH is revisited. It is shown that, if improved values are used for the heterolytic C–H dissociation energies of di- and trimethylamine involved in the experimental determination, the experimental values for the dissociation energies of VH and CrH are increased by 18 kJ/mol, such that D0(VH) = 223 ± 7 kJ/mol and D0(CrH) = 204 ± 7 kJ/mol (or De(VH) = 233 ± 7 kJ/mol and De(CrH) = 214 ± 7 kJ/mol). Finally, the new experimental values agree quite well with the calculated values, showing the consistency of the computation and the measured reaction thresholds.« less
Exact computation of the 3-j and 6-j symbols
NASA Astrophysics Data System (ADS)
Lai, Shan-Tao; Chiu, Ying-Nan
1990-12-01
A simple FORTRAN program for the exact computation of 3- j and 6- j symbols has been written for the VAX with VMS version v5.1 in our university's computing center. It goes beyond and contains all of the 3- j and 6- j symbols evaluated in the book by M. Rotenberg, R. Bivins, N. Metropolis and J.K. Wooten Jr. The 3- j symbols up to ( 30m130m2 30 m3)] and 6- j symbols up to { 202020202020} can be computed exactly by this program. Approximate values for larger j's up to 200m1200m2200m3 and { 200200200200200220} can also be computed by this program.
Noncommutative Quantum Scalar Field Cosmology
Diaz Barron, L. R.; Lopez-Dominguez, J. C.; Sabido, M.; Yee, C.
2010-07-12
In this work we study noncommutative Friedmann-Robertson-Walker (FRW) cosmology coupled to a scalar field endowed with an exponential potential. The quantum scenario is analyzed in the Bohmian formalism of quantum trajectories to investigate the effects of noncommutativity in the evolution of the universe.
Scalar-tensor linear inflation
NASA Astrophysics Data System (ADS)
Artymowski, Michał; Racioppi, Antonio
2017-04-01
We investigate two approaches to non-minimally coupled gravity theories which present linear inflation as attractor solution: a) the scalar-tensor theory approach, where we look for a scalar-tensor theory that would restore results of linear inflation in the strong coupling limit for a non-minimal coupling to gravity of the form of f(varphi)R/2; b) the particle physics approach, where we motivate the form of the Jordan frame potential by loop corrections to the inflaton field. In both cases the Jordan frame potentials are modifications of the induced gravity inflationary scenario, but instead of the Starobinsky attractor they lead to linear inflation in the strong coupling limit.
NASA Astrophysics Data System (ADS)
Lasukov, V. V.
2012-06-01
It is shown that negative Scalars can claim to be the object referred to as black holes, therefore observation of black holes means observation of Scalars. In contrast to blackholes, negative Scalars contain no singularity inside. Negative Scalars can be observed from the effect of generation of ordinary matter by the Lemaître primordial atom.
Maximum J Pairing and Asymptotic Behavior of the 3j and 9j Coefficients
NASA Astrophysics Data System (ADS)
Hertz-Kintish, Daniel; Zamick, Larry; Kleszyk, Brian
2014-09-01
We investigate the large j behavior of certain 3 j and 9 j symbols, where j is the total angular momentum of one particle in a given shell. Our motivation is the problem of maximum J pairing in nuclei, along with the more familiar J = 0 pairing. Maximum J pairing leads to an increase in J = 2 coupling of two protons and two neutrons relative to J = 0 . We find that a coupling unitary 9 j symbol (U 9 j) is very weak as j increases, leading to wavefunctions which are to an excellent approximation single U 9 j coefficients. Our study of the large j behavior of coupling unitary 9 j symbols is through the consideration of the case when the total angular momentum I is equal to Imax - 2 n and Imax ≡ 4 j - 2 , where n = 0 , 1 , 2 , ... . We here derive asymptotic approximations of coupling 3 j symbols and find that the 3 j ~j - 3 / 4 in the high j limit. One major analytical tool we used is the Stirling Approximation. Through analytical, numerical, and graphical methods, we show the power law behavior of the coupling unitary 9 j symbols in the n / j << 1 limit, i.e. U 9 j ~j-n . Power-law behavior is evident if there is a linear dependence of ln | U 9 j | vs. ln j . We also present some examples of percent errors in our approximations. We investigate the large j behavior of certain 3 j and 9 j symbols, where j is the total angular momentum of one particle in a given shell. Our motivation is the problem of maximum J pairing in nuclei, along with the more familiar J = 0 pairing. Maximum J pairing leads to an increase in J = 2 coupling of two protons and two neutrons relative to J = 0 . We find that a coupling unitary 9 j symbol (U 9 j) is very weak as j increases, leading to wavefunctions which are to an excellent approximation single U 9 j coefficients. Our study of the large j behavior of coupling unitary 9 j symbols is through the consideration of the case when the total angular momentum I is equal to Imax - 2 n and Imax ≡ 4 j - 2 , where n = 0 , 1 , 2 , ... . We here
Creation of the universe with a stealth scalar field
NASA Astrophysics Data System (ADS)
Maeda, Hideki; Maeda, Kei-ichi
2012-12-01
The stealth scalar field is a nontrivial configuration without any backreaction to geometry, which is characteristic for nonminimally coupled scalar fields. Studying the creation probability of the de Sitter universe with a stealth scalar field by Hartle and Hawking’s semiclassical method, we show that the effect of the stealth field can be significant. For the class of scalar fields we consider, creation with a stealth field is possible for a discrete value of the coupling constant, and its creation probability is always less than that with a trivial scalar field. However, those creation rates can be almost the same depending on the parameters of the theory.
Exact scalar-tensor cosmological models
NASA Astrophysics Data System (ADS)
Belinchón, J. A.; Harko, T.; Mak, M. K.
Scalar-tensor gravitational theories are important extensions of standard general relativity, which can explain both the initial inflationary evolution, as well as the late accelerating expansion of the universe. In the present paper, we investigate the cosmological solution of a scalar-tensor gravitational theory, in which the scalar field ϕ couples to the geometry via an arbitrary function F(ϕ). The kinetic energy of the scalar field as well as its self-interaction potential V (ϕ) are also included in the gravitational action. By using a standard mathematical procedure, the Lie group approach, and Noether symmetry techniques, we obtain several exact solutions of the gravitational field equations describing the time evolutions of a flat Friedman-Robertson-Walker universe in the framework of the scalar-tensor gravity. The obtained solutions can describe both accelerating and decelerating phases during the cosmological expansion of the universe.
Black hole hair in generalized scalar-tensor gravity.
Sotiriou, Thomas P; Zhou, Shuang-Yong
2014-06-27
The most general action for a scalar field coupled to gravity that leads to second-order field equations for both the metric and the scalar--Horndeski's theory--is considered, with the extra assumption that the scalar satisfies shift symmetry. We show that in such theories, the scalar field is forced to have a nontrivial configuration in black hole spacetimes, unless one carefully tunes away a linear coupling with the Gauss-Bonnet invariant. Hence, black holes for generic theories in this class will have hair. This contradicts a recent no-hair theorem which seems to have overlooked the presence of this coupling.
Dynamical scalar hair formation around a Schwarzschild black hole
NASA Astrophysics Data System (ADS)
Benkel, Robert; Sotiriou, Thomas P.; Witek, Helvi
2016-12-01
Scalar fields coupled to the Gauss-Bonnet invariant evade the known no-hair theorems and have nontrivial configurations around black holes. We focus on a scalar field that couples linearly to the Gauss-Bonnet invariant and hence exhibits shift symmetry. We study its dynamical evolution and the formation of scalar hair in a Schwarzschild background. We show that the evolution eventually settles to the known static hairy solutions in the appropriate limit.
Phenomenology of bulk scalar singlets in the Randall-Sundrum model
NASA Astrophysics Data System (ADS)
Abu-Ajamieh, Fayez; Houtz, Rachel; Zheng, Rui
2017-06-01
We present a Randall-Sundrum toy model with an added scalar singlet that couples only to KK fermions in the bulk. Such a scalar would nontrivially affect radion phenomenology. In addition, we examine the radion phenomenology in light of the new scalar and show how this scalar could present another probe to search for the radion.
Inflation in anisotropic scalar-tensor theories
NASA Technical Reports Server (NTRS)
Pimentel, Luis O.; Stein-Schabes, Jaime
1988-01-01
The existence of an inflationary phase in anisotropic Scalar-Tensor Theories is investigated by means of a conformal transformation that allows us to rewrite these theories as gravity minimally coupled to a scalar field with a nontrivial potential. The explicit form of the potential is then used and the No Hair Theorem concludes that there is an inflationary phase in all open or flat anisotropic spacetimes in these theories. Several examples are constructed where the effect becomes manifest.
29 CFR 451.4 - Labor organizations under section 3(j).
Code of Federal Regulations, 2010 CFR
2010-07-01
... 29 Labor 2 2010-07-01 2010-07-01 false Labor organizations under section 3(j). 451.4 Section 451.4... 1959 § 451.4 Labor organizations under section 3(j). (a) General. Section 3(j) sets forth five... one of these categories listed in section 3(j) is subject to the requirements of the Act....
29 CFR 451.4 - Labor organizations under section 3(j).
Code of Federal Regulations, 2013 CFR
2013-07-01
... 29 Labor 2 2013-07-01 2013-07-01 false Labor organizations under section 3(j). 451.4 Section 451.4... 1959 § 451.4 Labor organizations under section 3(j). (a) General. Section 3(j) sets forth five... one of these categories listed in section 3(j) is subject to the requirements of the Act. (b...
29 CFR 451.4 - Labor organizations under section 3(j).
Code of Federal Regulations, 2014 CFR
2014-07-01
... 29 Labor 2 2014-07-01 2014-07-01 false Labor organizations under section 3(j). 451.4 Section 451.4... 1959 § 451.4 Labor organizations under section 3(j). (a) General. Section 3(j) sets forth five... one of these categories listed in section 3(j) is subject to the requirements of the Act. (b...
29 CFR 451.4 - Labor organizations under section 3(j).
Code of Federal Regulations, 2012 CFR
2012-07-01
... 29 Labor 2 2012-07-01 2012-07-01 false Labor organizations under section 3(j). 451.4 Section 451.4... 1959 § 451.4 Labor organizations under section 3(j). (a) General. Section 3(j) sets forth five... one of these categories listed in section 3(j) is subject to the requirements of the Act. (b...
29 CFR 451.4 - Labor organizations under section 3(j).
Code of Federal Regulations, 2011 CFR
2011-07-01
... 29 Labor 2 2011-07-01 2011-07-01 false Labor organizations under section 3(j). 451.4 Section 451.4... 1959 § 451.4 Labor organizations under section 3(j). (a) General. Section 3(j) sets forth five... one of these categories listed in section 3(j) is subject to the requirements of the Act. (b...
NEUTRON STAR STRUCTURE IN THE PRESENCE OF SCALAR FIELDS
Crawford, James P.; Kazanas, Demosthenes
2009-08-20
Motivated by the possible presence of scalar fields on cosmological scales, suggested by the recent measurement of the deceleration parameter by supernovae surveys, we present models of neutron star structure under the assumption that a scalar field makes a significant contribution to the stress energy momentum tensor, in addition to that made by the normal matter. To that end we solve the coupled Einstein-scalar field-hydrostatic balance equations to compute the effect of the presence of the scalar field on the neutron star structure. We find that the presence of the scalar field does change the structure of the neutron star, especially in cases of strong coupling between the scalar field and the matter density. We present the neutron star radius as a function of the matter-scalar field coupling constant for different values of the neutron star central density. The presence of the scalar field does affect both the maximum neutron star mass and its radius, the latter increasing with the value of the above coupling constant. Our results can provide limits to the scalar field-matter coupling through spectro-temporal observations of accreting or isolated neutron stars.
Scalar self-interactions loosen constraints from fifth force searches
Gubser, Steven S.; Khoury, Justin
2004-11-15
The mass of a scalar field mediating a fifth force is tightly constrained by experiments. We show, however, that adding a quartic self-interaction for such a scalar makes most tests much less constraining: the nonlinear equation of motion masks the coupling of the scalar to matter through the chameleon mechanism. We discuss consequences for fifth force experiments. In particular, we find that, with quartic coupling of order unity, a gravitational strength interaction with matter is allowed by current constraints. We show that our chameleon scalar field results in experimental signatures that could be detected through modest improvements of current laboratory set-ups.
Neutron Star Structure in the Presence of Scalar Fields
NASA Technical Reports Server (NTRS)
Kazanas, Demosthenes
2004-01-01
Motivated by the possible presence of scalar fields on astrophysical scales, suggested by the apparent acceleration of the universe implied by the supernovae surveys, we present models of neutron star structure including the contribution of a (massless) scalar field to the stress energy momentum tensor, in addition to that made by the normal matter. To that end we solve the coupled Einstein -- scalar field -- hydrostatic balance equations to compute the effect of the presence of the scalar field on the neutron star structure. We find that the presence of the scalar field does change the structure of the neutron star, especially in cases of strong coupling between the scalar field and the matter density. We present the neutron star radius as a function of the matter--scalar field coupling constant for different values of the neutron star central density. The presence of the scalar field affects both the maximum neutron star mass and Its radius, the latter increasing with the value of the above coupling constant. We also compute particle and photon geodesics in the geometry of these neutron stars as well as to the geometry of black holes with different values of the scalar field. Our results may be testable with timing observations of accreting neutron stars.
CDSM - A New Scalar Magnetometer
NASA Astrophysics Data System (ADS)
Pollinger, Andreas; Lammegger, Roland; Magnes, Werner; Ellmeier, Michaela; Baumjohann, Wolfgang; Windholz, Laurentius
2010-05-01
There are potential advantages of flying a magnetometer sensor suite combining a vector fluxgate with a scalar absolute sensor. Absolute sensors offer superior stability over temperature and time, lower intrinsic noise and offset-free measurements; the latter is very useful for fluxgate calibration on a 3-axis stabilized spacecraft. A space-adapted design of a new type of scalar magnetometer, called Coupled Dark State Magnetometer (CDSM), is under development jointly by the Institute of Experimental Physics of the Graz University of Technology and the Space Research Institute of the Austrian Academy of Sciences. The CDSM is based on two-photon spectroscopy of free alkali atoms using a multi chromatic laser field. The measurement is made completely independent of the sensor temperature by a clever coupling of several coherent population trapping resonances. The CDSM promises a less resource-demanding instrument design (500g, 1W) compared to previously flown scalar magnetometers. A significant advantage is the fact that the extended measurement range of 7 decades is covered by only one sensor cell filled with Rubidium atoms (and a buffer gas), making the sensor core small and compact. Neither a radio frequency-based excitation at the sensor unit (150g) is needed for the operation, nor is it necessary to implement motor driven moving parts or a double cell unit in order to guarantee isotropic measurements like for other scalar sensors. A noise floor of 70pTrms/√Hz was measured in a first configuration. It is worth to mention that there is no 1/f noise below the implemented corner frequency of 3Hz. By changing from Rubidium D2 to D1 excitation line we are able to reduce the noise by a factor of 10 to 7pT. The technology readiness level of the CDSM is 3 at the moment and it shall reach level 5 (breadboard validation in relevant environment) by beginning of 2011.
Scalar explanation of diphoton excess at LHC
NASA Astrophysics Data System (ADS)
Han, Huayong; Wang, Shaoming; Zheng, Sibo
2016-06-01
Inspired by the diphoton signal excess observed in the latest data of 13 TeV LHC, we consider either a 750 GeV real scalar or pseudo-scalar responsible for this anomaly. We propose a concrete vector-like quark model, in which the vector-like fermion pairs directly couple to this scalar via Yukawa interaction. For this setting the scalar is mainly produced via gluon fusion, then decays at the one-loop level to SM diboson channels gg , γγ , ZZ , WW. We show that for the vector-like fermion pairs with exotic electric charges, such model can account for the diphoton excess and is consistent with the data of 8 TeV LHC simultaneously in the context of perturbative analysis.
A Search for Scalar Chameleons with ADMX
Rybka, G.; Hotz, M.; Rosenberg, L.J.; Asztalos, S.J.; Carosi, G.; Hagmann, C.; Kinion, D.; van Bibber, K.; Hoskins, J.; Martin, C.; Sikivie, P.; Tanner, D.B.; Bradley, R.; Clarke, J.
2010-04-26
Scalar fields with a"chameleon" property, in which the effective particle mass is a function of its local environment, are common to many theories beyond the standard model and could be responsible for dark energy. If these fields couple weakly to the photon, they could be detectable through the afterglow effect of photon-chameleon-photon transitions. The ADMX experiment was used in the first chameleon search with a microwave cavity to set a new limit on scalar chameleon-photon coupling beta_gamma excluding values between 2x109 and 5x1014 for effective chameleon masses between 1.9510 and 1:9525 micro eV.
Spacetime of Constant Scalar Curvature in N = 1 Supergravity
Gunara, Bobby Eka
2010-12-23
In this short paper we show the existence of solitonic solutions of four dimensional ungauged N = 1 supergravity coupled to arbitrary vector and chiral multiplets whose Ricci scalar curvature is constant. The Ricci scalar of spacetimes indeed depends on the {sigma}-model, namely the complex scalars and their first derivative. Then, we give two explicit models, namely static domain walls and static spherical symmetric black holes which are related to our previous works.
Kempgens, Pierre; Rosé, Jacky
2011-03-01
Two-dimensional ⁵⁹Co correlation spectroscopy (COSY) and double-quantum-filtered (DQF) COSY NMR experiments are reported for the tetrahedral mixed-metal cluster HFeCo₃(CO)₁₀(PCyH₂)(PPh₂[CH₂C(O)Ph]), which consists from the point of view of ⁵⁹Co NMR spectroscopy, of an AMX system of three-spin S=7/2. Both 2D NMR spectra prove the existence of a J scalar coupling constant between non-equivalent ⁵⁹Co nuclei. By contrast to what happens with the conventional 2D ⁵⁹Co COSY NMR spectrum, it was possible to simulate the 2D ⁵⁹Co DQF-COSY NMR spectrum by density matrix calculations in order to extract the values of the ¹J(⁵⁹Co-⁵⁹Co) coupling constants. The comparison between experimental and theoretical 2D NMR spectra gives spin-couplings constants of several hundreds Hertz for this cluster. Copyright © 2010 Elsevier Inc. All rights reserved.
Phenomenology of a pseudo-scalar inflaton: naturally large nongaussianity
Barnaby, Neil; Namba, Ryo; Peloso, Marco E-mail: namba@physics.umn.edu
2011-04-01
Many controlled realizations of chaotic inflation employ pseudo-scalar axions. Pseudo-scalars φ are naturally coupled to gauge fields through cφF F-tilde . In the presence of this coupling, gauge field quanta are copiously produced by the rolling inflaton. The produced gauge quanta, in turn, source inflaton fluctuations via inverse decay. These new cosmological perturbations add incoherently with the ''vacuum'' perturbations, and are highly nongaussian. This provides a natural mechanism to generate large nongaussianity in single or multi field slow-roll inflation. The resulting phenomenological signatures are highly distinctive: large nongaussianity of (nearly) equilateral shape, in addition to detectably large values of both the scalar spectral tilt and tensor-to-scalar ratio (both being typical of large field inflation). The WMAP bound on nongaussianity implies that the coupling c of the pseudo-scalar inflaton to any gauge field must be smaller than about 10{sup 2} M{sub p}{sup −1}.
Inflation as AN Attractor in Scalar Cosmology
NASA Astrophysics Data System (ADS)
Kim, Hyeong-Chan
2013-06-01
We study an inflation mechanism based on attractor properties in cosmological evolutions of a spatially flat Friedmann-Robertson-Walker spacetime based on the Einstein-scalar field theory. We find a new way to get the Hamilton-Jacobi equation solving the field equations. The equation relates a solution "generating function" with the scalar potential. We analyze its stability and find a later time attractor which describes a Universe approaching to an eternal-de Sitter inflation driven by the potential energy, V0>0. The attractor exists when the potential is regular and does not have a linear and quadratic terms of the field. When the potential has a mass term, the attractor exists if the scalar field is in a symmetric phase and is weakly coupled, λ<9V0/16. We also find that the attractor property is intact under small modifications of the potential. If the scalar field has a positive mass-squared or is strongly coupled, there exists a quasi-attractor. However, the quasi-attractor property disappears if the potential is modified. On the whole, the appearance of the eternal inflation is not rare in scalar cosmology in the presence of an attractor.
NASA Astrophysics Data System (ADS)
Mendes, Raissa F. P.; Ortiz, Néstor
2016-06-01
Scalar-tensor theories of gravity are extensions of general relativity (GR) including an extra, nonminimally coupled scalar degree of freedom. A wide class of these theories, albeit indistinguishable from GR in the weak field regime, predicts a radically different phenomenology for neutron stars, due to a nonperturbative, strong-field effect referred to as spontaneous scalarization. This effect is known to occur in theories where the effective linear coupling β0 between the scalar and matter fields is sufficiently negative, i.e. β0≲-4.35 , and has been strongly constrained by pulsar timing observations. In the test-field approximation, spontaneous scalarization manifests itself as a tachyonic-like instability. Recently, it was argued that, in theories where β0>0 , a similar instability would be triggered by sufficiently compact neutron stars obeying realistic equations of state. In this work we investigate the end state of this instability for some representative coupling functions with β0>0 . This is done both through an energy balance analysis of the existing equilibrium configurations, and by numerically determining the nonlinear Cauchy development of unstable initial data. We find that, contrary to the β0<0 case, the final state of the instability is highly sensitive to the details of the coupling function, varying from gravitational collapse to spontaneous scalarization. In particular, we show, for the first time, that spontaneous scalarization can happen in theories with β0>0 , which could give rise to novel astrophysical tests of the theory of gravity.
Self-accelerating solutions of scalar-tensor gravity
Barenboim, Gabriela; Lykken, Joseph D E-mail: lykken@fnal.gov
2008-03-15
Scalar-tensor gravity is the simplest and best understood modification of general relativity, consisting of a real scalar field coupled directly to the Ricci scalar curvature. Models of this type have self-accelerating solutions. In an example inspired by string dilaton couplings, scalar-tensor gravity coupled to ordinary matter exhibits a de Sitter type expansion, even in the presence of a negative cosmological constant whose magnitude exceeds that of the matter density. This unusual behavior does not require phantoms, ghosts or other exotic sources. More generally, we show that any expansion history can be interpreted as arising partly or entirely from scalar-tensor gravity. To distinguish any quintessence or inflation model from its scalar-tensor variants, we use the fact that scalar-tensor models imply deviations of the post-Newtonian parameters of general relativity and time variation of Newton's gravitational coupling G. We emphasize that next-generation probes of modified GR and the time variation of G are an essential complement to dark energy probes based on luminosity-distance measurements.
Liu Yunhu; Shao Jianxin; Wang Xiaogang; Zhang Ziying; Li Demin
2008-02-01
Based on the main assumption that the D{sub sJ}(2860) belongs to the 2{sup 3}P{sub 0} qq multiplet, the masses of the scalar meson nonet are estimated in the framework of the relativistic independent quark model, Regge phenomenology, and meson-meson mixing. We suggest that the a{sub 0}(1005), K{sub 0}*(1062), f{sub 0}(1103), and f{sub 0}(564) constitute the ground scalar meson nonet; it is supposed that these states would likely correspond to the observed states a{sub 0}(980), {kappa}(900), f{sub 0}(980), and f{sub 0}(600)/{sigma}, respectively. Also a{sub 0}(1516), K{sub 0}*(1669), f{sub 0}(1788), and f{sub 0}(1284) constitute the first radial scalar meson nonet, it is supposed that these states would likely correspond to the observed states a{sub 0}(1450), K{sub 0}*(1430), f{sub 0}(1710), and f{sub 0}(1370), respectively. The scalar state f{sub 0}(1500) may be a good candidate for the ground scalar glueball. The agreement between the present findings and those given by other different approaches is satisfactory.
Neutrino masses and scalar singlet dark matter
NASA Astrophysics Data System (ADS)
Bhattacharya, Subhaditya; Jana, Sudip; Nandi, S.
2017-03-01
We propose a simple extension of the Standard Model (SM) which has a viable dark matter (DM) candidate and can explain the generation of tiny neutrino masses. The DM is an electroweak (EW) singlet scalar S , odd under an imposed exact Z2 symmetry, that interacts with the SM through the "Higgs portal" coupling, while all other particles are even under Z2. The model also has an EW isospin 3 /2 scalar Δ and a pair of EW isospin vectors Σ and Σ ¯, which are responsible for generating tiny neutrino mass via the effective dimension-seven operator. Thanks to the additional interactions with Δ , the scalar singlet DM S survives a large region of parameter space by relic density constraints from WMAP/Planck and direct search bounds from updated LUX data. Constraints on the model from the LHC are also discussed.
On the late-time cosmology of a condensed scalar field
NASA Astrophysics Data System (ADS)
Ghalee, Amir
2016-04-01
We study the late-time cosmology of a scalar field with a kinetic term non-minimally coupled to gravity. It is demonstrated that the scalar field dominate the radiation matter and the cold dark matter (CDM). Moreover, we show that eventually the scalar field will be condensed and results in an accelerated expansion. The metric perturbations around the condensed phase of the scalar field are investigated and it has been shown that the ghost instability and gradient instability do not exist.
Scalar and anisotropic J interactions in undoped InP: A triple-resonance NMR study
NASA Astrophysics Data System (ADS)
Tomaselli, Marco; Degraw, David; Yarger, Jeffery L.; Augustine, Matthew P.; Pines, Alexander
1998-10-01
The heteronuclear J-coupling tensor between nearest neighbor 31P and 113In spins in undoped InP is investigated by means of 113In-->31P polarization transfer under rapid magic angle spinning (MAS). The scalar contribution can be measured directly and is found to have the value \\|Jiso(31P-113,115In)\\|=(225+/-10) Hz. The principal value of the traceless anisotropic J-coupling tensor (pseudodipolar coupling) is determined to be Janiso(31P-113,115In)=2/3[J||(31P-113,115In)-J⊥(31P-113,115In)]=(813+/-50) or (1733+/-50) Hz, assuming axial symmetry with the principal axis parallel to the In-P bond. Our values deviate from those reported previously [M. Engelsberg and R. E. Norberg, Phys. Rev. B 5, 3395 (1972)] [based on a moment analysis of the 31P resonance \\|Jiso(31P-113,115In)\\|=350 Hz and Janiso(31P-113,115In)=1273 Hz], but confirm the postulate that the nearest neighbor 31P-113,115In magnetic dipolar and pseudodipolar interactions are of the same order of magnitude and partially cancel each other.
A geometrical approach to degenerate scalar-tensor theories
NASA Astrophysics Data System (ADS)
Chagoya, Javier; Tasinato, Gianmassimo
2017-02-01
Degenerate scalar-tensor theories are recently proposed covariant theories of gravity coupled with a scalar field. Despite being characterised by higher order equations of motion, they do not propagate more than three degrees of freedom, thanks to the existence of constraints. We discuss a geometrical approach to degenerate scalar-tensor systems, and analyse its consequences. We show that some of these theories emerge as a certain limit of DBI Galileons. In absence of dynamical gravity, these systems correspond to scalar theories enjoying a symmetry which is different from Galileon invariance. The scalar theories have however problems concerning the propagation of fluctuations around a time dependent background. These issues can be tamed by breaking the symmetry by hand, or by minimally coupling the scalar with dynamical gravity in a way that leads to degenerate scalar-tensor systems. We show that distinct theories can be connected by a relation which generalizes Galileon duality, in certain cases also when gravity is dynamical. We discuss some implications of our results in concrete examples. Our findings can be helpful for assessing stability properties and understanding the non-perturbative structure of systems based on degenerate scalar-tensor systems.
NASA Astrophysics Data System (ADS)
Rejon-Barrera, Fernando; Robbins, Daniel
2016-01-01
We work out all of the details required for implementation of the conformal bootstrap program applied to the four-point function of two scalars and two vectors in an abstract conformal field theory in arbitrary dimension. This includes a review of which tensor structures make appearances, a construction of the projectors onto the required mixed symmetry representations, and a computation of the conformal blocks for all possible operators which can be exchanged. These blocks are presented as differential operators acting upon the previously known scalar conformal blocks. Finally, we set up the bootstrap equations which implement crossing symmetry. Special attention is given to the case of conserved vectors, where several simplifications occur.
NASA Astrophysics Data System (ADS)
Claeys, Pieter W.; De Baerdemacker, Stijn; Van Raemdonck, Mario; Van Neck, Dimitri
2015-10-01
Starting from integrable su(2) (quasi-)spin Richardson-Gaudin (RG) XXZ models we derive several properties of integrable spin models coupled to a bosonic mode. We focus on the Dicke-Jaynes-Cummings-Gaudin models and the two-channel (p + ip)-wave pairing Hamiltonian. The pseudo-deformation of the underlying su(2) algebra is here introduced as a way to obtain these models in the contraction limit of different RG models. This allows for the construction of the full set of conserved charges, the Bethe ansatz state, and the resulting RG equations. For these models an alternative and simpler set of quadratic equations can be found in terms of the eigenvalues of the conserved charges. Furthermore, the recently proposed eigenvalue-based determinant expressions for the overlaps and form factors of local operators are extended to these models, linking the results previously presented for the Dicke-Jaynes-Cummings-Gaudin models with the general results for RG XXZ models.
Pragmatic Aspects of Scalar Modifiers
ERIC Educational Resources Information Center
Sawada, Osamu
2010-01-01
This dissertation investigates the pragmatic aspects of scalar modifiers from the standpoint of the interface between semantics and pragmatics, focusing on (i) the (non) parallelism between the truth-conditional scalar modifiers and the non-truth-conditional scalar modifiers, (ii) the compositionality and dimensionality of non-truth-conditional…
Plasmon effects in light scalar and pseudo-scalar emission from a supernova.
NASA Astrophysics Data System (ADS)
Altherr, T.
1991-05-01
The emission of light scalars and pseudo-scalars (axion-like particles) coupled to the chromo/electric field from a QCD/AED plasma at high temperature and very high density is studied in detail. The calculation is then applied to the SN 1987A event for which new bounds on the Peccei-Quinn symmetry breaking scale fa are derived, fa ⪆ 3×109GeV in presence of a quark-gluon core and fa ⪆ 107GeV, which is the same bound as the one obtained from red giant stars, by considering axion emission from the electron gas.
NASA Astrophysics Data System (ADS)
Anderson, David; Yunes, Nicolás; Barausse, Enrico
2016-11-01
Certain scalar-tensor theories of gravity that generalize Jordan-Fierz-Brans-Dicke theory are known to predict nontrivial phenomenology for neutron stars. In these theories, first proposed by Damour and Esposito-Farèse, the scalar field has a standard kinetic term and couples conformally to the matter fields. The weak equivalence principle is therefore satisfied, but scalar effects may arise in strong-field regimes, e.g., allowing for violations of the strong equivalence principle in neutron stars ("spontaneous scalarization") or in sufficiently tight binary neutron-star systems ("dynamical/induced scalarization"). The original scalar-tensor theory proposed by Damour and Esposito-Farèse is in tension with Solar System constraints (for couplings that lead to scalarization), if one accounts for cosmological evolution of the scalar field and no mass term is included in the action. We extend here the conformal coupling of that theory, in order to ascertain if, in this way, Solar System tests can be passed, while retaining a nontrivial phenomenology for neutron stars. We find that, even with this generalized conformal coupling, it is impossible to construct a theory that passes both big bang nucleosynthesis and Solar System constraints, while simultaneously allowing for scalarization in isolated/binary neutron stars.
A nonlinear dynamics for the scalar field in Randers spacetime
NASA Astrophysics Data System (ADS)
Silva, J. E. G.; Maluf, R. V.; Almeida, C. A. S.
2017-03-01
We investigate the properties of a real scalar field in the Finslerian Randers spacetime, where the local Lorentz violation is driven by a geometrical background vector. We propose a dynamics for the scalar field by a minimal coupling of the scalar field and the Finsler metric. The coupling is intrinsically defined on the Randers spacetime, and it leads to a non-canonical kinetic term for the scalar field. The nonlinear dynamics can be split into a linear and nonlinear regimes, which depend perturbatively on the even and odd powers of the Lorentz-violating parameter, respectively. We analyze the plane-waves solutions and the modified dispersion relations, and it turns out that the spectrum is free of tachyons up to second-order.
Scalar and Pseudoscalar Glueballs
NASA Astrophysics Data System (ADS)
Cheng, Hai-Yang
We employ two simple and robust results to constrain the mixing matrix of the isosinglet scalar mesons f0(1710), f0(1500), f0(1370): one is the approximate SU(3) symmetry empirically observed in the scalar sector above 1 GeV and confirmed by lattice QCD, and the other is the scalar glueball mass at 1710 MeV in the quenched approximation. In the SU(3) symmetry limit, f0(1500) becomes a pure SU(3) octet and is degenerate with a0(1450), while f0(1370) is mainly an SU(3) singlet with a slight mixing with the scalar glueball which is the primary component of f0(1710). These features remain essentially unchanged even when SU(3) breaking is taken into account. The observed enhancement of ωf0(1710) production over ɸf0(1710) in hadronic J/ψ decays and the copious f0(1710) production in radiative J/ψ decays lend further support to the prominent glueball nature of f0(1710). We deduce the mass of the pseudoscalar glueball G from an η-η‧-G mixing formalism based on the anomalous Ward identity for transition matrix elements. With the inputs from the recent KLOE experiment, we find a solution for the pseudoscalar glueball mass around (1.4±0.1) GeV, which is fairly insensitive to a range of inputs with or without Okubo-Zweig-Iizuka-rule violating effects. This affirms that η(1405), having a large production rate in the radiative J/ψ decay and not seen in γγ reactions, is indeed a leading candidate for the pseudoscalar glueball. It is much lower than the results from quenched lattice QCD (> 2.0 GeV) due to the dynamic fermion effect. It is thus urgent to have a full QCD lattice calculation of pseudoscalar glueball masses.
NASA Astrophysics Data System (ADS)
Bittencourt, E.; Moschella, U.; Novello, M.; Toniato, J. D.
2016-06-01
We discuss a class of models for gravity based on a scalar field. The models include and generalize the old approach by Nordström which predated and, in some ways, inspired general relativity. The class include also a model that we have recently introduced and discussed in terms of its cosmological aspects (GSG). We present here a complete characterization of the Schwarschild geometry as a vacuum solution of GSG and sketch a discussion of the first post-Newtonian approximation.
Scalar field perturbations in Hořava-Lifshitz cosmology
NASA Astrophysics Data System (ADS)
Wang, Anzhong; Wands, David; Maartens, Roy
2010-03-01
We study perturbations of a scalar field cosmology in Hořava-Lifshitz gravity, adopting the most general setup without detailed balance but with the projectability condition. We derive the generalized Klein-Gordon equation, which is sixth-order in spatial derivatives. Then we investigate scalar field perturbations coupled to gravity in a flat Friedmann-Robertson-Walker background. In the sub-horizon regime, the metric and scalar field modes have independent oscillations with different frequencies and phases except in particular cases. On super-horizon scales, the perturbations become adiabatic during slow-roll inflation driven by a single field, and the comoving curvature perturbation is constant.
Gauge invariant perturbations of scalar-tensor cosmologies: The vacuum case
Carloni, Sante; Dunsby, Peter K. S.; Rubano, Claudio
2006-12-15
The covariant gauge-invariant perturbation theory of scalar cosmological perturbations is developed for a general scalar-tensor Friedmann-Lemaitre-Robertson-Walker cosmology in a vacuum. The perturbation equations are then solved exactly in the long wavelength limit for a specific coupling, potential, and background. Differences with the minimally coupled case are briefly discussed.
NASA Astrophysics Data System (ADS)
Egorov, A. I.; Kashargin, P. E.; Sushkov, Sergey V.
2016-09-01
In 1921 Bach and Weyl derived the method of superposition to construct new axially symmetric vacuum solutions of general relativity. In this paper we extend the Bach-Weyl approach to non-vacuum configurations with massless scalar fields. Considering a phantom scalar field with the negative kinetic energy, we construct a multi-wormhole solution describing an axially symmetric superposition of N wormholes. The solution found is static, everywhere regular and has no event horizons. These features drastically tell the multi-wormhole configuration from other axially symmetric vacuum solutions which inevitably contain gravitationally inert singular structures, such as ‘struts’ and ‘membranes’, that keep the two bodies apart making a stable configuration. However, the multi-wormholes are static without any singular struts. Instead, the stationarity of the multi-wormhole configuration is provided by the phantom scalar field with the negative kinetic energy. Anther unusual property is that the multi-wormhole spacetime has a complicated topological structure. Namely, in the spacetime there exist 2 N asymptotically flat regions connected by throats.
Scalar-Qed β-FUNCTIONS Near Planck's Scale
NASA Astrophysics Data System (ADS)
Pires, Gentil O.
The Renormalization Group Flow Equations of the Scalar-QED model near Planck's scale are computed within the framework of the average effective action. Exact Flow Equations, corrected by Einstein Gravity, for the running self-interacting scalar coupling parameter and for the running v.e.v. of ϕ*ϕ, are computed taking into account threshold effects. Analytic solutions are given in the infrared and ultraviolet limits.
Kerr black holes with scalar hair.
Herdeiro, Carlos A R; Radu, Eugen
2014-06-06
We present a family of solutions of Einstein's gravity minimally coupled to a complex, massive scalar field, describing asymptotically flat, spinning black holes with scalar hair and a regular horizon. These hairy black holes (HBHs) are supported by rotation and have no static limit. Besides mass M and angular momentum J, they carry a conserved, continuous Noether charge Q measuring the scalar hair. HBHs branch off from the Kerr metric at the threshold of the superradiant instability and reduce to spinning boson stars in the limit of vanishing horizon area. They overlap with Kerr black holes for a set of (M, J) values. A single Killing vector field preserves the solutions, tangent to the null geodesic generators of the event horizon. HBHs can exhibit sharp physical differences when compared to the Kerr solution, such as J/M^{2}>1, a quadrupole moment larger than J^{2}/M, and a larger orbital angular velocity at the innermost stable circular orbit. Families of HBHs connected to the Kerr geometry should exist in scalar (and other) models with more general self-interactions.
The scalar-photon 3-point vertex in massless quenched scalar QED
NASA Astrophysics Data System (ADS)
Concha-Sánchez, Y.; Gutiérrez-Guerrero, L. X.; Fernández-Rangel, L. A.
2016-10-01
Non perturbative studies of Schwinger-Dyson equations (SDEs) require their infinite, coupled tower to be truncated in order to reduce them to a practically solvable set. In this connection, a physically acceptable ansatz for the three point vertex is the most favorite choice. Scalar quantum electrodynamics (sQED) provides a simple and neat platform to address this problem. The most general form of the scalar-photon three point vertex can be expressed in terms of only two independent form factors, longitudinal and transverse. Ball and Chiu have demonstrated that the longitudinal vertex is fixed by requiring the Ward-Fradkin-Green- Takahashi identity (WFGTI), while the transverse vertex remains undetermined. In massless quenched sQED, we propose the transverse part of the non perturbative scalar-photon vertex.
All one-loop scalar vertices in the effective potential approach
NASA Astrophysics Data System (ADS)
Camargo-Molina, José Eliel; Morais, António P.; Pasechnik, Roman; Sampaio, Marco O. P.; Wessén, Jonas
2016-08-01
Using the one-loop Coleman-Weinberg effective potential, we derive a general analytic expression for all the derivatives of the effective potential with respect to any number of classical scalar fields. The result is valid for a renormalisable theory in four dimensions with any number of scalars, fermions or gauge bosons. This result corresponds to the zero-external momentum contribution to a general one-loop diagram with N scalar external legs. We illustrate the use of the general result in two simple scalar singlet extensions of the Standard Model, to obtain the dominant contributions to the triple couplings of light scalar particles under the zero external momentum approximation.
Bi-scalar modified gravity and cosmology with conformal invariance
Saridakis, Emmanuel N.; Tsoukalas, Minas E-mail: minasts@central.ntua.gr
2016-04-01
We investigate the cosmological applications of a bi-scalar modified gravity that exhibits partial conformal invariance, which could become full conformal invariance in the absence of the usual Einstein-Hilbert term and introducing additionally either the Weyl derivative or properly rescaled fields. Such a theory is constructed by considering the action of a non-minimally conformally-coupled scalar field, and adding a second scalar allowing for a nonminimal derivative coupling with the Einstein tensor and the energy-momentum tensor of the first field. At a cosmological framework we obtain an effective dark-energy sector constituted from both scalars. In the absence of an explicit matter sector we extract analytical solutions, which for some parameter regions correspond to an effective matter era and/or to an effective radiation era, thus the two scalars give rise to 'mimetic dark matter' or to 'dark radiation' respectively. In the case where an explicit matter sector is included we obtain a cosmological evolution in agreement with observations, that is a transition from matter to dark energy era, with the onset of cosmic acceleration. Furthermore, for particular parameter regions, the effective dark-energy equation of state can transit to the phantom regime at late times. These behaviors reveal the capabilities of the theory, since they arise purely from the novel, bi-scalar construction and the involved couplings between the two fields.
Scalar meson spectroscopy with lattice staggered fermions
Bernard, Claude; DeTar, Carleton; Fu Ziwen; Prelovsek, Sasa
2007-11-01
With sufficiently light up and down quarks the isovector (a{sub 0}) and isosinglet (f{sub 0}) scalar meson propagators are dominated at large distance by two-meson states. In the staggered-fermion formulation of lattice quantum chromodynamics, taste-symmetry breaking causes a proliferation of two-meson states that further complicates the analysis of these channels. Many of them are unphysical artifacts of the lattice approximation. They are expected to disappear in the continuum limit. The staggered-fermion fourth-root procedure has its purported counterpart in rooted staggered chiral perturbation theory (rS{chi}PT). Fortunately, the rooted theory provides a strict framework that permits the analysis of scalar meson correlators in terms of only a small number of low-energy couplings. Thus the analysis of the point-to-point scalar meson correlators in this context gives a useful consistency check of the fourth-root procedure and its proposed chiral realization. Through numerical simulation we have measured correlators for both the a{sub 0} and f{sub 0} channels in the 'Asqtad' improved staggered-fermion formulation in a lattice ensemble with lattice spacing a=0.12 fm. We analyze those correlators in the context of rS{chi}PT and obtain values of the low-energy chiral couplings that are reasonably consistent with previous determinations.
Constructing scalar-photon three point vertex in massless quenched scalar QED
NASA Astrophysics Data System (ADS)
Fernández-Rangel, L. Albino; Bashir, Adnan; Gutiérrez-Guerrero, L. X.; Concha-Sánchez, Y.
2016-03-01
Nonperturbative studies of Schwinger-Dyson equations require their infinite, coupled tower to be truncated in order to reduce them to a practically solvable set. In this connection, a physically acceptable Ansatz for the three point vertex is the most favorite choice. Scalar quantum electrodynamics (sQED) provides a simple and neat platform to address this problem. The most general form of the three point scalar-photon vertex can be expressed in terms of only two independent form factors, a longitudinal and a transverse one. Ball and Chiu have demonstrated that the longitudinal vertex is fixed by requiring the Ward-Fradkin-Green-Takahashi identity while the transverse vertex remains undetermined. In massless quenched sQED, we construct the transverse part of the nonperturbative scalar-photon vertex. This construction (i) ensures multiplicative renormalizability of the scalar propagator in keeping with the Landau-Khalatnikov-Fradkin transformations, (ii) has the same transformation properties as the bare vertex under charge conjugation, parity and time reversal, (iii) has no kinematic singularities and (iv) reproduces the one-loop asymptotic result in the weak coupling regime of the theory.
Fermion-scalar conformal blocks
Iliesiu, Luca; Kos, Filip; Poland, David; ...
2016-04-13
In this study, we compute the conformal blocks associated with scalar-scalar-fermionfermion 4-point functions in 3D CFTs. Together with the known scalar conformal blocks, our result completes the task of determining the so-called ‘seed blocks’ in three dimensions. In addition, conformal blocks associated with 4-point functions of operators with arbitrary spins can now be determined from these seed blocks by using known differential operators.
Fermion-scalar conformal blocks
Iliesiu, Luca; Kos, Filip; Poland, David; Pufu, Silviu S.; Simmons-Duffin, David; Yacoby, Ran
2016-04-13
In this study, we compute the conformal blocks associated with scalar-scalar-fermionfermion 4-point functions in 3D CFTs. Together with the known scalar conformal blocks, our result completes the task of determining the so-called ‘seed blocks’ in three dimensions. In addition, conformal blocks associated with 4-point functions of operators with arbitrary spins can now be determined from these seed blocks by using known differential operators.
New stability results for Einstein scalar gravity
NASA Astrophysics Data System (ADS)
Faulkner, Thomas; Horowitz, Gary T.; Roberts, Matthew M.
2010-10-01
We consider asymptotically anti de Sitter gravity coupled to a scalar field with mass slightly above the Breitenlohner-Freedman bound. This theory admits a large class of consistent boundary conditions characterized by an arbitrary function W. An important open question is to determine which W admit stable ground states. It has previously been shown that the total energy is bounded from below if W is bounded from below, and the bulk scalar potential V(phi) admits a suitable superpotential. We extend this result and show that the energy remains bounded even in some cases where W can become arbitrarily negative. As one application, this leads to the possibility that in gauge/gravity duality, one can add a double trace operator with negative coefficient to the dual field theory and still have a stable vacuum.
Detecting chameleons: The astronomical polarization produced by chameleonlike scalar fields
Burrage, Clare; Davis, Anne-Christine; Shaw, Douglas J.
2009-02-15
We show that a coupling between chameleonlike scalar fields and photons induces linear and circular polarization in the light from astrophysical sources. In this context chameleonlike scalar fields include those of the Olive-Pospelov (OP) model, which describes a varying fine structure constant. We determine the form of this polarization numerically and give analytic expressions in two useful limits. By comparing the predicted signal with current observations we are able to improve the constraints on the chameleon-photon coupling and the coupling in the OP model by over 2 orders of magnitude. It is argued that, if observed, the distinctive form of the chameleon induced circular polarization would represent a smoking gun for the presence of a chameleon. We also report a tentative statistical detection of a chameleonlike scalar field from observations of starlight polarization in our galaxy.
Antibiofilm Activity of the Marine Bacterium Pseudoalteromonas sp. Strain 3J6▿
Dheilly, Alexandra; Soum-Soutéra, Emmanuelle; Klein, Géraldine L.; Bazire, Alexis; Compère, Chantal; Haras, Dominique; Dufour, Alain
2010-01-01
Biofilm formation results in medical threats or economic losses and is therefore a major concern in a variety of domains. In two-species biofilms of marine bacteria grown under dynamic conditions, Pseudoalteromonas sp. strain 3J6 formed mixed biofilms with Bacillus sp. strain 4J6 but was largely predominant over Paracoccus sp. strain 4M6 and Vibrio sp. strain D01. The supernatant of Pseudoalteromonas sp. 3J6 liquid culture (SN3J6) was devoid of antibacterial activity against free-living Paracoccus sp. 4M6 and Vibrio sp. D01 cells, but it impaired their ability to grow as single-species biofilms and led to higher percentages of nonviable cells in 48-h biofilms. Antibiofilm molecules of SN3J6 were able to coat the glass surfaces used to grow biofilms and reduced bacterial attachment about 2-fold, which might partly explain the biofilm formation defect but not the loss of cell viability. SN3J6 had a wide spectrum of activity since it affected all Gram-negative marine strains tested except other Pseudoalteromonas strains. Biofilm biovolumes of the sensitive strains were reduced 3- to 530-fold, and the percentages of nonviable cells were increased 3- to 225-fold. Interestingly, SN3J6 also impaired biofilm formation by three strains belonging to the human-pathogenic species Pseudomonas aeruginosa, Salmonella enterica, and Escherichia coli. Such an antibiofilm activity is original and opens up a variety of applications for Pseudoalteromonas sp. 3J6 and/or its active exoproducts in biofilm prevention strategies. PMID:20363799
Antibiofilm activity of the marine bacterium Pseudoalteromonas sp. strain 3J6.
Dheilly, Alexandra; Soum-Soutéra, Emmanuelle; Klein, Géraldine L; Bazire, Alexis; Compère, Chantal; Haras, Dominique; Dufour, Alain
2010-06-01
Biofilm formation results in medical threats or economic losses and is therefore a major concern in a variety of domains. In two-species biofilms of marine bacteria grown under dynamic conditions, Pseudoalteromonas sp. strain 3J6 formed mixed biofilms with Bacillus sp. strain 4J6 but was largely predominant over Paracoccus sp. strain 4M6 and Vibrio sp. strain D01. The supernatant of Pseudoalteromonas sp. 3J6 liquid culture (SN(3J6)) was devoid of antibacterial activity against free-living Paracoccus sp. 4M6 and Vibrio sp. D01 cells, but it impaired their ability to grow as single-species biofilms and led to higher percentages of nonviable cells in 48-h biofilms. Antibiofilm molecules of SN(3J6) were able to coat the glass surfaces used to grow biofilms and reduced bacterial attachment about 2-fold, which might partly explain the biofilm formation defect but not the loss of cell viability. SN(3J6) had a wide spectrum of activity since it affected all Gram-negative marine strains tested except other Pseudoalteromonas strains. Biofilm biovolumes of the sensitive strains were reduced 3- to 530-fold, and the percentages of nonviable cells were increased 3- to 225-fold. Interestingly, SN(3J6) also impaired biofilm formation by three strains belonging to the human-pathogenic species Pseudomonas aeruginosa, Salmonella enterica, and Escherichia coli. Such an antibiofilm activity is original and opens up a variety of applications for Pseudoalteromonas sp. 3J6 and/or its active exoproducts in biofilm prevention strategies.
Frisch, E.; Johnson, C.G.
1962-05-15
A detachable coupling arrangement is described which provides for varying the length of the handle of a tool used in relatively narrow channels. The arrangement consists of mating the key and keyhole formations in the cooperating handle sections. (AEC)
General analytic solutions of scalar field cosmology with arbitrary potential
NASA Astrophysics Data System (ADS)
Dimakis, N.; Karagiorgos, A.; Zampeli, Adamantia; Paliathanasis, Andronikos; Christodoulakis, T.; Terzis, Petros A.
2016-06-01
We present the solution space for the case of a minimally coupled scalar field with arbitrary potential in a Friedmann-Lemaître-Robertson-Walker metric. This is made possible due to the existence of a nonlocal integral of motion corresponding to the conformal Killing field of the two-dimensional minisuperspace metric. Both the spatially flat and nonflat cases are studied first in the presence of only the scalar field and subsequently with the addition of noninteracting perfect fluids. It is verified that this addition does not change the general form of the solution, but only the particular expressions of the scalar field and the potential. The results are applied in the case of parametric dark energy models where we derive the scalar field equivalence solution for some proposed models in the literature.
A new approach to the formulation of scalar flux closure
NASA Technical Reports Server (NTRS)
Shabany, Y.; Durbin, P.
1995-01-01
This report shows that if a stochastic differential equation (Langevin equation) for velocity fluctuation vector is known, it is possible to derive the equations for scalar flux transport. Durbin and Speziale (1994) showed that the second moment of this stochastic differential equation gives an equation for the evolution of Reynolds stress tensor. Similarly, the stochastic equation will give an equation for scalar flux. Therefore, a coupling between these two is present. The basis for the present work is that there should be Langevin equations that can produce acceptable models for both the Reynolds stress tensor and the scalar flux vector. Having found this basic Langevin equation, the amount of work needed to model the second order closure problems is reduced; using the well developed models for Reynolds stress equations, it will be possible to derive corresponding models for scalar flux equation.
Properties of Robinson-Trautman solution with scalar hair
NASA Astrophysics Data System (ADS)
Tahamtan, T.; Svítek, O.
2016-09-01
An explicit Robinson-Trautman solution with a minimally coupled free scalar field was derived and analyzed recently. It was shown that this solution possesses a curvature singularity which is initially naked but later enveloped by a horizon. However, this study concentrated on the general branch of the solution where all free constants are nonzero. Interesting special cases arise when some of the parameters are set to zero. In most of these cases, the scalar field is still present. One of the cases is a static solution which represents a parametric limit of the Janis-Newman-Winicour scalar field spacetime. Additionally, we provide a calculation of the Bondi mass which clarifies the interpretation of the general solution. Finally, by a complex rotation of a parameter describing the strength of the scalar field, we obtain a dynamical wormhole solution.
Scalar gravitational waves in the effective theory of gravity
NASA Astrophysics Data System (ADS)
Mottola, Emil
2017-07-01
As a low energy effective field theory, classical General Relativity receives an infrared relevant modification from the conformal trace anomaly of the energy-momentum tensor of massless, or nearly massless, quantum fields. The local form of the effective action associated with the trace anomaly is expressed in terms of a dynamical scalar field that couples to the conformal factor of the spacetime metric, allowing it to propagate over macroscopic distances. Linearized around flat spacetime, this semi-classical EFT admits scalar gravitational wave solutions in addition to the transversely polarized tensor waves of the classical Einstein theory. The amplitude of the scalar wave modes, as well as their energy and energy flux which are positive and contain a monopole moment, are computed. Astrophysical sources for scalar gravitational waves are considered, with the excited gluonic condensates in the interiors of neutron stars in merger events with other compact objects likely to provide the strongest burst signals.
Scalar Deformations of Schwarzschild Holes and Their Stability
NASA Astrophysics Data System (ADS)
Dennhardt, Helge; Lechtenfeld, Olaf
We construct two solutions of the minimally coupled Einstein-scalar field equations, representing regular deformations of Schwarzschild black holes by a self-interacting, static, scalar field. One solution features an exponentially decaying scalar field and a triple-well interaction potential; the other one is completely analytic and sprouts Coulomb-like scalar hair. Both evade the no-hair theorem by having partially negative potential, in conflict with the dominant energy condition. The linear perturbation theory around such backgrounds is developed in general, and yields stability criteria in terms of effective potentials for an analog Schrödinger problem. We can test for more than half of the perturbation modes, and our solutions prove to be stable against those.
On the stability and causality of scalar-vector theories
Fleury, Pierre; Pitrou, Cyril; Uzan, Jean-Philippe; Almeida, Juan P. Beltrán E-mail: juanpbeltran@uan.edu.co E-mail: uzan@iap.fr
2014-11-01
Various extensions of standard inflationary models have been proposed recently by adding vector fields. Because they are generally motivated by large-scale anomalies, and the possibility of statistical anisotropy of primordial fluctuations, such models require to introduce non-standard couplings between vector fields on the one hand, and either gravity or scalar fields on the other hand. In this article, we study models involving a vector field coupled to a scalar field. We derive restrictive necessary conditions for these models to be both stable (Hamiltonian bounded by below) and causal (hyperbolic equations of motion)
Gravity quantized: Loop quantum gravity with a scalar field
Domagala, Marcin; Kaminski, Wojciech; Giesel, Kristina; Lewandowski, Jerzy
2010-11-15
...''but we do not have quantum gravity.'' This phrase is often used when analysis of a physical problem enters the regime in which quantum gravity effects should be taken into account. In fact, there are several models of the gravitational field coupled to (scalar) fields for which the quantization procedure can be completed using loop quantum gravity techniques. The model we present in this paper consists of the gravitational field coupled to a scalar field. The result has similar structure to the loop quantum cosmology models, except that it involves all the local degrees of freedom of the gravitational field because no symmetry reduction has been performed at the classical level.
Scalar self-force on static charge in a long throat
NASA Astrophysics Data System (ADS)
Popov, A.; Aslan, O.
2015-08-01
We compute the self-force on a scalar charge at rest in the space-time of long throat. We consider arbitrary values of the mass of the scalar field and the constant of nonminimal coupling of the scalar field to the curvature of space-time. We also show the coincidence of explicit calculations of self-force in the limit of large mass of the field with known results.
Charged black holes in a generalized scalar-tensor gravity model
NASA Astrophysics Data System (ADS)
Brihaye, Yves; Hartmann, Betti
2017-09-01
We study 4-dimensional charged and static black holes in a generalized scalar-tensor gravity model, in which a shift symmetry for the scalar field exists. For vanishing scalar field the solution corresponds to the Reissner-Nordström (RN) solution, while solutions of the full scalar-gravity model have to be constructed numerically. We demonstrate that these black holes support Galilean scalar hair up to a maximal value of the scalar-tensor coupling that depends on the value of the charge and can be up to roughly twice as large as that for uncharged solutions. The Hawking temperature TH of the hairy black holes at maximal scalar-tensor coupling decreases continuously with the increase of the charge and reaches TH = 0 for the highest possible charge that these solutions can carry. However, in this limit, the scalar-tensor coupling needs to vanish. The limiting solution hence corresponds to the extremal RN solution, which does not support regular Galilean scalar hair due to its AdS2 ×S2 near-horizon geometry.
Astrophysical constraints on singlet scalars at LHC
NASA Astrophysics Data System (ADS)
Hertzberg, Mark P.; Masoumi, Ali
2017-04-01
We consider the viability of new heavy gauge singlet scalar particles at colliders such as the LHC . Our original motivation for this study came from the possibility of a new heavy particle of mass ~ TeV decaying significantly into two photons at colliders, such as LHC, but our analysis applies more broadly. We show that there are significant constraints from astrophysics and cosmology on the simplest UV complete models that incorporate such new particles and its associated collider signal. The simplest and most obvious UV complete model that incorporates such signals is that it arises from a new singlet scalar (or pseudo-scalar) coupled to a new electrically charged and colored heavy fermion. Here we show that these new fermions (and anti-fermions) would be produced in the early universe, then form new color singlet heavy mesons with light quarks, obtain a non-negligible freeze-out abundance, and remain in kinetic equilibrium until decoupling. These heavy mesons possess interesting phenomenology, dependent on their charge, including forming new bound states with electrons and protons. We show that a significant number of these heavy states would survive for the age of the universe and an appreciable number would eventually be contained within the earth and solar system. We show that this leads to detectable consequences, including the production of highly energetic events from annihilations on earth, new spectral lines, and, spectacularly, the destabilization of stars. The lack of detection of these consequences rules out such simple UV completions, putting pressure on the viability of such new particles at LHC . To incorporate such a scalar would require either much more complicated UV completions or even further new physics that provides a decay channel for the associated fermion.
Chiba, Takeshi; Yamaguchi, Masahide E-mail: gucci@phys.aoyama.ac.jp
2009-01-15
As an extension of our previous study, we derive slow-roll conditions for multiple scalar fields which are non-minimally coupled with gravity and for generalized gravity theories of the form f({phi}, R). We provide simple formulae of the spectral indices of scalar/tensor perturbations in terms of the slow-roll parameters.
Vacuum polarization of a quantized scalar field in the thermal state in a long throat
NASA Astrophysics Data System (ADS)
Popov, Arkady A.
2016-12-01
Vacuum polarization of scalar fields in the background of a long throat is investigated. The field is assumed to be both massive or massless, with arbitrary coupling to the scalar curvature, and in a thermal state at an arbitrary temperature. Analytical approximation for ⟨φ2⟩ren is obtained.
Scalar transport in inline mixers with spatially periodic flows
NASA Astrophysics Data System (ADS)
Baskan, Ozge; Rajaei, Hadi; Speetjens, Michel F. M.; Clercx, Herman J. H.
2017-01-01
Spatially persisting patterns form during the downstream evolution of passive scalars in three-dimensional (3D) spatially periodic flows due to the coupled effect of stretching and folding mechanisms of the flow field. This has been investigated in many computational and theoretical studies of 2D time-periodic and 3D spatially periodic flow fields. However, experimental studies, to date, have mainly focused on flow visualization with streaks of dye rather than fully 3D scalar field measurements. Our study employs 3D particle tracking velocimetry and 3D laser-induced fluorescence to analyze the evolution of 3D flow and scalar fields and the correlation between the coherent flow/scalar field structures in a representative inline mixer, the Quatro static mixer. For this purpose an experimental setup that consists of an optically accessible test section with transparent internal elements accommodating a pressure-driven pipe flow has been built. The flow and scalar fields clearly underline the complementarity of the experimental results with numerical simulations and provide validation of the periodicity assumption needed in numerical studies. The experimental procedure employed in this investigation, which allows studying the scalar transport in the advective limit, demonstrates the suitability of the present method for exploratory mixing studies of a variety of mixing devices, beyond the Quatro static mixer.
A consistent scalar-tensor cosmology for inflation, dark energy and the Hubble parameter
NASA Astrophysics Data System (ADS)
Wang, C. H.-T.; Reid, J. A.; Murphy, A. St. J.; Rodrigues, D.; Al Alawi, M.; Bingham, R.; Mendonça, J. T.; Davies, T. B.
2016-11-01
A Friedman cosmology is investigated based on scalar-tensor gravitation with general metric coupling and scalar potential functions. We show that for a broad class of such functions, the scalar field can be dynamically trapped using a recently suggested mechanism. The trapped scalar can drive inflation and accelerated cosmic expansion, compatible with standard requirements. The inflationary phase admits a natural exit with a value of the Hubble parameter dictated by the duration of inflation in a parameter independent manner. For inflationary duration consistent with the GUT description, the resulting Hubble parameter is found to be consistent with its observed value.
Brans-Dicke scalar field as a chameleon
Das, Sudipta; Banerjee, Narayan
2008-08-15
In this paper it is shown that in Brans-Dicke theory, if one considers a nonminimal coupling between the matter and the scalar field, it can give rise to a late time accelerated expansion for the Universe preceded by a decelerated expansion for very high values of the Brans-Dicke parameter {omega}.
Quantum Theory of a Strongly-Dissipative Scalar Field
NASA Astrophysics Data System (ADS)
Jafari, Marjan; Kheirandish, Fardin
2017-04-01
The properties of a quantum dissipative scalar field is analyzed by Caldeira-Leggett model in strong-coupling regime. The Lagrangian of the total system is canonically quantized and the full Hamiltonian is diagonalized using Fano technique. A mode-dependent probability density is introduced. The steady state energy and correlation functions at finite temperature are calculated in terms of the probability density.
Impact of other scalar fields on oscillons after hilltop inflation
Antusch, Stefan; Orani, Stefano E-mail: stefano.orani@unibas.ch
2016-03-01
Oscillons are spatially localized and relatively stable field fluctuations which can form after inflation under suitable conditions. In order to reheat the universe, the fields which dominate the energy density after inflation have to couple to other degrees of freedom and finally produce the matter particles present in the universe today. In this study, we use lattice simulations in 2+1 dimensions to investigate how such couplings can affect the formation and stability of oscillons. We focus on models of hilltop inflation, where we have recently shown that hill crossing oscillons generically form, and consider the coupling to an additional scalar field which, depending on the value of the coupling parameter, can get resonantly enhanced from the inhomogeneous inflaton field. We find that three cases are realized: without a parametric resonance, the additional scalar field has no effects on the oscillons. For a fast and strong parametric resonance of the other scalar field, oscillons are strongly suppressed. For a delayed parametric resonance, on the other hand, the oscillons get imprinted on the other scalar field and their stability is even enhanced compared to the single-field oscillons.
Tensor-multi-scalar theories: relativistic stars and 3 + 1 decomposition
NASA Astrophysics Data System (ADS)
Horbatsch, Michael; Silva, Hector O.; Gerosa, Davide; Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo; Sperhake, Ulrich
2015-10-01
Gravitational theories with multiple scalar fields coupled to the metric and each other—a natural extension of the well studied single-scalar-tensor theories—are interesting phenomenological frameworks to describe deviations from general relativity in the strong-field regime. In these theories, the N-tuple of scalar fields takes values in a coordinate patch of an N-dimensional Riemannian target-space manifold whose properties are poorly constrained by weak-field observations. Here we introduce for simplicity a non-trivial model with two scalar fields and a maximally symmetric target-space manifold. Within this model we present a preliminary investigation of spontaneous scalarization for relativistic, perfect fluid stellar models in spherical symmetry. We find that the scalarization threshold is determined by the eigenvalues of a symmetric scalar-matter coupling matrix, and that the properties of strongly scalarized stellar configurations additionally depend on the target-space curvature radius. In preparation for numerical relativity simulations, we also write down the 3 + 1 decomposition of the field equations for generic tensor-multi-scalar theories.
Inflation and the Higgs Scalar
Green, Dan
2014-12-05
This note makes a self-contained exposition of the basic facts of big bang cosmology as they relate to inflation. The fundamental problems with that model are then explored. A simple scalar model of inflation is evaluated which provides the solution of those problems and makes predictions which will soon be definitively tested. The possibility that the recently discovered fundamental Higgs scalar field drives inflation is explored.
Scalar graviton as dark matter
Pirogov, Yu. F.
2015-06-15
The basics of the theory of unimodular bimode gravity built on the principles of unimodular gauge invariance/relativity and general covariance are exposed. Besides the massless tensor graviton of General Relativity, the theory includes an (almost) massless scalar graviton treated as the gravitational dark matter. A spherically symmetric vacuum solution describing the coherent scalar-graviton field for the soft-core dark halos, with the asymptotically flat rotation curves, is demonstrated as an example.
Scalar graviton as dark matter
NASA Astrophysics Data System (ADS)
Pirogov, Yu. F.
2015-06-01
The basics of the theory of unimodular bimode gravity built on the principles of unimodular gauge invariance/relativity and general covariance are exposed. Besides the massless tensor graviton of General Relativity, the theory includes an (almost) massless scalar graviton treated as the gravitational dark matter. A spherically symmetric vacuum solution describing the coherent scalar-graviton field for the soft-core dark halos, with the asymptotically flat rotation curves, is demonstrated as an example.
Gravitational scalar-tensor theory
NASA Astrophysics Data System (ADS)
Naruko, Atsushi; Yoshida, Daisuke; Mukohyama, Shinji
2016-05-01
We consider a new form of gravity theories in which the action is written in terms of the Ricci scalar and its first and second derivatives. Despite the higher derivative nature of the action, the theory is ghost-free under an appropriate choice of the functional form of the Lagrangian. This model possesses 2 + 2 physical degrees of freedom, namely 2 scalar degrees and 2 tensor degrees. We exhaust all such theories with the Lagrangian of the form f(R,{({{\
Quintessence dynamics with two scalar fields and mixed kinetic terms
Bruck, Carsten van de; Weller, Joel M.
2009-12-15
The dynamical properties of a model of dark energy in which two scalar fields are coupled by a noncanonical kinetic term are studied. We show that overall the addition of the coupling has only minor effects on the dynamics of the two-field system for both potentials studied, even preserving many of the features of the assisted quintessence scenario. The coupling of the kinetic terms enlarges the regions of stability of the critical points. When the potential is of an additive form, we find the kinetic coupling has an interesting effect on the dynamics of the fields as they approach the inflationary attractor, with the result that the combined equation of state of the scalar fields can approach -1 during the transition from a matter dominated universe to the recent period of acceleration.
Black hole hair formation in shift-symmetric generalised scalar-tensor gravity
NASA Astrophysics Data System (ADS)
Benkel, Robert; Sotiriou, Thomas P.; Witek, Helvi
2017-03-01
A linear coupling between a scalar field and the Gauss–Bonnet invariant is the only known interaction term between a scalar and the metric that: respects shift symmetry; does not lead to higher order equations; inevitably introduces black hole hair in asymptotically flat, 4-dimensional spacetimes. Here we focus on the simplest theory that includes such a term and we explore the dynamical formation of scalar hair. In particular, we work in the decoupling limit that neglects the backreaction of the scalar onto the metric and evolve the scalar configuration numerically in the background of a Schwarzschild black hole and a collapsing dust star described by the Oppenheimer–Snyder solution. For all types of initial data that we consider, the scalar relaxes at late times to the known, static, analytic configuration that is associated with a hairy, spherically symmetric black hole. This suggests that the corresponding black hole solutions are indeed endpoints of collapse.
Spontaneous Scalarization: Dead or Alive?
NASA Astrophysics Data System (ADS)
Berti, Emanuele; Crispino, Luis; Gerosa, Davide; Gualtieri, Leonardo; Horbatsch, Michael; Macedo, Caio; Okada da Silva, Hector; Pani, Paolo; Sotani, Hajime; Sperhake, Ulrich
2015-04-01
In 1993, Damour and Esposito-Farese showed that a wide class of scalar-tensor theories can pass weak-field gravitational tests and exhibit nonperturbative strong-field deviations away from General Relativity in systems involving neutron stars. These deviations are possible in the presence of ``spontaneous scalarization,'' a phase transition similar in nature to spontaneous magnetization in ferromagnets. More than twenty years after the original proposal, binary pulsar experiments have severely constrained the possibility of spontaneous scalarization occurring in nature. I will show that these experimental constraints have important implications for the torsional oscillation frequencies of neutron stars and for the so-called ``I-Love-Q'' relations in scalar-tensor theories. I will also argue that there is still hope to observe strong scalarization effects, despite the strong experimental bounds on the original mechanism. In particular, I will discuss two mechanisms that could produce strong scalarization in neutron stars: anisotropy and multiscalarization. This work was supported by NSF CAREER Award PHY-1055103.
Semi-Classical Dirac Vacuum Polarisation in a Scalar Field
NASA Astrophysics Data System (ADS)
Lampart, Jonas; Lewin, Mathieu
2016-08-01
We study vacuum polarisation effects of a Dirac field coupled to an external scalar field and derive a semi-classical expansion of the regu-larised vacuum energy. The leading order of this expansion is given by a classical formula due to Chin, Lee-Wick and Walecka, for which our result provides the first rigorous proof. We then discuss applications to the non-relativistic large-coupling limit of an interacting system, and to the stability of homogeneous systems.
Transport of Passive Scalars in Rayleigh-Benard Convection
NASA Astrophysics Data System (ADS)
Chiam, Keng-Hwee; Cross, Michael C.; Greenside, Henry S.
2002-03-01
Using direct numerical simulations of the full Boussinesq equations coupled to the transport equation for a passive scalar, we show how the diffusivity of a passive scalar is enhanced in the presence of bouyancy-driven convection. We consider time-independent and time-dependent flow structures in both two and three dimensions, and show how the enhanced diffusivity varies as a function of the Peclet number and the Rayleigh and Prandtl numbers. We compare our simulation results with previous experiments as well as theoretical predictions.
Light colored scalars and the up quarks phenomenology
NASA Astrophysics Data System (ADS)
Fajfer, Svjetlana; Doršner, Ilja; Kamenik, Jernej F.; Košnik, Nejc
2010-12-01
A colored weak singlet scalar can accommodate the 2 σ disagreement of the measured forward-backward asymmetry from the Standard model prediction in the tt¯ production at the Tevatron. Such colored scalars appear in a class of grand unified theories. Their couplings to up quarks can be fully constrained using D-D oscillation observables, as well as di-jet and single top production measurements at the Tevatron. After making predictions for the flavour changing neutral current transitions in the charm and top quark sectors, we discuss the impact of these constraints on the texture of the up-quark mass matrix within a class of grand unified models.
Very light cosmological scalar fields from a tiny cosmological constant
Calmet, Xavier
2007-10-15
I discuss a mechanism which generates a mass term for a scalar field in an expanding universe. The mass of this field turns out to be generated by the cosmological constant and can be naturally small if protected by a conformal symmetry which is, however, broken in the gravitational sector. The mass is comparable today to the Hubble time. This scalar field could thus impact our Universe today and, for example, be at the origin of a time variation of the couplings and masses of the parameters of the standard model.
Color Sextet Scalars in Early LHC Experiments
Berger, Edmond L.; Cao Qinghong; Chen, Chuan-Ren; Shaughnessy, Gabe; Zhang Hao
2010-10-29
We explore the potential for discovery of an exotic color sextet scalar in same-sign top quark pair production in early running at the LHC. We present the first phenomenological analysis at colliders of color sextet scalars with full top quark spin correlations included. We demonstrate that one can measure the scalar mass, the top quark polarization, and confirm the scalar resonance with 1 fb{sup -1} of integrated luminosity. The top quark polarization can distinguish gauge triplet and singlet scalars.
NASA Astrophysics Data System (ADS)
Berberian, John Edwin
1999-01-01
matching interface, and scalar-tensor coupling function) to which they can be joined. The screening procedure is independent of the particular spherically symmetric coordinate system in which the candidate solution is expressed. Scalar field coordinates are also used to examine succinctly the problem of perturbative expansion of scalar-tensor vacuum solutions about the vacuum solution of general relativity. All solutions are shown to fall into three categories: perturbation about the Schwarzschild solution, perturbation about a two dimensional metric, and non-perturbative solutions. In the process of classification, the Birkhoff theorem for vacuum solutions of general relativity is explicitly shown. In the final section, future directions are discussed. They are: exploiting Lie-theoretic methods to find new solution families which may lead to an explicit matched solution, searching for the Choptuik critical solution, and application of scalar field coordinates to relativistic perfect fluids (T = 0) in order to find exact solutions. Finally, a re-examination of classical gravitational collapse of a scalar field is advocated using matched solutions.
Hawking radiation of five-dimensional charged black holes with scalar fields
NASA Astrophysics Data System (ADS)
Miao, Yan-Gang; Xu, Zhen-Ming
2017-09-01
We investigate the Hawking radiation cascade from the five-dimensional charged black hole with a scalar field coupled to higher-order Euler densities in a conformally invariant manner. We give the semi-analytic calculation of greybody factors for the Hawking radiation. Our analysis shows that the Hawking radiation cascade from this five-dimensional black hole is extremely sparse. The charge enhances the sparsity of the Hawking radiation, while the conformally coupled scalar field reduces this sparsity.
Big bang nucleosynthesis constraints on scalar-tensor theories of gravity
Coc, Alain; Olive, Keith A.; Uzan, Jean-Philippe; Vangioni, Elisabeth
2006-04-15
We investigate Big bang nucleosynthesis (BBN) in scalar-tensor theories of gravity with arbitrary matter couplings and self-interaction potentials. We first consider the case of a massless dilaton with a quadratic coupling to matter. We perform a full numerical integration of the evolution of the scalar field and compute the resulting light element abundances. We demonstrate in detail the importance of particle mass thresholds on the evolution of the scalar field in a radiation dominated universe. We also consider the simplest extension of this model including a cosmological constant in either the Jordan or Einstein frame.
Dynamical Characteristics of a Non-canonical Scalar-Torsion Model of Dark Energy
NASA Astrophysics Data System (ADS)
Banijamali, A.; Ghasemi, E.
2016-08-01
In this paper, we analyze the phase-space of a model of dark energy in which a non-canonical scalar field (tachyon) non-minimally coupled to torsion scalar in the framework of teleparallelism. Scalar field potential and non-minimal coupling function are chosen as V( ϕ) = V 0 ϕ n and f( ϕ) = ϕ N , respectively. We obtain a critical point that behaves like a stable or saddle point depending on the values of N and n. Additionally we find an unstable critical line. We have shown such a behavior of critical points using numerical computations and phase-space trajectories explicitly.
Towards understanding turbulent scalar mixing
NASA Technical Reports Server (NTRS)
Girimaji, Sharath S.
1992-01-01
In an effort towards understanding turbulent scalar mixing, we study the effect of molecular mixing, first in isolation and then by accounting for the effects of the velocity field. The chief motivation for this approach stems from the strong resemblance of the scalar probability density function (PDF) obtained from the scalar field evolving from the heat conduction equation that arises in a turbulent velocity field. However, the evolution of the scalar dissipation is different for the two cases. We attempt to account for these differences, which are due to the velocity field, using a Lagrangian frame analysis. After establishing the usefulness of this approach, we use the heat-conduction simulations (HCS), in lieu of the more expensive direct numerical simulations (DNS), to study many of the less understood aspects of turbulent mixing. Comparison between the HCS data and available models are made whenever possible. It is established that the beta PDF characterizes the evolution of the scalar PDF during mixing from all types of non-premixed initial conditions.
Scalar field dark matter and the Higgs field
NASA Astrophysics Data System (ADS)
Bertolami, O.; Cosme, Catarina; Rosa, João G.
2016-08-01
We discuss the possibility that dark matter corresponds to an oscillating scalar field coupled to the Higgs boson. We argue that the initial field amplitude should generically be of the order of the Hubble parameter during inflation, as a result of its quasi-de Sitter fluctuations. This implies that such a field may account for the present dark matter abundance for masses in the range 10-6-10-4eV, if the tensor-to-scalar ratio is within the range of planned CMB experiments. We show that such mass values can naturally be obtained through either Planck-suppressed non-renormalizable interactions with the Higgs boson or, alternatively, through renormalizable interactions within the Randall-Sundrum scenario, where the dark matter scalar resides in the bulk of the warped extra-dimension and the Higgs is confined to the infrared brane.
Screening of scalar fields in Dirac-Born-Infeld theory
NASA Astrophysics Data System (ADS)
Burrage, Clare; Khoury, Justin
2014-07-01
We study a new screening mechanism which is present in Dirac-Born-Infeld (DBI)-like theories. A scalar field with a DBI-like Lagrangian is minimally coupled to matter. In the vicinity of sufficiently dense sources, nonlinearities in the scalar dominate and result in an approximately constant acceleration on a test particle, thereby suppressing the scalar force relative to gravity. Unlike generic P(X) or chameleon theories, screening happens within the regime of validity of the effective field theory thanks to the DBI symmetry. We derive an exact form for the field profile around multiple sources and determine the constraints on the theory parameters from tests of gravity. Perturbations around the spherically-symmetric background propagate superluminally, but we argue for a chronology protection analogous to Galileons. This is the first example of a screening mechanism for which quantum corrections to the theory are under control and exact solutions to cosmological N-body problems can be found.
Unified cosmology with scalar-tensor theory of gravity
NASA Astrophysics Data System (ADS)
Tajahmad, Behzad; Sanyal, Abhik Kumar
2017-04-01
Unlike the Noether symmetry, a metric independent general conserved current exists for non-minimally coupled scalar-tensor theory of gravity if the trace of the energy-momentum tensor vanishes. Thus, in the context of cosmology, a symmetry exists both in the early vacuum and radiation dominated era. For slow roll, symmetry is sacrificed, but at the end of early inflation, such a symmetry leads to a Friedmann-like radiation era. Late-time cosmic acceleration in the matter dominated era is realized in the absence of symmetry, in view of the same decayed and redshifted scalar field. Thus, unification of early inflation with late-time cosmic acceleration with a single scalar field may be realized.
A scalar field dark energy model: Noether symmetry approach
NASA Astrophysics Data System (ADS)
Dutta, Sourav; Panja, Madan Mohan; Chakraborty, Subenoy
2016-04-01
Scalar field dark energy cosmology has been investigated in the present paper in the frame work of Einstein gravity. In the context of Friedmann-Lemaitre-Robertson-Walker space time minimally coupled scalar field with self interacting potential and non-interacting perfect fluid with barotropic equation of state (dark matter) is chosen as the matter context. By imposing Noether symmetry on the Lagrangian of the system the symmetry vector is obtained and the self interacting potential for the scalar field is determined. Then we choose a point transformation (a, φ )→ (u, v) such that one of the transformation variable (say u) is cyclic for the Lagrangian. Subsequently, using conserved charge (corresponding to the cyclic co-ordinate) and the constant of motion, solutions are obtained. Finally, the cosmological implication of the solutions in the perspective of recent observation has been examined.
Scalar gravitation: A laboratory for numerical relativity. III. Axisymmetry
Scheel, M.A. ); Shapiro, S.L.; Teukolsky, S.A. )
1994-02-15
We construct a two-dimensional axisymmetric mean-field particle simulation scheme that solves the equations of relativistic scalar gravitation coupled to collisionless matter. Although scalar gravitation theory disagrees with experiment, it is useful as a testing ground for numerical methods used to solve the equations of general relativity, particularly in the generation of gravitational waves. We discuss methods for extracting the gravitational wave amplitude from the field variables, as well as methods for imposing an accurate outgoing-wave boundary condition on the scalar field at a finite radius. We find that for continuous matter distributions, our code is able to calculate smooth and accurate gravitational wave forms, despite the stochastic representation of the matter source terms caused by sampling with a finite number of particles. A similar scheme should provide accurate wave forms in general relativity, provided sufficient computer resources are used.
Thick branes from self-gravitating scalar fields
Novikov, Oleg O.; Andrianov, Vladimir A.; Andrianov, Alexander A.
2014-07-23
The formation of a domain wall ('thick brane') induced by scalar matter dynamics and triggered by a thin brane defect is considered in noncompact five-dimensional space-time with warped AdS type geometry. The scalar matter is composed of two fields with softly broken O(2) symmetry and minimal coupling to gravity. The nonperturbative effects in the invariant mass spectrum of light localized scalar states are investigated for different values of the tension of the thin brane defect. Especially interesting is the case of the thin brane with negative tension when the singular barriers form a potential well with two infinitely tall walls and the discrete spectrum of localized states arises completely isolated from the bulk.
Attractor universe in the scalar-tensor theory of gravitation
Maeda, Kei-ichi; Fujii, Yasunori
2009-04-15
In the scalar-tensor theory of gravitation it seems nontrivial to establish if solutions of the cosmological equations in the presence of a cosmological constant (or a vacuum energy) behave as attractors independently of the initial values. We develop a general formulation in terms of two-dimensional phase space, mainly according to the Brans-Dicke model requiring the scalar field decoupled from the matter Lagrangian in the Jordan frame. We show that there are two kinds of fixed points, one of which is an attractor depending on the coupling constant and equation of state. We find that the static universe in the Jordan frame is an attractor in the presence of a cosmological constant for some range of the coupling constant. We extend our analysis to a power-law potential, finding a new type of power-law inflation caused by the coupling to the matter fluid, also as an attractor.
Expanding and collapsing scalar field thin shell
NASA Astrophysics Data System (ADS)
Sharif, M.; Abbas, G.
2012-09-01
This paper deals with the dynamics of scalar field thin shell in the Reissner-Nordstr öm geometry. The Israel junction conditions between Reissner-Nordstr öm spacetimes are derived, which lead to the equation of motion of scalar field shell and Klien-Gordon equation. These equations are solved numerically by taking scalar field model with the quadratic scalar potential. It is found that solution represents the expanding and collapsing scalar field shell. For the better understanding of this problem, we investigate the case of massless scalar field (by taking the scalar field potential zero). Also, we evaluate the scalar field potential when p is an explicit function of R. We conclude that both massless as well as massive scalar field shell can expand to infinity at constant rate or collapse to zero size forming a curvature singularity or bounce under suitable conditions.
Long-lived, colour-triplet scalars from unnaturalness
NASA Astrophysics Data System (ADS)
Barnard, James; Cox, Peter; Gherghetta, Tony; Spray, Andrew
2016-03-01
Long-lived, colour-triplet scalars are a generic prediction of unnatural, or split, composite Higgs models where the spontaneous global-symmetry breaking scale f ≳ 10 TeV and an unbroken SU(5) symmetry is preserved. Since the triplet scalars are pseudo NambuGoldstone bosons they are split from the much heavier composite-sector resonances and are the lightest exotic, coloured states. This makes them ideal to search for at colliders. Due to discrete symmetries the triplet scalar decays via a dimension-six term and given the large suppression scale f is often metastable. We show that existing searches for collider-stable R-hadrons from Run-I at the LHC forbid a triplet scalar mass below 845 GeV, whereas with 300 fb-1 at 13 TeV triplet scalar masses up to 1.4 TeV can be discovered. For shorter lifetimes displaced-vertex searches provide a discovery reach of up to 1.8 TeV. In addition we present exclusion and discovery reaches of future hadron colliders as well as indirect limits that arise from modifications of the Higgs couplings.
Late time solution for interacting scalar in accelerating spaces
Prokopec, Tomislav
2015-11-01
We consider stochastic inflation in an interacting scalar field in spatially homogeneous accelerating space-times with a constant principal slow roll parameter ε. We show that, if the scalar potential is scale invariant (which is the case when scalar contains quartic self-interaction and couples non-minimally to gravity), the late-time solution on accelerating FLRW spaces can be described by a probability distribution function (PDF) ρ which is a function of φ/H only, where φ=φ( x-vector ) is the scalar field and H=H(t) denotes the Hubble parameter. We give explicit late-time solutions for ρarrow ρ{sub ∞}(φ/H), and thereby find the order ε corrections to the Starobinsky-Yokoyama result. This PDF can then be used to calculate e.g. various n-point functions of the (self-interacting) scalar field, which are valid at late times in arbitrary accelerating space-times with ε= constant.
Iron Kα line of Kerr black holes with scalar hair
NASA Astrophysics Data System (ADS)
Ni, Yueying; Zhou, Menglei; Cárdenas-Avendaño, Alejandro; Bambi, Cosimo; Herdeiro, Carlos A. R.; Radu, Eugen
2016-07-01
Recently, a family of hairy black holes in 4-dimensional Einstein gravity minimally coupled to a complex, massive scalar field was discovered [1]. Besides the mass M and spin angular momentum J, these objects are characterized by a Noether charge Q, measuring the amount of scalar hair, which is not associated to a Gauss law and cannot be measured at spatial infinity. Introducing a dimensionless scalar hair parameter q, ranging from 0 to 1, we recover (a subset of) Kerr black holes for q = 0 and a family of rotating boson stars for q = 1. In the present paper, we explore the possibility of measuring q for astrophysical black holes with current and future X-ray missions. We study the iron Kα line expected in the reflection spectrum of such hairy black holes and we simulate observations with Suzaku and eXTP. As a proof of concept, we point out, by analyzing a sample of hairy black holes, that current observations can already constrain the scalar hair parameter q, because black holes with q close to 1 would have iron lines definitively different from those we observe in the available data. We conclude that a detailed scanning of the full space of solutions, together with data from the future X-ray missions, like eXTP, will be able to put relevant constraints on the astrophysical realization of Kerr black holes with scalar hair.
Long-lived, colour-triplet scalars from unnaturalness
Barnard, James; Cox, Peter; Gherghetta, Tony; Spray, Andrew
2016-03-01
We study that long-lived, colour-triplet scalars are a generic prediction of unnatural, or split, composite Higgs models where the spontaneous global-symmetry breaking scale f ≳ 10TeV and an unbroken SU(5) symmetry is preserved. Since the triplet scalars are pseudo Nambu- Goldstone bosons they are split from the much heavier composite-sector resonances and are the lightest exotic, coloured states. This makes them ideal to search for at colliders. Due to discrete symmetries the triplet scalar decays via a dimension-six term and given the large suppression scale f is often metastable. We show that existing searches for collider-stable R-hadrons from Run-I at the LHC forbid a triplet scalar mass below 845 GeV, whereas with 300 fb^{-1} at 13TeV triplet scalar masses up to 1.4TeV can be discovered. For shorter lifetimes displaced-vertex searches provide a discovery reach of up to 1.8TeV. Also, we present exclusion and discovery reaches of future hadron colliders as well as indirect limits that arise from modi cations of the Higgs couplings.
Long-lived, colour-triplet scalars from unnaturalness
Barnard, James; Cox, Peter; Gherghetta, Tony; ...
2016-03-01
We study that long-lived, colour-triplet scalars are a generic prediction of unnatural, or split, composite Higgs models where the spontaneous global-symmetry breaking scale f ≳ 10TeV and an unbroken SU(5) symmetry is preserved. Since the triplet scalars are pseudo Nambu- Goldstone bosons they are split from the much heavier composite-sector resonances and are the lightest exotic, coloured states. This makes them ideal to search for at colliders. Due to discrete symmetries the triplet scalar decays via a dimension-six term and given the large suppression scale f is often metastable. We show that existing searches for collider-stable R-hadrons from Run-I atmore » the LHC forbid a triplet scalar mass below 845 GeV, whereas with 300 fb-1 at 13TeV triplet scalar masses up to 1.4TeV can be discovered. For shorter lifetimes displaced-vertex searches provide a discovery reach of up to 1.8TeV. Also, we present exclusion and discovery reaches of future hadron colliders as well as indirect limits that arise from modi cations of the Higgs couplings.« less
Scalar transport by planktonic swarms
NASA Astrophysics Data System (ADS)
Martinez-Ortiz, Monica; Dabiri, John O.
2012-11-01
Nutrient and energy transport in the ocean is primarily governed by the action of physical phenomena. In previous studies it has been suggested that aquatic fauna may significantly contribute to this process through the action of the induced drift mechanism. In this investigation, the role of planktonic swarms as ecosystem engineers is assessed through the analysis of scalar transport within a stratified water column. The vertical migration of Artemia salina is controlled via luminescent signals on the top and bottom of the column. The scalar transport of fluorescent dye is visualized and quantified through planar laser induced fluorescence (PLIF). Preliminary results show that the vertical movement of these organisms enhances scalar transport relative to control cases in which only buoyancy forces and diffusion are present. Funded by the BSF program (2011553).
The emergence of scalar meanings
Etxeberria, Urtzi; Irurtzun, Aritz
2015-01-01
This paper analyzes the emergence of scalar additive meanings. We show that in Basque the same particle ere can obtain both the “simple additive” reading (akin to English too) and the “scalar additive” reading (akin to English even) but we argue that we do not have to distinguish two types of ere. We provide evidence, by means of a production and a perception experiment, that the reading is disambiguated by means of prosody (the placement of nuclear stress), which is a correlate of focus. We argue that the scalarity effect is generated by the combination of two presuppositions (a focus-induced one and a lexical one) and the assertion of the sentence. PMID:25745405
Controlling the fine-tuning problem with singlet scalar dark matter
NASA Astrophysics Data System (ADS)
Chakraborty, Indrani; Kundu, Anirban
2013-03-01
Assuming that no other conventional new physics is found immediately at the LHC, we investigate how just the consistent solution of the scalar mass hierarchy problem points towards the minimal necessary field content. We show that to ameliorate the fine-tuning problem, one needs to introduce more scalar degrees of freedom. The simplest solution is one or more real singlets (with the possibility of combining two of them in a complex singlet), which may act as viable cold dark matter candidates, because the constraints on the scalar potential disfavor any mixing between the new scalar(s) with the SM doublet. Furthermore, the fine-tuning problem of the new scalars necessitates the introduction of vectorlike fermions. Thus, singlet scalar(s) and vector fermions are minimal enhancements over the Standard Model to alleviate the fine-tuning problem. We also show that the model predicts Landau poles for all the scalar couplings, whose positions depend only on the number of such singlets. Thus, introduction of some new physics at that scale becomes inevitable. We also discuss how the model confronts the LHC constraints and the latest XENON100 data.
Kinetic mixing in scalar-tensor theories of gravity
NASA Astrophysics Data System (ADS)
Bettoni, Dario; Zumalacárregui, Miguel
2015-05-01
Kinetic mixing between the metric and scalar degrees of freedom is an essential ingredient in contemporary scalar-tensor theories. This often makes it hard to understand their physical content, especially when derivative mixing is present, as is the case for Horndeski action. In this work we develop a method that allows us to write a Ricci-curvature-free scalar field equation, and we discuss some of the advantages of such a rephrasing in the study of stability issues in the presence of matter, the existence of an Einstein frame, and the generalization of the disformal screening mechanism. For quartic Horndeski theories, such a procedure leaves, in general, a residual coupling to the curvature, given by the Weyl tensor. This gives rise to a binary classification of scalar-tensor theories into stirred theories, in which the curvature can be substituted, and shaken theories, in which a residual coupling to the curvature remains. Quite remarkably, we have found that generalized Dirac-Born-Infeld Galileons belong to the first class. Finally, we discuss kinetic mixing in quintic theories, in which nonlinear mixing terms appear, and in the recently proposed theories beyond Horndeski that display a novel form of kinetic mixing, in which the field equation is sourced by derivatives of the energy-momentum tensor.
Evolution of dark energy perturbations in scalar-tensor cosmologies
Bueno Sanchez, J. C.; Perivolaropoulos, L.
2010-05-15
We solve analytically and numerically the generalized Einstein equations in scalar-tensor cosmologies to obtain the evolution of dark energy and matter linear perturbations. We compare our results with the corresponding results for minimally coupled quintessence perturbations. We find that scalar-tensor dark energy density perturbations are amplified by a factor of about 10{sup 4} compared to minimally coupled quintessence perturbations on scales less than about 1000 h{sup -1} Mpc (sub-Hubble scales). On these scales dark energy perturbations constitute a fraction of about 10% compared to matter density perturbations. Scalar-tensor dark energy density perturbations are anticorrelated with matter linear perturbations on sub-Hubble scales. This anticorrelation of matter with negative pressure perturbations induces a mild amplification of matter perturbations by about 10% on sub-Hubble scales. The evolution of scalar field perturbations on sub-Hubble scales is scale independent and therefore corresponds to a vanishing effective speed of sound (c{sub s{Phi}=}0). We briefly discuss the observational implications of our results, which may include predictions for galaxy and cluster halo profiles that are modified compared to {Lambda}CDM. The observed properties of these profiles are known to be in some tension with the predictions of {Lambda}CDM.
NLO electroweak corrections in general scalar singlet models
NASA Astrophysics Data System (ADS)
Costa, Raul; Sampaio, Marco O. P.; Santos, Rui
2017-07-01
If no new physics signals are found, in the coming years, at the Large Hadron Collider Run-2, an increase in precision of the Higgs couplings measurements will shift the discussion to the effects of higher order corrections. In Beyond the Standard Model (BSM) theories this may become the only tool to probe new physics. Extensions of the Standard Model (SM) with several scalar singlets may address several of its problems, namely to explain dark matter, the matter-antimatter asymmetry, or to improve the stability of the SM up to the Planck scale. In this work we propose a general framework to calculate one loop-corrections to the propagators and to the scalar field vacuum expectation values of BSM models with an arbitrary number of scalar singlets. We then apply our method to a real and to a complex scalar singlet models. We assess the importance of the one-loop radiative corrections first by computing them for a tree level mixing sum constraint, and then for the main Higgs production process gg → H. We conclude that, for the currently allowed parameter space of these models, the corrections can be at most a few percent. Notably, a non-zero correction can survive when dark matter is present, in the SM-like limit of the Higgs couplings to other SM particles.
Global structure of exact scalar hairy dynamical black holes
NASA Astrophysics Data System (ADS)
Fan, Zhong-Ying; Chen, Bin; Lü, H.
2016-05-01
We study the global structure of some exact scalar hairy dynamical black holes which were constructed in Einstein gravity either minimally or non-minimally coupled to a scalar field. We find that both the apparent horizon and the local event horizon (measured in luminosity coordinate) monotonically increase with the advanced time as well as the Vaidya mass. At late advanced times, the apparent horizon approaches the event horizon and gradually becomes future outer. Correspondingly, the space-time arrives at stationary black hole states with the relaxation time inversely proportional to the 1/( n-1) power of the final black hole mass, where n is the space-time dimension. These results strongly support the solutions describing the formation of black holes with scalar hair. We also obtain new charged dynamical solutions in the non-minimal theory by introducing an Maxwell field which is non-minimally coupled to the scalar. The presence of the electric charge strongly modifies the dynamical evolution of the space-time.
Abnormal Sperm Development in pcd3J-/- Mice: the Importance of Agtpbp1 in Spermatogenesis
Kim, Nameun; Xiao, Rui; Choi, Hojun; Kim, Jin-Hoi; Sang-Jun, Uhm; Chankyu, Park
2011-01-01
Homozygous Purkinje cell degeneration (pcd) mutant males exhibit abnormal sperm development. Microscopic examination of the testes from pcd3J-/- mice at postnatal days 12, 15, 18 and 60 revealed histological differences, in comparison to wild-type mice, which were evident by day 18. Greatly reduced numbers of spermatocytes and spermatids were found in the adult testes, and apoptotic cells were identified among the differentiating germ cells after day 15. Our immunohistological analysis using an antihuman AGTPBP1 antibody showed that AGTPBP1 was expressed in spermatogenic cells between late stage primary spermatocytes and round spermatids. A global gene expression analysis from the testes of pcd3J-/- mice showed that expression of cyclin B3 and de-ubiquitinating enzymes USP2 and USP9y was altered by >1.5-fold compared to the expression levels in the wild-type. Our results suggest that the pcd mutant mice have defects in spermatogenesis that begin with the pachytene spermatocyte stage and continue through subsequent stages. Thus, Agtpbp1, the gene responsible for the pcd phenotype, plays an important role in spermatogenesis and is important for survival of germ cells at spermatocytes stage onward. PMID:21110128
Scalar fields and particle accelerators
NASA Astrophysics Data System (ADS)
Sultana, Joseph; Bose, Benjamin
2015-06-01
The phenomenon discovered in 2009 by Bañados, Silk and West where particle collisions can achieve arbitrary high center-of-mass (c.m.) energies close to the event horizon of an extreme Kerr black hole, has generated a lot of interest. Although rotation seemed to be an essential requirement, it was later shown that arbitrary high energies can also be achieved for collisions between radially moving particles near the horizon of the electrically charged extreme Reissner-Nordström black hole. Recently Patil and Joshi claimed that instead of spinning up the black hole one can also crank up the c.m. energy of particle collisions by "charging up" a static black hole with a massless scalar field. In this regard they showed that infinite energies can be attained in the vicinity of the naked singularity of the Janis-Newman-Wincour (JNW) spacetime, which contains a massless scalar field that also becomes infinite at the position of the curvature singularity. In this study we show that Patil and Joshi's claim does not apply for other static black hole systems endowed with a massless scalar field. In particular we consider the well-known Bekenstein black hole and the recently discovered Martínez-Troncoso-Zanelli black hole, and show that the expression of the c.m. energy for particle collisions near the event horizons of these black holes is no different than the corresponding case with vanishing scalar field represented by the Schwarzschild solution. Moreover by studying the motion of scalar test charges that interact with the background scalar field in these black hole spacetimes we show that the resulting c.m. energies are even smaller than in the case of free particles. This shows that the infinite energies obtained by Patil and Joshi may not be due to the fact that the black hole contains a massless scalar field, but may be instead related to the geometry of the naked singularity in the JNW spacetime. An analogous case of infinite c.m. energy in the vicinity of a naked
Electromagnetic fields with vanishing scalar invariants
NASA Astrophysics Data System (ADS)
Ortaggio, Marcello; Pravda, Vojtěch
2016-06-01
We determine the class of p-forms {\\boldsymbol{F}} that possess vanishing scalar invariants (VSIs) at arbitrary order in an n-dimensional spacetime. Namely, we prove that {\\boldsymbol{F}} is a VSI if and only if if it is of type N, its multiple null direction {\\boldsymbol{\\ell }} is ‘degenerate Kundt’, and {\\pounds }{\\boldsymbol{\\ell }}{\\boldsymbol{F}}=0. The result is theory-independent. Next, we discuss the special case of Maxwell fields, both at the level of test fields and of the full Einstein-Maxwell equations. These describe electromagnetic non-expanding waves propagating in various Kundt spacetimes. We further point out that a subset of these solutions possesses a universal property, i.e. they also solve (virtually) any generalized (non-linear and with higher derivatives) electrodynamics, possibly also coupled to Einstein’s gravity.
Scalar meson spectroscopy with a fine lattice
NASA Astrophysics Data System (ADS)
Fu, Zi-Wen; Carleton, DeTar
2011-10-01
With sufficiently light u and d quarks the isovector (a0) and isosinglet (f0) scalar meson propagators are dominated at large distances by two-meson states. In the staggered fermion formulation of lattice QCD, taste-symmetry breaking causes a proliferation of multihadron states that complicates the analysis of these channels. Of special interest is the bubble contribution, which makes a considerable contribution to these channels. Using numerical simulation we have measured the correlators for both a0 and f0 channels in the “Asqtad" improved staggered fermion formulation in a MILC fine (a = 0.09 fm) lattice ensemble. We analyze those correlators using rooted staggered chiral perturbation theory (rSχPT) and achieve chiral couplings that are well consistent with previous determinations.
LHC constraints on color octet scalars
NASA Astrophysics Data System (ADS)
Hayreter, Alper; Valencia, German
2017-08-01
We extract constraints on the parameter space of the Manohar and Wise model by comparing the cross sections for dijet, top-pair, dijet-pair, t t ¯t t ¯ and b b ¯b b ¯ productions at the LHC with the strongest available experimental limits from ATLAS or CMS at 8 or 13 TeV. Overall we find mass limits around 1 TeV in the most sensitive regions of parameter space, and lower elsewhere. This is at odds with generic limits for color octet scalars often quoted in the literature where much larger production cross sections are assumed. The constraints that can be placed on coupling constants are typically weaker than those from existing theoretical considerations, with the exception of the parameter ηD.
Brooks, Joshua D.; Milne, Ginger L.; Yin, Huiyong; Sanchez, Stephanie C.; Porter, Ned A.; Morrow, Jason D.
2008-01-01
Omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) found in marine fish oils are known to suppress inflammation associated with a wide variety of diseases. Eicosapentaenoic acid (EPA) is one of the most abundant ω-3 fatty acids in fish oil, but the mechanism(s) by which EPA exerts its beneficial effects is unknown. Recent studies, however, have demonstrated that oxidized EPA, rather than native EPA, possesses anti-atherosclerotic, anti-inflammatory, and anti-proliferative effects. Very few studies to date have investigated which EPA oxidation products are responsible for this bioactivity. Our research group has previously reported that anti-inflammatory prostaglandin A2-like and prostaglandin J2-like compounds, termed A2/J2-isoprostanes (IsoPs), are produced in vivo by the free radical-catalyzed peroxidation of arachidonic acid and represent one of the major products resulting from the oxidation of this PUFA. Based on these observations, we questioned whether cyclopentenone-IsoP compounds are formed from the oxidation of EPA in vivo. Herein, we report the formation of cyclopentenone-IsoP molecules, termed A3/J3-IsoPs, formed in abundance in vitro and in vivo from EPA peroxidation. Chemical approaches coupled with gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) were used to structurally characterize these compounds as A3/J3-IsoPs. We found that levels of these molecules increase ∼200-fold with oxidation of EPA in vitro from a basal level of 0.8 ± 0.4 ng/mg EPA to 196 ± 23 ng/mg EPA after 36 h. We also detected these compounds in significant amounts in fresh liver tissue from EPA-fed rats at basal levels of 19 ± 2 ng/g tissue. Amounts increased to 102 ± 15 ng/g tissue in vivo in settings of oxidative stress. These studies have, for the first time, definitively characterized novel, highly reactive A/J-ring IsoP compounds that form in abundance from the oxidation of EPA in vivo. PMID:18263929
Scalar-tensor cosmology at the general relativity limit: Jordan versus Einstein frame
Jaerv, Laur; Kuusk, Piret; Saal, Margus
2007-11-15
We consider the correspondence between the Jordan frame and the Einstein frame descriptions of scalar-tensor theory of gravitation. We argue that since the redefinition of the scalar field is not differentiable at the limit of general relativity the correspondence between the two frames is lost at this limit. To clarify the situation we analyze the dynamics of the scalar field in different frames for two distinct scalar-tensor cosmologies with specific coupling functions and demonstrate that the corresponding scalar field phase portraits are not equivalent for regions containing the general relativity limit. Therefore the answer to the question of whether general relativity is an attractor for the theory depends on the choice of the frame.
Scalar-tensor cosmologies: Fixed points of the Jordan frame scalar field
Jaerv, Laur; Kuusk, Piret; Saal, Margus
2008-10-15
We study the evolution of homogeneous and isotropic, flat cosmological models within the general scalar-tensor theory of gravity with arbitrary coupling function and potential. After introducing the limit of general relativity we describe the details of the phase space geometry. Using the methods of dynamical systems for the decoupled equation of the Jordan frame scalar field we find the fixed points of flows in two cases: potential domination and matter domination. We present the conditions on the mathematical form of the coupling function and potential which determine the nature of the fixed points (attractor or other). There are two types of fixed points, both are characterized by cosmological evolution mimicking general relativity, but only one of the types is compatible with the Solar System parametrized post-Newtonian (PPN) constraints. The phase space structure should also carry over to the Einstein frame as long as the transformation between the frames is regular which however is not the case for the latter (PPN compatible) fixed point.
The trace anomaly and massless scalar degrees of freedom
Gianotti, Maurizio; Mottola, Emil
2008-01-01
The trace anomaly of quantum fields in electromagnetic or gravitational backgrounds implies the existence of massless scalar poles in physical amplitudes involving the stress-energy tensor. Considering first the axial anomaly and using QED as an example, we compute the full one-loop triangle amplitude of the fermionic stress tensor with two current vertices, {open_square}T{sup {mu}{nu}}J{sup {alpha}}J{sup {beta}}, and exhibit the scalar pole in this amplitude associated with the trace anomaly, in the limit of zero electron mass m{yields}0. To emphasize the infrared aspect of the anomaly, we use a dispersive approach and show that this amplitude and the existence of the massless scalar pole is determined completely by its ultraviolet finite terms, together with the requirements of Poincare invariance of the vacuum, Bose symmetry under interchange of J{sup {alpha}} and J{sup {beta}}, and vector current and stress-tensor conservation. We derive a sum rule for the appropriate positive spectral function corresponding to the discontinuity of the triangle amplitude, showing that it becomes proportional to {delta}(k{sup 2}) and therefore contains a massless scalar intermediate state in the conformal limit of zero electron mass. The effective action corresponding to the trace of the triangle amplitude can be expressed in local form by the introduction of two scalar auxiliary fields which satisfy massless wave equations. These massless scalar degrees of freedom couple to classical sources, contribute to gravitational scattering processes, and can have long range gravitational effects.
Comment on "SU(5) octet scalar at the LHC"
NASA Astrophysics Data System (ADS)
Doršner, Ilja
2015-06-01
I address the validity of results presented in [S. Khalil, S. Salem, and M. Allam, Phys. Rev. D 89, 095011 (2014)] with regard to unification of gauge couplings within a particular S U (5 ) framework. The scalar sector of the proposed S U (5 ) model contains one 5-dimensional, one 24-dimensional, and one 45-dimensional representation. The authors discuss one specific unification scenario that supports the case for the LHC accessible color octet scalar. I show that the unification analysis in question is based on (i) an erroneous assumption related to the issue of nucleon stability and (ii) an incorrect input for the applicable set of renormalization group equations. This, in my view, invalidates the aforementioned gauge coupling unification study. I also question a source of the fermion mass relations presented in that work.
Chameleon scalar fields in relativistic gravitational backgrounds
Tsujikawa, Shinji; Tamaki, Takashi; Tavakol, Reza E-mail: tamaki@gravity.phys.waseda.ac.jp
2009-05-15
We study the field profile of a scalar field {phi} that couples to a matter fluid (dubbed a chameleon field) in the relativistic gravitational background of a spherically symmetric spacetime. Employing a linear expansion in terms of the gravitational potential {Phi}{sub c} at the surface of a compact object with a constant density, we derive the thin-shell field profile both inside and outside the object, as well as the resulting effective coupling with matter, analytically. We also carry out numerical simulations for the class of inverse power-law potentials V({phi}) = M{sup 4+n}{phi}{sup -n} by employing the information provided by our analytical solutions to set the boundary conditions around the centre of the object and show that thin-shell solutions in fact exist if the gravitational potential {Phi}{sub c} is smaller than 0.3, which marginally covers the case of neutron stars. Thus the chameleon mechanism is present in the relativistic gravitational backgrounds, capable of reducing the effective coupling. Since thin-shell solutions are sensitive to the choice of boundary conditions, our analytic field profile is very helpful to provide appropriate boundary conditions for {Phi}{sub c}{approx}
Cosmological evolution and Solar System consistency of massive scalar-tensor gravity
NASA Astrophysics Data System (ADS)
de Pirey Saint Alby, Thibaut Arnoulx; Yunes, Nicolás
2017-09-01
The scalar-tensor theory of Damour and Esposito-Farèse recently gained some renewed interest because of its ability to suppress modifications to general relativity in the weak field, while introducing large corrections in the strong field of compact objects through a process called scalarization. A large sector of this theory that allows for scalarization, however, has been shown to be in conflict with Solar System observations when accounting for the cosmological evolution of the scalar field. We here study an extension of this theory by endowing the scalar field with a mass to determine whether this allows the theory to pass Solar System constraints upon cosmological evolution for a larger sector of coupling parameter space. We show that the cosmological scalar field goes first through a quiescent phase, similar to the behavior of a massless field, but then it enters an oscillatory phase, with an amplitude (and frequency) that decays (and grows) exponentially. We further show that after the field enters the oscillatory phase, its effective energy density and pressure are approximately those of dust, as expected from previous cosmological studies. Due to these oscillations, we show that the scalar field cannot be treated as static today on astrophysical scales, and so we use time-dependent perturbation theory to compute the scalar-field-induced modifications to Solar System observables. We find that these modifications are suppressed when the mass of the scalar field and the coupling parameter of the theory are in a wide range, allowing the theory to pass Solar System constraints, while in principle possibly still allowing for scalarization.
A late time accelerated FRW model with scalar and vector fields via Noether symmetry
NASA Astrophysics Data System (ADS)
Vakili, Babak
2014-11-01
We study the evolution of a three-dimensional minisuperspace cosmological model by the Noether symmetry approach. The phase space variables turn out to correspond to the scale factor of a flat Friedmann-Robertson-Walker (FRW) model, a scalar field with potential function V (ϕ) with which the gravity part of the action is minimally coupled and a vector field of its kinetic energy is coupled with the scalar field by a coupling function f (ϕ). Then, the Noether symmetry of such a cosmological model is investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generator of the desired symmetry. We explicitly calculate the form of the coupling function between the scalar and the vector fields and also the scalar field potential function for which such symmetry exists. Finally, by means of the corresponding Noether current, we integrate the equations of motion and obtain exact solutions for the scale factor, scalar and vector fields. It is shown that the resulting cosmology is an accelerated expansion universe for which its expansion is due to the presence of the vector field in the early times, while the scalar field is responsible of its late time expansion.
De Bruck, Carsten van; Longden, Chris; Koivisto, Tomi E-mail: timoko@kth.se
2016-03-01
A disformal coupling between two scalar fields is considered in the context of cosmological inflation. The coupling introduces novel derivative interactions mixing the kinetic terms of the fields but without introducing superluminal or unstable propagation of the two scalar fluctuation modes. Though the typical effect of the disformal coupling is to inhibit one of the fields from inflating the universe, the energy density of the other field can drive viable near Sitter -inflation in the presence of nontrivial disformal dynamics, in particular when one assumes exponential instead of power-law form for the couplings. The linear perturbation equations are written for the two-field system, its canonical degrees of freedom are quantised, their spectra are derived and the inflationary predictions are reported for numerically solved exponential models. A generic prediction is low tensor-to-scalar ratio.
Scalar-tensor teleparallel wormholes by Noether symmetries
NASA Astrophysics Data System (ADS)
Bahamonde, Sebastian; Camci, Ugur; Capozziello, Salvatore; Jamil, Mubasher
2016-10-01
A gravitational theory of a scalar field nonminimally coupled with torsion and a boundary term is considered with the aim to construct Lorentzian wormholes. Geometrical parameters including shape and redshift functions are obtained for these solutions. We adopt the formalism of the Noether gauge symmetry approach in order to find symmetries, Lie brackets and invariants (conserved quantities). Furthermore by imposing specific forms of potential function, we are able to calculate metric coefficients and discuss their geometrical behavior.
GravitoMagnetic Field in Tensor-Vector-Scalar Theory
Exirifard, Qasem
2013-04-01
We study the gravitomagnetism in the TeVeS theory. We compute the gravitomagnetic field that a slow moving mass distribution produces in its Newtonian regime. We report that the consistency between the TeVeS gravitomagnetic field and that predicted by the Einstein-Hilbert theory leads to a relation between the vector and scalar coupling constants of the theory. We translate the Lunar Laser Ranging measurement's data into a constraint on the deviation from this relation.
Entanglement between two scalar fields in an expanding spacetime
NASA Astrophysics Data System (ADS)
Alexander, Helder; da Paz, I. G.; Sampaio, Marcos
2017-06-01
We study the evolution of two scalar fields entangled via a mutual interaction in an expanding spacetime. We compute the logarithmic negativity to leading order in perturbation theory and show that for the lowest order in the coupling constants, the mutual interaction will give rise to the survival of the quantum correlations in the limit of the smooth expansion. The results suggest that interacting fields can codify more information about the underlying expansion spacetime and lead to interesting observable effects.
Early-time cosmological solutions in Einstein-scalar-Gauss-Bonnet theory
NASA Astrophysics Data System (ADS)
Kanti, Panagiota; Gannouji, Radouane; Dadhich, Naresh
2015-10-01
In this work, we consider a generalized gravitational theory that contains the Einstein term, a scalar field, and the quadratic Gauss-Bonnet (GB) term. We focus on the early-universe dynamics, and demonstrate that a simple choice of the coupling function between the scalar field and the Gauss-Bonnet term and a simplifying assumption regarding the role of the Ricci scalar can lead to new, analytical, elegant solutions with interesting characteristics. We first argue, and demonstrate in the context of two different models, that the presence of the Ricci scalar in the theory at early times (when the curvature is strong) does not affect the actual cosmological solutions. By considering therefore a pure scalar-GB theory with a quadratic coupling function we derive a plethora of interesting, analytic solutions: for a negative coupling parameter, we obtain inflationary, de Sitter-type solutions or expanding solutions with a de Sitter phase in their past and a natural exit mechanism at later times; for a positive coupling function, we find instead singularity-free solutions with no big bang singularity. We show that the aforementioned solutions arise only for this particular choice of coupling function, a result that may hint at some fundamental role that this coupling function may hold in the context of an ultimate theory.
Constrained inflaton due to a complex scalar
Budhi, Romy H. S.; Kashiwase, Shoichi; Suematsu, Daijiro
2015-09-14
We reexamine inflation due to a constrained inflaton in the model of a complex scalar. Inflaton evolves along a spiral-like valley of special scalar potential in the scalar field space just like single field inflation. Sub-Planckian inflaton can induce sufficient e-foldings because of a long slow-roll path. In a special limit, the scalar spectral index and the tensor-to-scalar ratio has equivalent expressions to the inflation with monomial potential φ{sup n}. The favorable values for them could be obtained by varying parameters in the potential. This model could be embedded in a certain radiative neutrino mass model.
CP violating scalar Dark Matter
NASA Astrophysics Data System (ADS)
Cordero-Cid, A.; Hernández-Sánchez, J.; Keus, V.; King, S. F.; Moretti, S.; Rojas, D.; Sokołowska, D.
2016-12-01
We study an extension of the Standard Model (SM) in which two copies of the SM scalar SU(2) doublet which do not acquire a Vacuum Expectation Value (VEV), and hence are inert, are added to the scalar sector. We allow for CP-violation in the inert sector, where the lightest inert state is protected from decaying to SM particles through the conservation of a Z 2 symmetry. The lightest neutral particle from the inert sector, which has a mixed CP-charge due to CP-violation, is hence a Dark Matter (DM) candidate. We discuss the new regions of DM relic density opened up by CP-violation, and compare our results to the CP-conserving limit and the Inert Doublet Model (IDM). We constrain the parameter space of the CP-violating model using recent results from the Large Hadron Collider (LHC) and DM direct and indirect detection experiments.
Slow-roll inflation in loop quantum cosmology of scalar-tensor theories of gravity
NASA Astrophysics Data System (ADS)
Han, Yu
2015-07-01
The slow-roll inflation of scalar-tensor theories (STTs) of gravity in the context of loop quantum cosmology (LQC) is investigated in this paper. After deriving the effective Hamiltonian, we obtain the semiclassical equations of motion for the background variables in both Jordan frame and Einstein frame of STTs. Then we apply these equations in the slow-roll limit and derive the LQC corrections to the scalar spectral index ns and the tensor-to-scalar ratio r in the two frames of STTs. Finally, we take two special sectors of STTs as specific examples, namely the Starobinsky model and the non-minimally coupled scalar field model (with the coupling function ξϕ2R and the potential λ 4 ϕ4). We derive the detailed expressions of the LQC corrections to ns and r in terms of the e-folding number for these two models in both frames.
Fodor, Gyula; Forgacs, Peter; Mezei, Mark
2010-03-15
Spherically symmetric oscillatons (also referred to as oscillating soliton stars) i.e. gravitationally bound oscillating scalar lumps are considered in theories containing a massive self-interacting real scalar field coupled to Einstein's gravity in 1+D dimensional spacetimes. Oscillations are known to decay by emitting scalar radiation with a characteristic time scale which is, however, extremely long, it can be comparable even to the lifetime of our universe. In the limit when the central density (or amplitude) of the oscillaton tends to zero (small-amplitude limit) a method is introduced to compute the transcendentally small amplitude of the outgoing waves. The results are illustrated in detail on the simplest case, a single massive free scalar field coupled to gravity.
NASA Astrophysics Data System (ADS)
Hod, Shahar
2016-12-01
The physical properties of bound-state charged massive scalar field configurations linearly coupled to a spherically symmetric charged reflecting shell are studied analytically. To that end, we solve the Klein-Gordon wave equation for a static scalar field of proper mass μ, charge coupling constant q, and spherical harmonic index l in the background of a charged shell of radius R and electric charge Q. It is proved that the dimensionless inequality μR <√{(qQ) 2 -(l + 1 / 2) 2 } provides an upper bound on the regime of existence of the composed charged-spherical-shell-charged-massive-scalar-field configurations. Interestingly, we explicitly show that the discrete spectrum of shell radii {Rn(μ,qQ,l)}n = 0 n = ∞ which can support the static bound-state charged massive scalar field configurations can be determined analytically. We confirm our analytical results by numerical computations.
Scalar speed limits and cosmology: Acceleration from D-cceleration
NASA Astrophysics Data System (ADS)
Silverstein, Eva; Tong, David
2004-11-01
Causality on the gravity side of the AdS/CFT correspondence restricts motion on the moduli space of the N=4 super Yang-Mills theory by imposing a speed limit on how fast the scalar field may roll. This effect can be traced to higher-derivative operators arising from integrating out light degrees of freedom near the origin. In the strong coupling limit of the theory, the dynamics is well approximated by the Dirac-Born-Infeld Lagrangian for a probe D3-brane moving toward the horizon of the AdS Poincaré patch, combined with an estimate of the (ultimately suppressed) rate of particle and string production in the system. We analyze the motion of a rolling scalar field explicitly in the strong coupling regime of the field theory and extend the analysis to cosmological systems obtained by coupling this type of field theory to four-dimensional gravity. This leads to a mechanism for slow roll inflation for a massive scalar at sub-Planckian vacuum expectation value without need for a flat potential (realizing a version of k inflation in a microphysical framework). It also leads to a variety of novel Friedman-Roberston-Walker cosmologies, some of which are related to those obtained with tachyon matter.
Scalar Speed Limits and Cosmology: Acceleration from Deceleration
Silverstein, E
2003-11-21
Causality on the gravity side of the AdS/CFT correspondence restricts motion on the moduli space of the N = 4 super Yang Mills theory by imposing a speed limit on how fast the scalar field may roll. This effect can be traced to higher derivative operators arising from integrating out light degrees of freedom near the origin. In the strong coupling limit of the theory, the dynamics is well approximated by the Dirac-Born-Infeld Lagrangian for a probe D3-brane moving toward the horizon of the AdS Poincare patch, combined with an estimate of the (ultimately suppressed) rate of particle and string production in the system. We analyze the motion of a rolling scalar field explicitly in the strong coupling regime of the field theory, and extend the analysis to cosmological systems obtained by coupling this type of field theory to four dimensional gravity. This leads to a mechanism for slow roll inflation for a massive scalar at subPlanckian VEV without need for a flat potential (realizing a version of k-inflation in a microphysical framework). It also leads to a variety of novel FRW cosmologies, some of which are related to those obtained with tachyon matter.
Random scalar fields and hyperuniformity
NASA Astrophysics Data System (ADS)
Ma, Zheng; Torquato, Salvatore
2017-06-01
Disordered many-particle hyperuniform systems are exotic amorphous states of matter that lie between crystals and liquids. Hyperuniform systems have attracted recent attention because they are endowed with novel transport and optical properties. Recently, the hyperuniformity concept has been generalized to characterize two-phase media, scalar fields, and random vector fields. In this paper, we devise methods to explicitly construct hyperuniform scalar fields. Specifically, we analyze spatial patterns generated from Gaussian random fields, which have been used to model the microwave background radiation and heterogeneous materials, the Cahn-Hilliard equation for spinodal decomposition, and Swift-Hohenberg equations that have been used to model emergent pattern formation, including Rayleigh-Bénard convection. We show that the Gaussian random scalar fields can be constructed to be hyperuniform. We also numerically study the time evolution of spinodal decomposition patterns and demonstrate that they are hyperuniform in the scaling regime. Moreover, we find that labyrinth-like patterns generated by the Swift-Hohenberg equation are effectively hyperuniform. We show that thresholding (level-cutting) a hyperuniform Gaussian random field to produce a two-phase random medium tends to destroy the hyperuniformity of the progenitor scalar field. We then propose guidelines to achieve effectively hyperuniform two-phase media derived from thresholded non-Gaussian fields. Our investigation paves the way for new research directions to characterize the large-structure spatial patterns that arise in physics, chemistry, biology, and ecology. Moreover, our theoretical results are expected to guide experimentalists to synthesize new classes of hyperuniform materials with novel physical properties via coarsening processes and using state-of-the-art techniques, such as stereolithography and 3D printing.
Spinning boson stars and Kerr black holes with scalar hair: The effect of self-interactions
NASA Astrophysics Data System (ADS)
Herdeiro, Carlos A. R.; Radu, Eugen; Rúnarsson, Helgi F.
2016-05-01
Self-interacting boson stars (BSs) have been shown to alleviate the astrophysically low maximal mass of their nonself-interacting counterparts. We report some physical features of spinning self-interacting BSs, namely their compactness, the occurrence of ergo-regions and the scalar field profiles, for a sample of values of the coupling parameter. The results agree with the general picture that these BSs are comparatively less compact than the nonself-interacting ones. We also briefly discuss the effect of scalar self-interactions on the properties of Kerr black holes with scalar hair.
NASA Astrophysics Data System (ADS)
Kim, Nakwoo
2015-03-01
We consider scalar fields which are coupled to Einstein gravity with a negative cosmological constant, and construct periodic solutions perturbatively. In particular, we study tachyonic scalar fields whose mass is at or above the Breitenlohner-Freedman bound in four, five, and seven spacetime dimensions. The critical amplitude of the leading order perturbation, for which the perturbative expansion breaks down, increases as we consider less massive fields. We present various examples including a model with a self-interacting scalar field which is derived from a consistent truncation of IIB supergravity.
Johnson, W.M.
1989-01-01
A super-scalar processor is one that is capable of sustaining an instruction-execution rate of more than one instruction per clock cycle. Maintaining this execution rate is primarily a problem of scheduling processor resources (such as functional units) for high utilization. This study uses trace-driven simulation to evaluate many different super-scalar hardware organizations. It uses general-purpose bench-mark programs executed with a typical RISC instruction set. Highly-optimized versions of the benchmark programs are used, to avoid measuring concurrency that is due to a lack of compiler optimization. In contrast to previous studies, this study examines a wide range of cost and performance tradeoffs, rather than focusing on one specific processor organization or scheduling algorithm. Furthermore, the results are not based on idealizations; for example, they include the effects of realistic functional-unit latencies, instruction and data caches, and multi-tasking. Within this framework, super-scalar performance is limited primarily by instruction-fetch inefficiencies caused by both branch delays and instruction misalignment. Because of this instruction-fetch limitation, it is not worthwhile to explore highly-concurrent execution hardware. Rather, it is more appropriate to explore economical execution hardware that more closely matches the instruction throughout provided by the instruction fetcher. This study examines techniques for reducing the instruction-fetch inefficiencies and explores the resulting hardware organizations.
Wheeler-DeWitt equation and Lie symmetries in Bianchi scalar-field cosmology
NASA Astrophysics Data System (ADS)
Paliathanasis, A.; Karpathopoulos, L.; Wojnar, A.; Capozziello, S.
2016-04-01
Lie symmetries are discussed for the Wheeler-De Witt equation in Bianchi Class A cosmologies. In particular, we consider general relativity, minimally coupled scalar-field gravity and hybrid gravity as paradigmatic examples of the approach. Several invariant solutions are determined and classified according to the form of the scalar-field potential. The approach gives rise to a suitable method to select classical solutions and it is based on the first principle of the existence of symmetries.
Gauge-invariant perturbations at second order: multiple scalar fields on large scales
NASA Astrophysics Data System (ADS)
Malik, Karim A.
2005-11-01
We derive the governing equations for multiple scalar fields minimally coupled to gravity in a flat Friedmann Robertson Walker background spacetime on large scales. We include scalar perturbations up to second order and write the equations in terms of physically transparent gauge-invariant variables at first and second order. This allows us to write the perturbed Klein Gordon equation at second order solely in terms of the field fluctuations on flat slices at first and second order.
A new approach to exact solutions construction in scalar cosmology with a Gauss-Bonnet term
NASA Astrophysics Data System (ADS)
Fomin, I. V.; Chervon, S. V.
2017-08-01
We study the cosmological model based on Einstein-Gauss-Bonnet gravity with non-minimal coupling of a scalar field to a Gauss-Bonnet term in four-dimensional (4D) Friedmann universe. We show how constructing the exact solutions by the method based on a confrontation of the Hubble parameter in the model under consideration is achieved with that in a standard scalar field inflationary cosmology.
Scalar gravitational waves in the effective theory of gravity
Mottola, Emil
2017-07-10
As a low energy effective field theory, classical General Relativity receives an infrared relevant modification from the conformal trace anomaly of the energy-momentum tensor of massless, or nearly massless, quantum fields. The local form of the effective action associated with the trace anomaly is expressed in terms of a dynamical scalar field that couples to the conformal factor of the spacetime metric, allowing it to propagate over macroscopic distances. Linearized around flat spacetime, this semi-classical EFT admits scalar gravitational wave solutions in addition to the transversely polarized tensor waves of the classical Einstein theory. The amplitude of the scalar wavemore » modes, as well as their energy and energy flux which are positive and contain a monopole moment, are computed. As a result, astrophysical sources for scalar gravitational waves are considered, with the excited gluonic condensates in the interiors of neutron stars in merger events with other compact objects likely to provide the strongest burst signals.« less
Propagation of Scalar Fields in a Plane Symmetric Spacetime
NASA Astrophysics Data System (ADS)
Celestino, Juliana; Alves, Márcio E. S.; Barone, F. A.
2016-12-01
The present article deals with solutions for a minimally coupled scalar field propagating in a static plane symmetric spacetime. The considered metric describes the curvature outside a massive infinity plate and exhibits an intrinsic naked singularity (a singular plane) that makes the accessible universe finite in extension. This solution can be interpreted as describing the spacetime of static domain walls. In this context, a first solution is given in terms of zero order Bessel functions of the first and second kind and presents a stationary pattern which is interpreted as a result of the reflection of the scalar waves at the singular plane. This is an evidence, at least for the massless scalar field, of an old interpretation given by Amundsen and Grøn regarding the behaviour of test particles near the singularity. A second solution is obtained in the limit of a weak gravitational field which is valid only far from the singularity. In this limit, it was possible to find out an analytic solution for the scalar field in terms of the Kummer and Tricomi confluent hypergeometric functions.
Scalar triplet flavored leptogenesis: a systematic approach
Sierra, D. Aristizabal; Dhen, Mikaël; Hambye, Thomas E-mail: mikadhen@ulb.ac.be
2014-08-01
Type-II seesaw is a simple scenario in which Majorana neutrino masses are generated by the exchange of a heavy scalar electroweak triplet. When endowed with additional heavy fields, such as right-handed neutrinos or extra triplets, it also provides a compelling framework for baryogenesis via leptogenesis. We derive in this context the full network of Boltzmann equations for studying leptogenesis in the flavored regime. To this end we determine the relations which hold among the chemical potentials of the various particle species in the thermal bath. This takes into account the standard model Yukawa interactions of both leptons and quarks as well as sphaleron processes which, depending on the temperature, may be classified as faster or slower than the Universe Hubble expansion. We find that when leptogenesis is enabled by the presence of an extra triplet, lepton flavor effects allow the production of the B-L asymmetry through lepton number conserving CP asymmetries. This scenario becomes dominant as soon as the triplets couple more to leptons than to standard model scalar doublets. In this case, the way the B-L asymmetry is created through flavor effects is novel: instead of invoking the effect of L-violating inverse decays faster than the Hubble rate, it involves the effect of L-violating decays slower than the Hubble rate. We also analyze the more general situation where lepton number violating CP asymmetries are present and actively participate in the generation of the B-L asymmetry, pointing out that as long as L-violating triplet decays are still in thermal equilibrium when the triplet gauge scattering processes decouple, flavor effects can be striking, allowing to avoid all washout suppression effects from seesaw interactions. In this case the amount of B-L asymmetry produced is limited only by a universal gauge suppression effect, which nevertheless goes away for large triplet decay rates.
Neutrino Oscillations as a Probe of Light Scalar Dark Matter.
Berlin, Asher
2016-12-02
We consider a class of models involving interactions between ultralight scalar dark matter and standard model neutrinos. Such couplings modify the neutrino mass splittings and mixing angles to include additional components that vary in time periodically with a frequency and amplitude set by the mass and energy density of the dark matter. Null results from recent searches for anomalous periodicities in the solar neutrino flux strongly constrain the dark matter-neutrino coupling to be orders of magnitude below current and projected limits derived from observations of the cosmic microwave background.
Neutrino Oscillations as a Probe of Light Scalar Dark Matter
NASA Astrophysics Data System (ADS)
Berlin, Asher
2016-12-01
We consider a class of models involving interactions between ultralight scalar dark matter and standard model neutrinos. Such couplings modify the neutrino mass splittings and mixing angles to include additional components that vary in time periodically with a frequency and amplitude set by the mass and energy density of the dark matter. Null results from recent searches for anomalous periodicities in the solar neutrino flux strongly constrain the dark matter-neutrino coupling to be orders of magnitude below current and projected limits derived from observations of the cosmic microwave background.
Stabilization of semilocal strings by dark scalar condensates
NASA Astrophysics Data System (ADS)
Forgács, Péter; Lukács, Árpád
2017-02-01
Semilocal and electroweak strings are well known to be unstable against unwinding by the condensation of the second Higgs component in their cores. A large class of current models of dark matter contains dark scalar fields coupled to the Higgs sector of the Standard Model (Higgs portal) and/or dark U(1) gauge fields. It is shown that Higgs-portal-type couplings and a gauge kinetic mixing term of the dark U(1) gauge field have a significant stabilizing effect on semilocal strings in the "visible" sector.
Signals from flavor changing scalar currents at the future colliders
Atwood, D.; Reina, L.; Soni, A.
1996-11-22
We present a general phenomenological analysis of a class of Two Higgs Doublet Models with Flavor Changing Neutral Currents arising at the tree level. The existing constraints mainly affect the couplings of the first two generations of quarks, leaving the possibility for non negligible Flavor Changing couplings of the top quark open. The next generation of lepton and hadron colliders will offer the right environment to study the physics of the top quark and to unravel the presence of new physics beyond the Standard Model. In this context we discuss some interesting signals from Flavor Changing Scalar Neutral Currents.
Running vacuum cosmological models: linear scalar perturbations
NASA Astrophysics Data System (ADS)
Perico, E. L. D.; Tamayo, D. A.
2017-08-01
In cosmology, phenomenologically motivated expressions for running vacuum are commonly parameterized as linear functions typically denoted by Λ(H2) or Λ(R). Such models assume an equation of state for the vacuum given by bar PΛ = - bar rhoΛ, relating its background pressure bar PΛ with its mean energy density bar rhoΛ ≡ Λ/8πG. This equation of state suggests that the vacuum dynamics is due to an interaction with the matter content of the universe. Most of the approaches studying the observational impact of these models only consider the interaction between the vacuum and the transient dominant matter component of the universe. We extend such models by assuming that the running vacuum is the sum of independent contributions, namely bar rhoΛ = Σibar rhoΛi. Each Λ i vacuum component is associated and interacting with one of the i matter components in both the background and perturbation levels. We derive the evolution equations for the linear scalar vacuum and matter perturbations in those two scenarios, and identify the running vacuum imprints on the cosmic microwave background anisotropies as well as on the matter power spectrum. In the Λ(H2) scenario the vacuum is coupled with every matter component, whereas the Λ(R) description only leads to a coupling between vacuum and non-relativistic matter, producing different effects on the matter power spectrum.
Sweetener preference of C57BL/6ByJ and 129P3/J mice
Bachmanov, Alexander A.; Tordoff, Michael G.; Beauchamp, Gary K.
2013-01-01
Previous studies have shown large differences in taste responses to several sweeteners between mice from the C57BL/6ByJ (B6) and 129P3/J (129) inbred strains. The goal of this study was to compare behavioral responses of the B6 and 129 mice to a wider variety of sweeteners. Seventeen sweeteners were tested using two-bottle preference tests with water. Three main patterns of strain differences were evident. First, sucrose, maltose, saccharin, acesulfame, sucralose and SC-45647 were preferred by both strains, but the B6 mice had lower preference thresholds and higher solution intakes. Second, the amino acids D-phenylalanine, D-tryptophan, L-proline and glycine were highly preferred by the B6 mice, but not by the 129 mice. Third, glycyrrhizic acid, neohesperidin dihydrochalcone, thaumatin and cyclamate did not evoke strong preferences in either strain. Aspartame was neutral to all 129 mice and some B6 mice, but other B6 mice strongly preferred it. Thus, compared with the 129 mice, the B6 mice had higher preferences for sugars, sweet-tasting amino acids and several but not all non-caloric sweeteners. Glycyrrhizic acid, neohesperidin, thaumatin and cyclamate are not palatable to B6 or 129 mice. PMID:11555485
Sweetener preference of C57BL/6ByJ and 129P3/J mice.
Bachmanov, A A; Tordoff, M G; Beauchamp, G K
2001-09-01
Previous studies have shown large differences in taste responses to several sweeteners between mice of the C57BL/6ByJ (B6) and 129P3/J (129) inbred strains. The goal of this study was to compare behavioral responses of B6 and 129 mice to a wider variety of sweeteners. Seventeen sweeteners were tested using two-bottle preference tests with water. Three main patterns of strain differences were evident. First, sucrose, maltose, saccharin, acesulfame-K, sucralose and SC-45647 were preferred by both strains, but the B6 mice had lower preference thresholds and higher solution intakes. Second, the amino acids D-phenylalanine, D-tryptophan, L-proline and glycine were highly preferred by B6 mice, but not by 129 mice. Third, glycyrrhizic acid, neohesperidin dihydrochalcone, thaumatin and cyclamate did not evoke strong preferences in either strain. Aspartame was neutral to all 129 and some B6 mice, but other B6 mice strongly preferred it. Thus, compared with the 129 mice the B6 mice had higher preferences for sugars, sweet tasting amino acids and several but not all non-caloric sweeteners. Glycyrrhizic acid, neohesperidin, thaumatin and cyclamate are not palatable to B6 or 129 mice.
Embedding DBI inflation in scalar-tensor theory
Bruck, Carsten van de; Weller, Joel M.; Mota, David F. E-mail: d.f.mota@astro.uio.no
2011-03-01
The Dirac-Born-Infeld (DBI) action has been widely studied as an interesting example of a model of k-inflation in which the sound speed of the cosmological perturbations differs from unity. In this article we consider a scalar-tensor theory in which the matter component is a field with a DBI action. Transforming to the Einstein frame, we explore the effect of the resulting coupling on the background dynamics of the fields and the first-order perturbations. We find that the coupling forces the scalar field into the minimum of its effective potential. While the additional scalar field contributes significantly to the energy density during inflation, the dynamics are determined by the DBI field, which has the interesting effect of increasing the number of efolds of inflation and decreasing the boost factor of the DBI field. Focusing on this case, we show, with the benefit of numerical examples, that the power spectrum of the primordial perturbations is determined by the behaviour of the perturbations of the modified DBI field.
Scalar field evolution in Gauss-Bonnet black holes
Abdalla, E.; Konoplya, R.A.; Molina, C.
2005-10-15
It is presented a thorough analysis of scalar perturbations in the background of Gauss-Bonnet, Gauss-Bonnet-de Sitter and Gauss-Bonnet-anti-de Sitter black hole spacetimes. The perturbations are considered both in frequency and time domain. The dependence of the scalar field evolution on the values of the cosmological constant {lambda} and the Gauss-Bonnet coupling {alpha} is investigated. For Gauss-Bonnet and Gauss-Bonnet-de Sitter black holes, at asymptotically late times either power-law or exponential tails dominate, while for Gauss-Bonnet-anti-de Sitter black hole, the quasinormal modes govern the scalar field decay at all times. The power-law tails at asymptotically late times for odd-dimensional Gauss-Bonnet black holes does not depend on {alpha}, even though the black hole metric contains {alpha} as a new parameter. The corrections to quasinormal spectrum due to Gauss-Bonnet coupling is not small and should not be neglected. For the limit of near extremal value of the (positive) cosmological constant and pure de Sitter and anti-de Sitter modes in Gauss-Bonnet gravity we have found analytical expressions.
Entropic quantization of scalar fields
Ipek, Selman; Caticha, Ariel
2015-01-13
Entropic Dynamics is an information-based framework that seeks to derive the laws of physics as an application of the methods of entropic inference. The dynamics is derived by maximizing an entropy subject to constraints that represent the physically relevant information that the motion is continuous and non-dissipative. Here we focus on the quantum theory of scalar fields. We provide an entropic derivation of Hamiltonian dynamics and using concepts from information geometry derive the standard quantum field theory in the Schrödinger representation.
NASA Astrophysics Data System (ADS)
Maiani, L.; Piccinini, F.; Polosa, A. D.; Riquer, V.
2004-11-01
Light scalar mesons are found to fit rather well a diquark-antidiquark description. The resulting nonet obeys mass formulas which respect, to a good extent, the Okubo-Zweig-Iizuka (OZI) rule. OZI allowed strong decays are reasonably reproduced by a single amplitude describing the switch of a qq¯ pair, which transforms the state into two colorless pseudoscalar mesons. Predicted heavy states with one or more quarks replaced by charm or beauty are briefly described; they should give rise to narrow states with exotic quantum numbers.
Maiani, L; Piccinini, F; Polosa, A D; Riquer, V
2004-11-19
Light scalar mesons are found to fit rather well a diquark-antidiquark description. The resulting nonet obeys mass formulas which respect, to a good extent, the Okubo-Zweig-Iizuka (OZI) rule. OZI allowed strong decays are reasonably reproduced by a single amplitude describing the switch of a qq pair, which transforms the state into two colorless pseudoscalar mesons. Predicted heavy states with one or more quarks replaced by charm or beauty are briefly described; they should give rise to narrow states with exotic quantum numbers.
Protein kinase CK2 potentiates translation efficiency by phosphorylating eIF3j at Ser127.
Borgo, Christian; Franchin, Cinzia; Salizzato, Valentina; Cesaro, Luca; Arrigoni, Giorgio; Matricardi, Laura; Pinna, Lorenzo A; Donella-Deana, Arianna
2015-07-01
In eukaryotic protein synthesis the translation initiation factor 3 (eIF3) is a key player in the recruitment and assembly of the translation initiation machinery. Mammalian eIF3 consists of 13 subunits, including the loosely associated eIF3j subunit that plays a stabilizing role in the eIF3 complex formation and interaction with the 40S ribosomal subunit. By means of both co-immunoprecipitation and mass spectrometry analyses we demonstrate that the protein kinase CK2 interacts with and phosphorylates eIF3j at Ser127. Inhibition of CK2 activity by CX-4945 or down-regulation of the expression of CK2 catalytic subunit by siRNA cause the dissociation of j-subunit from the eIF3 complex as judged from glycerol gradient sedimentation. This finding proves that CK2-phosphorylation of eIF3j is a prerequisite for its association with the eIF3 complex. Expression of Ser127Ala-eIF3j mutant impairs both the interaction of mutated j-subunit with the other eIF3 subunits and the overall protein synthesis. Taken together our data demonstrate that CK2-phosphorylation of eIF3j at Ser127 promotes the assembly of the eIF3 complex, a crucial step in the activation of the translation initiation machinery. Copyright © 2015 Elsevier B.V. All rights reserved.
eIF3j is located in the decoding center of the human 40S ribosomal subunit.
Fraser, Christopher S; Berry, Katherine E; Hershey, John W B; Doudna, Jennifer A
2007-06-22
Protein synthesis in all cells begins with the ordered binding of the small ribosomal subunit to messenger RNA (mRNA) and transfer RNA (tRNA). In eukaryotes, translation initiation factor 3 (eIF3) is thought to play an essential role in this process by influencing mRNA and tRNA binding through indirect interactions on the backside of the 40S subunit. Here we show by directed hydroxyl radical probing that the human eIF3 subunit eIF3j binds to the aminoacyl (A) site and mRNA entry channel of the 40S subunit, placing eIF3j directly in the ribosomal decoding center. eIF3j also interacts with eIF1A and reduces 40S subunit affinity for mRNA. A high affinity for mRNA is restored upon recruitment of initiator tRNA, even though eIF3j remains in the mRNA-binding cleft in the presence of tRNA. These results suggest that eIF3j functions in part by regulating access of the mRNA-binding cleft in response to initiation factor binding.
Glueball-QQ¯ mixings in the scalars
NASA Astrophysics Data System (ADS)
Zhao, Qiang
2006-02-01
Possibly significant Okuba-Zweig-Iizuka (OZI) rule violation is found important for the scalar meson production in J / ψ hadronic decays. Its correlation with the glueball-QQ¯ mixings provides a natural explanation for the "scalar puzzle" arising from the data for J / ψ → V f0 at BES. Nevertheless, such a correlation can be examined at different energy scales and other heavy quarkonium hadronic decays, where insights into the scalar meson structures can be gained.
Scalar excursions in large-eddy simulations
NASA Astrophysics Data System (ADS)
Matheou, Georgios; Dimotakis, Paul E.
2016-12-01
The range of values of scalar fields in turbulent flows is bounded by their boundary values, for passive scalars, and by a combination of boundary values, reaction rates, phase changes, etc., for active scalars. The current investigation focuses on the local conservation of passive scalar concentration fields and the ability of the large-eddy simulation (LES) method to observe the boundedness of passive scalar concentrations. In practice, as a result of numerical artifacts, this fundamental constraint is often violated with scalars exhibiting unphysical excursions. The present study characterizes passive-scalar excursions in LES of a shear flow and examines methods for diagnosis and assesment of the problem. The analysis of scalar-excursion statistics provides support of the main hypothesis of the current study that unphysical scalar excursions in LES result from dispersive errors of the convection-term discretization where the subgrid-scale model (SGS) provides insufficient dissipation to produce a sufficiently smooth scalar field. In the LES runs three parameters are varied: the discretization of the convection terms, the SGS model, and grid resolution. Unphysical scalar excursions decrease as the order of accuracy of non-dissipative schemes is increased, but the improvement rate decreases with increasing order of accuracy. Two SGS models are examined, the stretched-vortex and a constant-coefficient Smagorinsky. Scalar excursions strongly depend on the SGS model. The excursions are significantly reduced when the characteristic SGS scale is set to double the grid spacing in runs with the stretched-vortex model. The maximum excursion and volume fraction of excursions outside boundary values show opposite trends with respect to resolution. The maximum unphysical excursions increase as resolution increases, whereas the volume fraction decreases. The reason for the increase in the maximum excursion is statistical and traceable to the number of grid points (sample size
The scalar singlet-triplet dark matter model
Fischer, O.; Van der Bij, J.J. E-mail: vdbij@physik.uni-freiburg.de
2014-01-01
We consider a model for cold dark matter, which combines a real scalar singlet and a real scalar SU(2){sub L} triplet field, both of which are residing in the odd representation of a global Z{sub 2} symmetry. The parameter space of the model is constrained by the inferred dark matter abundance from the WMAP and Planck data, the most recent results from the direct dark matter search experiment LUX, the Z boson decay width from LEP-I and perturbativity of the coupling parameters. The phenomenology of the remaining parameter space is studied. We find that the model allows for DM masses near the electroweak scale and a variety of decay scenarios.
Galilean-invariant scalar fields can strengthen gravitational lensing.
Wyman, Mark
2011-05-20
The mystery of dark energy suggests that there is new gravitational physics on long length scales. Yet light degrees of freedom in gravity are strictly limited by Solar System observations. We can resolve this apparent contradiction by adding a Galilean-invariant scalar field to gravity. Called Galileons, these scalars have strong self-interactions near overdensities, like the Solar System, that suppress their dynamical effect. These nonlinearities are weak on cosmological scales, permitting new physics to operate. In this Letter, we point out that a massive-gravity-inspired coupling of Galileons to stress energy can enhance gravitational lensing. Because the enhancement appears at a fixed scaled location for dark matter halos of a wide range of masses, stacked cluster analysis of weak lensing data should be able to detect or constrain this effect.
New class of consistent scalar-tensor theories.
Gleyzes, Jérôme; Langlois, David; Piazza, Federico; Vernizzi, Filippo
2015-05-29
We introduce a new class of scalar-tensor theories of gravity that extend Horndeski, or "generalized Galileon," models. Despite possessing equations of motion of higher order in derivatives, we show that the true propagating degrees of freedom obey well-behaved second-order equations and are thus free from Ostrogradski instabilities, in contrast to standard lore. Remarkably, the covariant versions of the original Galileon Lagrangians-obtained by direct replacement of derivatives with covariant derivatives-belong to this class of theories. These extensions of Horndeski theories exhibit an uncommon, interesting phenomenology: The scalar degree of freedom affects the speed of sound of matter, even when the latter is minimally coupled to gravity.
Baryogenesis from baryon-number-violating scalar interactions
NASA Astrophysics Data System (ADS)
Bowes, J. P.; Volkas, R. R.
1997-03-01
In the following work we consider the possibility of explaining the observed baryon-number asymmetry in the universe from simple baryon-number-violating modifications, involving massive scalar bosons, to the standard model. In these cases baryon-number violation is mediated through a combination of Yukawa and scalar self-coupling interactions. Starting with a previously compiled catalogue of baryon-number-violating extensions of the standard model, we identify the minimal subsets which can induce a B-L asymmetry and thus be immune to sphaleron washout. For each of these models, we identify the region of parameter space that leads to the production of a baryon number asymmetry of the correct order of magnitude.
Dark matter relic density in scalar-tensor gravity revisited
Meehan, Michael T.; Whittingham, Ian B. E-mail: Ian.Whittingham@jcu.edu.au
2015-12-01
We revisit the calculation of dark matter relic abundances in scalar-tensor gravity using a generic form A(φ{sub *}) = e{sup βφ{sub *}{sup 2/2}} for the coupling between the scalar field φ{sub *} and the metric, for which detailed Big Bang Nucleosynthesis constraints are available. We find that BBN constraints restrict the modified expansion rate in these models to be almost degenerate with the standard expansion history at the time of dark matter decoupling. In this case the maximum level of enhancement of the dark matter relic density was found to be a factor of ∼ 3, several orders of magnitude below that found in previous investigations.
Unifying framework for scalar-tensor theories of gravity
NASA Astrophysics Data System (ADS)
Gao, Xian
2014-10-01
A general framework for effective theories propagating two tensor and one scalar degrees of freedom is investigated. Geometrically, it describes dynamical foliation of spacelike hypersurfaces coupled to a general background, in which the scalar mode encodes the fluctuation of the hypersurfaces. Within this framework, various models in the literature—including k-essence, Horndeski theory, the effective field theory of inflation, ghost condensate as well as the Hořava gravity—get unified. Our framework generalizes the Horndeski theory in the sense that, it propagates the correct number of degrees of freedom, although the equations of motion are generally higher order. We also identify new operators beyond the Horndeski theory, which yield second order equations of motion for linear perturbations around a Friedmann-Robertson-Walker background.
Visualization of scalar topology for structural enhancement
Bajaj, C.L.; Pascucci, V.; Schikore, D.R.
1998-09-22
Scalar fields arise in every scientific application. Existing scalar visualization techniques require that the user infer the global scalar structure from what is frequently an insufficient display of information. We present a visualization technique which numerically detects the structure at all scales, removing from the user the responsibility of extracting information implicit in the data, and presenting the structure explicitly for analysis. We further demonstrate how scalar topology detection proves useful for correct visualization and image processing applications such as image co-registration, isocontouring, and mesh compression.
Schwarzschild black holes can wear scalar wigs.
Barranco, Juan; Bernal, Argelia; Degollado, Juan Carlos; Diez-Tejedor, Alberto; Megevand, Miguel; Alcubierre, Miguel; Núñez, Darío; Sarbach, Olivier
2012-08-24
We study the evolution of a massive scalar field surrounding a Schwarzschild black hole and find configurations that can survive for arbitrarily long times, provided the black hole or the scalar field mass is small enough. In particular, both ultralight scalar field dark matter around supermassive black holes and axionlike scalar fields around primordial black holes can survive for cosmological times. Moreover, these results are quite generic in the sense that fairly arbitrary initial data evolve, at late times, as a combination of those long-lived configurations.
Quasinormal modes, bifurcations, and nonuniqueness of charged scalar-tensor black holes
Doneva, Daniela D.; Yazadjiev, Stoytcho S.; Kokkotas, Kostas D.; Stefanov, Ivan Zh.
2010-09-15
In the present paper, we study the scalar sector of the quasinormal modes of charged general relativistic, static, and spherically symmetric black holes coupled to nonlinear electrodynamics and embedded in a class of scalar-tensor theories. We find that for a certain domain of the parametric space, there exists unstable quasinormal modes. The presence of instabilities implies the existence of scalar-tensor black holes with primary hair that bifurcate from the embedded general relativistic black-hole solutions at critical values of the parameters corresponding to the static zero modes. We prove that such scalar-tensor black holes really exist by solving the full system of scalar-tensor field equations for the static, spherically symmetric case. The obtained solutions for the hairy black holes are nonunique, and they are in one-to-one correspondence with the bounded states of the potential governing the linear perturbations of the scalar field. The stability of the nonunique hairy black holes is also examined, and we find that the solutions for which the scalar field has zeros are unstable against radial perturbations. The paper ends with a discussion of possible formulations of a new classification conjecture.
O(N)-Scalar Model in Curved Spacetime with Boundaries: A Renormalization Group Approach
NASA Astrophysics Data System (ADS)
Brevik, I.; Odintsov, S. D.
1996-04-01
We discuss the volume and surface running couplings forO(N) scalar theory in curved spacetime with boundaries. The IR limit of the theory-in which it becomes asymptotically conformally invariant-is studied, and the existence of IR fixed points for all couplings (also inD=4-ɛdimensions) is shown. ForN=4 the behaviour of some gravitational couplings in the IR limit is changing qualitatively, from a growth forN<=4 to a decrease forN>4. The non-local renormalization group (RG) improved effective action, account being taken of the boundary terms, is found. ForO(N) scalar theory and for scalar electrodynamics, the RG improved effective action in the spherical cap is constructed. The relevance of surface effects for the effective equations of motion for the spherical cap is considered (which may be important in quantum cosmology). Some preliminary remarks on the connection with Casimir theory are also given.
Dark matter relics and the expansion rate in scalar-tensor theories
NASA Astrophysics Data System (ADS)
Dutta, Bhaskar; Jimenez, Esteban; Zavala, Ivonne
2017-06-01
We study the impact of a modified expansion rate on the dark matter relic abundance in a class of scalar-tensor theories. The scalar-tensor theories we consider are motivated from string theory constructions, which have conformal as well as disformally coupled matter to the scalar. We investigate the effects of such a conformal coupling to the dark matter relic abundance for a wide range of initial conditions, masses and cross-sections. We find that exploiting all possible initial conditions, the annihilation cross-section required to satisfy the dark matter content can differ from the thermal average cross-section in the standard case. We also study the expansion rate in the disformal case and find that physically relevant solutions require a nontrivial relation between the conformal and disformal functions. We study the effects of the disformal coupling in an explicit example where the disformal function is quadratic.
Characterization of the tyramine-producing pathway in Sporolactobacillus sp. P3J.
Coton, Monika; Fernández, María; Trip, Hein; Ladero, Victor; Mulder, Niels L; Lolkema, Juke S; Alvarez, Miguel A; Coton, Emmanuel
2011-06-01
A sporulated lactic acid bacterium (LAB) isolated from cider must was shown to harbour the tdc gene encoding tyrosine decarboxylase. The isolate belonged to the Sporolactobacillus genus and may correspond to a novel species. The ability of the tdc-positive strain, Sporolactobacillus sp. strain P3J, to produce tyramine in vitro was demonstrated by using HPLC. A 7535 bp nucleotide sequence harbouring the putative tdc gene was determined. Analysis of the obtained sequence showed that four tyramine production-associated genes [tyrosyl-tRNA synthetase (tyrS), tyrosine decarboxylase (tdc), tyrosine permease (tyrP) and Na(+)/H(+) antiporter (nhaC)] were present and were organized as already described in other tyramine-producing LAB. This operon was surrounded by genes showing the highest identities with mobile elements: a putative phage terminase and a putative transposase (downstream and upstream, respectively), suggesting that the tyramine-forming trait was acquired through horizontal gene transfer. Transcription analyses of the tdc gene cluster suggested that tyrS and nhaC are expressed as monocistronic genes while tdc would be part of a polycistronic mRNA together with tyrP. The presence of tyrosine in the culture medium induced the expression of all genes except for tyrS. A clear correlation was observed between initial tyrosine concentration and tyramine production combined with an increase in the final pH reached by the culture. Finally, cloning and expression of the tyrP gene in Lactococcus lactis demonstrated that its product catalyses the exchange of tyrosine and tyramine.
Code of Federal Regulations, 2010 CFR
2010-04-01
... Respect to Section 8a(2)(C) and (E) and Section 8a(3)(J) and (M) of the Commodity Exchange Act A Appendix... Section 8a(3)(J) and (M) of the Commodity Exchange Act Section 8a(2) (C) and (E) The provisions of... amend this interpretation if deemed appropriate. Section 8a(3) (J) and (M) Section 8a(3) authorizes...
Searching for scalar gravitational interactions in current and future cosmological data
NASA Astrophysics Data System (ADS)
Hojjati, Alireza; Plahn, Aaron; Zucca, Alex; Pogosian, Levon; Brax, Philippe; Davis, Anne-Christine; Zhao, Gong-Bo
2016-02-01
Modified gravity theories often contain a scalar field of gravitational strength which interacts with matter. We examine constraints on the range and the coupling strength of a scalar gravitational degree of freedom using a subset of current data that can be safely analyzed within the linear perturbation theory. Using a model-independent implementation of scalar-tensor theories in mgcamb in terms of two functions of the scale factor describing the mass and the coupling of the scalar degree of freedom, we derive constraints on the f (R ), generalized chameleon, symmetron and dilaton models. Since most of the large scale structure data available today is from relatively low redshifts, only a limited range of observed scales is in the linear regime, leading to relatively weak constraints. We then perform a forecast for a future large scale structure survey, such as the Large Synoptic Survey Telescope (LSST), which will map a significant volume at higher redshifts, and show that it will produce much stronger constraints on scalar interactions in specific models. We also perform a principal component analysis and find that future surveys should be able to provide tight constraints on several eigenmodes of the scalar mass evolution.
Clues on the Majorana scale from scalar resonances at the LHC
NASA Astrophysics Data System (ADS)
Fischer, Oliver
2017-02-01
In order to address the observation of the neutrino oscillations and the metastability of the Standard Model (SM), we extend the fermion sector with two right-handed (i.e. sterile) neutrinos, and the scalar sector of the SM with a real scalar, the Hill field. The latter takes the role of a Majoron and generates the Majorana masses for the neutrino sector, such that the particle spectrum features two CP-even scalars h1 and h2, and also two heavy, mass degenerate neutrinos. When the h1 is identified with the scalar resonance at ˜ 125 GeV and the condition is imposed that the h1 self-coupling and its running vanish at the Planck scale, the scalar mixing and the vacuum expectation value of the Hill field are fixed by the h2 mass. The h2 can be searched for at the LHC, and it has prospects of being discovered for the target integrated luminosities of the HL-LHC and the Future Circular hadron Collider (FCC-hh) when its mass is on the weak scale. The knowledge of the h2 mass and its decay properties can yield an insight into its coupling to the heavy neutrinos, and thus also on the heavy neutrino mass scale. This yields an interesting connection between potentially detectable heavy scalars in high-energy proton collisions and the mass scale of the heavy neutrinos that is testable at the LHC and at future colliders.
Search for Ultralight Scalar Dark Matter with Atomic Spectroscopy.
Van Tilburg, Ken; Leefer, Nathan; Bougas, Lykourgos; Budker, Dmitry
2015-07-03
We report new limits on ultralight scalar dark matter (DM) with dilatonlike couplings to photons that can induce oscillations in the fine-structure constant α. Atomic dysprosium exhibits an electronic structure with two nearly degenerate levels whose energy splitting is sensitive to changes in α. Spectroscopy data for two isotopes of dysprosium over a two-year span are analyzed for coherent oscillations with angular frequencies below 1 rad s-1. No signal consistent with a DM coupling is identified, leading to new constraints on dilatonlike photon couplings over a wide mass range. Under the assumption that the scalar field comprises all of the DM, our limits on the coupling exceed those from equivalence-principle tests by up to 4 orders of magnitude for masses below 3×10(-18) eV. Excess oscillatory power, inconsistent with fine-structure variation, is detected in a control channel, and is likely due to a systematic effect. Our atomic spectroscopy limits on DM are the first of their kind, and leave substantial room for improvement with state-of-the-art atomic clocks.
Maximum mass limit of neutron stars in scalar-tensor gravity
NASA Astrophysics Data System (ADS)
Sotani, Hajime; Kokkotas, Kostas D.
2017-02-01
The maximum mass limits of neutron stars in scalar-tensor gravity is discussed and compared with the limits set by general relativity. The limit is parametrized with respect to the combination of the nuclear saturation parameters and the maximum sound velocity in the core. It is shown that, for smaller values of the sound velocity in the core, the maximum mass limit of the scalarized neutron stars is larger than that in general relativity. However, for stiff equations of state with sound velocity higher than 79% of the velocity of light, the maximum mass limit in general relativity is larger than that in scalar-tensor gravity. The results suggest that future observations of massive neutron stars may constrain the maximum sound velocity as well as the coupling parameter in scalar-tensor gravity.
Self-regulation of infrared correlations for massless scalar fields during inflation
NASA Astrophysics Data System (ADS)
Garbrecht, Björn; Rigopoulos, Gerasimos
2011-09-01
Self-energies of a minimally coupled scalar field with quartic and trilinear interactions are calculated in a de Sitter background, using a position space propagator. For quartic interactions, we recover earlier results for the seagull diagram, namely, that it contributes an effective mass for the scalar field at leading order in the infrared enhancement in a steady-state de Sitter background. We further show that the sunset diagram also contributes to this effective mass and argue that these two contributions are sufficient in order to determine a self-consistent dynamical mass. In addition, trilinear interactions also induce a dynamical mass for the scalar field which we calculate. Since an interacting scalar field in de Sitter acquires a dynamical mass through these loop corrections, the infrared divergences of the two-point correlator are naturally self-regulated.
Scalar-tensor cosmologies with a potential in the general relativity limit: Phase space view
Jaerv, Laur; Kuusk, Piret; Saal, Margus
2010-05-15
We consider Friedmann-Lemaitre-Robertson-Walker flat cosmological models in the framework of general Jordan frame scalar-tensor theories of gravity with arbitrary coupling functions, in the era when the energy density of the scalar potential dominates over the energy density of ordinary matter. We focus upon the phase space of the scalar field. To study the regime suggested by the local weak field tests (i.e. close to the so-called limit of general relativity) we propose a nonlinear approximation scheme, solve for the phase trajectories, and provide a complete classification of possible phase portraits. We argue that the topology of trajectories in the nonlinear approximation is representative of those of the full system, and thus can tell for which scalar-tensor models general relativity functions as an attractor.
Rapidly rotating neutron stars with a massive scalar field—structure and universal relations
NASA Astrophysics Data System (ADS)
Doneva, Daniela D.; Yazadjiev, Stoytcho S.
2016-11-01
We construct rapidly rotating neutron star models in scalar-tensor theories with a massive scalar field. The fact that the scalar field has nonzero mass leads to very interesting results since the allowed range of values of the coupling parameters is significantly broadened. Deviations from pure general relativity can be very large for values of the parameters that are in agreement with the observations. We found that the rapid rotation can magnify the differences several times compared to the static case. The universal relations between the normalized moment of inertia and quadrupole moment are also investigated both for the slowly and rapidly rotating cases. The results show that these relations are still EOS independent up to a large extend and the deviations from pure general relativity can be large. This places the massive scalar-tensor theories amongst the few alternative theories of gravity that can be tested via the universal I-Love-Q relations.
Dynamics of a scalar field in a polymer-like representation
NASA Astrophysics Data System (ADS)
Han, Muxin; Ma, Yongge
2006-04-01
In the last 20 years, loop quantum gravity, a background-independent approach to unify general relativity and quantum mechanics, has been widely investigated. We consider the quantum dynamics of a real massless scalar field coupled to gravity in this framework. A Hamiltonian operator for the scalar field can be well defined in the coupled diffeomorphism-invariant Hilbert space, which is both self-adjoint and positive. On the other hand, the Hamiltonian constraint operator for the scalar field coupled to gravity can be well defined in the coupled kinematical Hilbert space. There are one-parameter ambiguities due to scalar field in the construction of both operators. The results heighten our confidence that there is no divergence within this background-independent and diffeomorphism-invariant quantization approach of matter coupled to gravity. Moreover, to avoid possible quantum anomaly, the master constraint programme can be carried out in this coupled system by employing a self-adjoint master constraint operator on the diffeomorphism-invariant Hilbert space.
Cross Sections From Scalar Field Theory
NASA Technical Reports Server (NTRS)
Norbury, John W.; Dick, Frank; Norman, Ryan B.; Nasto, Rachel
2008-01-01
A one pion exchange scalar model is used to calculate differential and total cross sections for pion production through nucleon- nucleon collisions. The collisions involve intermediate delta particle production and decay to nucleons and a pion. The model provides the basic theoretical framework for scalar field theory and can be applied to particle production processes where the effects of spin can be neglected.
Phenomenology of supersymmetry with scalar sequestering
Perez, Gilad; Roy, Tuhin S.; Schmaltz, Martin
2009-05-01
The defining feature of scalar sequestering is that the minimal supersymmetric standard model squark and slepton masses as well as all entries of the scalar Higgs mass matrix vanish at some high scale. This ultraviolet boundary condition--scalar masses vanish while gaugino and Higgsino masses are unsuppressed--is independent of the supersymmetry breaking mediation mechanism. It is the result of renormalization group scaling from approximately conformal strong dynamics in the hidden sector. We review the mechanism of scalar sequestering and prove that the same dynamics which suppresses scalar soft masses and the B{sub {mu}} term also drives the Higgs soft masses to -|{mu}|{sup 2}. Thus the supersymmetric contribution to the Higgs mass matrix from the {mu} term is exactly canceled by the soft masses. Scalar sequestering has two tell-tale predictions for the superpartner spectrum in addition to the usual gaugino mediation predictions: Higgsinos are much heavier ({mu} > or approx. TeV) than scalar Higgses (m{sub A}{approx}few hundred GeV), and third generation scalar masses are enhanced because of new positive contributions from Higgs loops.
Horndeski scalar-tensor black hole geodesics
NASA Astrophysics Data System (ADS)
Tretyakova, Darya; Melkoserov, Dmitry; Adyev, Timur
2016-10-01
We examine massive particles and null geodesics for the scalar-tensor black hole in the Horndeski-Galileon framework. Our analysis shows that first kind relativistic orbits, corresponding to circular and elliptic orbits, are absent for the black hole solution with the static scalar field. This is a highly pathological behavior contradicting to the black hole accretion and Solar System observations.
Scalar gain interpretation of large order filters
NASA Technical Reports Server (NTRS)
Mason, Paul A. C.; Mook, D. Joseph
1993-01-01
A technique is developed which demonstrates how to interpret a large fully-populated filter gain matrix as a set of scalar gains. The inverse problem is also solved, namely, how to develop a large-order filter gain matrix from a specified set of scalar gains. Examples are given to illustrate the method.
Distinguishing Speed from Accuracy in Scalar Implicatures
ERIC Educational Resources Information Center
Bott, Lewis; Bailey, Todd M.; Grodner, Daniel
2012-01-01
Scalar implicatures are inferences that arise when a weak expression is used instead of a stronger alternative. For example, when a speaker says, "Some of the children are in the classroom," she often implies that not all of them are. Recent processing studies of scalar implicatures have argued that generating an implicature carries a…
Psycholinguistic and Neurolinguistic Investigations of Scalar Implicature
ERIC Educational Resources Information Center
Politzer-Ahles, Stephen
2013-01-01
The present study examines the representation and composition of meaning in scalar implicatures. Scalar implicature is the phenomenon whereby the use of a less informative term (e.g., "some") is inferred to mean the negation of a more informative term (e.g., to mean "not all"). The experiments reported here investigate how the…
Extended scalar-tensor theory of gravitation
Borneas, M.
1984-08-15
A link between several scalar-tensor theories of gravitation and Einstein's theory is proposed. It is based on a Lagrangian in which the part depending on the scalar field vanishes under the usual conditions, but under special conditions new aspects of gravitation can be forecast.
Scalar Quantum Electrodynamics: Perturbation Theory and Beyond
Bashir, A.; Gutierrez-Guerrero, L. X.; Concha-Sanchez, Y.
2006-09-25
In this article, we calculate scalar propagator in arbitrary dimensions and gauge and the three-point scalar-photon vertex in arbitrary dimensions and Feynman gauge, both at the one loop level. We also discuss constraints on their non perturbative structure imposed by requirements of gauge invariance and perturbation theory.
Scalar Potential Model of light
NASA Astrophysics Data System (ADS)
Hodge, John
2008-04-01
Some observations of light are inconsistent with a wave--like model. Other observations of light are inconsistent with a particle--like model. A model of light is proposed wherein Newton's and Democritus's speculations are combined with the cosmological scalar potential model (SPM). The SPM was tested by confrontation with observations of galaxy HI rotation curves (RCs), asymmetric RCs, redshift, discrete redshift, galaxy central mass, and central velocity dispersion; and with observations of the Pioneer Anomaly. The resulting model of light will be tested by numerical simulation of a photon behaving in a wave-like manner such as diffusion, interference, reflection, spectrography, and the Afshar experiment. Although the SPM light model requires more work, early results are beginning to emerge that suggest possible tests because a few predictions are inconsistent with both the current particle and wave models of light and that suggest a re-interpretation of the equations of quantum mechanics.
Spectral functions of scalar mesons
NASA Astrophysics Data System (ADS)
Giacosa, Francesco; Pagliara, Giuseppe
2007-12-01
In this work we study the spectral functions of scalar mesons in one- and two-channel cases by using nonlocal interaction Lagrangian(s). When the propagators satisfy the Källen-Lehman representation, a normalized spectral function is obtained, allowing one to take into account finite-width effects in the evaluation of decay rates. In the one-channel case, suitable to the light σ and k mesons, the spectral function can deviate consistently from a Breit-Wigner shape. In the two-channel case with one subthreshold channel, the evaluated spectral function is well approximated by a Flatté distribution; when applying the study to the a0(980) and f0(980) mesons, the tree-level forbidden KK decay is analyzed.
Chameleons with field-dependent couplings
Brax, Philippe; Mota, David F.; Winther, Hans A.; Nunes, Nelson J.
2010-10-15
Certain scalar-tensor theories exhibit the so-called chameleon mechanism, whereby observational signatures of scalar fields are hidden by a combination of self-interactions and interactions with ambient matter. Not all scalar-tensor theories exhibit such a chameleon mechanism, which has been originally found in models with inverse power runaway potentials and field-independent couplings to matter. In this paper we investigate field theories with field-dependent couplings and a power-law potential for the scalar field. We show that the theory indeed is a chameleon field theory. We find the thin-shell solution for a spherical body and investigate the consequences for Eoet-Wash experiments, fifth-force searches and Casimir-force experiments. Requiring that the scalar field evades gravitational tests, we find that the coupling is sensitive to a mass scale which is of order of the Hubble scale today.
Transfer of passive scalar variance in decaying grid turbulence with a mean scalar gradient
NASA Astrophysics Data System (ADS)
Danaila, Luminita; Mydlarski, Laurent
2013-11-01
The present work focuses on the mixing of a passive scalar for Sc = 0 . 7 (Sc is the Schmidt number) in decaying, homogeneous isotropic turbulence, where the scalar fluctuations are produced via a large-scale, mean scalar gradient. The overall philosophy is to understand and predict the scalar behaviour, when the velocity field is known. Of particular interest is the transfer of scalar variance and its comparison with that of the kinetic energy. The experimental evidence suggests that the scalar variance transfer is closer to the asymptotic value of 4 / 3 than its kinetic energy counterpart. This behaviour is explained analytically by modelling the scalar variance transfer as a function of the scalar variance at scale r, and a characteristic time resulting from the strain effected by a range of scales of sizes slightly larger than r, up to r itself. This model is consistent with the experimental data, measured in grid turbulence with a mean scalar gradient, over a relatively wide range of Reynolds numbers (Rλ up to 600). We highlight the fact that the cascade mechanism of the scalar variance appears to be insensitive to whether the scalar field is dominated by decay or by production. Support for this work was provided by the CORIA, CNRS, Université de Rouen, ANR and NSERC.
Einstein-Born-Infeld black holes with a scalar hair in three dimensions
NASA Astrophysics Data System (ADS)
Mazharimousavi, S. Habib; Halilsoy, M.
2015-09-01
We present black hole solutions in (2+1)-dimensional Einstein’s theory of gravity coupled with Born-Infeld (BI) nonlinear electrodynamic and a massless self-interacting scalar field. The model has five free parameters: mass M, cosmological constant ℓ, electric q and scalar r0 charges and BI parameter β. To attain exact solution for such a highly nonlinear system we adjust, i.e. finely tune, the parameters of the theory with the integration constants. In the limit β → 0, we recover the results of Einstein-Maxwell-Scalar theory, obtained before. The self-interacting potential admits finite minima apt for the vacuum contribution. Hawking temperature of the model is investigated versus properly tuned parameters. By employing this tuned-solution as basis, we obtain also a dynamic solution which in the proper limit admits the known solution in Einstein gravity coupled with self-interacting scalar field. Finally, we establish the equations of a general scalar-tensor field coupled to nonlinear electrodynamics (NED) field in 2+1 dimensions without searching for exact solutions.
Effects of a scalar scaling field on quantum mechanics
Benioff, Paul
2016-04-18
This paper describes the effects of a complex scalar scaling field on quantum mechanics. The field origin is an extension of the gauge freedom for basis choice in gauge theories to the underlying scalar field. The extension is based on the idea that the value of a number at one space time point does not determine the value at another point. This, combined with the description of mathematical systems as structures of different types, results in the presence of separate number fields and vector spaces as structures, at different space time locations. Complex number structures and vector spaces at each location are scaled by a complex space time dependent scaling factor. The effect of this scaling factor on several physical and geometric quantities has been described in other work. Here the emphasis is on quantum mechanics of one and two particles, their states and properties. Multiparticle states are also briefly described. The effect shows as a complex, nonunitary, scalar field connection on a fiber bundle description of nonrelativistic quantum mechanics. Here, the lack of physical evidence for the presence of this field so far means that the coupling constant of this field to fermions is very small. It also means that the gradient of the field must be very small in a local region of cosmological space and time. Outside this region, there are no restrictions on the field gradient.
Effects of a scalar scaling field on quantum mechanics
Benioff, Paul
2016-04-18
This paper describes the effects of a complex scalar scaling field on quantum mechanics. The field origin is an extension of the gauge freedom for basis choice in gauge theories to the underlying scalar field. The extension is based on the idea that the value of a number at one space time point does not determine the value at another point. This, combined with the description of mathematical systems as structures of different types, results in the presence of separate number fields and vector spaces as structures, at different space time locations. Complex number structures and vector spaces at eachmore » location are scaled by a complex space time dependent scaling factor. The effect of this scaling factor on several physical and geometric quantities has been described in other work. Here the emphasis is on quantum mechanics of one and two particles, their states and properties. Multiparticle states are also briefly described. The effect shows as a complex, nonunitary, scalar field connection on a fiber bundle description of nonrelativistic quantum mechanics. Here, the lack of physical evidence for the presence of this field so far means that the coupling constant of this field to fermions is very small. It also means that the gradient of the field must be very small in a local region of cosmological space and time. Outside this region, there are no restrictions on the field gradient.« less
Effects of a scalar scaling field on quantum mechanics
Benioff, Paul
2016-04-18
This paper describes the effects of a complex scalar scaling field on quantum mechanics. The field origin is an extension of the gauge freedom for basis choice in gauge theories to the underlying scalar field. The extension is based on the idea that the value of a number at one space time point does not determine the value at another point. This, combined with the description of mathematical systems as structures of different types, results in the presence of separate number fields and vector spaces as structures, at different space time locations. Complex number structures and vector spaces at each location are scaled by a complex space time dependent scaling factor. The effect of this scaling factor on several physical and geometric quantities has been described in other work. Here the emphasis is on quantum mechanics of one and two particles, their states and properties. Multiparticle states are also briefly described. The effect shows as a complex, nonunitary, scalar field connection on a fiber bundle description of nonrelativistic quantum mechanics. Here, the lack of physical evidence for the presence of this field so far means that the coupling constant of this field to fermions is very small. It also means that the gradient of the field must be very small in a local region of cosmological space and time. Outside this region, there are no restrictions on the field gradient.
Stability in Einstein-scalar gravity with a logarithmic branch
NASA Astrophysics Data System (ADS)
Amsel, Aaron J.; Roberts, Matthew M.
2012-05-01
We investigate the nonperturbative stability of asymptotically anti-de Sitter gravity coupled to tachyonic scalar fields with mass saturating the Breitenlohner-Freedman bound. Such “designer gravity” theories admit a large class of boundary conditions at asymptotic infinity. At this mass, the asymptotic behavior of the scalar field develops a logarithmic branch, and previous attempts at proving a minimum energy theorem failed due to a large radius divergence in the spinor charge. In this paper, we finally resolve this issue and derive a lower bound on the conserved energy. Just as for masses slightly above the Breitenlohner-Freedman bound, a given scalar potential can admit two possible branches of the corresponding superpotential, one analytic and one nonanalytic. The key point again is that existence of the nonanalytic branch is necessary for the energy bound to hold. We discuss several AdS/CFT applications of this result, including the use of double-trace deformations to induce spontaneous symmetry breaking.
New charged black holes with conformal scalar hair
NASA Astrophysics Data System (ADS)
Anabalón, Andrés; Maeda, Hideki
2010-02-01
A new class of four-dimensional, hairy, stationary solutions of the Einstein-Maxwell-Λ system with a conformally coupled scalar field is obtained. The metric belongs to the Plebański-Demiański family and hence its static limit has the form of the charged (A)dS C metric. It is shown that, in the static case, a new family of hairy black holes arises. They turn out to be cohomogeneity-two, with horizons that are neither Einstein nor homogenous manifolds. The conical singularities in the C metric can be removed due to the backreaction of the scalar field providing a new kind of regular, radiative spacetime. The scalar field carries a continuous parameter proportional to the usual acceleration present in the C metric. In the zero-acceleration limit, the static solution reduces to the dyonic Bocharova-Bronnikov-Melnikov-Bekenstein solution or the dyonic extension of the Martínez-Troncoso-Zanelli black holes, depending on the value of the cosmological constant.
Quantization of massive scalar fields over static black string backgrounds
Fernandez Piedra, Owen Pavel; Montes de Oca, Alejandro Cabo
2007-05-15
The renormalized mean value of the corresponding components of the energy-momentum tensor for massive scalar fields coupled to an arbitrary gravitational field configuration having cylindrical symmetry are analytically evaluated using the Schwinger-DeWitt approximation, up to second order in the inverse mass value. The general results are employed to explicitly derive compact analytical expressions for the energy-momentum tensor in the particular background of the black-string space-time. In the case of the black string considered in this work, we prove that a violation of the weak energy condition occurs at the horizon of the space-time for values of the coupling constant, which include as particular cases the most interesting of minimal and conformal coupling.
Status of the scalar singlet dark matter model
NASA Astrophysics Data System (ADS)
Athron, Peter; Balázs, Csaba; Bringmann, Torsten; Buckley, Andy; Chrząszcz, Marcin; Conrad, Jan; Cornell, Jonathan M.; Dal, Lars A.; Edsjö, Joakim; Farmer, Ben; Jackson, Paul; Kahlhoefer, Felix; Krislock, Abram; Kvellestad, Anders; McKay, James; Mahmoudi, Farvah; Martinez, Gregory D.; Putze, Antje; Raklev, Are; Rogan, Christopher; Saavedra, Aldo; Savage, Christopher; Scott, Pat; Serra, Nicola; Weniger, Christoph; White, Martin
2017-08-01
One of the simplest viable models for dark matter is an additional neutral scalar, stabilised by a \\mathbb {Z}_2 symmetry. Using the GAMBIT package and combining results from four independent samplers, we present Bayesian and frequentist global fits of this model. We vary the singlet mass and coupling along with 13 nuisance parameters, including nuclear uncertainties relevant for direct detection, the local dark matter density, and selected quark masses and couplings. We include the dark matter relic density measured by Planck, direct searches with LUX, PandaX, SuperCDMS and XENON100, limits on invisible Higgs decays from the Large Hadron Collider, searches for high-energy neutrinos from dark matter annihilation in the Sun with IceCube, and searches for gamma rays from annihilation in dwarf galaxies with the Fermi-LAT. Viable solutions remain at couplings of order unity, for singlet masses between the Higgs mass and about 300 GeV, and at masses above ˜ 1 TeV. Only in the latter case can the scalar singlet constitute all of dark matter. Frequentist analysis shows that the low-mass resonance region, where the singlet is about half the mass of the Higgs, can also account for all of dark matter, and remains viable. However, Bayesian considerations show this region to be rather fine-tuned.
Nonuniversal scalar-tensor theories and big bang nucleosynthesis
Coc, Alain; Olive, Keith A.; Uzan, Jean-Philippe; Vangioni, Elisabeth
2009-05-15
We investigate the constraints that can be set from big bang nucleosynthesis on two classes of models: extended quintessence and scalar-tensor theories of gravity in which the equivalence principle between standard matter and dark matter is violated. In the latter case, and for a massless dilaton with quadratic couplings, the phase space of theories is investigated. We delineate those theories where attraction toward general relativity occurs. It is shown that big bang nucleosynthesis sets more stringent constraints than those obtained from Solar System tests.
Electroweak baryogenesis and gravitational waves from a real scalar singlet
NASA Astrophysics Data System (ADS)
Vaskonen, Ville
2017-06-01
We consider a real scalar singlet field which provides a strong first-order electroweak phase transition via its coupling to the Higgs boson, and gives a C P violating contribution on the top quark mass via a dimension-6 operator. We study the correlation between the baryon-to-entropy ratio produced by electroweak baryogenesis, and the gravitational wave signal from the electroweak phase transition. We show that future gravitational wave experiments can test, in particular, the region of the model parameter space where the observed baryon-to-entropy ratio can be obtained even if the new physics scale, which is explicit in the dimension-6 operator, is high.
Four-dimensional black holes with scalar hair in nonlinear electrodynamics
NASA Astrophysics Data System (ADS)
Barrientos, José; González, P. A.; Vásquez, Yerko
2016-12-01
We consider a gravitating system consisting of a scalar field minimally coupled to gravity with a self-interacting potential and a U(1) nonlinear electromagnetic field. Solving analytically and numerically the coupled system for both power-law and Born-Infeld type electrodynamics, we find charged hairy black hole solutions. Then we study the thermodynamics of these solutions and we find that at a low temperature the topological charged black hole with scalar hair is thermodynamically preferred, whereas the topological charged black hole without scalar hair is thermodynamically preferred at a high temperature for power-law electrodynamics. Interestingly enough, these phase transitions occur at a fixed critical temperature and do not depend on the exponent p of the nonlinear electrodynamics.
Reconstruction of the Scalar Field Potential in Inflationary Models with a Gauss-Bonnet term
NASA Astrophysics Data System (ADS)
Koh, Seoktae; Lee, Bum-Hoon; Tumurtushaa, Gansukh
2017-06-01
We consider inflationary models with a Gauss-Bonnet term to reconstruct the scalar-field potentials and the Gauss-Bonnet coupling functions. Both expressions are derived from the observationally favored configurations of ns and r . Our result implies that, for the reconstructed potentials and coupling functions, the blue tilt of inflationary tensor fluctuations can be realized. To achieve a blue tilt for the inflationary tensor fluctuations, a scalar field must climb up its potential before rolling down. We further investigate the properties of propagation of the perturbation modes in Friedmann-Robertson-Walker spacetime. For the reconstructed configurations that give rise to the blue tilt for the inflationary tensor fluctuations, we show that the ghosts and instabilities are absent with the superluminal propagation speeds for the scalar perturbation modes, whereas the propagation speeds of the tensor perturbations are subluminal.
Decoherence and disentanglement of qubits detecting scalar fields in an expanded spacetime
NASA Astrophysics Data System (ADS)
Li, Yujie; Dai, Yue; Shi, Yu
2017-09-01
We consider Unruh-Wald qubit detector model adopted for the far future region of an exactly solvable 1+1 dimensional scalar field theory in a toy model of Robertson-Walker expanding spacetime. It is shown that the expansion of the spacetime in its history enhances the decoherence of the qubit coupled with a scalar field. Moreover, we consider two entangled qubits, each locally coupled with a scalar field. The expansion of the spacetime in its history degrades the entanglement between the qubits, and it can lead to entanglement's sudden death if the initial entanglement is small enough. The details depend on the parameters characterizing the expansion of the spacetime. This work, on a toy model, suggests that the history of the spacetime might be probed through the coherent and entanglement behavior of the future detectors of quantum fields. In the present toy model, the two cosmological parameters can be determined from the quantum informational quantities of the detectors.
Propagation of massless scalar field in standard-like cosmological models.
NASA Astrophysics Data System (ADS)
Zecca, A.
1999-06-01
The propagation of the massless scalar waves in Robertson-Walker space-times does not lie, in general, on the light cones and is very sensible to the underlying cosmological time evolution. This can be put in particular evidence for a class of Robertson-Walker space-times by means of the previously determined explicit solutions of the corresponding massless generalized Klein-Gordon equation. A simple condition on the parameters of the cosmological model (that is satisfied in Standard Cosmology) is determined such that the massless scalar field has a tail-free propagation, that is it entirely propagates on the light cones. The property is proved for a countable set of values of the coupling constant between the scalar field and the gravitational field that includes the minimally and the conformally coupled case.
Turbulent transport of a passive-scalar field by using a renormalization-group method
NASA Technical Reports Server (NTRS)
Hossain, Murshed
1992-01-01
A passive-scalar field is considered to evolve under the influence of a turbulent fluid governed by the Navier-Stokes equation. Turbulent-transport coefficients are calculated by small-scale elimination using a renormalization-group method. Turbulent processes couple both the viscosity and the diffusivity. In the absence of any correlation between the passive-scalar fluctuations and any component of the fluid velocity, the renormalized diffusivity is essentially the same as if the fluid velocity were frozen, although the renormalized equation does contain higher-order nonlinear terms involving viscosity. This arises due to the nonlinear interaction of the velocity with itself. In the presence of a finite correlation, the turbulent diffusivity becomes coupled with both the velocity field and the viscosity. There is then a dependence of the turbulent decay of the passive scalar on the turbulent Prandtl number.
Turbulent transport of a passive-scalar field by using a renormalization-group method
NASA Technical Reports Server (NTRS)
Hossain, Murshed
1992-01-01
A passive-scalar field is considered to evolve under the influence of a turbulent fluid governed by the Navier-Stokes equation. Turbulent-transport coefficients are calculated by small-scale elimination using a renormalization-group method. Turbulent processes couple both the viscosity and the diffusivity. In the absence of any correlation between the passive-scalar fluctuations and any component of the fluid velocity, the renormalized diffusivity is essentially the same as if the fluid velocity were frozen, although the renormalized equation does contain higher-order nonlinear terms involving viscosity. This arises due to the nonlinear interaction of the velocity with itself. In the presence of a finite correlation, the turbulent diffusivity becomes coupled with both the velocity field and the viscosity. There is then a dependence of the turbulent decay of the passive scalar on the turbulent Prandtl number.
Refining inflation using non-canonical scalars
Unnikrishnan, Sanil; Sahni, Varun; Toporensky, Aleksey E-mail: varun@iucaa.ernet.in
2012-08-01
This paper revisits the Inflationary scenario within the framework of scalar field models possessing a non-canonical kinetic term. We obtain closed form solutions for all essential quantities associated with chaotic inflation including slow roll parameters, scalar and tensor power spectra, spectral indices, the tensor-to-scalar ratio, etc. We also examine the Hamilton-Jacobi equation and demonstrate the existence of an inflationary attractor. Our results highlight the fact that non-canonical scalars can significantly improve the viability of inflationary models. They accomplish this by decreasing the tensor-to-scalar ratio while simultaneously increasing the value of the scalar spectral index, thereby redeeming models which are incompatible with the cosmic microwave background (CMB) in their canonical version. For instance, the non-canonical version of the chaotic inflationary potential, V(φ) ∼ λφ{sup 4}, is found to agree with observations for values of λ as large as unity! The exponential potential can also provide a reasonable fit to CMB observations. A central result of this paper is that steep potentials (such as V∝φ{sup −n}) usually associated with dark energy, can drive inflation in the non-canonical setting. Interestingly, non-canonical scalars violate the consistency relation r = −8n{sub T}, which emerges as a smoking gun test for this class of models.
NASA Astrophysics Data System (ADS)
Levin, A.; Rubakov, V.
We consider Friedberg-Lee-Sirlin Q-balls in a (3+1)-dimensional model with vanishing scalar potential of one of the fields. We show that, unlike in (2+1) and (1+1) dimensions, the Q-ball is stabilized by the gradient energy of this field and carries scalar charge, over and beyond the global charge. The latter property is also inherent in a model with the scalar potential that does not vanish in a finite field region near the origin.
Two-dimensionally-periodic diffractive optical elements: limitations of scalar analysis.
Glytsis, Elias N
2002-04-01
The range of validity of the scalar diffraction analysis is quantified for the case of two-dimensionally-periodic diffractive optical elements (crossed gratings). Three canonical classes of two-dimensionally-periodic grating structures are analyzed by using the rigorous coupled-wave analysis as well as the scalar diffraction analysis. In all cases the scalar-analysis diffraction efficiencies are compared with the exact diffraction efficiencies. The error in using the scalar analysis is then determined as a function of the grating-period(s)-to-wavelength ratio(s), the minimum feature size, the grating depth, the refractive index of the grating, the incident polarization, and the number of phase levels. The three classes of two-dimensional (2-D) unit cells are as follows: (1) a rectangular pillar, (2) an elliptical pillar, and (3) an arbitrarily pixellated multilevel 2-D unit cell that is representative of more complicated diffractive optical elements such as computer-generated holograms. In all cases a normally incident electromagnetic plane wave is considered. It is shown that the error of the scalar diffraction analysis in the case of two-dimensionally-periodic diffractive optical elements is greater than that for the corresponding one-dimensionally-periodic counterparts. In addition, the accuracy of the scalar diffraction analysis degrades with increasing refractive index, grating thickness, and asymmetry of the 2-D unit cell and with decreasing grating-period-to-wavelength ratio and feature size.
Properties and uncertainties of scalar field models of dark energy with barotropic equation of state
Novosyadlyj, Bohdan; Sergijenko, Olga; Apunevych, Stepan; Pelykh, Volodymyr
2010-11-15
The dynamics of expansion and large scale structure formation in the multicomponent Universe with dark energy modeled by the minimally coupled scalar field with generalized linear barotropic equation of state are analyzed. It is shown that the past dynamics of expansion and future of the Universe - eternal accelerated expansion or turnaround and collapse - are completely defined by the current energy density of a scalar field and relation between its current and early equation of state parameters. The clustering properties of such models of dark energy and their imprints in the power spectrum of matter density perturbations depend on the same relation and, additionally, on the 'effective sound speed' of a scalar field, defined by its Lagrangian. It is concluded that such scalar fields with different values of these parameters are distinguishable in principle. This gives the possibility to constrain them by confronting the theoretical predictions with the corresponding observational data. For that we have used the 7-year Wilkinson Microwave Anisotropy Probe data on cosmic microwave background anisotropies, the Union2 data set on Supernovae Ia and the seventh data release of the Sloan Digital Sky Survey data on luminous red galaxies space distribution. Using the Markov Chain Monte Carlo technique the marginalized posterior and mean likelihood distributions are computed for the scalar fields with two different Lagrangians: Klein-Gordon and Dirac-Born-Infeld ones. The properties of such scalar field models of dark energy with best fitting parameters and uncertainties of their determination are also analyzed in the paper.
Prospects for three-body Higgs boson decays into extra light scalars
NASA Astrophysics Data System (ADS)
Helmboldt, Alexander J.; Lindner, Manfred
2017-03-01
Within models containing a very light scalar particle coupled to the 125 GeV Higgs boson, we present the first detailed study of Higgs decays into three of these light scalars. We determine model-independent conditions which the scalar sector after electroweak symmetry breaking has to satisfy in order for the three-body channel to become relevant. Using a specific model—the real scalar singlet-extension of the Standard Model (SM)—we then identify scenarios, where the rates of scalar three-body Higgs decays are comparable to or even exceed those of the well-studied two-body channel. All those scenarios are shown to be compatible with current experimental and theoretical constraints. We finally argue that scalar three-body Higgs decays lead to exciting new collider signatures with six SM fermions in the final state. Calculating the corresponding event rates, we find that e.g. six-muon or six-tau final states may be in reach of dedicated searches at the LHC or ILC experiments.
Searching for the Scalar Glueball
Ochs, Wolfgang
2008-08-31
Existence of gluonic resonances is among the early expectations of QCD. Today, QCD calculations predict the lightest glueball to be a scalar state with mass within a range of about 900-1700 MeV but there is no consensus about its experimental evidence. In a re-analysis of the phase shifts for {pi}{pi} scattering up to 1800 MeV where such states should show up we find the broad resonance f{sub 0}(600)/{sigma} contributing to the full mass range and the narrow f{sub 0}(980) and f{sub 0}(1500) but no evidence for f{sub 0}(1370). Phenomenological arguments for the broad state to be a glueball are recalled. It is argued that the large radiative width of f{sub 0}(600)/{sigma} reported recently is not in contradiction to this hypothesis but is mainly due to {pi}{pi}-rescattering. The small 'direct' radiative component is consistent with QCD sum rule predictions for the light glueball.
Searching for the Scalar Glueball
NASA Astrophysics Data System (ADS)
Ochs, Wolfgang
2008-08-01
Existence of gluonic resonances is among the early expectations of QCD. Today, QCD calculations predict the lightest glueball to be a scalar state with mass within a range of about 900-1700 MeV but there is no consensus about its experimental evidence. In a re-analysis of the phase shifts for ππ scattering up to 1800 MeV where such states should show up we find the broad resonance f0(600)/σ contributing to the full mass range and the narrow f0(980) and f0(1500) but no evidence for f0(1370). Phenomenological arguments for the broad state to be a glueball are recalled. It is argued that the large radiative width of f0(600)/σ reported recently is not in contradiction to this hypothesis but is mainly due to ππ-rescattering. The small "direct" radiative component is consistent with QCD sum rule predictions for the light glueball.
Hees, A; Guéna, J; Abgrall, M; Bize, S; Wolf, P
2016-08-05
We use 6 yrs of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions, and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but provide improved constraints on the coupling of the putative scalar field to standard matter. Our limits are complementary to previous results that were only sensitive to the fine structure constant and improve them by more than an order of magnitude when only a coupling to electromagnetism is assumed.
NASA Astrophysics Data System (ADS)
Hees, A.; Guéna, J.; Abgrall, M.; Bize, S.; Wolf, P.
2016-08-01
We use 6 yrs of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions, and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but provide improved constraints on the coupling of the putative scalar field to standard matter. Our limits are complementary to previous results that were only sensitive to the fine structure constant and improve them by more than an order of magnitude when only a coupling to electromagnetism is assumed.
Ford, Gregory D.; Ford, Byron D.; Steele, Ernest C.; Gates, Alicia; Hood, Darryl; Matthews, Mika A.B.; Mirza, Sophia; MacLeish, Peter R.
2008-01-01
The Purkinje cell degeneration (PCD) mutant mouse is characterized by a degeneration of cerebellar Purkinje cells and progressive ataxia. To identify the molecular mechanisms that lead to the death of Purkinje neurons in PCD mice, we used Affymetrix microarray technology to compare cerebellar gene expression profiles in pcd3J mutant mice 14 days of age (prior to Purkinje cell loss) to unaffected littermates. Microarray analysis, Ingenuity Pathway Analysis (IPA) and Expression Analysis Systematic Explorer (EASE) software were used to identify biological and molecular pathways implicated in the progression of Purkinje cell degeneration. IPA analysis indicated that mutant pcd3J mice showed dysregulation of specific processes that may lead to Purkinje cell death, including several molecules known to control neuronal apoptosis such as Bad, CDK5 and PTEN. These findings demonstrate the usefulness of these powerful microarray analysis tools and have important implications for understanding the mechanisms of selective neuronal death and for developing therapeutic strategies to treat neurodegenerative disorders. PMID:18930027
Dark sector impact on gravitational collapse of an electrically charged scalar field
NASA Astrophysics Data System (ADS)
Nakonieczna, Anna; Rogatko, Marek; Nakonieczny, Łukasz
2015-11-01
Dark matter and dark energy are dominating components of the Universe. Their presence affects the course and results of processes, which are driven by the gravitational interaction. The objective of the paper was to examine the influence of the dark sector on the gravitational collapse of an electrically charged scalar field. A phantom scalar field was used as a model of dark energy in the system. Dark matter was modeled by a complex scalar field with a quartic potential, charged under a U(1)-gauge field. The dark components were coupled to the electrically charged scalar field via the exponential coupling and the gauge field-Maxwell field kinetic mixing, respectively. Complete non-linear simulations of the investigated process were performed. They were conducted from regular initial data to the end state, which was the matter dispersal or a singularity formation in a spacetime. During the collapse in the presence of dark energy dynamical wormholes and naked singularities were formed in emerging spacetimes. The wormhole throats were stabilized by the violation of the null energy condition, which occurred due to a significant increase of a value of the phantom scalar field function in its vicinity. The square of mass parameter of the dark matter scalar field potential controlled the formation of a Cauchy horizon or wormhole throats in the spacetime. The joint impact of dark energy and dark matter on the examined process indicated that the former decides what type of an object forms, while the latter controls the amount of time needed for the object to form. Additionally, the dark sector suppresses the natural tendency of an electrically charged scalar field to form a dynamical Reissner-Nordström spacetime during the gravitational collapse.
Jordan frame no-hair for spherical scalar-tensor black holes
NASA Astrophysics Data System (ADS)
Faraoni, Valerio
2017-06-01
A no-hair theorem for spherical black holes in scalar-tensor gravity is presented. Contrary to the existing theorems, which are proved in the Einstein conformal frame, this proof is performed entirely in the Jordan frame. The theorem is limited to spherical symmetry (instead of axisymmetry) but holds for nonconstant Brans-Dicke couplings.
AdS and Lifshitz scalar hairy black holes in Gauss-Bonnet gravity
NASA Astrophysics Data System (ADS)
Chen, Bin; Fan, Zhong-Ying; Zhu, Lu-Yao
2016-09-01
We consider Gauss-Bonnet (GB) gravity in general dimensions, which is nonminimally coupled to a scalar field. By choosing a scalar potential of the type V (ϕ )=2 Λ0+1/2 m2ϕ2+γ4ϕ4 , we first obtain large classes of scalar hairy black holes with spherical/hyperbolic/planar topologies that are asymptotic to locally anti- de Sitter (AdS) space-times. We derive the first law of black hole thermodynamics using Wald formalism. In particular, for one class of the solutions, the scalar hair forms a thermodynamic conjugate with the graviton and nontrivially contributes to the thermodynamical first law. We observe that except for one class of the planar black holes, all these solutions are constructed at the critical point of GB gravity where there exist unique AdS vacua. In fact, a Lifshitz vacuum is also allowed at the critical point. We then construct many new classes of neutral and charged Lifshitz black hole solutions for an either minimally or nonminimally coupled scalar and derive the thermodynamical first laws. We also obtain new classes of exact dynamical AdS and Lifshitz solutions which describe radiating white holes. The solutions eventually become AdS or Lifshitz vacua at late retarded times. However, for one class of the solutions, the final state is an AdS space-time with a globally naked singularity.
Preferred frame parameters in the tensor-vector-scalar theory of gravity and its generalization
Sagi, Eva
2009-08-15
The tensor-vector-scalar theory of gravity, which was designed as a relativistic implementation to the modified dynamics paradigm, has fared quite well as an alternative to dark matter, on both galactic and cosmological scales. However, its performance in the Solar System, as embodied in the post-Newtonian formalism, has not yet been fully investigated. We calculate the post-Newtonian parameters for TeVeS with the cosmological value of the scalar field taken into account, and show that in this situation the cosmological value of the scalar field is tightly linked to the vector field coupling constant K, preventing the former from evolving as predicted by its equation of motion. We show that generalizing TeVeS to have an Aether-type vector action, as suggested by Skordis, removes the aforesaid link, and this generalized version of TeVes has its {beta}, {gamma}, and {xi} parameterized post-Newtonian parameters identical to those in GR, while solar system constraints on the preferred frame parameters {alpha}{sub 1} and {alpha}{sub 2} can be satisfied within a modest range of small values of the scalar and vector fields coupling parameters, and for cosmological values of the scalar field consistent with evolution within the framework of existing cosmological models.
Self-consistent Dark Matter simplified models with an s-channel scalar mediator
NASA Astrophysics Data System (ADS)
Bell, Nicole F.; Busoni, Giorgio; Sanderson, Isaac W.
2017-03-01
We examine Simplified Models in which fermionic DM interacts with Standard Model (SM) fermions via the exchange of an s-channel scalar mediator. The single-mediator version of this model is not gauge invariant, and instead we must consider models with two scalar mediators which mix and interfere. The minimal gauge invariant scenario involves the mixing of a new singlet scalar with the Standard Model Higgs boson, and is tightly constrained. We construct two Higgs doublet model (2HDM) extensions of this scenario, where the singlet mixes with the 2nd Higgs doublet. Compared with the one doublet model, this provides greater freedom for the masses and mixing angle of the scalar mediators, and their coupling to SM fermions. We outline constraints on these models, and discuss Yukawa structures that allow enhanced couplings, yet keep potentially dangerous flavour violating processes under control. We examine the direct detection phenomenology of these models, accounting for interference of the scalar mediators, and interference of different quarks in the nucleus. Regions of parameter space consistent with direct detection measurements are determined.
Intermediate inflation driven by DBI scalar field
NASA Astrophysics Data System (ADS)
Nazavari, N.; Mohammadi, A.; Ossoulian, Z.; Saaidi, Kh.
2016-06-01
Picking out a DBI scalar field as inflation, the slow-rolling inflationary scenario is studied by attributing an exponential time function to scale factor, known as intermediate inflation. The perturbation parameters of the model are estimated numerically for two different cases, and the final result is compared with Planck data. The diagram of tensor-to-scalar ratio r versus scalar spectra index ns is illustrated, and it is found that they are within an acceptable range as suggested by Planck. In addition, the acquired values for amplitude of scalar perturbation reveal the ability of the model to depict a good picture of the Universe in one of its earliest stages. As a further argument, the non-Gaussianity is investigated, displaying that the model prediction stands in a 68% C.L. regime according to the latest Planck data.
Entangled scalar and tensor fluctuations during inflation
Collins, Hael; Vardanyan, Tereza
2016-11-29
We show how the choice of an inflationary state that entangles scalar and tensor fluctuations affects the angular two-point correlation functions of the T, E, and B modes of the cosmic microwave background. The propagators for a state starting with some general quadratic entanglement are solved exactly, leading to predictions for the primordial scalar-scalar, tensor-tensor, and scalar-tensor power spectra. These power spectra are expressed in terms of general functions that describe the entangling structure of the initial state relative to the standard Bunch-Davies vacuum. We illustrate how such a state would modify the angular correlations in the CMB with a simple example where the initial state is a small perturbation away from the Bunch-Davies state. Because the state breaks some of the rotational symmetries, the angular power spectra no longer need be strictly diagonal.
Standard model EFT and extended scalar sectors
Dawson, Sally; Murphy, Christopher W.
2017-07-31
One of the simplest extensions of the Standard Model is the inclusion of an additional scalar multiplet, and we consider scalars in the S U ( 2 ) L singlet, triplet, and quartet representations. Here, we examine models with heavy neutral scalars, m H ~1 – 2 TeV , and the matching of the UV complete theories to the low energy effective field theory. We also demonstrate the agreement of the kinematic distributions obtained in the singlet models for the gluon fusion of a Higgs pair with the predictions of the effective field theory. Finally, the restrictions on the extendedmore » scalar sectors due to unitarity and precision electroweak measurements are summarized and lead to highly restricted regions of viable parameter space for the triplet and quartet models.« less
Subfemtotesla scalar atomic magnetometry using multipass cells.
Sheng, D; Li, S; Dural, N; Romalis, M V
2013-04-19
Scalar atomic magnetometers have many attractive features but their sensitivity has been relatively poor. We describe a Rb scalar gradiometer using two multipass optical cells. We use a pump-probe measurement scheme to suppress spin-exchange relaxation and two probe pulses to find the spin precession zero crossing times with a resolution of 1 psec. We realize a magnetic field sensitivity of 0.54 fT/Hz(1/2), which improves by an order of magnitude the best scalar magnetometer sensitivity and exceeds, for example, the quantum limit set by the spin-exchange collisions for a scalar magnetometer with the same measurement volume operating in a continuous regime.
Entangled scalar and tensor fluctuations during inflation
NASA Astrophysics Data System (ADS)
Collins, Hael; Vardanyan, Tereza
2016-11-01
We show how the choice of an inflationary state that entangles scalar and tensor fluctuations affects the angular two-point correlation functions of the T, E, and B modes of the cosmic microwave background. The propagators for a state starting with some general quadratic entanglement are solved exactly, leading to predictions for the primordial scalar-scalar, tensor-tensor, and scalar-tensor power spectra. These power spectra are expressed in terms of general functions that describe the entangling structure of the initial state relative to the standard Bunch-Davies vacuum. We illustrate how such a state would modify the angular correlations in the CMB with a simple example where the initial state is a small perturbation away from the Bunch-Davies state. Because the state breaks some of the rotational symmetries, the angular power spectra no longer need be strictly diagonal.
Standard model EFT and extended scalar sectors
NASA Astrophysics Data System (ADS)
Dawson, Sally; Murphy, Christopher W.
2017-07-01
One of the simplest extensions of the Standard Model is the inclusion of an additional scalar multiplet, and we consider scalars in the S U (2 )L singlet, triplet, and quartet representations. We examine models with heavy neutral scalars, mH˜1 - 2 TeV , and the matching of the UV complete theories to the low energy effective field theory. We demonstrate the agreement of the kinematic distributions obtained in the singlet models for the gluon fusion of a Higgs pair with the predictions of the effective field theory. The restrictions on the extended scalar sectors due to unitarity and precision electroweak measurements are summarized and lead to highly restricted regions of viable parameter space for the triplet and quartet models.
Searching for chameleon-like scalar fields with the ammonia method
NASA Astrophysics Data System (ADS)
Levshakov, S. A.; Molaro, P.; Lapinov, A. V.; Reimers, D.; Henkel, C.; Sakai, T.
2010-03-01
Aims: We probe the dependence of the electron-to-proton mass ratio, μ = me/mp, on the ambient matter density by means of radio astronomical observations. Methods: The ammonia method, which has been proposed to explore the electron-to-proton mass ratio, is applied to nearby dark clouds in the Milky Way. This ratio, which is measured in different physical environments of high (terrestrial) and low (interstellar) densities of baryonic matter is supposed to vary in chameleon-like scalar field models, which predict strong dependences of both masses and coupling constant on the local matter density. High resolution spectral observations of molecular cores in lines of NH3 (J,K) = (1,1), HC_3N J = 2-1, and N_2H^+ J = 1-0 were performed at three radio telescopes to measure the radial velocity offsets, Δ V ≡ Vrot - Vinv, between the inversion transition of NH_3 (1,1) and the rotational transitions of other molecules with different sensitivities to the parameter Δμ/μ ≡ (μ_obs - μ_lab)/μ_lab. Results: The measured values of Δ V exhibit a statistically significant velocity offset of 23±4_stat ± 3_sys m s-1 . When interpreted in terms of the electron-to-proton mass ratio variation, this infers that Δμ/μ = (2.2±0.4_stat ± 0.3_sys) × 10-8. If only a conservative upper bound is considered, then the maximum offset between ammonia and the other molecules is |Δ V| ≤ 30 m s-1 . This provides the most accurate reference point at z = 0 for Δμ/μ of |Δ μ/μ| ≤ 3×10-8. Based on observations obtained with the Medicina 32-m telescope operated by INAF - Istituto di Radioastronomia, the 100-m telescope of the Max-Planck Institut für Radioastronomie at Effelsberg, and the Nobeyama Radio Observatory 45-m telescope of the National Astronomical Observatory of Japan.
Scalar-pseudoscalar interaction in the francium atom
NASA Astrophysics Data System (ADS)
Skripnikov, L. V.; Maison, D. E.; Mosyagin, N. S.
2017-02-01
Fr atom can be successively used to search for the atomic permanent electric dipole moment (EDM) [Hyperfine Interact. 236, 53 (2015), 10.1007/s10751-015-1193-1; J. Phys.: Conference Series 691, 012017 (2016), 10.1088/1742-6596/691/1/012017]. It can be induced by the permanent electron EDM predicted by modern extensions of the standard model to be nonzero at the level accessible by the new generation of EDM experiments. We consider another mechanism of the atomic EDM generation in Fr. This is caused by the scalar-pseudoscalar nucleus-electron neutral current interaction with the dimensionless strength constant kT ,P. Similar to the electron EDM this interaction violates both spatial parity and time-reversal symmetries and can also induce permanent atomic EDM. It was shown in [Phys. Rev. D 89, 056006 (2014), 10.1103/PhysRevD.89.056006] that the scalar-pseudoscalar contribution to the atomic EDM can dominate over the direct contribution from the electron EDM within the standard model. We report high-accuracy combined all-electron and two-step relativistic coupled cluster treatment of the effect from the scalar-pseudoscalar interaction in the Fr atom. Up to the quadruple cluster amplitudes within the coupled cluster method with single, double, triple, and noniterative quadruple amplitudes, CCSDT(Q), were included in correlation treatment. This calculation is required for the interpretation of the experimental data in terms of kT ,P. The resulted EDM of the Fr atom expressed in terms of kT ,P is dFr=kT ,P4.50 ×10-18e cm , where e is the (negative) charge of the electron. The value of the ionization potential of the 2S1 /2 ground state of Fr calculated within the same methods is in very good agreement with the experimental datum.
Bianchi type-I model with cosmological constant in a generalized scalar-tensor theory of gravitation
Banerjee, A.; Duttachoudhury, S.B.; Banerjee, N.
1985-12-15
Bianchi type-I cosmological models are discussed in the Bergmann-Wagoner-Nordtvedt scalar-tensor theory where both the so-called cosmological constant ..lambda.. and the coupling parameter ..omega.. are taken to be functions of the scalar field phi. Exact solutions are obtained in Dicke's revised units assuming a very simple relationship between ..lambda.. and phi. The properties of the models are discussed in special cases.
Cellular automaton formulation of passive scalar dynamics
NASA Technical Reports Server (NTRS)
Chen, Hudong; Matthaeus, William H.
1987-01-01
Cellular automata modeling of the advection of a passive scalar in a two-dimensional flow is examined in the context of discrete lattice kinetic theory. It is shown that if the passive scalar is represented by tagging or 'coloring' automation particles a passive advection-diffusion equation emerges without use of perturbation expansions. For the specific case of the hydrodynamic lattice gas model of Frisch et al. (1986), the diffusion coefficient is calculated by perturbation.
Cellular automaton formulation of passive scalar dynamics
NASA Technical Reports Server (NTRS)
Chen, Hudong; Matthaeus, William H.
1987-01-01
Cellular automata modeling of the advection of a passive scalar in a two-dimensional flow is examined in the context of discrete lattice kinetic theory. It is shown that if the passive scalar is represented by tagging or 'coloring' automation particles a passive advection-diffusion equation emerges without use of perturbation expansions. For the specific case of the hydrodynamic lattice gas model of Frisch et al. (1986), the diffusion coefficient is calculated by perturbation.
Line segments in homogeneous scalar turbulence
NASA Astrophysics Data System (ADS)
Gauding, Michael; Goebbert, Jens Henrik; Hasse, Christian; Peters, Norbert
2015-09-01
The local structure of a turbulent scalar field in homogeneous isotropic turbulence is analyzed by direct numerical simulations (DNS) with different Taylor micro-scale based Reynolds numbers between 119 and 529. A novel signal decomposition approach is introduced where the signal of the scalar along a straight line is partitioned into segments based on the local extremal points of the scalar field. These segments are then parameterized by the distance ℓ between adjacent extremal points and the scalar difference Δϕ at the extrema. Both variables are statistical quantities and a joint distribution function of these quantities contains most information to statistically describe the scalar field. It is highlighted that the marginal distribution function of the length becomes independent of Reynolds number when normalized by the mean length ℓm. From a statistical approach, it is further shown that the mean length scales with the Kolmogorov length, which is also confirmed by DNS. For turbulent mixing, the scalar gradient plays a paramount role. Turbulent scalar fields are characterized by cliff-ramp-like structures manifesting the occurrence of localized large scalar gradients. To study turbulent mixing, a segment-based gradient is defined as Δϕ/ℓ. Joint statistics of the length and the segment-based gradient provide novel understanding of cliff-ramp-like structures. Ramp-like structures are unveiled by the asymmetry of the joint distribution function of the segment-based gradient and the length. Cliff-like structures are further analyzed by conditional statistics and it is shown from DNS that the width of cliffs scales with the Kolmogorov length scale.
QCD tests of the puzzling scalar mesons
NASA Astrophysics Data System (ADS)
Narison, Stephan
2006-06-01
Motivated by several recent data, we test the QCD spectral sum rules (QSSR) predictions based on different proposals (q¯q, q¯q¯qq, and gluonium) for the nature of scalar mesons. In the I=1 and 1/2 channels, the unusual wrong splitting between the a0(980) and κ(900) and the a0(980) width can be understood from QSSR within a q¯q assignment. However, none of the q¯q and q¯q¯qq results can explain the large κ width, which may suggest that it can result from a strong interference with nonresonant backgrounds. In the I=0 channel, QSSR and some low-energy theorems (LET) require the existence of a low mass gluonium σB(1GeV) coupled strongly to Goldstone boson pairs which plays in the U(1)V channel, a similar role as the η' for the value of the U(1)A topological charge. The observed σ(600) and f0(980) mesons result from a maximal mixing between the gluonium σB and q¯q (1 GeV) mesons, a mixing scheme which passes several experimental tests. Okubo-Zweig-Izuki (OZI) violating J/ψ→ϕπ+π-, Ds→3π decays, and J/ψ→γS glueball filter processes may indicate that the f0(1500), f0(1710), and f0(1790) have significant gluonium components in their wave functions, while the f0(1370) is mostly q¯q. Tests of these results can be provided by the measurements of the pure gluonium η'η and 4π specific U(1)A decay channels.
Self-gravitating black hole scalar wigs
NASA Astrophysics Data System (ADS)
Barranco, Juan; Bernal, Argelia; Degollado, Juan Carlos; Diez-Tejedor, Alberto; Megevand, Miguel; Núñez, Darío; Sarbach, Olivier
2017-07-01
It has long been known that no static, spherically symmetric, asymptotically flat Klein-Gordon scalar field configuration surrounding a nonrotating black hole can exist in general relativity. In a series of previous papers, we proved that, at the effective level, this no-hair theorem can be circumvented by relaxing the staticity assumption: for appropriate model parameters, there are quasibound scalar field configurations living on a fixed Schwarzschild background which, although not being strictly static, have a larger lifetime than the age of the universe. This situation arises when the mass of the scalar field distribution is much smaller than the black hole mass, and following the analogies with the hair in the literature we dubbed these long-lived field configurations wigs. Here we extend our previous work to include the gravitational backreaction produced by the scalar wigs. We derive new approximate solutions of the spherically symmetric Einstein-Klein-Gordon system which represent self-gravitating scalar wigs surrounding black holes. These configurations interpolate between boson star configurations and Schwarzschild black holes dressed with the long-lived scalar test field distributions discussed in previous papers. Nonlinear numerical evolutions of initial data sets extracted from our approximate solutions support the validity of our approach. Arbitrarily large lifetimes are still possible, although for the parameter space that we analyze in this paper they seem to decay faster than the quasibound states. Finally, we speculate about the possibility that these configurations could describe the innermost regions of dark matter halos.
Black Holes with a Conformally Coupled Scalar Field
NASA Astrophysics Data System (ADS)
Henneaux, marc
The unexpected and fascinating emergence of hyperbolic Coxeter groups and Lorentzian Kac-Moody algebras in the investigation of gravitational theories in the vicinity of a cosmological singularity is briefly reviewed. Some open questions raised by this intriguing result, and some attempts to answer them, are outlined.
Search for first-generation scalar and vector leptoquarks
NASA Astrophysics Data System (ADS)
Abazov, V. M.; Abbott, B.; Abdesselam, A.; Abolins, M.; Abramov, V.; Acharya, B. S.; Adams, D. L.; Adams, M.; Ahmed, S. N.; Alexeev, G. D.; Alves, G. A.; Amos, N.; Anderson, E. W.; Arnoud, Y.; Baarmand, M. M.; Babintsev, V. V.; Babukhadia, L.; Bacon, T. C.; Baden, A.; Baldin, B.; Balm, P. W.; Banerjee, S.; Barberis, E.; Baringer, P.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bauer, D.; Bean, A.; Begel, M.; Belyaev, A.; Beri, S. B.; Bernardi, G.; Bertram, I.; Besson, A.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhattacharjee, M.; Blazey, G.; Blessing, S.; Boehnlein, A.; Bojko, N. I.; Borcherding, F.; Bos, K.; Brandt, A.; Breedon, R.; Briskin, G.; Brock, R.; Brooijmans, G.; Bross, A.; Buchholz, D.; Buehler, M.; Buescher, V.; Burtovoi, V. S.; Butler, J. M.; Canelli, F.; Carvalho, W.; Casey, D.; Casilum, Z.; Castilla-Valdez, H.; Chakraborty, D.; Chan, K. M.; Chekulaev, S. V.; Cho, D. K.; Choi, S.; Chopra, S.; Christenson, J. H.; Chung, M.; Claes, D.; Clark, A. R.; Cochran, J.; Coney, L.; Connolly, B.; Cooper, W. E.; Coppage, D.; Crépé-Renaudin, S.; Cummings, M. A.; Cutts, D.; Davis, G. A.; Davis, K.; de, K.; de Jong, S. J.; del Signore, K.; Demarteau, M.; Demina, R.; Demine, P.; Denisov, D.; Denisov, S. P.; Desai, S.; Diehl, H. T.; Diesburg, M.; di Loreto, G.; Doulas, S.; Draper, P.; Ducros, Y.; Dudko, L. V.; Duensing, S.; Duflot, L.; Dugad, S. R.; Duperrin, A.; Dyshkant, A.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O. V.; Estrada, J.; Evans, H.; Evdokimov, V. N.; Fahland, T.; Feher, S.; Fein, D.; Ferbel, T.; Filthaut, F.; Fisk, H. E.; Fisyak, Y.; Flattum, E.; Fleuret, F.; Fortner, M.; Fox, H.; Frame, K. C.; Fu, S.; Fuess, S.; Gallas, E.; Galyaev, A. N.; Gao, M.; Gavrilov, V.; Genik, R. J.; Genser, K.; Gerber, C. E.; Gershtein, Y.; Gilmartin, R.; Ginther, G.; Gómez, B.; Gómez, G.; Goncharov, P. I.; González Solís, J. L.; Gordon, H.; Goss, L. T.; Gounder, K.; Goussiou, A.; Graf, N.; Graham, G.; Grannis, P. D.; Green, J. A.; Greenlee, H.; Grinstein, S.; Groer, L.; Grünendahl, S.; Gupta, A.; Gurzhiev, S. N.; Gutierrez, G.; Gutierrez, P.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hall, R. E.; Hanlet, P.; Hansen, S.; Hauptman, J. M.; Hays, C.; Hebert, C.; Hedin, D.; Heinmiller, J. M.; Heinson, A. P.; Heintz, U.; Heuring, T.; Hildreth, M. D.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Huang, Y.; Illingworth, R.; Ito, A. S.; Jaffré, M.; Jain, S.; Jesik, R.; Johns, K.; Johnson, M.; Jonckheere, A.; Jones, M.; Jöstlein, H.; Juste, A.; Kahl, W.; Kahn, S.; Kajfasz, E.; Kalinin, A. M.; Karmanov, D.; Karmgard, D.; Ke, Z.; Kehoe, R.; Khanov, A.; Kharchilava, A.; Kim, S. K.; Klima, B.; Knuteson, B.; Ko, W.; Kohli, J. M.; Kostritskiy, A. V.; Kotcher, J.; Kothari, B.; Kotwal, A. V.; Kozelov, A. V.; Kozlovsky, E. A.; Krane, J.; Krishnaswamy, M. R.; Krivkova, P.; Krzywdzinski, S.; Kubantsev, M.; Kuleshov, S.; Kulik, Y.; Kunori, S.; Kupco, A.; Kuznetsov, V. E.; Landsberg, G.; Lee, W. M.; Leflat, A.; Leggett, C.; Lehner, F.; Li, J.; Li, Q. Z.; Li, X.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Lucotte, A.; Lueking, L.; Lundstedt, C.; Luo, C.; Maciel, A. K.; Madaras, R. J.; Malyshev, V. L.; Manankov, V.; Mao, H. S.; Marshall, T.; Martin, M. I.; Martin, R. D.; Mauritz, K. M.; May, B.; Mayorov, A. A.; McCarthy, R.; McMahon, T.; Melanson, H. L.; Merkin, M.; Merritt, K. W.; Miao, C.; Miettinen, H.; Mihalcea, D.; Mishra, C. S.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Moore, R. W.; Mostafa, M.; da Motta, H.; Nagy, E.; Nang, F.; Narain, M.; Narasimham, V. S.; Neal, H. A.; Negret, J. P.; Negroni, S.; Nunnemann, T.; O'neil, D.; Oguri, V.; Olivier, B.; Oshima, N.; Padley, P.; Pan, L. J.; Papageorgiou, K.; Para, A.; Parashar, N.; Partridge, R.; Parua, N.; Paterno, M.; Patwa, A.; Pawlik, B.; Perkins, J.; Peters, M.; Peters, O.; Pétroff, P.; Piegaia, R.; Pope, B. G.; Popkov, E.; Prosper, H. B.; Protopopescu, S.; Qian, J.; Raja, R.; Rajagopalan, S.; Ramberg, E.; Rapidis, P. A.; Reay, N. W.; Reucroft, S.; Ridel, M.; Rijssenbeek, M.; Rizatdinova, F.; Rockwell, T.; Roco, M.; Rubinov, P.; Ruchti, R.; Rutherfoord, J.; Sabirov, B. M.; Sajot, G.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Schwartzman, A.; Sen, N.; Shabalina, E.; Shivpuri, R. K.; Shpakov, D.; Shupe, M.; Sidwell, R. A.; Simak, V.; Singh, H.; Singh, J. B.; Sirotenko, V.; Slattery, P.; Smith, E.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snow, J.; Snyder, S.; Solomon, J.; Sorín, V.; Sosebee, M.; Sotnikova, N.; Soustruznik, K.; Souza, M.; Stanton, N. R.; Steinbrück, G.; Stephens, R. W.; Stichelbaut, F.; Stoker, D.; Stolin, V.; Stone, A.; Stoyanova, D. A.; Strauss, M.; Strovink, M.; Stutte, L.; Sznajder, A.; Talby, M.; Taylor, W.; Tentindo-Repond, S.; Tripathi, S. M.; Trippe, T. G.; Turcot, A. S.; Tuts, P. M.; van Gemmeren, P.; Vaniev, V.; van Kooten, R.; Varelas, N.; Vertogradov, L. S.; Villeneuve-Seguier, F.; Volkov, A. A.; Vorobiev, A. P.; Wahl, H. D.; Wang, H.; Wang, Z.-M.; Warchol, J.; Watts, G.; Wayne, M.; Weerts, H.; White, A.; White, J. T.; Whiteson, D.; Wightman, J. A.; Wijngaarden, D. A.; Willis, S.; Wimpenny, S. J.; Womersley, J.; Wood, D. R.; Yamada, R.; Yamin, P.; Yasuda, T.; Yatsunenko, Y. A.; Yip, K.; Youssef, S.; Yu, J.; Yu, Z.; Zanabria, M.; Zheng, H.; Zhou, Z.; Zielinski, M.; Zieminska, D.; Zieminski, A.; Zutshi, V.; Zverev, E. G.; Zylberstejn, A.
2001-11-01
We describe a search for the pair production of first-generation scalar and vector leptoquarks in the eejj and eνjj channels by the DØ Collaboration. The data are from the 1992-1996 pp¯ run at s=1.8 TeV at the Fermilab Tevatron collider. We find no evidence for leptoquark production; in addition, no kinematically interesting events are observed using relaxed selection criteria. The results from the eejj and eνjj channels are combined with those from a previous DØ analysis of the ννjj channel to obtain 95% confidence level (C.L.) upper limits on the leptoquark pair-production cross section as a function of mass and of β, the branching fraction to a charged lepton. These limits are compared to next-to-leading-order theory to set 95% C.L. lower limits on the mass of a first-generation scalar leptoquark of 225, 204, and 79 GeV/c2 for β=1, 12, and 0, respectively. For vector leptoquarks with gauge (Yang-Mills) couplings, 95% C.L. lower limits of 345, 337, and 206 GeV/c2 are set on the mass for β=1, 12, and 0, respectively. Mass limits for vector leptoquarks are also set for anomalous vector couplings.
Absorption of scalars by extremal black holes in string theory
NASA Astrophysics Data System (ADS)
Moura, Filipe
2017-09-01
We show that the low frequency absorption cross section of minimally coupled test massless scalar fields by extremal spherically symmetric black holes in d dimensions is equal to the horizon area, even in the presence of string-theoretical α ' corrections. Classically one has the relation σ = 4 GS between that absorption cross section and the black hole entropy. By comparing in each case the values of the horizon area and Wald's entropy, we discuss the validity of such relation in the presence of higher derivative corrections for extremal black holes in many different contexts: in the presence of electric and magnetic charges; for nonsupersymmetric and supersymmetric black holes; in d=4 and d=5 dimensions. The examples we consider seem to indicate that this relation is not verified in the presence of α ' corrections in general, although being valid in some specific cases (electrically charged maximally supersymmetric black holes in d=5). We argue that the relation σ = 4 GS should in general be valid for the absorption cross section of scalar fields which, although being independent from the black hole solution, have their origin from string theory, and therefore are not minimally coupled.
Quantum corrections in Higgs inflation: the real scalar case
George, Damien P.; Mooij, Sander; Postma, Marieke E-mail: sander.mooij@ing.uchile.cl
2014-02-01
We present a critical discussion of quantum corrections, renormalisation, and the computation of the beta functions and the effective potential in Higgs inflation. In contrast with claims in the literature, we find no evidence for a disagreement between the Jordan and Einstein frames, even at the quantum level. For clarity of discussion we concentrate on the case of a real scalar Higgs. We first review the classical calculation and then discuss the back reaction of gravity. We compute the beta functions for the Higgs quartic coupling and non-minimal coupling constant. Here, the mid-field regime is non-renormalisable, but we are able to give an upper bound on the 1-loop corrections to the effective potential. We show that, in computing the effective potential, the Jordan and Einstein frames are compatible if all mass scales are transformed between the two frames. As such, it is consistent to take a constant cutoff in either the Jordan or Einstein frame, and both prescriptions yield the same result for the effective potential. Our results are extended to the case of a complex scalar Higgs.
Exact solutions in a scalar-tensor model of dark energy
Granda, L.N.; Loaiza, E. E-mail: edwin.loaiza@correounivalle.edu.co
2012-09-01
We consider a model of scalar field with non minimal kinetic and Gauss Bonnet couplings as a source of dark energy. Based on asymptotic limits of the generalized Friedmann equation, we impose restrictions on the kinetic an Gauss-Bonnet couplings. This restrictions considerable simplify the equations, allowing for exact solutions unifying early time matter dominance with transitions to late time quintessence and phantom phases. The stability of the solutions in absence of matter has been studied.
Anatomy of coannihilation with a scalar top partner
NASA Astrophysics Data System (ADS)
Ibarra, A.; Pierce, A.; Shah, N. R.; Vogl, S.
2015-05-01
We investigate a simplified model of dark matter where a Majorana fermion χ coannihilates with a colored scalar top partner t ˜. We explore the cosmological history, with particular emphasis on the most relevant low-energy parameters: the mass splitting between the dark matter and the coannihilator, and the Yukawa coupling yχ that connects these fields to the Standard Model top quarks. We also allow a free quartic coupling λh between a pair of Higgs bosons and t ˜ pairs. We pay special attention to the case where the values take on those expected where t ˜ corresponds to the superpartner of the right-handed top, and χ is a bino. Direct detection, indirect detection, and colliders are complementary probes of this simple model.
Warped-AdS3 black holes with scalar halo
NASA Astrophysics Data System (ADS)
Giribet, Gaston; Tsoukalas, Minas
2015-09-01
We construct a stretched (aka warped) anti-de Sitter black hole in three dimensions supported by a real scalar field configuration. The latter is regular everywhere outside and on the horizon. No-hair theorems in three dimensions demand the matter be coupled to the curvature in a nonminimal way; however, this coupling can still be of the Horndeski type, i.e. yielding second order field equations similar to those appearing in the context of Galileon theories. These warped-anti-de Sitter black holes exhibit interesting thermodynamical properties, such as finite Hawking temperature and entropy. We compute the black hole entropy in the gravity theory and speculate on the possibility of this to admit a microscopic description in terms of a dual (warped) conformal field theory. We also discuss the inner and outer black hole mechanics.
Dispersive analysis of the scalar form factor of the nucleon
NASA Astrophysics Data System (ADS)
Hoferichter, M.; Ditsche, C.; Kubis, B.; Meißner, U.-G.
2012-06-01
Based on the recently proposed Roy-Steiner equations for pion-nucleon ( πN) scattering [1], we derive a system of coupled integral equations for the π π to overline N N and overline K K to overline N N S-waves. These equations take the form of a two-channel Muskhelishvili-Omnès problem, whose solution in the presence of a finite matching point is discussed. We use these results to update the dispersive analysis of the scalar form factor of the nucleon fully including overline K K intermediate states. In particular, we determine the correction {Δ_{σ }} = σ ( {2M_{π }^2} ) - {σ_{{π N}}} , which is needed for the extraction of the pion-nucleon σ term from πN scattering, as a function of pion-nucleon subthreshold parameters and the πN coupling constant.
Darkflation-One scalar to rule them all?
NASA Astrophysics Data System (ADS)
Lalak, Zygmunt; Nakonieczny, Łukasz
2017-03-01
The problem of explaining both inflationary and dark matter physics in the framework of a minimal extension of the Standard Model was investigated. To this end, the Standard Model completed by a real scalar singlet playing a role of the dark matter candidate has been considered. We assumed both the dark matter field and the Higgs doublet to be nonminimally coupled to gravity. Using quantum field theory in curved spacetime we derived an effective action for the inflationary period and analyzed its consequences. In this approach, after integrating out both dark matter and Standard Model sectors we obtained the effective action expressed purely in terms of the gravitational field. We paid special attention to determination, by explicit calculations, of the form of coefficients controlling the higher-order in curvature gravitational terms. Their connection to the Standard Model coupling constants has been discussed.
Passive scalar transport mediated by laminar vortex rings
NASA Astrophysics Data System (ADS)
Hernández, R. H.; Rodríguez, G.
2017-04-01
Numerical simulations were used to study the dynamics of a passive conserved scalar quantity entrained by a self-propelling viscous vortex ring. The transport and mixing process of the passive scalar variable were studied considering two initial scalar distributions: (i) The scalar substance was introduced into the ring during its formation, further focusing in the shedding into the wake of the ring; (ii) A disk-like scalar layer was placed in the ring’s path where the entrainment of the scalar substance into the ring bubble was studied as a function of the ring strength. In both cases, the scalar concentration inside the vortex bubble exhibits a steady decay with time. In the second case, it was shown that the entrained scalar mass grows with both the Reynolds number of the ring and the thickness of the scalar layer in the propagation direction. The ring can be viewed as a mechanism for scalar transportation along important distances.
Calculation of scalar structure functions from a vortex model of turbulent passive scalar transport
NASA Astrophysics Data System (ADS)
Higgins, Keith; Ooi, Andrew; Chong, M. S.
2008-02-01
A Saffman and Pullin [Phys. Fluids 8, 3072 (1996)] type vortex model for passive scalar structure functions is formulated. The intermittent turbulent fine-scale dynamics in the model is represented by numerical solutions of the advection-diffusion and Navier-Stokes equations in the form of axially strained vortex-scalar structures. The use of these structures is motivated by Pullin and Lundgren's [Phys. Fluids 13, 2553 (2001)] asymptotic strained spiral vortex model of turbulent passive scalar transport. Ensemble-averaged scalar structure functions, of even orders 2-10, are calculated from a range of vortex-scalar structures using Monte Carlo integration. For axisymmetric strained scalar fields, acceptable agreement of the second-order structure function with experimental data reported by Antonia and Van Atta [J. Fluid Mech. 84, 561 (1978)] is obtained. Structure functions are also calculated for a range of passive scalar spiral structures. These are generated by the winding of single and double scalar patches in single strained vortex patches and in merging strained vortices. Power-law scaling of the second- and higher-order structure functions is obtained from cases involving the winding of single scalar patches in an axisymmetric strained vortex patch. The second-order scaling exponents from these cases are in reasonable agreement with Kolmogorov-Oboukhov-Corrsin scaling and the experimental results of Antonia et al. [Phys. Rev. A 30, 2704 (1984)] and Gylfason and Warhaft [Phys. Fluids 16, 4012 (2004)]. However, the higher-order scaling exponents from these cases fall below theoretical predictions and experimental results. Higher-order moments are sensitive to the composition of the vortex-scalar structures, and various improvements are suggested that could enhance the performance of the model. The present approach is promising, and it is the first demonstration that a vortex model using simplified Navier-Stokes dynamics can produce some scalar structure
Absorption of a Massive Scalar Field by Wormhole Space-Times
NASA Astrophysics Data System (ADS)
Huang, Hai; Chen, Juhua; Wang, Yongjiu; Jin, Yao
2017-04-01
In this paper we consider the problem of the test massive scalar field propagating in the background of a class of wormhole space-times. Basing on the quantum scattering theory, we analyze the Schrödinger-type scalar wave equation and compute transmission coefficients for arbitrary coupling of the field to the background geometry with the WKB approximation. We numerically investigate its absorption cross section and analyze them in the high frequency regime. We find that the absorption cross section oscillates about the geometric optical value and the limit of absorption cross section is uniform in the high frequency regime.
Bouncing universes in scalar-tensor gravity models admitting negative potentials
Boisseau, B.; Giacomini, H.; Starobinsky, A.A. E-mail: hector.giacomini@lmpt.univ-tours.fr E-mail: alstar@landau.ac.ru
2015-07-01
We consider the possibility to produce a bouncing universe in the framework of scalar-tensor gravity models in which the scalar field potential may be negative, and even unbounded from below. We find a set of viable solutions with nonzero measure in the space of initial conditions passing a bounce, even in the presence of a radiation component, and approaching a constant gravitational coupling afterwards. Hence we have a model with a minimal modification of gravity in order to produce a bounce in the early universe with gravity tending dynamically to general relativity (GR) after the bounce.
Absorption of a Massive Scalar Field by Wormhole Space-Times
NASA Astrophysics Data System (ADS)
Huang, Hai; Chen, Juhua; Wang, Yongjiu; Jin, Yao
2017-01-01
In this paper we consider the problem of the test massive scalar field propagating in the background of a class of wormhole space-times. Basing on the quantum scattering theory, we analyze the Schrödinger-type scalar wave equation and compute transmission coefficients for arbitrary coupling of the field to the background geometry with the WKB approximation. We numerically investigate its absorption cross section and analyze them in the high frequency regime. We find that the absorption cross section oscillates about the geometric optical value and the limit of absorption cross section is uniform in the high frequency regime.
Diffraction analysis of blazed transmission gratings with a modified extended scalar theory.
Wang, Huaijun; Kuang, Dengfeng; Fang, Zhiliang
2008-06-01
An alternative interpretation of the diffraction of blazed transmission gratings with moderate structure period is proposed according to a modified extended scalar theory (MEST). The diffraction field on the bottom facet of the grating is considered to be the interference of four subfields investigated in the problem of diffraction of a plane wave by an infinite half-plane. It is observed that MEST gives the total field that agrees with rigorous coupled-wave analysis (RCWA), and the result is more reliable than that of extended scalar theory (EST). The MEST is still a ray-optical-based approximation approach, and the region of validity is compared with EST and RCWA.
The scalar-scalar-tensor inflationary three-point function in the axion monodromy model
NASA Astrophysics Data System (ADS)
Chowdhury, Debika; Sreenath, V.; Sriramkumar, L.
2016-11-01
The axion monodromy model involves a canonical scalar field that is governed by a linear potential with superimposed modulations. The modulations in the potential are responsible for a resonant behavior which gives rise to persisting oscillations in the scalar and, to a smaller extent, in the tensor power spectra. Interestingly, such spectra have been shown to lead to an improved fit to the cosmological data than the more conventional, nearly scale invariant, primordial power spectra. The scalar bi-spectrum in the model too exhibits continued modulations and the resonance is known to boost the amplitude of the scalar non-Gaussianity parameter to rather large values. An analytical expression for the scalar bi-spectrum had been arrived at earlier which, in fact, has been used to compare the model with the cosmic microwave background anisotropies at the level of three-point functions involving scalars. In this work, with future applications in mind, we arrive at a similar analytical template for the scalar-scalar-tensor cross-correlation. We also analytically establish the consistency relation (in the squeezed limit) for this three-point function. We conclude with a summary of the main results obtained.
Scalar transport in plane mixing layers
NASA Astrophysics Data System (ADS)
Vanormelingen, J.; Van den Bulck, E.
This paper describes the application of the Eulerian, single-point, single-time joint-scalar probability density function (PDF) equation for predicting the scalar transport in mixing layer with a high-speed and a low-speed stream. A finite-volume procedure is applied to obtain the velocity field with the k-ɛ closure being used to describe turbulent transport. The scalar field is represented through the modelled evolution equation for the scalar PDF and is solved using a Monte Carlo simulation. The PDF equation employs gradient transport modelling to represent the turbulent diffusion, and the molecular mixing term is modelled by the LMSE closure. There is no source term for chemical reaction as only an inert mixing layer is considered here. The experimental shear layer data published by Batt is used to validate the computational results despite the fact that comparisons between experiments and computational results are difficult because of the high sensitivity of the shear layer to initial conditions and free stream turbulence phenomena. However, the bimodal shape of the RMS scalar fluctuation as was measured by Batt can be reproduced with this model, whereas standard gradient diffusion calculations do not predict the dip in this profile. In this work for the first time an explanation is given for this phenomenon and the importance of a micromixing model is stressed. Also it is shown that the prediction of the PDF shape by the LMSE model is very satisfactory.
The weak gravity conjecture and scalar fields
NASA Astrophysics Data System (ADS)
Palti, Eran
2017-08-01
We propose a generalisation of the Weak Gravity Conjecture in the presence of scalar fields. The proposal is guided by properties of extremal black holes in N=2 supergravity, but can be understood more generally in terms of forbidding towers of stable gravitationally bound states. It amounts to the statement that there must exist a particle on which the gauge force acts more strongly than gravity and the scalar forces combined. We also propose that the scalar force itself should act on this particle stronger than gravity. This implies that generically the mass of this particle decreases exponentially as a function of the scalar field expectation value for super-Planckian variations, which is behaviour predicted by the Refined Swampland Conjecture. In the context of N=2 supergravity the Weak Gravity Conjecture bound can be tied to bounds on scalar field distances in field space. Guided by this, we present a general proof that for any linear combination of moduli in any Calabi-Yau compactification of string theory the proper field distance grows at best logarithmically with the moduli values for super-Planckian distances.
Scalar Implicatures: The Psychological Reality of Scales.
de Carvalho, Alex; Reboul, Anne C; Van der Henst, Jean-Baptiste; Cheylus, Anne; Nazir, Tatjana
2016-01-01
Scalar implicatures, the phenomena where a sentence like "The pianist played some Mozart sonatas" is interpreted, as "The pianist did not play all Mozart sonatas" have been given two different analyses. Neo-Griceans (NG) claim that this interpretation is based on lexical scales (e.g.,
Diphoton decay for a 750 GeV scalar boson in a U(1)X model
NASA Astrophysics Data System (ADS)
Martinez, R.; Ochoa, F.; Sierra, C. F.
2016-12-01
In the context of a nonuniversal and anomaly free U(1)X extension of the standard model, we examine the decay of a 750 GeV scalar singlet state, ξχ, as a possible explanation of the observed diphoton excess announced by the ATLAS and CMS collaborations at CERN-LHC collider. The one-loop decay to photons is allowed through three heavy singlet quarks and one charged Higgs boson into the loop. We obtain, for different width approximations and for masses of the exotic singlet quarks in the region [ 900 , 3000 ] GeV, a production cross section σ (pp →ξχ → γγ) compatible with ATLAS and CMS collaborations data. We also include another scalar singlet, σ, as a dark matter candidate that may couple with the 750 GeV scalar at tree level with production cross sections in agreement with ATLAS and CMS.
Light scalar field constraints from gravitational-wave observations of compact binaries
NASA Astrophysics Data System (ADS)
Berti, Emanuele; Gualtieri, Leonardo; Horbatsch, Michael; Alsing, Justin
2012-06-01
Scalar-tensor theories are among the simplest extensions of general relativity. In theories with light scalars, deviations from Einstein’s theory of gravity are determined by the scalar mass ms and by a Brans-Dicke-like coupling parameter ωBD. We show that gravitational-wave observations of nonspinning neutron star-black hole binary inspirals can be used to set lower bounds on ωBD and upper bounds on the combination ms/ωBD. We estimate via a Fisher matrix analysis that individual observations with signal-to-noise ratio ρ would yield (ms/ωBD)(ρ/10)≲10-15, 10-16, and 10-19eV for Advanced LIGO, ET, and eLISA, respectively. A statistical combination of multiple observations may further improve these bounds.
WIMP dark matter and unitarity-conserving inflation via a gauge singlet scalar
Kahlhoefer, Felix; McDonald, John E-mail: j.mcdonald@lancaster.ac.uk
2015-11-01
A gauge singlet scalar with non-minimal coupling to gravity can drive inflation and later freeze out to become cold dark matter. We explore this idea by revisiting inflation in the singlet direction (S-inflation) and Higgs Portal Dark Matter in light of the Higgs discovery, limits from LUX and observations by Planck. We show that large regions of parameter space remain viable, so that successful inflation is possible and the dark matter relic abundance can be reproduced. Moreover, the scalar singlet can stabilise the electroweak vacuum and at the same time overcome the problem of unitarity-violation during inflation encountered by Higgs Inflation, provided the singlet is a real scalar. The 2-σ Planck upper bound on n{sub s} imposes that the singlet mass is below 2 TeV, so that almost the entire allowed parameter range can be probed by XENON1T.
Accessing directly the properties of fundamental scalars in the confinement and Higgs phase
NASA Astrophysics Data System (ADS)
Maas, Axel
2011-02-01
The properties of elementary particles are encoded in their respective propagators and interaction vertices. For a SU(2) gauge theory coupled to a doublet of fundamental complex scalars these propagators are determined in both the Higgs phase and the confinement phase and compared to the Yang-Mills case, using lattice gauge theory. Since the propagators are gauge dependent, this is done in the Landau limit of the 't Hooft gauge, permitting to also determine the ghost propagator. It is found that neither the gauge boson nor the scalar differ qualitatively in the different cases. In particular, the gauge boson acquires a screening mass, and the scalar's screening mass is larger than the renormalized mass. Only the ghost propagator shows a significant change. Furthermore, indications are found that the consequences of the residual non-perturbative gauge freedom due to Gribov copies could be different in the confinement and the Higgs phase.
Symmetry breaking and onset of cosmic acceleration in scalar field models
NASA Astrophysics Data System (ADS)
Mohseni Sadjadi, H.; Honardoost, M.; Sepangi, H. R.
2016-12-01
We propose a new scenario for the onset of positive acceleration of our Universe based on symmetry breaking in coupled dark energy scalar field model. In a symmetry breaking process where the scalar field rolls down its own potential, the potential reduction is not in favor of acceleration. In our model, when dark matter density becomes less than a critical value, the shape of the effective potential is changed and, the quintessence field climbs up along its own potential while rolls down the effective potential. We show that this procedure may establish the positivity of the potential required for the Universe to accelerate. In addition, we show that by choosing an appropriate interaction between dark sectors there is the possibility that the scalar field resides in a new vacuum giving rise to a positive cosmological constant which is responsible for a permanent late time acceleration.
Real singlet scalar dark matter extension of the Georgi-Machacek model
NASA Astrophysics Data System (ADS)
Campbell, Robyn; Godfrey, Stephen; Logan, Heather E.; Poulin, Alexandre
2017-01-01
The Georgi-Machacek model extends the Standard Model Higgs sector with the addition of isospin-triplet scalar fields in such a way as to preserve the custodial symmetry. The presence of higher-isospin scalars contributing to electroweak symmetry breaking offers the interesting possibility that the couplings of the 125 GeV Higgs boson to both gluons and vector boson pairs could be larger than those of the Standard Model Higgs boson. Constraining this possibility using measurements of Higgs production and decay at the CERN Large Hadron Collider is notoriously problematic if a new, non-Standard Model decay mode of the 125 GeV Higgs boson is present. We study an implementation of this scenario in which the Georgi-Machacek model is extended by a real singlet scalar dark matter candidate, and require that the singlet scalar account for all the dark matter in the Universe. The combination of the observed dark matter relic density and direct-detection constraints exclude singlet scalar masses below about 57 GeV. Higgs measurements are not yet precise enough to be very sensitive to h →S S in the remaining allowed kinematic region, so that constraints from Higgs measurements are so far the same as in the GM model without a singlet scalar. We also find that, above the Higgs pole, a substantial region of parameter space yielding the correct dark matter relic density can escape the near-future direct-detection experiments DEAP and XENON 1T for dark matter masses as low as 120 GeV and even have a direct-detection cross section below the neutrino floor for mS≳150 GeV . This is in contrast to the singlet scalar dark matter extension of the Standard Model, for which these future experiments are expected to exclude dark matter masses above the Higgs pole up to the multi-TeV range.
Numerical errors in the computation of subfilter scalar variance in large eddy simulations
NASA Astrophysics Data System (ADS)
Kaul, C. M.; Raman, V.; Balarac, G.; Pitsch, H.
2009-05-01
Subfilter scalar variance is a key quantity for scalar mixing at the small scales of a turbulent flow and thus plays a crucial role in large eddy simulation of combustion. While prior studies have mainly focused on the physical aspects of modeling subfilter variance, the current work discusses variance models in conjunction with the numerical errors due to their implementation using finite-difference methods. A priori tests on data from direct numerical simulation of homogeneous turbulence are performed to evaluate the numerical implications of specific model forms. Like other subfilter quantities, such as kinetic energy, subfilter variance can be modeled according to one of two general methodologies. In the first of these, an algebraic equation relating the variance to gradients of the filtered scalar field is coupled with a dynamic procedure for coefficient estimation. Although finite-difference methods substantially underpredict the gradient of the filtered scalar field, the dynamic method is shown to mitigate this error through overestimation of the model coefficient. The second group of models utilizes a transport equation for the subfilter variance itself or for the second moment of the scalar. Here, it is shown that the model formulation based on the variance transport equation is consistently biased toward underprediction of the subfilter variance. The numerical issues in the variance transport equation stem from discrete approximations to chain-rule manipulations used to derive convection, diffusion, and production terms associated with the square of the filtered scalar. These approximations can be avoided by solving the equation for the second moment of the scalar, suggesting that model's numerical superiority.
Effects of quantized scalar fields in cosmological spacetimes with big rip singularities
Bates, Jason D.; Anderson, Paul R.
2010-07-15
Effects of quantized free scalar fields in cosmological spacetimes with big rip singularities are investigated. The energy densities for these fields are computed at late times when the expansion is very rapid. For the massless minimally coupled field it is shown that an attractor state exists in the sense that, for a large class of states, the energy density of the field asymptotically approaches the energy density it would have if it was in the attractor state. Results of numerical computations of the energy density for the massless minimally coupled field and for massive fields with minimal and conformal couplings to the scalar curvature are presented. For the massive fields the energy density is seen to always asymptotically approach that of the corresponding massless field. The question of whether the energy densities of quantized fields can be large enough for backreaction effects to remove the big rip singularity is addressed.
Kerr black holes with self-interacting scalar hair: Hairier but not heavier
NASA Astrophysics Data System (ADS)
Herdeiro, Carlos A. R.; Radu, Eugen; Rúnarsson, Helgi
2015-10-01
The maximal Arnowitt-Deser-Misner (ADM) mass for (mini)boson stars (BSs)—gravitating solitons of Einstein's gravity minimally coupled to a free, complex, mass μ , Klein-Gordon field—is MADMmax˜MPl2/μ . Adding quartic self-interactions to the scalar field theory, described by the Lagrangian LI=λ |Ψ |4 , the maximal ADM mass becomes MADMmax˜√{λ }MPl3/μ2 . Thus, for mini-BSs, astrophysically interesting masses require ultralight scalar fields, whereas self-interacting BSs can reach such values for bosonic particles with Standard Model range masses. We investigate how these same self-interactions affect Kerr black holes with scalar hair (KBHsSH) [C. A. R. Herdeiro and E. Radu, Kerr Black Holes with Scalar Hair, Phys. Rev. Lett. 112, 221101 (2014).], which can be regarded as (spinning) BSs in stationary equilibrium with a central horizon. Remarkably, whereas the ADM mass scales in the same way as for BSs, the horizon mass MH does not increases with the coupling λ , and, for fixed μ , it is maximized at the "Hod point," corresponding to the extremal Kerr black hole obtained in the vanishing hair limit. This mass is always MHmax˜MPl2/μ . Thus, introducing these self-interactions, the black hole spacetimes may become considerably "hairier" but the trapped regions cannot become "heavier." We present evidence that this observation also holds in a model with LI=β |Ψ |6-λ |Ψ |4 ; if it extends to general scalar field models, KBHsSH with astrophysically interesting horizon masses require ultralight scalar fields. Their existence, therefore, would be a smoking gun for such (beyond the Standard Model) particles.
Gao, Hong; Sneha, Mahima; Bouakline, Foudhil; Althorpe, Stuart C; Zare, Richard N
2015-12-17
We report rovibrationally selected differential cross sections (DCSs) of the benchmark reaction H + D2 → HD(v' = 3, j' = 4-10) + D at a collision energy of 3.26 eV, which exceeds the conical intersection of the H3 potential energy surface at 2.74 eV. We use the PHOTOLOC technique in which a fluorine excimer laser at 157.64 nm photodissociates hydrogen bromide (HBr) molecules to generate fast H atoms and the HD product is detected in a state-specific manner by resonance-enhanced multiphoton ionization. Fully converged quantum wave packet calculations were performed for this reaction at this high collision energy without inclusion of the geometric phase (GP) effect, which takes into account coupling to the first excited state of the H3 potential energy surface. Multimodal structures can be observed in most of the DCSs up to j' = 10, which is predicted by theory and also well-reproduced by experiment. The theoretically calculated DCSs are in good overall agreement with the experimental measurements, which indicates that the GP effect is not large enough that its existence can be verified experimentally at this collision energy.
The role of the scalar and enstrophy flux in entrainment processes
NASA Astrophysics Data System (ADS)
Mistry, Dhiren; Dawson, James R.
2016-11-01
Turbulent entrainment is a multi-stage, multi-scale process that describes the growth of a turbulent region of flow. Ultimately, turbulent entrainment is achieved through viscous diffusion of vorticity, and molecular diffusion in the presence of scalars, with irrotational and unmixed regions of the flow at the smallest scales. We do not fully understand how these small-scale processes are coupled to or modulated by the large-scales of turbulence. This is partly because the mean entrainment rates in turbulent shear flows can be determined by considering large-scales quantities only. We present experimental evidence that the large-scale flux of enstrophy and scalar towards the turbulent/non-turbulent interface (TNTI) coincides with a local increase in the entrainment velocity along the TNTI. This is achieved using a passive scalar (Sc >> 1) to identify the TNTI, and a time-resolved interface-tracking method to measure the local entrainment velocity. Our results indicate that the both scalar and enstrophy fluxes towards the TNTI increase the vorticity and scalar gradients increasing the local rates of diffusion. These results show how local processes of small-scale diffusion are modulated by the large-scale turbulence.
A priori study of subgrid-scale flux of a passive scalar in isotropic homogeneous turbulence
Chumakov, Sergei
2008-01-01
We perform a direct numerical simulation (DNS) of forced homogeneous isotropic turbulence with a passive scalar that is forced by mean gradient. The DNS data are used to study the properties of subgrid-scale flux of a passive scalar in the framework of large eddy simulation (LES), such as alignment trends between the flux, resolved, and subgrid-scale flow structures. It is shown that the direction of the flux is strongly coupled with the subgrid-scale stress axes rather than the resolved flow quantities such as strain, vorticity, or scalar gradient. We derive an approximate transport equation for the subgrid-scale flux of a scalar and look at the relative importance of the terms in the transport equation. A particular form of LES tensor-viscosity model for the scalar flux is investigated, which includes the subgrid-scale stress. Effect of different models for the subgrid-scale stress on the model for the subgrid-scale flux is studied.
Oscillation modes of rapidly rotating neutron stars in scalar-tensor theories of gravity
NASA Astrophysics Data System (ADS)
Yazadjiev, Stoytcho S.; Doneva, Daniela D.; Kokkotas, Kostas D.
2017-09-01
We perform the first study of the oscillation frequencies of rapidly rotating neutron stars in alternative theories of gravity, focusing mainly on the fundamental f modes. We concentrated on a particular class of alternative theories—the (massive) scalar-tensor theories. The generalization to rapid rotation is important because on one hand the rapid rotation can magnify the deviations from general relativity compared to the static case and on the other hand some of the most efficient emitters of gravitational radiation, such as the binary neutron star merger remnants, are supposed to be rotating close to their Kepler (mass-shedding) limits shortly after their formation. We have constructed several sequences of models starting from the nonrotating case and reaching up to the Kepler limit, with different values of the scalar-tensor theory coupling constant and the scalar field mass. The results show that the deviations from pure Einstein's theory can be significant, especially in the case of nonzero scalar field mass. An important property of the oscillation modes of rapidly rotating stars is that they can become secularly unstable due to the emission of gravitational radiation, the so-called Chandrasekhar-Friedman-Schutz instability. Such unstable modes are efficient emitters of gravitational radiation. Our studies show that the inclusion of a nonzero scalar field would decrease the threshold value of the normalized angular momentum where this instability starts to operate, but the growth time of the instability seems to be increased compared to pure general relativity.
The Neural Computation of Scalar Implicature
Hartshorne, Joshua K.; Snedeker, Jesse; Azar, Stephanie Yen-Mun Liem; Kim, Albert E.
2014-01-01
Language comprehension involves not only constructing the literal meaning of a sentence but also going beyond the literal meaning to infer what was meant but not said. One widely-studied test case is scalar implicature: The inference that, e.g., Sally ate some of the cookies implies she did not eat all of them. Research is mixed on whether this is due to a rote, grammaticalized procedure or instead a complex, contextualized inference. We find that in sentences like If Sally ate some of the cookies, then the rest are on the counter, that the rest triggers a late, sustained positivity relative to Sally ate some of the cookies, and the rest are on the counter. This is consistent with behavioral results and linguistic theory suggesting that the former sentence does not trigger a scalar implicature. This motivates a view on which scalar implicature is contextualized but dependent on grammatical structure. PMID:25914890
Exploring scalar field dynamics with Gaussian processes
Nair, Remya; Jhingan, Sanjay; Jain, Deepak E-mail: sanjay.jhingan@gmail.com
2014-01-01
The origin of the accelerated expansion of the Universe remains an unsolved mystery in Cosmology. In this work we consider a spatially flat Friedmann-Robertson-Walker (FRW) Universe with non-relativistic matter and a single scalar field contributing to the energy density of the Universe. Properties of this scalar field, like potential, kinetic energy, equation of state etc. are reconstructed from Supernovae and BAO data using Gaussian processes. We also reconstruct energy conditions and kinematic variables of expansion, such as the jerk and the slow roll parameter. We find that the reconstructed scalar field variables and the kinematic quantities are consistent with a flat ΛCDM Universe. Further, we find that the null energy condition is satisfied for the redshift range of the Supernovae data considered in the paper, but the strong energy condition is violated.
Extended scalar-tensor theories of gravity
Crisostomi, Marco; Koyama, Kazuya; Tasinato, Gianmassimo
2016-04-21
We study new consistent scalar-tensor theories of gravity recently introduced by Langlois and Noui with potentially interesting cosmological applications. We derive the conditions for the existence of a primary constraint that prevents the propagation of an additional dangerous mode associated with higher order equations of motion. We then classify the most general, consistent scalar-tensor theories that are at most quadratic in the second derivatives of the scalar field. In addition, we investigate the possible connection between these theories and (beyond) Horndeski through conformal and disformal transformations. Finally, we point out that these theories can be associated with new operators in the effective field theory of dark energy, which might open up new possibilities to test dark energy models in future surveys.
Entanglement from longitudinal and scalar photons
Franson, J. D
2011-09-15
The covariant quantization of the electromagnetic field in the Lorentz gauge gives rise to longitudinal and scalar photons in addition to the usual transverse photons. It is shown here that the exchange of longitudinal and scalar photons can produce entanglement between two distant atoms or harmonic oscillators. The form of the entangled states produced in this way is very different from that obtained in the Coulomb gauge, where the longitudinal and scalar photons do not exist. A generalized gauge transformation is used to show that all physically observable effects are the same in the two gauges, despite the differences in the form of the entangled states. An approach of this kind may be useful for a covariant description of the dynamics of quantum information processing.
Passive scalar mixing in vortex rings
NASA Astrophysics Data System (ADS)
Sau, Rajes; Mahesh, Krishnan
2006-11-01
Direct numerical simulations of passive scalar mixing in vortex rings are performed, with and without crossflow. The simulation results without crossflow agree well with experimental data for `formation number', total circulation, trajectory and entrainment fraction. Scalar profiles, mixedness and volume of scalar carrying fluid are used to quantify mixing, whose characteristics are quite different in the formation and propagation phases of the ring. These results are explained in terms of entrainment by the ring. The simulations with crossflow show that the ring tilts and deforms. When the stroke ratio is greater than formation number, the ring tilts in the direction of the crossflow. On the other hand, when the stroke ratio is less than formation number, the ring tilts in the opposite direction, such that its induced velocity opposes the crossflow. The Magnus effect may be used to provide a simple explanation. The impact of this behavior on mixing will be discussed.
The Neural Computation of Scalar Implicature.
Hartshorne, Joshua K; Snedeker, Jesse; Azar, Stephanie Yen-Mun Liem; Kim, Albert E
2015-06-01
Language comprehension involves not only constructing the literal meaning of a sentence but also going beyond the literal meaning to infer what was meant but not said. One widely-studied test case is scalar implicature: The inference that, e.g., Sally ate some of the cookies implies she did not eat all of them. Research is mixed on whether this is due to a rote, grammaticalized procedure or instead a complex, contextualized inference. We find that in sentences like If Sally ate some of the cookies, then the rest are on the counter, that the rest triggers a late, sustained positivity relative to Sally ate some of the cookies, and the rest are on the counter. This is consistent with behavioral results and linguistic theory suggesting that the former sentence does not trigger a scalar implicature. This motivates a view on which scalar implicature is contextualized but dependent on grammatical structure.
Recent progress on light scalar mesons
Peláez, J. R.
2014-07-23
This is a brief account of the recent developments on the determination of the mass and widths of the much debated scalar mesons, paying particular attention to the causes of major revision of the σ or f{sub 0}(500) meson in the last edition of the Review of Particle Physics, which has finally acknowledged that the situation concerning the mass and width of this controversial state has been settled, although this was already well-known to scalar meson practitioners for about a decade. I will briefly comment on the dispersive approach, followed by several groups, which seems to have been the most decisive in support of the existence and precise determinations of scalar meson properties.
Extended scalar-tensor theories of gravity
NASA Astrophysics Data System (ADS)
Crisostomi, Marco; Koyama, Kazuya; Tasinato, Gianmassimo
2016-04-01
We study new consistent scalar-tensor theories of gravity recently introduced by Langlois and Noui with potentially interesting cosmological applications. We derive the conditions for the existence of a primary constraint that prevents the propagation of an additional dangerous mode associated with higher order equations of motion. We then classify the most general, consistent scalar-tensor theories that are at most quadratic in the second derivatives of the scalar field. In addition, we investigate the possible connection between these theories and (beyond) Horndeski through conformal and disformal transformations. Finally, we point out that these theories can be associated with new operators in the effective field theory of dark energy, which might open up new possibilities to test dark energy models in future surveys.
Stability of Gauss-Bonnet black holes in anti-de Sitter space-time against scalar field condensation
Brihaye, Yves; Hartmann, Betti
2011-10-15
We study the stability of static, hyperbolic Gauss-Bonnet black holes in (4+1)-dimensional anti-de Sitter (AdS) space-time against the formation of scalar hair. Close to extremality the black holes possess a near-horizon topology of AdS{sub 2}xH{sup 3} such that within a certain range of the scalar field mass one would expect that they become unstable to the condensation of an uncharged scalar field. We confirm this numerically and observe that there exists a family of hairy black hole solutions labeled by the number of nodes of the scalar field function. We construct explicit examples of solutions with a scalar field that possesses zero nodes, one node, and two nodes, respectively, and show that the solutions with nodes persist in the limit of Einstein gravity, i.e. for vanishing Gauss-Bonnet coupling. We observe that the interval of the mass for which scalar field condensation appears decreases with increasing Gauss-Bonnet coupling and/or with increasing node number.
NASA Astrophysics Data System (ADS)
Guter, W.; Kern, R.; Köstler, W.; Kubera, T.; Löckenhoff, R.; Meusel, M.; Shirnow, M.; Strobl, G.
2011-12-01
AZUR SPACE's current CPV product 3C40C is an advanced lattice-matched In0.50Ga0.50P/In0.01Ga0.99As/Ge triple junction (3J) solar cell. Recently, efficiencies up to 41.2% (450-600×AM1.5d) have been confirmed for this 40%-class product. This kind of solar cell structure has now reached its practical efficiency limit and went into production in 2010. AZUR offers customized cell structures, regarding size and grid design, as well as anti-reflection coatings adapted to the individual CPV system. Integration grades from diced wafers up to assemblies, such as dense arrays, are available. Special features and production results for the 3C40C structure are presented in this work. In order to further push efficiencies beyond 42% AZUR has successfully transferred the upright metamorphic cell from Fraunhofer ISE and advances this concept now for production. First results on metamorphic 3J solar cells at AZUR SPACE and the actual potential of this concept will be discussed. A target efficiency of 42% seems to be realistic.
A new extension of Hořava-Lifshitz gravity and curing pathologies of the scalar graviton
NASA Astrophysics Data System (ADS)
Moon, Taeyoon; Oh, Phillial; Park, Mu-In
2011-07-01
We consider an extension of the Hořava-Lifshitz gravity with extra conformal symmetry by introducing a scalar field with higher order curvature terms. Relaxing the exact local Weyl symmetry, we construct an action with three free parameters which breaks local anisotropic Weyl symmetry but still preserves residual global Weyl symmetry. At low energies, it reduces to a Lorentz-violating scalar-tensor gravity. With a constant scalar field background and particular choices of the parameters, it reduces to the Hořava-Lifshitz (HL) gravity, but any perturbation from these particular configurations produces some nontrivial extensions of HL gravity. The perturbation analysis of the new extended HL gravity in the Minkowski background shows that the pathological behaviors of scalar graviton, i.e., ghost or instability problem, and strong coupling problem do not emerge up to cubic order as well as quadratic order.
Halos of unified dark matter scalar field
Bertacca, Daniele; Bartolo, Nicola; Matarrese, Sabino E-mail: nicola.bartolo@pd.infn.it
2008-05-15
We investigate the static and spherically symmetric solutions of Einstein's equations for a scalar field with a non-canonical kinetic term, assumed to provide both the dark matter and dark energy components of the Universe. In particular, we give a prescription to obtain solutions (dark halos) whose rotation curve v{sub c}(r) is in good agreement with observational data. We show that there exist suitable scalar field Lagrangians that allow us to describe the cosmological background evolution and the static solutions with a single dark fluid.
Scalar discrete nonlinear multipoint boundary value problems
NASA Astrophysics Data System (ADS)
Rodriguez, Jesus; Taylor, Padraic
2007-06-01
In this paper we provide sufficient conditions for the existence of solutions to scalar discrete nonlinear multipoint boundary value problems. By allowing more general boundary conditions and by imposing less restrictions on the nonlinearities, we obtain results that extend previous work in the area of discrete boundary value problems [Debra L. Etheridge, Jesus Rodriguez, Periodic solutions of nonlinear discrete-time systems, Appl. Anal. 62 (1996) 119-137; Debra L. Etheridge, Jesus Rodriguez, Scalar discrete nonlinear two-point boundary value problems, J. Difference Equ. Appl. 4 (1998) 127-144].
Scalar operators in solid-state NMR
Sun, Boqin
1991-11-01
Selectivity and resolution of solid-state NMR spectra are determined by dispersion of local magnetic fields originating from relaxation effects and orientation-dependent resonant frequencies of spin nuclei. Theoretically, the orientation-dependent resonant frequencies can be represented by a set of irreducible tensors. Among these tensors, only zero rank tensors (scalar operators) are capable of providing high resolution NMR spectra. This thesis presents a series of new developments in high resolution solid-state NMR concerning the reconstruction of various scalar operators motion in solid C{sub 60} is analyzed.
Self tuning scalar tensor black holes
NASA Astrophysics Data System (ADS)
Charmousis, Christos; Iosifidis, Damianos
2015-04-01
Studying a certain sub class of higher order Horndeski (scalar-tensor) theories we discuss a method discovered recently permitting analytic black hole solutions with a non trivial and regular scalar field. One of the solutions found has de Sitter asymptotics and self tunes the bulk cosmological constant. Using the aforementioned method we find and analyse new black hole solutions which can also have de Sitter asymptotics. By looking at small deviations of the integration constant responsible for self tuning we discuss the robustness of the self tuning mechanism. We find that neighboring solutions to the one previously found present also self tuning properties with unaltered effective cosmological constant.
Scalar field in standard cosmology: time equation.
NASA Astrophysics Data System (ADS)
Zecca, A.
1999-11-01
The separated time equation relative to the generalized Klein-Gordon equation in the Robertson-Walker space-time is integrated in the background of the standard cosmology. The solutions are given in terms of series that are obtained by the usual integration method of differential equations with regular singularity. The normalization of the solutions implied by the requirement of second quantization of the scalar field is performed. The result exhausts the requirement of providing an explicit complete set of normal mode solutions of the scalar field equation in standard cosmology.
Visibility graphs of random scalar fields and spatial data
NASA Astrophysics Data System (ADS)
Lacasa, Lucas; Iacovacci, Jacopo
2017-07-01
We extend the family of visibility algorithms to map scalar fields of arbitrary dimension into graphs, enabling the analysis of spatially extended data structures as networks. We introduce several possible extensions and provide analytical results on the topological properties of the graphs associated to different types of real-valued matrices, which can be understood as the high and low disorder limits of real-valued scalar fields. In particular, we find a closed expression for the degree distribution of these graphs associated to uncorrelated random fields of generic dimension. This result holds independently of the field's marginal distribution and it directly yields a statistical randomness test, applicable in any dimension. We showcase its usefulness by discriminating spatial snapshots of two-dimensional white noise from snapshots of a two-dimensional lattice of diffusively coupled chaotic maps, a system that generates high dimensional spatiotemporal chaos. The range of potential applications of this combinatorial framework includes image processing in engineering, the description of surface growth in material science, soft matter or medicine, and the characterization of potential energy surfaces in chemistry, disordered systems, and high energy physics. An illustration on the applicability of this method for the classification of the different stages involved in carcinogenesis is briefly discussed.
M-flation: inflation from matrix valued scalar fields
Ashoorioon, Amjad; Firouzjahi, Hassan; Sheikh-Jabbari, M.M. E-mail: firouz@physics.mcgill.ca
2009-06-01
We propose an inflationary scenario, M-flation, in which inflation is driven by three N × N hermitian matrices Φ{sub i}, i = 1, 2, 3. The inflation potential of our model, which is strongly motivated from string theory, is constructed from Φ{sub i} and their commutators. We show that one can consistently restrict the classical dynamics to a sector in which the Φ{sub i} are proportional to the N × N irreducible representations of SU(2). In this sector our model effectively behaves as an N-flation model with 3N{sup 2} number of fields and the effective inflaton field has a super-Planckian field value. Furthermore, the fine-tunings associated with unnaturally small couplings in the chaotic type inflationary scenarios are removed. Due to the matrix nature of the inflaton fields there are 3N{sup 2}−1 extra scalar fields in the dynamics. These have the observational effects such as production of iso-curvature perturbations on cosmic microwave background. Moreover, the existence of these extra scalars provides us with a natural preheating mechanism and exit from inflation. As the effective inflaton field can traverse super-Planckian distances in the field space, the model is capable of producing a considerable amount of gravity waves that can be probed by future CMB polarization experiments such as PLANCK, QUIET and CMBPOL.
Gravitational waves and scalar perturbations from spectator fields
Biagetti, Matteo; Dimastrogiovanni, Emanuela; Peloso, Marco; Fasiello, Matteo E-mail: emanuela1573@gmail.com E-mail: peloso@physics.umn.edu
2015-04-01
The most conventional mechanism for gravitational waves (gw) production during inflation is the amplification of vacuum metric fluctuations. In this case the gw production can be uniquely related to the inflationary expansion rate H. For example, a gw detection close to the present experimental limit (tensor-to-scalar ratio r ∼ 0.1) would indicate an inflationary expansion rate close to 10{sup 14} GeV. This conclusion, however, would be invalid if the observed gw originated from a different source. We construct and study one of the possible covariant formulations of the mechanism suggested in [1], where a spectator field σ with a sound speed c{sub s} || 1 acts as a source for gw during inflation. In our formulation σ is described by a so-called P(X) Lagrangian and a non-minimal coupling to gravity. This field interacts only gravitationally with the inflaton, which has a standard action. We compute the amount of scalar and tensor density fluctuations produced by σ and find that, in our realization, r is not enhanced with respect to the standard result but it is strongly sensitive to c{sub s}, thus breaking the direct r ↔ H connection.
Massless scalar field vacuum in de Sitter spacetime
Page, Don N.; Wu, Xing E-mail: xwu5@ualberta.ca
2012-11-01
As a spacetime with compact spatial sections, de Sitter spacetime does not have a de Sitter-invariant ground state for a minimally-coupled massless scalar field that gives definite expectation values for any observables not invariant under constant shifts of the field. However, if one restricts to observables that are shift invariant, as the action is, then there is a unique vacuum state. Here we calculate the shift-invariant four-point function that is the vacuum expectation value of the product of the difference of the field values at one pair of points and of the difference of the field values at a second pair of points. We show that this vacuum expectation value obeys a cluster-decomposition property of vanishing in the limit that the one pair of points is moved arbitrarily far from the other pair. We also calculate the shift-invariant correlation of the gradient of the scalar field at two different points and show that it also obeys a cluster-decomposition property. Possible relevance to a putative de Sitter-invariant quantum state for gravity is discussed.
Vector and scalar charmonium resonances with lattice QCD
Lang, C. B.; Leskovec, Luka; Mohler, Daniel; Prelovsek, Sasa
2015-09-15
We perform an exploratory lattice QCD simulation of DD¯ scattering, aimed at determining the masses as well as the decay widths of charmonium resonances above open charm threshold. Neglecting coupling to other channels, the resulting phase shift for DD¯ scattering in p-wave yields the well-known vector resonance ψ(3770). For m_{π} = 156 MeV, the extracted resonance mass and the decay width agree with experiment within large statistical uncertainty. The scalar charmonium resonances present a puzzle, since only the ground state _{Χc0}(1P) is well understood, while there is no commonly accepted candidate for its first excitation. We simulate DD¯ scattering in s-wave in order to shed light on this puzzle. The resulting phase shift supports the existence of a yet-unobserved narrow resonance with a mass slightly below 4 GeV. A scenario with this narrow resonance and a pole at _{Χc0}(1P) agrees with the energy-dependence of our phase shift. In addition, further lattice QCD simulations and experimental efforts are needed to resolve the puzzle of the excited scalar charmonia.
Gravitational waves and scalar perturbations from spectator fields
NASA Astrophysics Data System (ADS)
Biagetti, Matteo; Dimastrogiovanni, Emanuela; Fasiello, Matteo; Peloso, Marco
2015-04-01
The most conventional mechanism for gravitational waves (gw) production during inflation is the amplification of vacuum metric fluctuations. In this case the gw production can be uniquely related to the inflationary expansion rate H. For example, a gw detection close to the present experimental limit (tensor-to-scalar ratio r ~ 0.1) would indicate an inflationary expansion rate close to 1014 GeV. This conclusion, however, would be invalid if the observed gw originated from a different source. We construct and study one of the possible covariant formulations of the mechanism suggested in [1], where a spectator field σ with a sound speed cs ll 1 acts as a source for gw during inflation. In our formulation σ is described by a so-called P(X) Lagrangian and a non-minimal coupling to gravity. This field interacts only gravitationally with the inflaton, which has a standard action. We compute the amount of scalar and tensor density fluctuations produced by σ and find that, in our realization, r is not enhanced with respect to the standard result but it is strongly sensitive to cs, thus breaking the direct r leftrightarrow H connection.
Vector and scalar charmonium resonances with lattice QCD
Lang, C. B.; Leskovec, Luka; Mohler, Daniel; ...
2015-09-15
We perform an exploratory lattice QCD simulation of DD¯ scattering, aimed at determining the masses as well as the decay widths of charmonium resonances above open charm threshold. Neglecting coupling to other channels, the resulting phase shift for DD¯ scattering in p-wave yields the well-known vector resonance ψ(3770). For mπ = 156 MeV, the extracted resonance mass and the decay width agree with experiment within large statistical uncertainty. The scalar charmonium resonances present a puzzle, since only the ground state Χc0(1P) is well understood, while there is no commonly accepted candidate for its first excitation. We simulate DD¯ scattering inmore » s-wave in order to shed light on this puzzle. The resulting phase shift supports the existence of a yet-unobserved narrow resonance with a mass slightly below 4 GeV. A scenario with this narrow resonance and a pole at Χc0(1P) agrees with the energy-dependence of our phase shift. In addition, further lattice QCD simulations and experimental efforts are needed to resolve the puzzle of the excited scalar charmonia.« less
Scalar Contribution to the Graviton Self-Energy During Inflation
Park, Sohyun
2012-01-01
We use dimensional regularization to evaluate the one loop contribution to the graviton self-energy from a massless, minimally coupled scalar on a locally de Sitter background. For noncoincident points our result agrees with the stress tensor correlators obtained recently by Perez-Nadal, Roura and Verdaguer. We absorb the ultraviolet divergences using the R^{2} and C^{2} counterterms first derived by ’t Hooft and Veltman, and we take the D = 4 limit of the finite remainder. The renormalized result is expressed as the sum of two transverse, 4th order differential operators acting on nonlocal, de Sitter invariant structure functions. In this form it can be used to quantum-correct the linearized Einstein equations so that one can study how the inflationary production of infrared scalars affects the propagation of dynamical gravitons and the force of gravity. We have seen that they have no effect on the propagation of dynamical gravitons. Our computation motivates a conjecture for the first correction to the vacuum state wave functional of gravitons. We comment as well on performing the same analysis for the more interesting contribution from inflationary gravitons, and on inferring one loop corrections to the force of gravity.
Instability of charged wormholes supported by a ghost scalar field
Gonzalez, J. A.; Guzman, F. S.; Sarbach, O.
2009-07-15
In previous work, we analyzed the linear and nonlinear stability of static, spherically symmetric wormhole solutions to Einstein's field equations coupled to a massless ghost scalar field. Our analysis revealed that all these solutions are unstable with respect to linear and nonlinear spherically symmetric perturbations and showed that the perturbation causes the wormholes to either decay to a Schwarzschild black hole or undergo a rapid expansion. Here, we consider charged generalization of the previous models by adding to the gravitational and ghost scalar field an electromagnetic one. We first derive the most general static, spherically symmetric wormholes in this theory and show that they give rise to a four-parameter family of solutions. This family can be naturally divided into subcritical, critical and supercritical solutions depending on the sign of the sum of the asymptotic masses. Then, we analyze the linear stability of these solutions. We prove that all subcritical and all critical solutions possess one exponentially in time growing mode. It follows that all subcritical and critical wormholes are linearly unstable. In the supercritical case we provide numerical evidence for the existence of a similar unstable mode.
An improved mixing model providing joint statistics of scalar and scalar dissipation
Meyer, Daniel W.; Jenny, Patrick
2008-11-15
For the calculation of nonpremixed turbulent flames with thin reaction zones the joint probability density function (PDF) of the mixture fraction and its dissipation rate plays an important role. The corresponding PDF transport equation involves a mixing model for the closure of the molecular mixing term. Here, the parameterized scalar profile (PSP) mixing model is extended to provide the required joint statistics. Model predictions are validated using direct numerical simulation (DNS) data of a passive scalar mixing in a statistically homogeneous turbulent flow. Comparisons between the DNS and the model predictions are provided, which involve different initial scalar-field lengthscales. (author)
Swarm Absolute Scalar Magnetometers first in-orbit results
NASA Astrophysics Data System (ADS)
Fratter, Isabelle; Léger, Jean-Michel; Bertrand, François; Jager, Thomas; Hulot, Gauthier; Brocco, Laura; Vigneron, Pierre
2016-04-01
The ESA Swarm mission will provide the best ever survey of the Earth's magnetic field and its temporal evolution. This will be achieved by a constellation of three identical satellites, launched together on the 22nd of November 2013. In order to observe the magnetic field thoroughly, each satellite carries two magnetometers: a Vector Field Magnetometer (VFM) coupled with a star tracker camera, to measure the direction of the magnetic field in space, and an Absolute Scalar Magnetometer (ASM), to measure its intensity. The ASM is the French contribution to the Swarm mission. This new generation instrument was designed by CEA-Leti and developed in close partnership with CNES, with scientific support from IPGP. Its operating principle is based on the atomic spectroscopy of the helium 4 metastable state. It makes use of the Zeeman's effect to transduce the magnetic field into a frequency, the signal being amplified by optical pumping. The primary role of the ASM is to provide absolute measurements of the magnetic field's strength at 1 Hz, for the in-flight calibration of the VFM. As the Swarm magnetic reference, the ASM scalar performance is crucial for the mission's success. Thanks to its innovative design, the ASM offers the best precision, resolution and absolute accuracy ever attained in space, with similar performance all along the orbit. In addition, thanks to an original architecture, the ASM implements on an experimental basis a capacity for providing simultaneously vector measurements at 1 Hz. This new feature makes it the first instrument capable of delivering both scalar and vector measurements simultaneously at the same point. Swarm offers a unique opportunity to validate the ASM vector data in orbit by comparison with the VFM's. Furthermore, the ASM can provide scalar data at a much higher sampling rate, when run in "burst" mode at 250 Hz, with a 100 Hz measurement bandwidth. An analysis of the spectral content of the magnetic field above 1 Hz becomes thus
Study of WIMP annihilations into a pair of on-shell scalar mediators
NASA Astrophysics Data System (ADS)
Jia, Lian-Bao
2016-11-01
In this article, we focus on new scalar ϕ mediated scalar/vectorial weakly interacting massive particles (WIMPs) with ϕ 's mass slightly below the WIMP mass. To explain the Galactic center 1-3 GeV gamma-ray excess, here we consider the case that a WIMP pair predominantly annihilates into an on-shell ϕ ϕ pair with ϕ mainly decaying to τ τ ¯. The masses of WIMPs are in a range about 14-22 GeV, and the annihilations of WIMPs are phase space suppressed today. In this annihilation scheme, the couplings of the ϕ -standard model (SM) particles are almost arbitrarily small, and the WIMP-nucleus spin-independent scattering can be tolerant by the present dark matter (DM) direct detections. A scalar mediator-Higgs field mixing is introduced, which is small and available. The lower limit on the couplings of the ϕ -SM particles set by the thermal equilibrium in the early Universe is derived, and this constraint is above the neutrino background for scalar DM in direct detections. The WIMPs may be detectable at the upgraded DM direct detection experiment in the next few years, and the exotic decay h →ϕ ϕ , the production of ϕ may be observable at the future high-luminosity e+e- collider.
How (not) to use the Palatini formulation of scalar-tensor gravity
Iglesias, Alberto; Kaloper, Nemanja; Park, Minjoon; Padilla, Antonio
2007-11-15
We revisit the problem of defining nonminimal gravity in the first order formalism. Specializing to scalar-tensor theories, which may be disguised as ''higher-derivative'' models with the gravitational Lagrangians that depend only on the Ricci scalar, we show how to recast these theories as Palatini-like gravities. The correct formulation utilizes the Lagrange multiplier method, which preserves the canonical structure of the theory, and yields the conventional metric scalar-tensor gravity. We explain the discrepancies between the naieve Palatini and the Lagrange multiplier approach, showing that the naieve Palatini approach really swaps the theory for another. The differences disappear only in the limit of ordinary general relativity, where an accidental redundancy ensures that the naieve Palatini approach works there. We outline the correct decoupling limits and the strong coupling regimes. As a corollary we find that the so-called ''modified source gravity'' models suffer from strong coupling problems at very low scales, and hence cannot be a realistic approximation of our universe. We also comment on a method to decouple the extra scalar using the chameleon mechanism.
PPN parameters in gravitational theory with nonminimally derivative coupling
NASA Astrophysics Data System (ADS)
Yi, Zhu; Gong, Yungui
The nonminimal coupling of the kinetic term to Einstein’s tensor helps the implementation of inflationary models due to the gravitationally enhanced friction. We calculate the parametrized post-Newtonian (PPN) parameters for the scalar-tensor theory of gravity with nonminimally derivative coupling. We find that under experimental constraint from the orbits of millisecond pulsars in our galaxy, the theory deviates from Einstein’s general relativity in the order of 10‑20, and the effect of the nonminimal coupling is negligible if we take the scalar field as dynamical dark energy. With the assumed conditions that the background scalar field is spatially homogeneous and evolves only on cosmological timescales and the contribution to stress-energy in the solar system from the background scalar field is subdominant, the scalar field is required to be massless.
Minkowski, Peter; Ochs, Wolfgang
2006-02-11
We summarize some persistent problems in scalar spectroscopy and discuss what could be learned here from charmless B-decays. Recent experimental results are discussed in comparison with theoretical expectations: a simple model based on penguin dominance leads to various symmetry relations in good agreement with recent data; a factorisation approach yields absolute predictions of rates.
Chiral scalars from an extended system
Kim, W.; Kim, J. ); Park, Y. )
1991-07-15
We propose a new action with a modified linear chiral constraint, which contains a chiral boson (a single self-dual theory) or left-right chiral bosons (free scalar field theory) according to the parameter {alpha}, and discuss the constraint algebra between the two theories.
NASA Astrophysics Data System (ADS)
Minkowski, Peter; Ochs, Wolfgang
2006-02-01
We summarize some persistent problems in scalar spectroscopy and discuss what could be learned here from charmless B-decays. Recent experimental results are discussed in comparison with theoretical expectations: a simple model based on penguin dominance leads to various symmetry relations in good agreement with recent data; a factorisation approach yields absolute predictions of rates. For more details, see [1].
Helmholtz Hodge decomposition of scalar optical fields.
Bahl, Monika; Senthilkumaran, P
2012-11-01
It is shown that the vector field decomposition method, namely, the Helmholtz Hodge decomposition, can also be applied to analyze scalar optical fields that are ubiquitously present in interference and diffraction optics. A phase gradient field that depicts the propagation and Poynting vector directions can hence be separated into solenoidal and irrotational components.
A two conserved scalar model for HCCI and PPCI engine applications
NASA Astrophysics Data System (ADS)
Hamosfakidis, Vasileios
There is a strong demand for a versatile computational model in the design of modern engines such as homogeneous charge compression ignition (HCCI) and partially premixed compression ignition (PPCI) engines. A robust model is required to describe accurately both the chemistry and turbulent mixing processes in the reacting flow. Although the existing computational fluid dynamics (CFD) codes coupled with detailed kinetics models may reproduce some realistic results, the excessive computational cost prevents them to be applicable as engineering tools. The present study aims at developing a new modeling approach that can describe the combustion process with high fidelity and computational efficiency. In this study, a two-conserved scalar approach is proposed to model HCCI and PPCI combustion. The first conserved scalar, the mixture fraction Z, is introduced to capture the inhomogeneities in the fuel-air mixture, and the second conserved scalar, the initial EGR fraction J, is introduced to capture the inhomogeneities in the fresh mixture-EGR charge. The main benefits of this approach are the reduction of dimensionality and the compactness of the domain in the conserved scalar plane, and the capability to use different resolutions for the chemistry and the fluid mechanics calculation. To solve the flow in the conserved scalar plane, two algorithms are proposed. First, the flamelet (zone) creation strategy is introduced to discretize the conserved scalar space based on its mass distribution and reactivity. The second part is the regeneration procedure which accounts for the nonlinear effect of EGR on reaction rates. Test results from the two-conserved scalar approach are compared to those obtained by direct calculation, and it is demonstrated that the regeneration process in the present approach can properly account for the nonlinear effects arising from chemical reactions, as an improvement over the representative interactive flamelet (RIF) approach. The two conserved
Inflationary predictions in scalar-tensor DBI inflation
Weller, Joel M.; Bruck, Carsten van de; Mota, David F. E-mail: c.vandebruck@sheffield.ac.uk
2012-06-01
The scalar-tensor Dirac-Born-Infeld (DBI) inflation scenario provides a simple mechanism to reduce the large values of the boost factor associated with single field models with DBI action, whilst still being able to drive 60 efolds of inflation. Using a slow-roll approach, we obtain an analytical expression for the spectral index of the perturbations and, moreover, determine numerically the regions of the parameter space of the model capable of giving rise to a power spectrum with amplitude and spectral index within the observed bounds. We find that regions that exhibit significant DBI effects throughout the inflationary period can be discarded by virtue of a blue-tilted spectral index, however, there are a number of viable cases — associated with a more red-tilted spectral index — for which the boost factor is initially suppressed by the effect of the coupling between the fields, but increases later to moderate values.
Scalar Implicatures: The Psychological Reality of Scales
de Carvalho, Alex; Reboul, Anne C.; Van der Henst, Jean-Baptiste; Cheylus, Anne; Nazir, Tatjana
2016-01-01
Scalar implicatures, the phenomena where a sentence like “The pianist played some Mozart sonatas” is interpreted, as “The pianist did not play all Mozart sonatas” have been given two different analyses. Neo-Griceans (NG) claim that this interpretation is based on lexical scales (e.g.,
Compressibility Effects on the Passive Scalar Flux Within Homogeneous Turbulence
NASA Technical Reports Server (NTRS)
Blaisdell, G. A.; Mansour, N. N.; Reynolds, W. C.
1994-01-01
Compressibility effects on turbulent transport of a passive scalar are studied within homogeneous turbulence using a kinematic decomposition of the velocity field into solenoidal and dilatational parts. It is found that the dilatational velocity does not produce a passive scalar flux, and that all of the passive scalar flux is due to the solenoidal velocity.
Unphysical scalar excursions in large-eddy simulations
NASA Astrophysics Data System (ADS)
Matheou, Georgios; Dimotakis, Paul
2016-11-01
The range of physically realizable values of passive scalar fields in any flow is bounded by their boundary values. The current investigation focuses on the local conservation of passive scalar concentration fields in turbulent flows and the ability of the large-eddy simulation (LES) method to observe the boundedness of passive scalar concentrations. In practice, as a result of numerical artifacts, this fundamental constraint is often violated with scalars exhibiting unphysical excursions. The present study characterizes passive-scalar excursions in LES of a turbulent shear flow and examines methods for error diagnosis. Typically, scalar-excursion errors are diagnosed as violations of global boundedness, i.e., detecting scalar-concentration values outside boundary/initial condition bounds. To quantify errors in mixed-fluid regions, a local scalar excursion error metric is defined with respect to the local non-diffusive limit. Analysis of such errors shows that unphysical scalar excursions in LES result from dispersive errors of the convection-term discretization where the subgrid-scale model (SGS) provides insufficient dissipation to produce a sufficiently smooth scalar field. Local scalar excursion errors are found not to be correlated with the local scalar-gradient magnitude. This work is supported by AFOSR, DOE, and Caltech.
Transport Of Passive Scalars In A Turbulent Channel Flow
NASA Technical Reports Server (NTRS)
Kim, John; Moin, Parviz
1990-01-01
Computer simulation of transport of passive scalars in turbulent channel flow described in report. Shows flow structures and statistical properties. As used here, "passive scalars" means scalar quantities like fluctuations in temperature or concentrations of contaminants that do not disturb flow appreciably. Examples include transport of heat in heat exchangers, gas turbines, and nuclear reactors and dispersal of pollution in atmosphere.
Black holes with surrounding matter in scalar-tensor theories.
Cardoso, Vitor; Carucci, Isabella P; Pani, Paolo; Sotiriou, Thomas P
2013-09-13
We uncover two mechanisms that can render Kerr black holes unstable in scalar-tensor gravity, both associated with the presence of matter in the vicinity of the black hole and the fact that this introduces an effective mass for the scalar. Our results highlight the importance of understanding the structure of spacetime in realistic, astrophysical black holes in scalar-tensor theories.
Cosmological dynamics of D-BIonic and DBI scalar field and coincidence problem of dark energy
NASA Astrophysics Data System (ADS)
Panpanich, Sirachak; Maeda, Kei-ichi; Mizuno, Shuntaro
2017-05-01
We study the cosmological dynamics of a D-BIonic and Dirac-Born-Infeld scalar field, which is coupled to matter fluid. For the exponential potential and the exponential couplings, we find a new analytic scaling solution yielding the accelerated expansion of the Universe. Since it is shown to be an attractor for some range of the coupling parameters, the density parameter of matter fluid can be the observed value, as in the coupled quintessence with a canonical scalar field. Contrary to the usual coupled quintessence, where the value of the matter coupling giving the observed density parameter is too large to satisfy the observational constraint from the cosmic microwave background, we show that the D-BIonic theory can give a similar solution with a much smaller value of matter coupling. As a result, together with the fact that the D-BIonic theory has a screening mechanism, the D-BIonic theory can solve the so-called coincidence problem as well as the dark energy problem.
NASA Astrophysics Data System (ADS)
Biekötter, Anke; Hewett, Joanne L.; Kim, Jong Soo; Krämer, Michael; Rizzo, Thomas G.; Rolbiecki, Krzysztof; Tattersall, Jamie; Weber, Torsten
2017-02-01
The elucidation of the nature of new phenomena requires a multi-pronged approach to understand the essential physics that underlies it. As an example, we study the simplified model containing a new scalar singlet accompanied by vector-like quarks. To be specific, we investigate three models with SU(2)L-doublet, vector-like quarks with Yukawa couplings to a new scalar singlet and which also couple off-diagonally to corresponding Standard Model fermions of the first or third generation through the usual Higgs boson. We demonstrate that three classes of searches can play important and complementary roles in constraining this model. In particular, we find that missing energy searches designed for sparticle production, are also very sensitive to vector-like quarks.
Search for Chameleon Scalar Fields with the Axion Dark Matter Experiment
Rybka, G.; Hotz, M.; Rosenberg, L. J; Asztalos, S. J.; Carosi, G.; Hagmann, C.; Kinion, D.; van Bibber, K.; Hoskins, J.; Martin, C.; Sikivie, P.; Tanner, D. B.; Bradley, R.; Clarke, J.
2010-07-30
Scalar fields with a 'chameleon' property, in which the effective particle mass is a function of its local environment, are common to many theories beyond the standard model and could be responsible for dark energy. If these fields couple weakly to the photon, they could be detectable through the afterglow effect of photon-chameleon-photon transitions. The ADMX experiment was used in the first chameleon search with a microwave cavity to set a new limit on scalar chameleon-photon coupling {beta}{sub {gamma}}excluding values between 2x10{sup 9} and 5x10{sup 14} for effective chameleon masses between 1.9510 and 1.9525 {mu}eV.
Floating and Sinking: The Imprint of Massive Scalars around Rotating Black Holes
NASA Astrophysics Data System (ADS)
Cardoso, Vitor; Chakrabarti, Sayan; Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo
2011-12-01
We study the coupling of massive scalar fields to matter in orbit around rotating black holes. It is generally expected that orbiting bodies will lose energy in gravitational waves, slowly inspiraling into the black hole. Instead, we show that the coupling of the field to matter leads to a surprising effect: because of superradiance, matter can hover into “floating orbits” for which the net gravitational energy loss at infinity is entirely provided by the black hole’s rotational energy. Orbiting bodies remain floating until they extract sufficient angular momentum from the black hole, or until perturbations or nonlinear effects disrupt the orbit. For slowly rotating and nonrotating black holes floating orbits are unlikely to exist, but resonances at orbital frequencies corresponding to quasibound states of the scalar field can speed up the inspiral, so that the orbiting body sinks. These effects could be a smoking gun of deviations from general relativity.
Scattering and bound states of fermions in a mixed vector–scalar smooth step potential
Castilho, W.M. Castro, A.S. de
2014-07-15
The scattering of a fermion in the background of a smooth step potential is considered with a general mixing of vector and scalar Lorentz structures with the scalar coupling stronger than or equal to the vector coupling. Charge-conjugation and chiral-conjugation transformations are discussed and it is shown that a finite set of intrinsically relativistic bound-state solutions appears as poles of the transmission amplitude. It is also shown that those bound solutions disappear asymptotically as one approaches the conditions for the realization of the so-called spin and pseudospin symmetries in a four-dimensional space–time. - Highlights: • Scattering and bound states of fermions in a kink-like potential. • No pair production despite the high localization. • No bounded solution under exact spin and pseudospin symmetries.
Connection dynamics of higher-dimensional scalar-tensor theories of gravity
NASA Astrophysics Data System (ADS)
Han, Yu; Ma, Yongge; Zhang, Xiangdong
2014-09-01
The scalar-tensor theories (STTs) of gravity in spacetime dimensions (D+1)>2 are studied. By performing Hamiltonian analysis, we obtain the geometrical dynamics of the theories from their Lagrangian. The Hamiltonian formalism indicates that the theories are naturally divided into two sectors by the coupling parameter ω. The Hamiltonian structures in both sectors are similar to the corresponding structures of four-dimensional cases. It turns out that, similar to the case of general relativity (GR), there is also a symplectic reduction from the canonical structure of so(D+1) Yang-Mills theories coupled to the scalar field to the canonical structure of the geometrical STTs. Therefore, the non-perturbative loop quantum (LQG) gravity techniques can also be applied to the STTs in D+1 dimensions based on their connection-dynamical formalism.
Floating and sinking: the imprint of massive scalars around rotating black holes.
Cardoso, Vitor; Chakrabarti, Sayan; Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo
2011-12-09
We study the coupling of massive scalar fields to matter in orbit around rotating black holes. It is generally expected that orbiting bodies will lose energy in gravitational waves, slowly inspiraling into the black hole. Instead, we show that the coupling of the field to matter leads to a surprising effect: because of superradiance, matter can hover into "floating orbits" for which the net gravitational energy loss at infinity is entirely provided by the black hole's rotational energy. Orbiting bodies remain floating until they extract sufficient angular momentum from the black hole, or until perturbations or nonlinear effects disrupt the orbit. For slowly rotating and nonrotating black holes floating orbits are unlikely to exist, but resonances at orbital frequencies corresponding to quasibound states of the scalar field can speed up the inspiral, so that the orbiting body sinks. These effects could be a smoking gun of deviations from general relativity.
Stealth dark matter: Dark scalar baryons through the Higgs portal
NASA Astrophysics Data System (ADS)
Appelquist, T.; Brower, R. C.; Buchoff, M. I.; Fleming, G. T.; Jin, X.-Y.; Kiskis, J.; Kribs, G. D.; Neil, E. T.; Osborn, J. C.; Rebbi, C.; Rinaldi, E.; Schaich, D.; Schroeder, C.; Syritsyn, S.; Vranas, P.; Weinberg, E.; Witzel, O.; Lattice Strong Dynamics LSD Collaboration
2015-10-01
We present a new model of stealth dark matter: a composite baryonic scalar of an S U (ND) strongly coupled theory with even ND≥4 . All mass scales are technically natural, and dark matter stability is automatic without imposing an additional discrete or global symmetry. Constituent fermions transform in vectorlike representations of the electroweak group that permit both electroweak-breaking and electroweak-preserving mass terms. This gives a tunable coupling of stealth dark matter to the Higgs boson independent of the dark matter mass itself. We specialize to S U (4 ), and investigate the constraints on the model from dark meson decay, electroweak precision measurements, basic collider limits, and spin-independent direct detection scattering through Higgs exchange. We exploit our earlier lattice simulations that determined the composite spectrum as well as the effective Higgs coupling of stealth dark matter in order to place bounds from direct detection, excluding constituent fermions with dominantly electroweak-breaking masses. A lower bound on the dark baryon mass mB≳300 GeV is obtained from the indirect requirement that the lightest dark meson not be observable at LEP II. We briefly survey some intriguing properties of stealth dark matter that are worthy of future study, including collider studies of dark meson production and decay; indirect detection signals from annihilation; relic abundance estimates for both symmetric and asymmetric mechanisms; and direct detection through electromagnetic polarizability, a detailed study of which will appear in a companion paper.
Exclusive central diffractive production of scalar, pseudoscalar and vector mesons
NASA Astrophysics Data System (ADS)
Lebiedowicz, P.; Nachtmann, O.; Szczurek, A.
2014-11-01
We discuss exclusive central diffractive production of scalar (ƒ0(980), ƒ0(1370), ƒ0(1500)), pseudoscalar (η, η'(958)), and vector (ρ0) mesons in proton-proton collisions. The amplitudes are formulated in terms of effective vertices required to respect standard rules of Quantum Field Theory and propagators for the exchanged pomeron and reggeons. Different pomeron-pomeron-meson tensorial (vectorial) coupling structures are possible in general. In most cases two lowest orbital angular momentum - spin couplings are necessary to describe experimental differential distributions. For the ƒ0(980) and η production the reggeon-pomeron, pomeron-reggeon, and reggeon-reggeon exchanges are included in addition, which seems to be necessary at relatively low energies. The theoretical results are compared with the WA102 experimental data, in order to determine the model parameters. For the ρ0 production the photon-pomeron and pomeron-photon exchanges are considered. The coupling parameters of tensor pomeron and/or reggeon are fixed from the H1 and ZEUS experimental data of the γp → ρ0 p reaction. We present first predictions of this mechanism for pp → ppπ+π- reaction being studied at COMPASS, RHIC, Tevatron, and LHC. Correlation in azimuthal angle between outgoing protons and distribution in pion rapidities at √s = 7 TeV are presented. We show that high-energy central production of mesons could provide crucial information on the spin structure of the soft pomeron.
Open charm-bottom scalar tetraquarks and their strong decays
NASA Astrophysics Data System (ADS)
Agaev, S. S.; Azizi, K.; Sundu, H.
2017-02-01
The mass and meson-current coupling of the diquark-antidiquark states with the quantum numbers JP=0+ and quark contents Zq=[c q ][b ¯ q ¯ ] and Zs=[c s ][b ¯ s ¯ ] are calculated using the two-point QCD sum rule approach. In calculations the quark, gluon, and mixing condensates up to eight dimensions are taken into account. The parameters of the scalar tetraquarks extracted from this analysis are employed to explore the strong vertices ZqBcπ , ZqBcη , and ZsBcη and compute the couplings gZqBcπ , gZqBcη , and gZsBcη. The strong couplings are obtained within the soft-meson approximation of the QCD light-cone sum rule method: they form, alongside with other parameters, the basis for evaluating the widths of Zq→Bcπ , Zq→Bcη , and Zs→Bcη decays. Results obtained in this work for the mass of the tetraquarks Zq and Zs are compared with available predictions presented in the literature.
Vacuum stress-energy tensor of a massive scalar field in a wormhole spacetime
Bezerra, V. B.; Bezerra de Mello, E. R.; Khusnutdinov, N. R.; Sushkov, S. V.
2010-04-15
The vacuum average value of the stress-energy tensor of a massive scalar field with nonminimal coupling {xi} to the curvature on the short-throat flat-space wormhole background is calculated. The final analysis is made numerically. It was shown that the energy-momentum tensor does not violate the null energy condition near the throat. Therefore, the vacuum polarization cannot self-consistently support the wormhole.
The galactic center excess from Z_3 scalar semi-annihilations
NASA Astrophysics Data System (ADS)
Cai, Yi; Spray, Andrew
2016-06-01
We investigate the possibility of the Z_3 scalar singlet model explaining the Fermi galactic centre excess. We find a good fit to the measured spectral excess in the region where the dark matter mass is comparable to the Higgs and the Higgs portal coupling λHS ˜ 0.04. This preferred region is consistent with constraints from vacuum stability and current dark matter experiments, and will be discovered or falsified soon by future dark matter direct detection experiment.
Gravitational wave, collider and dark matter signals from a scalar singlet electroweak baryogenesis
NASA Astrophysics Data System (ADS)
Beniwal, Ankit; Lewicki, Marek; Wells, James D.; White, Martin; Williams, Anthony G.
2017-08-01
We analyse a simple extension of the SM with just an additional scalar singlet coupled to the Higgs boson. We discuss the possible probes for electroweak baryogenesis in this model including collider searches, gravitational wave and direct dark matter detection signals. We show that a large portion of the model parameter space exists where the observation of gravitational waves would allow detection while the indirect collider searches would not.
Observed Ds(2317) and Tentative D(2100 2300) as the Charmed Cousins of the Light Scalar Nonet
NASA Astrophysics Data System (ADS)
van Beveren, Eef; Rupp, George
2003-07-01
The very recently observed D*sJ(2317)+ meson is described as a quasibound scalar cs¯ state in a unitarized meson model, owing its existence to the strong 3P0 Okubo-Zweig-Iizuka allowed coupling to the nearby S-wave DK threshold. By the same mechanism, a scalar D*0(2100 2300) resonance is predicted above the Dπ threshold. These scalars are the charmed cousins of the light scalar nonet f0(600), f0(980), K*0(800), and a0(980), reproduced by the same model. The standard cn¯ and cs¯ charmed scalars D0 and Ds0, cousins of the scalar nonet f0(1370), f0(1500), K*0(1430), and a0(1450), are predicted to lie at about 2.64 and 2.79GeV, respectively, both with a width of some 200MeV.
General solutions of integrable cosmological models with non-minimal coupling
NASA Astrophysics Data System (ADS)
Kamenshchik, A. Yu.; Pozdeeva, E. O.; Tronconi, A.; Venturi, G.; Vernov, S. Yu.
2017-03-01
We study the integrable model with minimally and non-minimally coupled scalar fields and the correspondence of their general solutions. Using the model with a minimally coupled scalar field and a the constant potential as an example we demonstrate the difference between the general solutions of the corresponding models in the Jordan and the Einstein frames.