Improvement of Wilson fermions and twisted mass lattice QCD
NASA Astrophysics Data System (ADS)
Wu, Jackson M. S.
2005-11-01
In order for Wilson fermions to be a competitive option to use in lattice QCD (LQCD) simulations, the large inherent discretization errors starting at O(a) (a being the lattice spacing) have to be removed. This can be accomplished through the Symanizk improvement program, where improvement terms have to be added to both the action and the operators of interest with coefficients appropriately chosen so that the rate of convergence to the continuum limit is quadratic in a. For this to be applicable to numerical simulations, improvement coefficients have to be determined non-perturbatively. A program for doing so has been pioneered by the Alpha collaboration. In this work, an extension of that program is made to improve all bilinear operators in QCD with two, three, and four flavours of non-degenerate quarks. With even numbers of quark flavours, an alternative approach is afforded by twisted mass LQCD (tmLQCD), where O(a) improvement in physical quantities can be achieved automatically at maximal twist. In this work, the features and utilities of tmLQCD are studied in detail in the framework of chiral perturbation theory (chiPT). By matching onto an effective chiral theory, the phase structure of tmLQCD and the properties of the mesons (pions) in the theory has been investigated. Pionic quantities easy to calculate in numerical simulations and useful for probing the symmetry breaking effects of tmLQCD have been calculated, and conditions under which automatic O(a) improvement holds at maximal twist has been carefully studied. The resulting twisted mass chiPT has also been extended to study the baryons in this work, which has not been done before. This allows one to probe tmLQCD with more quantities, and in particular, quantities that do not involve quark-disconnected diagrams and so are much easier to calculate in numerical simulations. A major part of this dissertation has already appeared in published form. Chapters 3 through 5 are based on Refs. [1--5].
Phase diagram of dynamical twisted-mass Wilson fermions at finite isospin chemical potential
NASA Astrophysics Data System (ADS)
Janssen, Oliver; Kieburg, Mario; Splittorff, K.; Verbaarschot, Jacobus J. M.; Zafeiropoulos, Savvas
2016-05-01
We consider the phase diagram of twisted-mass Wilson fermions of two-flavor QCD in the parameter space of the quark mass, the isospin chemical potential, the twist angle and the lattice spacing. This work extends earlier studies in the continuum and those at zero chemical potential. We evaluate the phase diagram as well as the spectrum of the (pseudo-)Goldstone bosons using the chiral Lagrangian for twisted-mass Wilson fermions at nonzero isospin chemical potential. The phases are obtained from a mean field analysis. At zero twist angle we find that already an infinitesimal isospin chemical potential destroys the Aoki phase. The reason is that in this phase we have massless Goldstone bosons with a nonzero isospin charge. At finite twist angle, only two different phases are present—one phase which is continuously connected to the Bose condensed phase at nonzero chemical potential, and another phase which is continuously connected to the normal phase. For either zero or maximal twist, the phase diagram is more complicated, as the saddle-point equations allow for more solutions.
Phenomenology with Wilson fermions using smeared sources
Patel, Apoorva; Daniel, D.; Kilcup, Gregory; Gupta, Rajan; Sharpe, Stephen
1992-01-01
We investigate the use of two types of non-local ("smeared") sources for quark propagators in quenched lattice QCD at beta=6.0 using Wilson fermions at k=0.154 and 0.155. We present results for the hadron mass spectrum, meson decay constants, quark masses, the chiral condensate and the quark distribution amplitude of the pion. The use of smeared sources leads to a considerable improvement over previous results. We find a disturbing discrepancy between the baryon spectra obtained using Wuppertal and wall sources. We find good signals in the ratio of correlators used to calculate the quark mass and the chiral condensate and show that the extrapolation to the chiral limit is smooth.
Wilson Fermions and Axion Electrodynamics in Optical Lattices
Bermudez, A.; Martin-Delgado, M. A.; Mazza, L.; Rizzi, M.; Goldman, N.; Lewenstein, M.
2010-11-05
We show that ultracold Fermi gases in optical superlattices can be used as quantum simulators of relativistic lattice fermions in 3+1 dimensions. By exploiting laser-assisted tunneling, we find an analogue of the so-called naive Dirac fermions, and thus provide a realization of the fermion doubling problem. Moreover, we show how to implement Wilson fermions, and discuss how their mass can be inverted by tuning the laser intensities. In this regime, our atomic gas corresponds to a phase of matter where Maxwell electrodynamics is replaced by axion electrodynamics: a 3D topological insulator.
[ital I]=2 pion scattering amplitude with Wilson fermions
Gupta, R. ); Patel, A. ); Sharpe, S.R. )
1993-07-01
We present an exploratory calculation of the [ital I]=2 [pi][pi] scattering amplitude at threshold using Wilson fermions in the quenched approximation, including all the required contractions. We find good agreement with the predictions of chiral perturbation theory even for pions of mass 560--700 MeV. Within 10% error, we do not see the onset of the bad chiral behavior expected for Wilson fermions. We also derive rigorous inequalities that apply to two-particle correlators and as a consequence show that the interaction in the antisymmetric state of two pions has to be attractive.
QCD thermodynamics with continuum extrapolated Wilson fermions. II.
NASA Astrophysics Data System (ADS)
Borsanyi, Szabolcs; Hoelbling, Christian; Toth, Balint C.; Durr, Stephan; Krieg, Stefan; Szabo, Kalman K.; Fodor, Zoltan; Katz, Sandor D.; Nogradi, Daniel; Trombitas, Norbert
2015-07-01
We continue our investigation of 2 +1 flavor QCD thermodynamics using dynamical Wilson fermions in the fixed scale approach. Two additional pion masses, approximately 440 MeV and 285 MeV, are added to our previous work at 545 MeV. The simulations were performed at 3 or 4 lattice spacings at each pion mass. The renormalized chiral condensate, strange quark number susceptibility and Polyakov loop is obtained as a function of the temperature and we observe a decrease in the light chiral pseudocritical temperature as the pion mass is lowered while the pseudocritical temperature associated with the strange quark number susceptibility or the Polyakov loop is only mildly sensitive to the pion mass. These findings are in agreement with previous continuum results obtained in the staggered formulation.
QCD at nonzero density and canonical partition functions with Wilson fermions
Alexandru, Andrei; Wenger, Urs
2011-02-01
We present a reduction method for Wilson-Dirac fermions with nonzero chemical potential which generates a dimensionally reduced fermion matrix. The size of the reduced fermion matrix is independent of the temporal lattice extent and the dependence on the chemical potential is factored out. As a consequence the reduced matrix allows a simple evaluation of the Wilson fermion determinant for any value of the chemical potential and hence the exact projection to the canonical partition functions.
Nature of the Roberge-Weiss transition in Nf=2 QCD with Wilson fermions
NASA Astrophysics Data System (ADS)
Philipsen, Owe; Pinke, Christopher
2014-05-01
At imaginary values of the quark chemical potential μ, quantum chromodynamics shows an interesting phase structure due to an exact center, or Roberge-Weiss (RW), symmetry. This can be used to constrain QCD at real μ, where the sign problem prevents Monte Carlo simulations of the lattice theory. In previous studies of this region with staggered fermions it was found that the RW endpoint, where the center transition changes from first order to a crossover, depends nontrivially on the quark mass: for high and low masses, it is a triple point connecting to the deconfinement and chiral transitions, respectively, changing to a second-order endpoint for intermediate mass values. These parameter regions are separated by tricritical points. Here we present a confirmation of these findings using Wilson fermions on Nτ=4 lattices. In addition, our results provide a successful quantitative check for a heavy quark effective lattice theory at finite density.
Nf=2 QCD chiral phase transition with Wilson fermions at zero and imaginary chemical potential
NASA Astrophysics Data System (ADS)
Philipsen, Owe; Pinke, Christopher
2016-06-01
The order of the thermal phase transition in the chiral limit of quantum chromodynamics (QCD) with two dynamical flavors of quarks is a long-standing issue and still not known in the continuum limit. Whether the transition is first or second order has important implications for the QCD phase diagram and the existence of a critical end point at finite densities. We follow a recently proposed approach to explicitly determine the region of first order chiral transitions at imaginary chemical potential, where it is large enough to be simulated, and extrapolate it to zero chemical potential with known critical exponents. Using unimproved Wilson fermions on coarse Nt=4 lattices, the first order region turns out to be so large that no extrapolation is necessary. The critical pion mass mπc≈560 MeV is by nearly a factor 10 larger than the corresponding one using staggered fermions. Our results are in line with investigations of three-flavor QCD using improved Wilson fermions and indicate that the systematic error on the two-flavor chiral transition is still of order 100%.
Calculation of K →π π decay amplitudes with improved Wilson fermion action in lattice QCD
NASA Astrophysics Data System (ADS)
Ishizuka, N.; Ishikawa, K.-I.; Ukawa, A.; Yoshié, T.
2015-10-01
We present our result for the K →π π decay amplitudes for both the Δ I =1 /2 and 3 /2 processes with the improved Wilson fermion action. Expanding on the earlier works by Bernard et al. and by Donini et al., we show that mixings with four-fermion operators with wrong chirality are absent even for the Wilson fermion action for the parity odd process in both channels due to CPS symmetry. Therefore, after subtraction of an effect from the lower dimensional operator, a calculation of the decay amplitudes is possible without complications from operators with wrong chirality, as for the case with chirally symmetric lattice actions. As a first step to verify the possibility of calculations with the Wilson fermion action, we consider the decay amplitudes at an unphysical quark mass mK˜2 mπ . Our calculations are carried out with Nf=2 +1 gauge configurations generated with the Iwasaki gauge action and nonperturbatively O (a )-improved Wilson fermion action at a =0.091 fm , mπ=280 MeV , and mK=580 MeV on a 323×64 (L a =2.9 fm ) lattice. For the quark loops in the penguin and disconnected contributions in the I =0 channel, the combined hopping parameter expansion and truncated solver method work very well for variance reduction. We obtain, for the first time with a Wilson-type fermion action, that Re A0=60 (36 )×1 0-8 GeV and Im A0=-67 (56 )×1 0-12 GeV for a matching scale q*=1 /a . The dependence on the matching scale q* for these values is weak.
QCD with two flavors of Wilson fermions: The QCD vacuum, the Aoki vacuum, and other vacua
Azcoiti, V.; Vaquero, A.; Di Carlo, G.
2009-01-01
We discuss the vacuum structure of QCD with two flavors of Wilson fermions. We derive two possible scenarios: (i) If the spectral density {rho}{sub U}({lambda},{kappa}) of the overlap Hamiltonian in a fixed background gauge field is not symmetric in {lambda}, Hermiticity is violated and Hermiticity violation effects could influence numerical determinations of the {eta} meson mass if we are not near enough to the continuum limit, where Hermiticity should be recovered; (ii) otherwise we argue that, under certain assumptions, new phases appear beside the Aoki phase, which can be characterized by a nonvanishing vacuum expectation value of i{psi}{sub u}{gamma}{sub 5}{psi}{sub u}+i{psi}{sub d}{gamma}{sub 5}{psi}{sub d}, and with vacuum states that cannot be connected with the Aoki vacua by parity-flavor symmetry transformations. Quenched numerical simulations suggest that the second scenario is more likely realized.
Vector Meson Mass Corrections at O(a{sup 2}) in PQChPT with Wilson and Ginsparg-Wilson quarks
Hovhannes R. Grigoryan; Anthony W. Thomas
2005-07-01
We derive the mixed as well as unmixed lattice heavy meson chiral Lagrangian up to order O(a{sup 2}), with Wilson and Ginsparg-Wilson fermions. We consider two flavor partially quenched theory and calculate vector meson mass corrections up to order O(a{sup 2}), including the corrections associated with the violation of O(4) rotational symmetry down to hypercubic group. The chiral extrapolation formula is then compared with that used in numerical simulations.
An anisotropic preconditioning for the Wilson fermion matrix on the lattice
Balint Joo, Robert G. Edwards, Michael J. Peardon
2010-01-01
A preconditioning for the Wilson fermion matrix on the lattice is defined which is particularly suited to the case when the temporal lattice spacing is much smaller than the spatial one. Details on the implementation of the scheme are given. The method is tested in numerical studies of QCD on anisotropic lattices.
Goeckeler, M.; Horsley, R.; Pleiter, D.; Rakow, P.E.L.; Schierholz, G.
2005-06-01
Within the framework of quenched lattice QCD and using O(a) improved Wilson fermions and nonperturbative renormalization, a high statistics computation of low moments of the unpolarized nucleon structure functions is given. Particular attention is paid to the chiral and continuum extrapolations.
Roberge-Weiss transition in Nf=2 QCD with Wilson fermions and Nτ =6
NASA Astrophysics Data System (ADS)
Czaban, Christopher; Cuteri, Francesca; Philipsen, Owe; Pinke, Christopher; Sciarra, Alessandro
2016-03-01
QCD with imaginary chemical potential is free of the sign problem and exhibits a rich phase structure constraining the phase diagram at real chemical potential. We simulate the critical end point of the Roberge-Weiss transition at imaginary chemical potential for Nf=2 QCD on Nτ=6 lattices with standard Wilson fermions. As found on coarser lattices, the Roberge-Weiss end point is a triple point connecting the deconfinement/chiral transitions in the heavy/light quark mass region and changes to a second-order end point for intermediate masses. These regimes are separated by two tricritical values of the quark mass, which we determine by extracting the critical exponent ν from a systematic finite size scaling analysis of the Binder cumulant of the imaginary part of the Polyakov loop. We are able to explain a previously observed finite size effect afflicting the scaling of the Binder cumulant in the regime of three-phase coexistence. Compared to Nτ=4 lattices, the tricritical masses are significantly shifted. Exploratory results on Nτ=8 as well as comparison with staggered simulations suggest that much finer lattices are needed before a continuum extrapolation becomes feasible.
Flavor symmetries and fermion masses
Rasin, A.
1994-04-01
We introduce several ways in which approximate flavor symmetries act on fermions and which are consistent with observed fermion masses and mixings. Flavor changing interactions mediated by new scalars appear as a consequence of approximate flavor symmetries. We discuss the experimental limits on masses of the new scalars, and show that the masses can easily be of the order of weak scale. Some implications for neutrino physics are also discussed. Such flavor changing interactions would easily erase any primordial baryon asymmetry. We show that this situation can be saved by simply adding a new charged particle with its own asymmetry. The neutrality of the Universe, together with sphaleron processes, then ensures a survival of baryon asymmetry. Several topics on flavor structure of the supersymmetric grand unified theories are discussed. First, we show that the successful predictions for the Kobayashi-Maskawa mixing matrix elements, V{sub ub}/V{sub cb} = {radical}m{sub u}/m{sub c} and V{sub td}/V{sub ts} = {radical}m{sub d}/m{sub s}, are a consequence of a large class of models, rather than specific properties of a few models. Second, we discuss how the recent observation of the decay {beta} {yields} s{gamma} constrains the parameter space when the ratio of the vacuum expectation values of the two Higgs doublets, tan{Beta}, is large. Finally, we discuss the flavor structure of proton decay. We observe a surprising enhancement of the branching ratio for the muon mode in SO(10) models compared to the same mode in the SU(5) model.
Quantum electrodynamics with complex fermion mass
McKellar, B.J.H. . School of Physics); Wu, D.D. . School of Physics Academia Sinica, Beijing, BJ . Inst. of High Energy Physics Superconducting Super Collider Lab., Dallas, TX )
1991-08-01
The quantum electrodynamics (QED) with a complex fermion mass -- that is, a fermion mass with a chiral phase -- is restudied, together with its chirally rotated version. We show how fake electric dipole moment can be obtained and how to avoid it. 10 refs.
Finite temperature QCD with two flavors of nonperturbatively improved Wilson fermions
Bornyakov, V.G.; Chernodub, M.N.; Ichie, H.; Mori, Y.; Nakamura, Y.; Suzuki, T.; Koma, Y.; Polikarpov, M.I.; Uvarov, P.V.; Veselov, A.I.; Schierholz, G.; Slavnov, A. A.; Stueben, H.
2005-06-01
We study QCD with two flavors of nonperturbatively improved Wilson fermions at finite temperature on the 16{sup 3}8 lattice. We determine the transition temperature at lattice spacing as small as a{approx}0.12 fm, and study string breaking below the finite temperature transition. We find that the static potential can be fitted by a two-state ansatz, including a string state and a two-meson state. We investigate the role of Abelian monopoles at finite temperature.
Mass-induced transition in fermion number
Aragao de Carvalho, C.; Pureza, J. M.
1989-05-15
We show that if we increase the mass of fermions in interaction with a topological (kink) scalar background in 1+1 dimensions, the fractional fermion number of the system will eventually vanish. The transition is sharp and corresponds to the disappearance of localized states from the spectrum of a Dirac operator which is exactly solvable. Possible applications to different physical systems are discussed.
NASA Astrophysics Data System (ADS)
Nagata, Keitaro; Nakamura, Atsushi
2011-06-01
The QCD phase diagram is studied in the lattice QCD simulation with the imaginary chemical potential approach. We employ a clover-improved Wilson fermion action of two flavors and a renormalization-group improved gauge action and perform the simulation at an intermediate quark mass on a 83×4 lattice. The QCD phase diagram in the imaginary chemical potential μI region is investigated by performing the simulation for more than 150 points on the (β,μI) plane. We find that the Roberge-Weiss phase transition at μI/T=π/3 is first order and its endpoint is second order, which are identified by the phase of the Polyakov loop. We determine the pseudocritical line from the susceptibility of the Polyakov loop modulus. We find a clear deviation from a linear dependence of the pseudocritical line on μI2.
Holographic Wilson Loops and Fermions in Consistent Truncations of String Theory and M-Theory
NASA Astrophysics Data System (ADS)
Faraggi, Alberto T.
In the holographic framework, a half-BPS Wilson loop in N = 4 supersymmetric Yang-Mills theory in the fundamental, symmetric or antisymmetric representation of
Resonant pairing between fermions with unequal masses
Wu, Shin-Tza; Pao, C.-H.; Yip, S.-K.
2006-12-01
We study via mean-field theory the pairing between fermions of different masses, especially at the unitary limit. At equal populations, the thermodynamic properties are identical with the equal mass case provided an appropriate rescaling is made. At unequal populations, for sufficiently light majority species, the system does not phase separate. For sufficiently heavy majority species, the phase separated normal phase have a density larger than that of the superfluid. For atoms in harmonic traps, the density profiles for unequal mass fermions can be drastically different from their equal-mass counterparts.
Fermion masses from SO(10) Hermitian matrices
Moorhouse, R. G.
2008-03-01
Masses of fermions in the SO(10) 16-plet are constructed using only the 10, 120, and 126 scalar multiplets. The mass matrices are restricted to be Hermitian and the theory is constructed to have certain assumed quark masses, charged lepton masses, and Cabibbo-Kobayashi-Maskawa (CKM) matrix in accord with data. The remaining free parameters are found by fitting to light neutrino masses and Maki-Nakagawa-Sakata (MNS) matrices result as predictions.
Fermion masses from SO(10) Hermitian matrices
NASA Astrophysics Data System (ADS)
Moorhouse, R. G.
2008-03-01
Masses of fermions in the SO(10) 16-plet are constructed using only the 10, 120, and 126¯ scalar multiplets. The mass matrices are restricted to be Hermitian and the theory is constructed to have certain assumed quark masses, charged lepton masses, and Cabibbo-Kobayashi-Maskawa (CKM) matrix in accord with data. The remaining free parameters are found by fitting to light neutrino masses and Maki-Nakagawa-Sakata (MNS) matrices result as predictions.
Negative-Parity Baryon Masses Using O(a)-improved Fermion Action
M. Gockeler; R. Horsley; D. Pleiter; P.E.L. Rakow; G. Schierholz; C.M. Maynard; D.G. Richards
2001-06-01
We present a calculation of the mass of the lowest-lying negative-parity J=1/2{sup {minus}} state in quenched QCD. Results are obtained using a non-perturbatively {Omicron}(a)-improved clover fermion action, and a splitting found between the masses of the nucleon, and its parity partner. The calculation is performed on two lattice volumes, and at three lattice spacings, enabling a study of both finite-volume and finite lattice-spacing uncertainties. A comparison is made with results obtained using the unimproved Wilson fermion action.
NASA Astrophysics Data System (ADS)
Wu, Liang-Kai; Meng, Xiang-Fei
2014-11-01
The phase structure of QCD with imaginary chemical potential provides information on the phase diagram of QCD with real chemical potential. With imaginary chemical potential i μI=i π T , previous studies show that the Roberge-Weiss (RW) transition endpoints are triple points at both large and small quark masses, and second order transition points at intermediate quark masses. The triple and second order endpoints are separated by two tricritical ones. We present simulations with Nf=2 Wilson fermions to investigate the nature of RW transition endpoints. The simulations are carried out at 8 values of the hopping parameter κ ranging from 0.020 to 0.140 on different lattice volumes. The Binder cumulant, susceptibility, and reweighted distribution of the imaginary part of the Polyakov loop are employed to determine the nature of RW transition endpoints. The simulations show that the two tricritical points are within the ranges 0.070-0.080 and 0.120-0.140, respectively.
Finite-size effects in lattice QCD with dynamical Wilson fermions
Orth, Boris; Lippert, Thomas; Schilling, Klaus
2005-07-01
As computing resources are limited, choosing the parameters for a full lattice QCD simulation always amounts to a compromise between the competing objectives of a lattice spacing as small, quarks as light, and a volume as large as possible. Aiming to push unquenched simulations with the Wilson action towards the computationally expensive regime of small quark masses we address the question whether one can possibly save computing time by extrapolating results from small lattices to the infinite volume, prior to the usual chiral and continuum extrapolations. In the present work the systematic volume dependence of simulated pion and nucleon masses is investigated and compared with a long-standing analytic formula by Luescher and with results from chiral perturbation theory (ChPT). We analyze data from hybrid Monte Carlo simulations with the standard (unimproved) two-flavor Wilson action at two different lattice spacings of a{approx_equal}0.08 and 0.13 fm. The quark masses considered correspond to approximately 85% and 50% (at the smaller a) and 36% (at the larger a) of the strange quark mass. At each quark mass we study at least three different lattices with L/a=10 to 24 sites in the spatial directions (L=0.85-2.08 fm). We find that an exponential ansatz fits the volume dependence of the pion masses well, but with a coefficient about an order of magnitude larger than the theoretical leading-order prediction. In the case of the nucleon we observe a remarkably good agreement between our lattice data and a recent formula from relativistic baryon ChPT.
Origin of fermion masses without spontaneous symmetry breaking
NASA Astrophysics Data System (ADS)
Ayyar, Venkitesh; Chandrasekharan, Shailesh
2016-04-01
Using large scale Monte Carlo calculations in a simple three dimensional lattice fermion model, we establish the existence of a second order quantum phase transition between a massless fermion phase and a massive one, both of which have the same symmetries. This shows that fermion masses can arise due to dynamics without the need for spontaneous symmetry breaking. Universality suggests that this alternate origin of the fermion mass should be of fundamental interest.
NASA Astrophysics Data System (ADS)
Brambilla, M.; Di Renzo, F.; Hasegawa, M.
2014-07-01
This is the third of a series of papers on three-loop computation of renormalization constants for Lattice QCD. Our main points of interest are results for the regularization defined by the Iwasaki gauge action and Wilson fermions. Our results for quark bilinears renormalized according to the RI'-MOM scheme can be compared to non-perturbative results. The latter are available for twisted mass QCD: being defined in the chiral limit, the renormalization constants must be the same. We also address more general problems. In particular, we discuss a few methodological issues connected to summing the perturbative series such as the effectiveness of boosted perturbation theory and the disentanglement of irrelevant and finite-volume contributions. Discussing these issues we consider not only the new results of this paper, but also those for the regularization defined by the tree-level Symanzik improved gauge action and Wilson fermions, which we presented in a recent paper of ours. We finally comment on the extent to which the techniques we put at work in the NSPT context can provide a fresher look into the lattice version of the RI'-MOM scheme.
Dynamical fermion mass generation and exciton spectra in graphene
Zhang Chunxu; Liu Guozhu; Huang Mingqiu
2011-03-15
The Coulomb interaction between massless Dirac fermions may induce dynamical chiral symmetry breaking by forming excitonic pairs in clean graphene, leading to semimetal-insulator transition. If the Dirac fermions have zero bare mass, an exact continuous chiral symmetry is dynamically broken and thus there are massless Goldstone excitons. If the Dirac fermions have a small bare mass, an approximate continuous chiral symmetry is dynamically broken and the resultant Goldstone-type excitons become massive, which is analogous to what happens in QCD. In this paper, after solving the Dyson-Schwinger gap equation in the presence of a small bare fermion mass, we found a remarkable reduction of the critical Coulomb interaction strength for excitonic pair formation and a strong enhancement of dynamical fermion mass. We then calculate the masses of Goldstone-type excitons using the Shifman-Vainshtein-Zakharov sum-rule method and operator product expansion technique developed in QCD and find that the exciton masses are much larger than bare fermion mass but smaller than the width of dynamical fermion mass gap. We also study the spin susceptibilities and estimate the masses of non-Goldstone-type excitons using the same tools.
Chiral lattice fermions with correct vacuum polarization and chiral anomaly
Pryor, C. )
1991-04-15
An action for chiral lattice fermions is proposed, which avoids the Nielsen-Ninomiya theorem by virtue of its nonlocality and nonbilinearity. The action is constructed by eliminating the extra fermion modes with a gauge-violating Majorana-type Wilson mass, which is then rendered invariant by an integration over gauge transformations. The free propagator is calculated, and the one-loop vacuum polarization is shown to be identical to that for Wilson fermions, even at nonzero lattice spacing. Also the chiral anomaly is shown to be the same as for Wilson fermions in the continuum limit.
Fermion Mass Renormalization Using Time-dependent Relativistic Quantum Mechanics
NASA Astrophysics Data System (ADS)
Kutnink, Timothy; Santrach, Amelia; Hocket, Sarah; Barcus, Scott; Petridis, Athanasios
2015-10-01
The time-dependent electromagnetically self-coupled Dirac equation is solved numerically by means of the staggered-leap-frog algorithm with refcecting boundary conditions. The stability region of the method versus the interaction strength and the spatial-grid size over time-step ratio is established. The expectation values of several dynamic operators are then evaluated as functions of time. These include the fermion and electromagnetic energies and the fermion dynamic mass, as the self-interacting spinors are no longer mass-eigenfunctions. There is a characteristic, non-exponential, oscillatory dependence leading to asymptotic constants of these expectation values. In the case of the fermion mass this amounts to renormalization. The dependence of the expectation values on the spatial-grid size is evaluated in detail. Statistical regularization is proposed to remove the grid-size dependence.
Radiative fermion masses in local D-brane models
NASA Astrophysics Data System (ADS)
Burgess, C. P.; Krippendorf, Sven; Maharana, Anshuman; Quevedo, Fernando
2011-05-01
In the context of D-brane model building, we present a realistic framework for generating fermion masses that are forbidden by global symmetries. We show that the string theoretical Large volume scenario circumvents the standard lore that fermion masses generated by loop effects are too small in generic gravity mediated scenarios. We argue that the fact that in toric singularity models, the up quark masses have always a zero eigenvalue, corresponding to the lightest generation, is due to the presence of approximate global symmetries that we explicitly identify in del Pezzo singularities. These symmetries are broken by global effects and therefore proportional to inverse powers of the volume. We estimate the generic size of radiative corrections to fermion masses in different phenomenological manifestations of the Large volume scenario. Concrete realizations in terms of flavor violating soft-terms are estimated and contrasted with current bounds on flavour changing neutral currents. Contributions from generic extra Higgs-like fields set bounds on their masses close to the GUT scale to produce realistic fermion masses.
Fermion Masses from Six Dimensions and Implications for Majorana Neutrinos
NASA Astrophysics Data System (ADS)
Frère, J.-M.; Libanov, M.; Mollet, S.; Troitsky, S.
2015-06-01
In these notes, we review the main results of our approach to fermion masses. The marge mass ratios between fermions, confronted with a unique breaking mechanism leading to vector bosons masses, led us to consider the possibility that they result from the overlap of fermion wave functions. Such overlaps vary indeed very strongly if the observed fermion families in 4 dimensions originate in a single family in 6 dimensions, through localized wave functions. This framework leads in a natural way to large mass ratios and small mixing angles between quarks. What came as a surprise is that if we impose that neutrinos behave as 2- component (“Majorana”) particles in 4D, a completely different situation is obtained for them. Instead of diagonal mass matrices, anti-diagonal ones emerge and lead to a generic prediction of combined inverted hierarchy, large mixing angles in the leptonicsector, and a suppression of neutrinoless-double beta decay placing it at the lower limit of the inverted hierarchy branch, a challenging situation for on-going and planned experiments. Our approach predicted the size of the θ13 mixing angle before its actual measurement. Possible signals at colliders are only briefly evoked.
Fermion masses and mixings from heterotic orbifold models
Park, Jae-hyeon
2005-12-02
We search for a possibility of getting realistic fermion mass ratios and mixing angles from renormalizable couplings on the Z6-I heterotic orbifold with one pair of Higgs doublets. In the quark sector, we find cases with reasonable results if we ignore the first family. In the lepton sector, we can fit the charged lepton mass ratios, the neutrino mass squared difference ratio, and the lepton mixing angles, considering all three families00.
Hadron Masses From Novel Fat-Link Fermion Actions
J. M. Zanotti; S. Bilson-Thompson; F. D. R. Bonnet; P. D. Coddington; D. B. Leinweber; A. G. Williams; J. B. Zhang; W. Melnitchouk; F. X. Lee
2001-11-01
The hadron mass spectrum is calculated in lattice QCD using a novel fat-link clover fermion action in which only the irrelevant operators in the fermion action are constructed using smeared links. The simulations are performed on a 16{sup 3} x 32 lattice with a lattice spacing of a=0.125 fm. We compare actions with n=4 and 12 smearing sweeps with a smearing fraction of 0.7. The n=4 Fat-Link Irrelevant Clover (FLIC) action provides scaling which is superior to mean-field improvement, and offers advantages over nonperturbative 0(a) improvement, including a reduced exceptional configuration problem.
O(a{sup 2}) cutoff effects in lattice Wilson fermion simulations
Dimopoulos, P.; Frezzotti, R.; Rossi, G. C.; Michael, C.; Urbach, C.
2010-02-01
In this paper we propose to interpret the large discretization artifacts affecting the neutral pion mass in maximally twisted lattice QCD simulations as O(a{sup 2}) effects, whose magnitude is roughly proportional to the modulus square of the (continuum) matrix element of the pseudoscalar density operator between vacuum and one-pion state. The numerical size of this quantity is determined by the dynamical mechanism of spontaneous chiral symmetry breaking and turns out to be substantially larger than its natural magnitude set by the value of {Lambda}{sub QCD}.
A Lagrangian for mass dimension one fermionic dark matter
NASA Astrophysics Data System (ADS)
Lee, Cheng-Yang
2016-09-01
The mass dimension one fermionic field associated with Elko satisfies the Klein-Gordon but not the Dirac equation. However, its propagator is not a Green's function of the Klein-Gordon operator. We propose an infinitesimal deformation to the propagator such that it admits an operator in which the deformed propagator is a Green's function. The field is still of mass dimension one, but the resulting Lagrangian is modified in accordance with the operator.
Infrared divergences, mass shell singularities and gauge dependence of the dynamical fermion mass
NASA Astrophysics Data System (ADS)
Das, Ashok K.; Frenkel, J.; Schubert, C.
2013-03-01
We study the behavior of the dynamical fermion mass when infrared divergences and mass shell singularities are present in a gauge theory. In particular, in the massive Schwinger model in covariant gauges we find that the pole of the fermion propagator is divergent and gauge dependent at one loop, but the leading singularities cancel in the quenched rainbow approximation. On the other hand, in physical gauges, we find that the dynamical fermion mass is finite and gauge independent at least up to one loop.
Fermion masses, flavour mixing and CP violation
Ross, G. G.
2008-11-23
The pattern of neutrino masses and mixings is characteristically different from those observed in the quark sector. I discuss how this can be elegantly explaned through a combination of an underlying family symmetry and the see-saw mechanism.
Fermion flavor mixing in models with dynamical mass generation
Benes, Petr
2010-03-15
We present a model-independent method of dealing with fermion flavor mixing in the case when instead of constant, momentum-independent mass matrices one has rather momentum-dependent self-energies. This situation is typical for strongly coupled models of dynamical fermion mass generation. We demonstrate our approach on the example of quark mixing. We show that quark self-energies with a generic momentum dependence lead to an effective Cabibbo-Kobayashi-Maskawa matrix, which turns out to be in general nonunitary, in accordance with previous claims of other authors, and to nontrivial flavor changing electromagnetic and neutral currents. We also discuss some conceptual consequences of the momentum-dependent self-energies and show that in such a case the interaction basis and the mass basis are not related by a unitary transformation. In fact, we argue that the latter is merely an effective concept, in a specified sense. While focusing mainly on the fermionic self-energies, we also study the effects of momentum-dependent radiative corrections to the gauge bosons and to the proper vertices. Our approach is based on an application of the Lehmann-Symanzik-Zimmermann reduction formula and for the special case of constant self-energies it gives the same results as the standard approach based on the diagonalization of mass matrices.
Texture of fermion mass matrices in partially unified theories
Dutta, B. |; Nandi, S. |
1996-12-31
We investigate the texture of fermion mass matrices in theories with partial unification (for example, SU(2){sub L} {times} SU(2){sub R} {times} SU(4){sub c}) at a scale of {approximately} 10{sup 12} GeV. Starting with the low energy values of the masses and the mixing angles, we find only two viable textures with at most four texture zeros. One of these corresponds to a somewhat modified Fritzsch textures. A theoretical derivation of these textures leads to new interesting relations among the masses and the mixing angles. 13 refs.
Lattice Calculation of Baryon Masses using Clover Fermion Action
D.G. Richards; M. Gockeler; P.E.L. Rakow; D. Pleiter; G. Schierholz; R. Horsley; C.M. Maynard
2002-03-01
We present a calculation of the lowest-lying baryon masses in the quenched approximation to QCD. The calculations are performed using a non-perturbatively improved clover fermion action, and a splitting found between the masses of the nucleon and its parity partner. An analysis of the mass of the first radial excitation of the nucleon finds a value considerably larger than that of the parity partner of the nucleon, and thus little evidence for the Roper resonance as a simple three-quark state.
PQChPT with Staggered Sea and Valence Ginsparg-Wilson Quarks: Vector Meson Masses
Hovhannes R. Grigoryan; Anthony W. Thomas
2005-09-16
We consider partially quenched, mixed chiral perturbation theory with staggered sea and Ginsparg-Wilson valence quarks in order to extract a chiral-continuum extrapolation expression for the vector meson mass up to order O(a{sup 2}), at one-loop level. Based on general principles, we accomplish the task without explicitly constructing a sophisticated, heavy vector meson chiral Lagrangian.
Fermion masses and mixing in general warped extra dimensional models
NASA Astrophysics Data System (ADS)
Frank, Mariana; Hamzaoui, Cherif; Pourtolami, Nima; Toharia, Manuel
2015-06-01
We analyze fermion masses and mixing in a general warped extra dimensional model, where all the Standard Model (SM) fields, including the Higgs, are allowed to propagate in the bulk. In this context, a slightly broken flavor symmetry imposed universally on all fermion fields, without distinction, can generate the full flavor structure of the SM, including quarks, charged leptons and neutrinos. For quarks and charged leptons, the exponential sensitivity of their wave functions to small flavor breaking effects yield hierarchical masses and mixing as it is usual in warped models with fermions in the bulk. In the neutrino sector, the exponential wave-function factors can be flavor blind and thus insensitive to the small flavor symmetry breaking effects, directly linking their masses and mixing angles to the flavor symmetric structure of the five-dimensional neutrino Yukawa couplings. The Higgs must be localized in the bulk and the model is more successful in generalized warped scenarios where the metric background solution is different than five-dimensional anti-de Sitter (AdS5 ). We study these features in two simple frameworks, flavor complimentarity and flavor democracy, which provide specific predictions and correlations between quarks and leptons, testable as more precise data in the neutrino sector becomes available.
Fitting fermion masses and mixings in F-theory GUTs
NASA Astrophysics Data System (ADS)
Carta, Federico; Marchesano, Fernando; Zoccarato, Gianluca
2016-03-01
We analyse the structure of Yukawa couplings in local SU(5) F-theory models with E 7 enhancement. These models are the minimal setting in which the whole flavour structure for the MSSM charged fermions is encoded in a small region of the entire compactification space. In this setup the E 7 symmetry is broken down to SU(5) by means of a 7-brane T-brane background, and further to the MSSM gauge group by means of a hypercharge flux that also implements doublet-triplet splitting. At tree-level only one family of quarks and charged leptons is massive, while the other two obtain hierarchically smaller masses when stringy non-perturbative effects are taken into account. We find that there is a unique E 7 model with such hierarchical flavour structure. The relative simplicity of the model allows to perform the computation of Yukawa couplings for a region of its parameter space wider than previous attempts, obtaining realistic fermion masses and mixings for large parameter regions. Our results are also valid for local models with E 8 enhancement, pointing towards a universal structure to describe realistic fermion masses within this framework.
Neutron electric dipole moment using Nf=2 +1 +1 twisted mass fermions
NASA Astrophysics Data System (ADS)
Alexandrou, C.; Athenodorou, A.; Constantinou, M.; Hadjiyiannakou, K.; Jansen, K.; Koutsou, G.; Ottnad, K.; Petschlies, M.
2016-04-01
We evaluate the neutron electric dipole moment |d→ N| using lattice QCD techniques. The gauge configurations analyzed are produced by the European Twisted Mass Collaboration using Nf=2 +1 +1 twisted mass fermions at one value of the lattice spacing of a ≃0.082 fm and a light quark mass corresponding to mπ≃373 MeV . Our approach to extract the neutron electric dipole moment is based on the calculation of the C P -odd electromagnetic form factor F3(Q2) for small values of the vacuum angle θ in the limit of zero Euclidean momentum transfer Q2. The limit Q2→0 is realized either by adopting a parametrization of the momentum dependence of F3(Q2) and performing a fit or by employing new position space methods, which involve the elimination of the kinematical momentum factor in front of F3(Q2). The computation in the presence of a C P -violating term requires the evaluation of the topological charge Q . This is computed by applying the cooling technique and the gradient flow with three different actions, namely the Wilson, the Symanzik tree-level improved and the Iwasaki action. We demonstrate that cooling and gradient flow give equivalent results for the neutron electric dipole moment. Our analysis yields a value of |d→ N|=0.045 (6 )(1 )θ ¯ e .fm for the ensemble with mπ=373 MeV considered.
Boaru, Sorina Georgiana; Merle, Uta; Uerlings, Ricarda; Zimmermann, Astrid; Flechtenmacher, Christa; Willheim, Claudia; Eder, Elisabeth; Ferenci, Peter; Stremmel, Wolfgang; Weiskirchen, Ralf
2015-01-01
Wilson's disease is an autosomal recessive disorder in which the liver does not properly release copper into bile, resulting in prominent copper accumulation in various tissues. Affected patients suffer from hepatic disorders and severe neurological defects. Experimental studies in mutant mice in which the copper-transporting ATPase gene (Atp7b) is disrupted revealed a drastic, time-dependent accumulation of hepatic copper that is accompanied by formation of regenerative nodes resembling cirrhosis. Therefore, these mice represent an excellent exploratory model for Wilson's disease. However, the precise time course in hepatic copper accumulation and its impact on other trace metals within the liver is yet poorly understood. We have recently established novel laser ablation inductively coupled plasma mass spectrometry protocols allowing quantitative metal imaging in human and murine liver tissue with high sensitivity, spatial resolution, specificity and quantification ability. By use of these techniques, we here aimed to comparatively analyse hepatic metal content in wild-type and Atp7b deficient mice during ageing. We demonstrate that the age-dependent accumulation of hepatic copper is strictly associated with a simultaneous increase in iron and zinc, while the intrahepatic concentration and distribution of other metals or metalloids is not affected. The same findings were obtained in well-defined human liver samples that were obtained from patients suffering from Wilson's disease. We conclude that in Wilson's disease the imbalances of hepatic copper during ageing are closely correlated with alterations in intrahepatic iron and zinc content. PMID:25704483
NASA Astrophysics Data System (ADS)
Bulava, John; Della Morte, Michele; Heitger, Jochen; Wittemeier, Christian
2016-06-01
We nonperturbatively determine the renormalization factor of the axial vector current in lattice QCD with Nf=3 flavors of Wilson-clover fermions and the tree-level Symanzik-improved gauge action. The (by now standard) renormalization condition is derived from the massive axial Ward identity, and it is imposed among Schrödinger functional states with large overlap on the lowest lying hadronic state in the pseudoscalar channel, in order to reduce kinematically enhanced cutoff effects. We explore a range of couplings relevant for simulations at lattice spacings of ≈0.09 fm and below. An interpolation formula for ZA(g02) , smoothly connecting the nonperturbative values to the 1-loop expression, is provided together with our final results.
NASA Astrophysics Data System (ADS)
Franco, E.; Maiani, L.; Martinelli, G.; Morelli, A.
1988-10-01
The K-pi and K-pi-pi elements of left-right four fermion operators in quenched lattice QCD at beta=6 are computed. The soft-pion relations derived from the chiral structure of the operators are checked. A large enhancement of matrix elements is observed and interpreted as the effect of a scalar octet pole in the pi-K channel. This observation has implications for the related calculation of weak matrix elements.
Mass anomalous dimension in SU(2) with two adjoint fermions
Bursa, Francis; Del Debbio, Luigi; Keegan, Liam; Pica, Claudio; Pickup, Thomas
2010-01-01
We study SU(2) lattice gauge theory with two flavors of Dirac fermions in the adjoint representation. We measure the running of the coupling in the Schroedinger functional scheme and find it is consistent with existing results. We discuss how systematic errors affect the evidence for an infrared fixed point (IRFP). We present the first measurement of the running of the mass in the Schroedinger functional scheme. The anomalous dimension of the chiral condensate, which is relevant for phenomenological applications, can be easily extracted from the running of the mass, under the assumption that the theory has an IRFP. At the current level of accuracy, we can estimate 0.05<{gamma}<0.56 at the IRFP.
Fermion masses in the economical 3-3-1 model
Dong, P. V.; Huong, Tr. T.; Huong, D. T.; Long, H. N.
2006-09-01
We show that, in frameworks of the economical 3-3-1 model, all fermions get masses. At the tree level, one up-quark and two down-quarks are massless, but the one-loop corrections give all quarks the consistent masses. This conclusion is in contradiction to the previous analysis in which the third scalar triplet has been introduced. This result is based on the key properties of the model: First, there are three quite different scales of vacuum expectation values: {omega}{approx}O(1) TeV, v{approx_equal}246 GeV, and u{approx}O(1) GeV. Second, there exist two types of Yukawa couplings with different strengths: the lepton-number conserving couplings h's and the lepton-number violating ones s's satisfying the condition in which the second are much smaller than the first ones: s<
Structure Group and Fermion-Mass-Term in General Nonlocality
NASA Astrophysics Data System (ADS)
Han, Lei; Wang, Hai-Jun
2016-01-01
In our previous work (Wang J. Math. Phys. 49, 033513 (2008)) two problems remain to be resolved. One is that we lack a minimal group to replace GL(4,C), the other is that the Equation of Motion (EoM) for fermion has no mass term. After careful investigation we find these two problems are linked by conformal group, a subgroup of GL(4,C). The Weyl group, a subgroup of conformal group, can bring about the running of mass, charge etc. while making it responsible for the transformation of interaction vertex. However, once concerning the generation of the mass term in EoM, we have to resort to the whole conformal group, in which the generators K μ play a crucial role in making vacuum vary from space-like (or light-cone-like)to time-like. Physically the starting points are our previous conclusion, ěc E2-ěc B2≠ 0 for massive bosons, and the two-photon process yielding e + e - pair. Finally we get to the conclusion that the mass term of strong interaction is linearly relevant to (chromo-)magnetic flux as well as angular momentum.
Some constraints on dynamical fermion mass generation in simple gauge theories
NASA Astrophysics Data System (ADS)
Hellman, William S.; Srikanth, M. L.
1980-11-01
Consistency conditions concerning dynamical fermion mass generation in simple gauge theories are examined in lowest order using the procedure of Nambu and Joma-Lasinio. The emerging constraints place strong limitations on the number of fermion multiplets and gauge groups allowed.
tmLQCD: A program suite to simulate Wilson twisted mass lattice QCD
NASA Astrophysics Data System (ADS)
Jansen, Karl; Urbach, Carsten
2009-12-01
We discuss a program suite for simulating Quantum Chromodynamics on a 4-dimensional space-time lattice. The basic Hybrid Monte Carlo algorithm is introduced and a number of algorithmic improvements are explained. We then discuss the implementations of these concepts as well as our parallelisation strategy in the actual simulation code. Finally, we provide a user guide to compile and run the program. Program summaryProgram title: tmLQCD Catalogue identifier: AEEH_v1_0 Program summary URL::http://cpc.cs.qub.ac.uk/summaries/AEEH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public Licence (GPL) No. of lines in distributed program, including test data, etc.: 122 768 No. of bytes in distributed program, including test data, etc.: 931 042 Distribution format: tar.gz Programming language: C and MPI Computer: any Operating system: any with a standard C compiler Has the code been vectorised or parallelised?: Yes. One or optionally any even number of processors may be used. Tested with up to 32 768 processors RAM: no typical values available Classification: 11.5 External routines: LAPACK [1] and LIME [2] library Nature of problem: Quantum Chromodynamics Solution method: Markov Chain Monte Carlo using the Hybrid Monte Carlo algorithm with mass preconditioning and multiple time scales [3]. Iterative solver for large systems of linear equations. Restrictions: Restricted to an even number of (not necessarily mass degenerate) quark flavours in the Wilson or Wilson twisted mass formulation of lattice QCD. Running time: Depending on the problem size, the architecture and the input parameters from a few minutes to weeks. References:http://www.netlib.org/lapack/. USQCD, http://usqcd.jlab.org/usqcd-docs/c-lime/. C. Urbach, K. Jansen, A. Shindler, U. Wenger, Comput. Phys. Commun. 174 (2006) 87, hep-lat/0506011.
NASA Astrophysics Data System (ADS)
Farchioni, F.; Jansen, K.; Montvay, I.; Scholz, E.; Scorzato, L.; Shindler, A.; Ukita, N.; Urbach, C.; Wetzorke, I.
2005-07-01
The effect of changing the lattice action for the gluon field on the recently observed [F. Farchioni, R. Frezzotti, K. Jansen, I. Montvay, G.C. Rossi, E. Scholz, A. Shindler, N. Ukita, C. Urbach, I. Wetzorke, Eur. Phys. J. C 39, 421 (2005); hep-lat/0406039] first order phase transition near zero quark mass is investigated by replacing the Wilson plaquette action by the DBW2 action. The lattice action for quarks is unchanged: it is in both cases the original Wilson action. It turns out that Wilson fermions with the DBW2 gauge action have a phase structure where the minimal pion mass and the jump of the average plaquette are decreased, when compared to Wilson fermions with Wilson plaquette action at similar values of the lattice spacing. Taking the DBW2 gauge action is advantageous also from the point of view of the computational costs of numerical simulations.
Ambiguities and subtleties in fermion mass terms in practical quantum field theory
Cheng, Yifan Kong, Otto C.W.
2014-09-15
This is a review on structure of the fermion mass terms in quantum field theory, under the perspective of its practical applications in the real physics of Nature—specifically, we discuss fermion mass structure in the Standard Model of high energy physics, which successfully describes fundamental physics up to the TeV scale. The review is meant to be pedagogical, with detailed mathematics presented beyond the level one can find any easily in the textbooks. The discussions, however, bring up important subtleties and ambiguities about the subject that may be less than well appreciated. In fact, the naive perspective of the nature and masses of fermions as one would easily drawn from the presentations of fermion fields and their equations of motion from a typical textbook on quantum field theory leads to some confusing or even wrong statements which we clarify here. In particular, we illustrate clearly that a Dirac fermion mass eigenstate is mathematically equivalent to two degenerated Majorana fermion mass eigenstates at least as long as the mass terms are concerned. There are further ambiguities and subtleties in the exact description of the eigenstate(s). Especially, for the case of neutrinos, the use of the Dirac or Majorana terminology may be mostly a matter of choice. The common usage of such terminology is rather based on the broken SU(2) charges of the related Weyl spinors hence conventional and may not be unambiguously extended to cover more complicate models. - Highlights: • Structure of fermion mass terms in practical quantum field theory is reviewed. • Important subtleties and ambiguities on the subject are clarified. • A mass eigenstate Dirac fermion and two degenerated Majorana ones are equivalent. • The conventional meaning of such terminology for neutrinos is critically discussed.
Nonperturbative results for the mass dependence of the QED fermion determinant
Fry, M. P.
2010-05-15
The fermion determinant in four-dimensional quantum electrodynamics in the presence of O(2)xO(3) symmetric background gauge fields with a nonvanishing global chiral anomaly is considered. It is shown that the leading mass singularity of the determinant's nonperturbative part is fixed by the anomaly. It is also shown that for a large class of such fields there is at least one value of the fermion mass at which the determinant's nonperturbative part reduces to its noninteracting value.
Fermion mass hierarchy and nonhierarchical mass ratios in SU(5)xU(1){sub F}
Duque, Luis F.; Gutierrez, Diego A.; Nardi, Enrico; Norena, Jorge
2008-08-01
We consider a SU(5)xU(1){sub F} grand unified theory (GUT)-flavor model in which the number of effects that determine the charged fermions Yukawa matrices is much larger than the number of observables, resulting in a hierarchical fermion spectrum with no particular regularities. The GUT-flavor symmetry is broken by flavons in the adjoint of SU(5), realizing a variant of the Froggatt-Nielsen mechanism that gives rise to a large number of effective operators. By assuming a common mass for the heavy fields and universality of the fundamental Yukawa couplings, we reduce the number of free parameters to one. The observed fermion mass spectrum is reproduced thanks to selection rules that discriminate among various contributions. Bottom-tau Yukawa unification is preserved at leading order, but there is no unification for the first two families. Interestingly, U(1){sub F} charges alone do not determine the hierarchy, and can only give upper bounds on the parametric suppression of the Yukawa operators.
Ambiguities and subtleties in fermion mass terms in practical quantum field theory
NASA Astrophysics Data System (ADS)
Cheng, Yifan; Kong, Otto C. W.
2014-09-01
This is a review on structure of the fermion mass terms in quantum field theory, under the perspective of its practical applications in the real physics of Nature-specifically, we discuss fermion mass structure in the Standard Model of high energy physics, which successfully describes fundamental physics up to the TeV scale. The review is meant to be pedagogical, with detailed mathematics presented beyond the level one can find any easily in the textbooks. The discussions, however, bring up important subtleties and ambiguities about the subject that may be less than well appreciated. In fact, the naive perspective of the nature and masses of fermions as one would easily drawn from the presentations of fermion fields and their equations of motion from a typical textbook on quantum field theory leads to some confusing or even wrong statements which we clarify here. In particular, we illustrate clearly that a Dirac fermion mass eigenstate is mathematically equivalent to two degenerated Majorana fermion mass eigenstates at least as long as the mass terms are concerned. There are further ambiguities and subtleties in the exact description of the eigenstate(s). Especially, for the case of neutrinos, the use of the Dirac or Majorana terminology may be mostly a matter of choice. The common usage of such terminology is rather based on the broken SU(2) charges of the related Weyl spinors hence conventional and may not be unambiguously extended to cover more complicate models.
Could fermion masses play a role in the stabilization of the dilaton in cosmology?
Cabo, Alejandro; Brandenberger, Robert E-mail: rhb@hep.physics.mcgill.ca
2009-02-15
We study the possibility that the Dilaton is stabilized by the contribution of fermion masses to its effective potential. We consider the Dilaton gravity action in four dimensions to which we add a mass term for a Dirac fermion. Such an action describes the interaction of the Dilaton with the fermions in the Yang-Mills sector of the coupled supergravity/super-Yang-Mills action which emerges as the low energy effective action of superstring theory after the extra spatial dimensions have been fixed. The Dilaton couples to the Fermion mass term via the usual exponential factor of this field which multiplies the non-kinetic terms of the matter Lagrangian, if we work in the Einstein frame. In the kinetic part of the Fermion action in the Einstein frame the Dilaton does not enter. Such masses can be generated in several ways: they can arise as a consequence of flux about internal spatial dimensions, they may arise as thermal fermion masses in a quasi-static phase in the early universe, and they will arise after the breaking of supersymmetry at late times. The vacuum contribution to the potential for the Dilaton is evaluated up to two loops. The result shows a minimum which could stabilize the Dilaton for reasonable ranges of parameter values.
Fermionic and bosonic mass deformations of mathcal{N} = 4 SYM and their bulk supergravity dual
NASA Astrophysics Data System (ADS)
Bena, Iosif; Graña, Mariana; Kuperstein, Stanislav; Ntokos, Praxitelis; Petrini, Michela
2016-05-01
We examine the AdS-CFT dual of arbitrary (non)supersymmetric fermionic mass deformations of mathcal{N} = 4 SYM, and investigate how the backreaction of the RR and NS-NS two-form potentials dual to the fermion masses contribute to Coulomb-branch potential of D3 branes, which we interpret as the bulk boson mass matrix. Using representation theory and supergravity arguments we show that the fermion masses completely determine the trace of this matrix, and that on the other hand its traceless components have to be turned on as non-normalizable modes. Our result resolves the tension between the belief that the AdS bulk dual of the trace of the boson mass matrix (which is not a chiral operator) is a stringy excitation with dimension of order ( g s N )1/4 and the existence of non-stringy supergravity flows describing theories where this trace is nonzero, by showing that the stringy mode does not parameterize the sum of the squares of the boson masses but rather its departure from the trace of the square of the fermion mass matrix. Hence, asymptotically-AdS flows can only describe holographically theories where the sums of the squares of the bosonic and fermionic masses are equal, which is consistent with the weakly-coupled result that only such theories can have a conformal UV fixed point.
Model for fermion masses and lepton mixing in SO(10)xA{sub 4}
Morisi, Stefano; Picariello, Marco; Torrente-Lujan, Emilio
2007-04-01
The discrete flavor symmetry A{sub 4} explains very well neutrino data at low energy, but it seems difficult to extend it to grand unified models since, in general, left-handed and right-handed fields belong to different A{sub 4} representations. Recently a model has been proposed where all the fermions equally transform under A{sub 4}. We study here a concrete SO(10) realization of such a model providing small neutrino masses through the see-saw mechanism. We fit the charged fermion masses run up to the unification scale. Some fermion masses properties come from the SO(10) symmetry while lepton mixing angles are a consequence of the A{sub 4} properties. Moreover, our model predicts the absolute value of the neutrino masses; these are in the range m{sub {nu}}{approx_equal}0.005-0.052 eV.
Vectorlike W± -boson coupling at TeV and third family fermion masses
NASA Astrophysics Data System (ADS)
Xue, She-Sheng
2016-04-01
In the third fermion family and gauge symmetry of the Standard Model, we study the quark-quark, lepton-lepton and quark-lepton four-fermion operators in an effective theory at high energies. These operators have nontrivial contributions to the Schwinger-Dyson equations for fermion self-energy functions and the W±-boson coupling vertex. As a result, the top-quark mass is generated via the spontaneous symmetry breaking of ⟨t ¯t ⟩-condensate and the W±-boson coupling becomes approximately vectorlike at TeV scale. The bottom-quark, tau-lepton and tau-neutrino masses are generated via the explicit symmetry breaking of W±-contributions and quark-lepton interactions. Their masses and Yukawa couplings are functions of the top-quark mass and Yukawa coupling. We qualitatively show the hierarchy of fermion masses and Yukawa couplings of the third fermion family. We also discuss the possible collider signatures due to the vectorlike (parity-restoration) feature of W±-boson coupling at high energies.
Origin of families of fermions and their mass matrices
Bracic, A. Borstnik; Borstnik, N. S. Mankoc
2006-10-01
,3)) weak chargeless quarks and leptons and the left handed weak charged quarks and leptons (with the right handed neutrino included). A part of the starting Lagrange density of a Weyl spinor in d=1+13 transforms right handed quarks and leptons into left handed quarks and leptons manifesting as the Yukawa couplings of the standard model. A kind of the Clifford algebra objects generates families of quarks and leptons and contributes to diagonal and off-diagonal Yukawa couplings. The approach predicts an even number of families, treating leptons and quarks equivalently (we do not study a possible appearance of Majorana fermions yet). In this paper we investigate within this approach the appearance of the Yukawa couplings within one family of quarks and leptons as well as among the families (without assuming any Higgs fields like in the standard model). We present the mass matrices for four families and investigate whether our way of generating families might explain the origin of families of quarks and leptons as well as their observed properties--the masses and the mixing matrices. Numerical results are presented in Ref. [M. Breskvar, D. Lukman, and N. S. Mankoc Borstnik, hep-ph/0606159.].
BCS to BEC evolution for mixtures of fermions with unequal masses
NASA Astrophysics Data System (ADS)
de Melo, Carlos A. R. Sa
2009-03-01
I discuss the zero and finite temperature phase diagrams of a mixture of fermions with unequal masses with and without population imbalance, which may correspond for example to mixtures of ^6Li and ^40K, ^6Li and ^87Sr, or ^40K and ^87Sr in the context of ultracold atoms. At zero temperature and when excess fermions are present, at least three phases may occur as the interaction parameter is changed from the BCS to the BEC regime. These phases correspond to normal, phase separation, or superfluid with coexistence between paired and excess fermions. The zero temperature phase diagram of population imbalance versus interaction parameter presents a remarkable asymmetry between the cases involving excess lighter or heavier fermions [1, 2], in sharp contrast with the symmetric phase diagram corresponding to the case of equal masses. At finite temperatures, the phase separation region of the phase diagram competes with superfluid regions possessing gapless elementary excitations [3] for certain ranges of the interaction parameter depending on the mass ratio. Furthermore, a phase transition may take place between two superfluid phases which are topologically distinct. The precise location of such transition is sensitive to the mass ratio between the two species of fermions. Signatures of this possible topological transition are present in the momentum distribution or structure factor, which may be measured experimentally in time-of-flight or through Bragg scattering, respectively. Lastly, throughout the evolution from BCS to BEC, I discuss the critical current and sound velocity for unequal mass systems as a function of interaction parameter and mass ratio. These quantities may also be measured via the same techniques already used in mixtures of fermions with equal masses. [1] M. Iskin, and C. A. R. Sa de Melo, Phys. Rev. Lett. 97, 100404 (2006). [2] M. Iskin and C. A. R. Sa de Melo, Phys. Rev. A 76, 013601 (2007). [3] Li Han, and C. A. R. Sa de Melo, arXiv:0812.xxxx
Aspect of Fermion Mass Hierarchy within Flavor Democracy for Yukawa Couplings
NASA Astrophysics Data System (ADS)
Higuchi, Katsuichi; Yamamoto, Katsuji
We discuss the fermion mass hierarchy by including vector-like fermions which are accommodated in E6 GUTs within flavor democracy for Yukawa couplings. In this framework, all Yukawa couplings for the standard Higgs doublet have the same strength, and all Yukawa couplings for the singlet Higgs have the same strength (New ansatz). In addition, singlet Higgs and right-handed neutrinos exist. Under this condition, the mass hierarchy mt ≫ mb ˜ mτ as well as mt ≫ mc, mu can be naturally explained.
Origin of families of fermions and their mass matrices
NASA Astrophysics Data System (ADS)
Bračič, A. Borštnik; Borštnik, N. S. Mankoč
2006-10-01
one family appear in one Weyl representation of a chosen handedness of the Lorentz group, if analyzed with respect to the standard model gauge groups, which are subgroups of the group SO(1,13): the right handed (with respect to SO(1,3)) weak chargeless quarks and leptons and the left handed weak charged quarks and leptons (with the right handed neutrino included). A part of the starting Lagrange density of a Weyl spinor in d=1+13 transforms right handed quarks and leptons into left handed quarks and leptons manifesting as the Yukawa couplings of the standard model. A kind of the Clifford algebra objects generates families of quarks and leptons and contributes to diagonal and off-diagonal Yukawa couplings. The approach predicts an even number of families, treating leptons and quarks equivalently (we do not study a possible appearance of Majorana fermions yet). In this paper we investigate within this approach the appearance of the Yukawa couplings within one family of quarks and leptons as well as among the families (without assuming any Higgs fields like in the standard model). We present the mass matrices for four families and investigate whether our way of generating families might explain the origin of families of quarks and leptons as well as their observed properties—the masses and the mixing matrices. Numerical results are presented in Ref. [M. Breskvar, D. Lukman, and N. S. Mankoč Borštnik, hep-ph/0606159.].
Mixed Meson Mass for Domain-Wall Valence and Staggered Sea Fermions
Konstantinos Orginos; Andre Walker-Loud
2007-05-01
Mixed action lattice calculations allow for an additive lattice spacing dependent mass renormalization of mesons composed of one sea and one valence quark, regardless of the type of fermion discretization methods used in the valence and sea sectors. The value of the mass renormalization depends upon the lattice actions used. This mixed meson mass shift is the most important lattice artifact to determine for mixed action calculations: because it modifies the pion mass, it plays a central role in the low energy dynamics of all hadronic correlation functions. We determine the leading order and next to leading order additive mass renormalization of valence-sea mesons for a mixed lattice action with domain-wall valence fermions and staggered sea fermions. We find that on the asqtad improved coarse MILC lattices, the leading order additive mass renormalization for the mixed mesons is Δ(am)^2 LO = 0.0409(11) which corresponds to a^2 Δ_Mix = (319 MeV)^2± (53 MeV)^2 for a = 0.125 fm. We also find significant next to leading order contributions which reduce the mass renormalization by a significant amount, such that for 0 < am_π ≤ 0.22 the mixed meson mass renormalization is well approximated by Δ(am)^2 = 0.0340 (23) or a^2δ_Mix = (290 MeV)^2 ± (76 MeV)^2. The full next-to-leading order analysis is presented in the text.
Wilson disease is a rare inherited disorder that prevents your body from getting rid of extra copper. You ... extra copper into bile, a digestive fluid. With Wilson disease, the copper builds up in your liver, and ...
Wilson disease is a rare inherited disorder that prevents your body from getting rid of extra copper. You need ... copper into bile, a digestive fluid. With Wilson disease, the copper builds up in your liver, and ...
... Share External Link Disclaimer Digestive Diseases Wilson Disease Alternate Versions Wilson Disease (444 KB) You can also ... things psychosis—when a person loses contact with reality Other Signs and Symptoms Other signs and symptoms ...
... Wilson disease. Growing knowledge of the copper transporting gene ATP7B, which in its mutated form causes WD, should lead to the design of better therapies for this disorder. NIH Patient Recruitment for Wilson ...
NASA Astrophysics Data System (ADS)
Finster, Felix; Murro, Simone; Röken, Christian
2016-07-01
We give a non-perturbative construction of the fermionic projector in Minkowski space coupled to a time-dependent external potential which is smooth and decays faster than quadratically for large times. The weak and strong mass oscillation properties are proven. We show that the integral kernel of the fermionic projector is of the Hadamard form, provided that the time integral of the spatial sup-norm of the potential satisfies a suitable bound. This gives rise to an algebraic quantum field theory of Dirac fields in an external potential with a distinguished pure quasi-free Hadamard state.
Fermionic q-deformation and its connection to thermal effective mass of a quasiparticle
NASA Astrophysics Data System (ADS)
Algin, Abdullah; Senay, Mustafa
2016-04-01
A fermionic deformation scheme is applied to a study on the low-temperature quantum statistical behavior of a quasifermion gas model with intermediate statistics. Such a model does not satisfy the Pauli exclusion principle, and its quantum statistical properties are based on a formalism of the fermionic q-calculus. For low temperatures, several thermostatistical functions of the model such as the chemical potential, the heat capacity, and the entropy are derived by means of a function of the model deformation parameter q. The effect of fermionic q-deformation on the low-temperature thermostatistical properties of the model are discussed in detail. Our results show that the present deformed (quasi)fermion model provides remarkable connections of the model deformation parameter q, first, with the thermal effective mass of a quasiparticle, and second, with the temperature parameter. Hence, it turns out that the model deformation parameter q has also a role controlling the strength of effective quasiparticle interactions in the model. Finally, we conclude that this work can be useful for understanding the details of interaction mechanism of fermions such as quasiparticle states emergent in the fractional quantum Hall effect.
Connecting Fermion Masses and Mixings to BSM Physics - Quarks
NASA Astrophysics Data System (ADS)
Goldman, Terrence; Stephenson, Gerard J., Jr.
2015-10-01
The ``democratic'' mass matrix with BSM physics assumptions has been studied without success. We invert the process and use the ``democratic'' mass matrix plus a parametrization of all possible BSM corrections to analyze the implications of the observed masses and CKM weak interaction current mixing for the BSM parameter values for the up-quarks and down-quarks. We observe that the small mixing of the so-called ``third generation'' is directly related to the large mass gap from the two lighter generations. Conversely, the relatively large value of the Cabibbo angle arises because the mass matrices in the light sub-sector (block diagonalized from the full three channel problem) are neither diagonal nor degenerate and differ significantly between the up and down cases. Alt email:t.goldman@gmail.com
Permutation symmetry and the origin of fermion mass hierarchy
Babu, K.S.; Mohapatra, R.N. )
1990-06-04
A realization of the flavor-democracy'' approach to quark and lepton masses is provided in the context of the standard model with a horizontal {ital S}{sub 3} permutation symmetry. In this model, {ital t} and {ital b} quarks pick up mass at the tree level, {ital c}, {ital s}-quark and {tau}-lepton masses arise at the one-loop level, {ital u}, {ital d}, and {mu} masses at the two-loop level, and the electron mass at the three-loop level, thus reproducing the observed hierarchial structure without fine tuning of the Yukawa couplings. The pattern of quark mixing angles also emerges naturally, with {ital V}{sub {ital u}{ital s}},{ital V}{sub {ital c}{ital b}}{approx}{ital O}({epsilon}), {ital V}{sub {ital u}{ital b}}{approx}{ital O}({epsilon}{sup 2}), where {epsilon} is a loop expansion parameter.
Fermion masses and mixing in Δ (27 ) flavor model
NASA Astrophysics Data System (ADS)
Abbas, Mohammed; Khalil, Shaaban
2015-03-01
An extension of the Standard Model (SM) based on the non-Abelian discrete group Δ (27 ) is considered. The Δ (27 ) flavor symmetry is spontaneously broken only by gauge singlet scalar fields, therefore our model is free from any flavor changing neutral current (FCNC). We show that the model accounts simultaneously for the observed quark and lepton masses and their mixing. In the quark sector, we find that the up-quark mass matrix is flavor diagonal and the Cabbibo-Kobayashi-Maskawa (CKM) mixing matrix arises from down quarks. In the lepton sector, we show that the charged lepton mass matrix is almost diagonal. We also adopt type-I seesaw mechanism to generate neutrino masses. A deviated mixing matrix from tri-bimaximal Maki-Nakagawa-Sakata (MNS), with a correlation between sin θ13 and sin2θ23 are illustrated.
The First Two Fermion Generations in Twisted Mass Lattice QCD
Jansen, Karl
2011-05-24
An account of the status of simulations from the European Twisted Mass Collaboration is given. We show selected results from computations with two mass degenerate quarks, in particular values for the low energy constants of the chiral Lagrangian, the I = 2 scattering length and the {rho}-meson resonance parameters. We also provide first results from simulations where the strange and the charm quarks are included as dynamical degree of freedom in the simulation.
Explorations of two empirical formulas for fermion masses
NASA Astrophysics Data System (ADS)
Gao, Guan-Hua; Li, Nan
2016-03-01
Two empirical formulas for the lepton and quark masses (i.e. Kartavtsev's extended Koide formulas), K_l=(sum _l m_l)/(sum _lsqrt{m_l})^2=2/3 and K_q=(sum _q m_q)/(sum _qsqrt{m_q})^2=2/3, are explored in this paper. For the lepton sector, we show that K_l=2/3, only if the uncertainty of the tauon mass is relaxed to about 2σ confidence level, and the neutrino masses can consequently be extracted with the current experimental data. For the quark sector, the extended Koide formula should only be applied to the running quark masses, and K_q is found to be rather insensitive to the renormalization effects in a large range of energy scales from GeV to 10^{12} GeV. We find that K_q is always slightly larger than 2/3, but the discrepancy is merely about 5 %.
Switching of Dirac-Fermion Mass at the Interface of Ultrathin Ferromagnet and Rashba Metal.
Honma, K; Sato, T; Souma, S; Sugawara, K; Tanaka, Y; Takahashi, T
2015-12-31
We have performed spin- and angle-resolved photoemission spectroscopy on tungsten (110) interfaced with an ultrathin iron (Fe) layer to study an influence of ferromagnetism on the Dirac-cone-like surface-interface states. We found an unexpectedly large energy gap of 340 meV at the Dirac point, and have succeeded in switching the Dirac-fermion mass by controlling the direction of Fe spins (in plane or out of plane) through tuning the thickness of the Fe overlayer or adsorbing oxygen on it. Such a manipulation of Dirac-fermion mass via the magnetic proximity effect opens a promising platform for realizing new spintronic devices utilizing a combination of exchange and Rashba-spin-orbit interactions. PMID:26765009
Neutrino masses via the Zee mechanism in the 5D split fermion model
Chang, We-Fu; Chen, I-Ting; Liou, Siao-Cing
2011-01-15
We study the original version of the Zee model, where both of the SU(2){sub L} Higgs doublets are allowed to couple to the leptons, in the framework of the split fermion model in M{sub 4}xS{sub 1}/Z{sub 2} space-time. The neutrino masses are generated through 1-loop diagrams without introducing the right-handed neutrinos. By assuming an order one anarchical complex 5D Yukawa couplings, all the effective 4D Yukawa couplings are determined by the wave function overlap between the split fermions and the bulk scalars in the fifth dimension. The predictability of the Yukawa couplings is in sharp contrast to the original Zee model in 4D where the Yukawa couplings are unknown free parameters. This setup exhibits a geometrical alternative to the lepton flavor symmetry. By giving four explicit sets of the split fermion locations, we demonstrate that it is possible to simultaneously fit the lepton masses and neutrino oscillation data by just a handful free parameters without much fine tuning. Moreover, we are able to make definite predictions for the mixing angle {theta}{sub 13}, the absolute neutrino masses, and the lepton flavor violation processes for each configuration.
Gauge U(1) dark symmetry and radiative light fermion masses
NASA Astrophysics Data System (ADS)
Kownacki, Corey; Ma, Ernest
2016-09-01
A gauge U (1) family symmetry is proposed, spanning the quarks and leptons as well as particles of the dark sector. The breaking of U (1) to Z2 divides the two sectors and generates one-loop radiative masses for the first two families of quarks and leptons, as well as all three neutrinos. We study the phenomenological implications of this new connection between family symmetry and dark matter. In particular, a scalar or pseudoscalar particle associated with this U (1) breaking may be identified with the 750 GeV diphoton resonance recently observed at the Large Hadron Collider (LHC).
Baryon Resonances from a Novel Fat-Link Fermion Action
W. Melnitchouk; S. Bilson-Thompson; F. D. R. Bonnet; P. D. Coddington; F. X. Lee; D. B. Leinweber; A. G. Williams; J. M. Zanotti; J. B. Zhang
2001-07-01
We present first results for masses of positive and negative parity excited baryons in lattice QCD using an O(a{sup 2}) improved gluon action and a Fat Link Irrelevant Clover (FLIC) fermion action in which only the irrelevant operators are constructed with fat links. The results are in agreement with earlier calculations of N* resonances using improved actions and exhibit a clear mass splitting between the nucleon and its chiral partner, even for the Wilson fermion action. The results also indicate a splitting between the lowest J{sup P}=1/2{sup -} states for the standard nucleon interpolating fields.
Axial charges of hyperons and charmed baryons using Nf=2 +1 +1 twisted mass fermions
NASA Astrophysics Data System (ADS)
Alexandrou, C.; Hadjiyiannakou, K.; Kallidonis, C.
2016-08-01
The axial couplings of the low lying baryons are evaluated using a total of five ensembles of dynamical twisted mass fermion gauge configurations. The simulations are performed using the Iwasaki gauge action and two degenerate flavors of light quarks, and a strange and a charm quark fixed to approximately their physical values at two values of the coupling constant. The lattice spacings, determined using the nucleon mass, are a =0.082 fm and a =0.065 fm , and the simulations cover a pion mass in the range of about 210 MeV to 430 MeV. We study the dependence of the axial couplings on the pion mass in the range of about 210 MeV to 430 MeV as well as the SU(3) breaking effects as we decrease the light quark mass toward its physical value.
Fermion mass hierarchies and flavour mixing from a minimal discrete symmetry
NASA Astrophysics Data System (ADS)
Feruglio, Ferruccio; Lin, Yin
2008-09-01
We construct a simple model of fermion masses based on a spontaneously broken S×Z flavour group. At the leading order, in the neutrino sector S is broken down to a ν-ν parity subgroup that enforces a maximal atmospheric mixing angle and a vanishing θ. In the charged lepton sector the ν-ν parity is maximally broken and the resulting mass matrix is nearly diagonal. The charged lepton mass hierarchy is automatically reproduced by the S symmetry breaking parameter alone. A careful analysis shows that, after the inclusion of all relevant subleading effects, the model predicts θ=π/4+O(λc2) and θ=O(λc2), λ denoting the Cabibbo angle. A simple extension to the quark sector is also illustrated, where the mass spectrum and the mixing angles are naturally reproduced, with the exception of the mixing angle between the first two generations, that requires a small accidental enhancement.
Hadron spectrum, quark masses, and decay constants from light overlap fermions on large lattices
Galletly, D.; Horsley, R.; Guertler, M.; Perlt, H.; Schiller, A.; Rakow, P. E. L.; Schierholz, G.; Streuer, T.
2007-04-01
We present results from a simulation of quenched overlap fermions with Luescher-Weisz gauge field action on lattices up to 24{sup 3}48 and for pion masses down to {approx_equal}250 MeV. Among the quantities we study are the pion, rho, and nucleon masses; the light and strange quark masses; and the pion decay constant. The renormalization of the scalar and axial vector currents is done nonperturbatively in the RI-MOM scheme. The simulations are performed at two different lattice spacings, a{approx_equal}0.1 fm and {approx_equal}0.15 fm, and on two different physical volumes, to test the scaling properties of our action and to study finite volume effects. We compare our results with the predictions of chiral perturbation theory and compute several of its low-energy constants. The pion mass is computed in sectors of fixed topology as well.
... too much copper is poisonous. Normally, the liver filters extra copper and releases it into bile. Bile ... tract. In Wilson disease, the liver does not filter copper correctly and copper builds up in the ...
The entropy-corrected holographic dark energy in Brans-Dicke cosmology with varying mass fermions
NASA Astrophysics Data System (ADS)
Farajollahi, H.; Tayebi, F.
2013-07-01
We aim in this paper to study Brans-Dicke cosmology in the presence of varying mass fermions and a self-interaction potential. Furthermore, we also probe the entropy corrected holographic dark energy (ECHDE) in the model in two non-interacting and interacting scenarios. The model parameters are constrained by using the recent SNe Ia observational data and tested against observational data of Hubble parameter. For a comparison, we also constrained and tested the cosmological parameters in ΛCDM model with the same observational data. We show that in non of the scenarios the model prediction is better than ΛCDM model.
Standard Model fermion masses and mixing angles generated in 3HDM
NASA Astrophysics Data System (ADS)
Ibarra, A.; Solaguren-Beascoa, A.
2016-05-01
We present a framework to generate the mass hierarchies and mixing angles of the fermionic sector of the Standard Model with two extra Higgs doublets and one right-handed neutrino. The masses of the first and second generation are generated by small quantum effects, explaining the hierarchy with the third generation. The model also generates a natural hierarchy between the first and second generation after the assumption that the Yukawa couplings are of rank 1. All the quark and lepton mixing matrices can also be generated by quantum effects, reproducing the hierarchies of the experimental values. The parameters generated radiatively depend logarithmically on the heavy Higgs masses. Therefore this framework can be reconciled with the stringent limits on flavour violation by postulating a sufficiently large new physics scale.
Is the Higgs mechanism of fermion mass generation a fact? A Yukawa-less first-two-generation model
NASA Astrophysics Data System (ADS)
Ghosh, Diptimoy; Gupta, Rick Sandeepan; Perez, Gilad
2016-04-01
It is now established that the major source of electroweak symmetry breaking (EWSB) is due to the observed Higgs particle. However, whether the Higgs mechanism is responsible for the generation of all the fermion masses, in particular, the fermions of the first two generations, is an open question. In this letter we present a construction where the light fermion masses are generated through a secondary, subdominant and sequestered source of EWSB. This fits well with the approximate U(2) global symmetry of the observed structure of the flavor sector. We first realise the above idea using a calculable two Higgs doublet model. We then show that the first two generation masses could come from technicolor dynamics, while the third generation fermions, as well as the electroweak gauge bosons get their masses dominantly from the Higgs mechanism. We also discuss how the small CKM mixing between the first two generations and the third generation, and soft mixing between the sequestered EWSB components arise in this setup. A typical prediction of this scenario is a significant reduction of the couplings of the observed Higgs boson to the first two generation of fermions.
STOUT SMEARING FOR TWISTED FERMIONS.
SCHOLZ,W.; JANSEN, K.; McNEILE, C.; MONTVAY, I.; RICHARDS, C.; URBACH, C.; WENGER, U.
2007-07-30
The effect of Stout smearing is investigated in numerical simulations with twisted mass Wilson quarks. The phase transition near zero quark mass is studied on 12{sup 3} x 24, 16{sup 3} x 32 and 24{sup 3} x 48 lattices at lattice spacings a {approx_equal} 0.1-0.125 fm. The phase structure of Wilson fermions with twisted mass ({mu}) has been investigated in [1,2]. As it is explained there, the observed first order phase transition limits the minimal pion mass which can be reached in simulations at a given lattice spacing: m{sub k}{sup min} {approx_equal} {theta}(a). The phase structure is schematically depicted in the left panel of Fig. I . The phase transition can be observed in simulations with twisted mass fermions, for instance, as a ''jump'' or even metastabilities in the average plaquette value as a function of the hopping parameter ({kappa}). One possibility to weaken the phase transition and therefore allow for lighter pion masses at a given lattice spacing is to use an improved gauge action like the DBW2, Iwasaki, or tree-level Symanzik (tlSym) improved gauge action instead of the simple Wilson gauge action. This has been successfully demonstrated in [3,4,5]. Here we report on our attempts to use a smeared gauge field in the fermion lattice Dirac operator to further reduce the strength of the phase transition. This is relevant in simulations with N{sub f} = 2 + 1 + 1 (u,d,s,c) quark flavors [6] where the first order phase transition becomes stronger compared to N{sub f} = 2 simulations. The main impact of the above mentioned improved gauge actions on the gauge fields occurring in simulations is to suppress short range fluctuations (''dislocations'') and the associated ''exceptionally small'' eigenvalues of the fermion matrix. The same effect is expected from smearing the gauge field links in the fermion action. The cumulated effect of the improved gauge action and smeared links should allow for a smaller pion mass at a given lattice spacing and volume. Our
Pati, Jogesh C.
2002-05-10
It is noted that one is now in possession of a set of facts, which may be viewed as the matching pieces of a puzzle; in that all of them can be resolved by just one idea--that is grand unification. These include (i) the observed family-structure, (ii) quantization of electric charge, (iii) the meeting of the three gauge couplings, (iv) neutrino oscillations [in particular the value {Delta}m{sup 2}({nu}{sub {mu}}-{nu}{sub {tau}}), suggested by SuperK], (v) the intricate pattern of the masses and mixings of the fermions, including the smallness of V{sub cb} and the largeness of {theta}{sub {nu}{sub {mu}}{nu}{sub {tau}}}{sup osc}, and (vi) the need for B-L as a generator to implement baryogenesis (via leptogenesis). All these pieces fit beautifully together within a single puzzle board framed by supersymmetric unification, based on either SO(10) or a string-unified G(224)-symmetry. The two notable pieces of the puzzle still missing, however, are proton decay and supersymmetry. A concrete proposal is presented within a predictive SO(10)/G(224)-framework that successfully describes the masses and mixings of all fermions, including the neutrinos--with eight predictions, all in agreement with observation. Within this framework, a systematic study of proton decay is carried out, which (a) pays special attention to its dependence on the fermion masses, and (b) limits the threshold corrections so as to preserve natural coupling unification. The study updates prior work by Babu, Pati and Wilczek, in the context of both MSSM and its (interesting) variant, the so-called ESSM, by allowing for improved values of the matrix elements and of the short- and long-distance renormalization effects. It shows that a conservative upper limit on the proton lifetime is about (1/3-2) x 10{sup 34} years, with {bar {nu}}K{sup +} being the dominant decay mode, and quite possibly {mu}{sup +}K{sup 0} and e{sup +}{pi}{sup 0} being prominent. This in turn strongly suggests that an improvement in the
Fermion actions extracted from lattice super Yang-Mills theories
NASA Astrophysics Data System (ADS)
Misumi, Tatsuhiro
2013-12-01
We revisit 2D = (2, 2) super Yang-Mills lattice formulation (Sugino model) to investigate its fermion action with two (Majorana) fermion flavors and exact chiral-U(1) R symmetry. We show that the reconcilement of chiral symmetry and absence of further species-doubling originates in the 4D clifford algebra structure of the action, where 2D two flavors are spuriously treated as a single 4D four-spinor with four 4D gamma matrices introduced into kinetic and Wilson terms. This fermion construction based on the higher-dimensional clifford algebra is extended to four dimensions in two manners: (1) pseudo-8D sixteen-spinor treatment of 4D four flavors with eight 8D gamma matrices, (2) pseudo-6D eight-spinor treatment of 4D two flavors with five out of six 6D gamma matrices. We obtain 4D four-species and two-species lattice fermions with unbroken subgroup of chiral symmetry and other essential properties. We discuss their relations to staggered and Wilson twisted-mass fermions. We also discuss their potential feedback to 4D super Yang-Mills lattice formulations.
Nucleon scalar and tensor charges from lattice QCD with light Wilson quarks
NASA Astrophysics Data System (ADS)
Green, J. R.; Negele, J. W.; Pochinsky, A. V.; Syritsyn, S. N.; Engelhardt, M.; Krieg, S.
2012-12-01
We present 2+1 flavor lattice QCD calculations of the nucleon scalar and tensor charges. Using the BMW clover-improved Wilson action with pion masses between 149 and 356 MeV and three source-sink separations between 0.9 and 1.4 fm, we achieve good control over excited-state contamination and extrapolation to the physical pion mass. As a consistency check, we also present results from calculations using unitary domain wall fermions with pion masses between 297 and 403 MeV, and using domain wall valence quarks and staggered sea quarks with pion masses between 293 and 597 MeV.
Overlap fermions on a 20{sup 4} lattice
K.-F. Liu; Shao-Jing Dong; Frank X. Lee; Jianbo Zhang
1994-03-01
We report results on hadron masses, fitting of the quenched chiral log, and quark masses from Neuberger's overlap fermion on a quenched 20{sup 4} lattice with lattice spacing a = 0.15 fm. We used the improved gauge action which is shown to lower the density of small eigenvalues for H{sup 2} as compared to the Wilson gauge action. This makes the calculation feasible on 64 nodes of CRAY-T3E. Also presented is the pion mass on a small volume (6{sup 3} x 12 with a Wilson gauge action at beta = 5.7). We find that for configurations that the topological charge Q {ne} 0, the pion mass tends to a constant and for configurations with trivial topology, it approaches zero possibly linearly with the quark mass.
SO(10) SUSY GUT for fermion masses: Lepton flavor and CP violation
Dermisek, R.; Harada, M.; Raby, S.
2006-08-01
We discuss the results of a global {chi}{sup 2} analysis of a simple SO(10) supersymmetric grand unified theory (SUSY GUT) with D{sub 3} family symmetry and low energy R parity. The model describes fermion mass matrices with 14 parameters and gives excellent fits to 20 observable masses and mixing angles in both quark and lepton sectors, giving six predictions. Bi-large neutrino mixing is obtained with hierarchical quark and lepton Yukawa matrices, thus avoiding the possibility of large lepton flavor violation. The model naturally predicts small 1-3 neutrino mixing, with sin{theta}{sub 13}{approx_equal}0.05-0.06. In this paper we evaluate the predictions for the lepton flavor violating processes, {mu}{yields}e{gamma}, {tau}{yields}{mu}{gamma} and {tau}{yields}e{gamma} and also the electric dipole moment of the electron (d{sub e}), the muon, and the tau, assuming universal squark and slepton masses (m{sub 16}) and a universal soft SUSY breaking A parameter (A{sub 0}) at the GUT scale. We find Br({mu}{yields}e{gamma}) is naturally below present bounds, but may be observable by MEG. Similarly, d{sub e} is below present bounds, but it is within the range of future experiments. We also give predictions for the light Higgs mass (using FeynHiggs). We find an upper bound given by m{sub h}{<=}127 GeV, with an estimated {+-}3 GeV theoretical uncertainty. Finally we present predictions for SUSY particle masses in the favored region of parameter space.
Anarchy and hierarchy: An approach to study models of fermion masses and mixings
NASA Astrophysics Data System (ADS)
Haba, Naoyuki; Murayama, Hitoshi
2001-03-01
We advocate a new approach to study models of fermion masses and mixings, namely, the anarchy proposed by Hall, Murayama, and Weiner. In this approach, we scan the O(1) coefficients randomly. We argue that this is the correct approach when the fundamental theory is sufficiently complicated. Assuming that there is no physical distinction among three generations of neutrinos, the probability distributions in Maki-Nakagawa-Sakata mixing angles can be predicted independent of the choice of the measure. This is because the mixing angles are distributed according to the Haar measure of the Lie groups whose elements diagonalize the mass matrices. The near-maximal mixings, as observed in the atmospheric neutrino data and as required in the large mixing angle solution to the solar neutrino problem, are highly probable. A small hierarchy between Δm2 for the atmospheric and the solar neutrinos is obtained very easily; the complex seesaw case gives a hierarchy of a factor of 20 as the most probable one, even though this conclusion is more measure dependent. Ue3 has to be just below the current limit from the CHOOZ experiment. The CP-violating parameter sin δ is preferred to be maximal. We present a simple SU(5)-like extension of anarchy to the charged lepton and quark sectors that works well phenomenologically.
Anarchy and hierarchy: An approach to study models of fermion masses and mixings
Haba, Naoyuki; Murayama, Hitoshi
2001-03-01
We advocate a new approach to study models of fermion masses and mixings, namely, the anarchy proposed by Hall, Murayama, and Weiner. In this approach, we scan the O(1) coefficients randomly. We argue that this is the correct approach when the fundamental theory is sufficiently complicated. Assuming that there is no physical distinction among three generations of neutrinos, the probability distributions in Maki-Nakagawa-Sakata mixing angles can be predicted independent of the choice of the measure. This is because the mixing angles are distributed according to the Haar measure of the Lie groups whose elements diagonalize the mass matrices. The near-maximal mixings, as observed in the atmospheric neutrino data and as required in the large mixing angle solution to the solar neutrino problem, are highly probable. A small hierarchy between {Delta}m{sup 2} for the atmospheric and the solar neutrinos is obtained very easily; the complex seesaw case gives a hierarchy of a factor of 20 as the most probable one, even though this conclusion is more measure dependent. U{sub e3} has to be just below the current limit from the CHOOZ experiment. The CP-violating parameter sin{delta} is preferred to be maximal. We present a simple SU(5)-like extension of anarchy to the charged lepton and quark sectors that works well phenomenologically.
NASA Astrophysics Data System (ADS)
Stone, Michael; Lopes, Pedro L. e. S.
2016-05-01
Motivated by an apparent paradox in [X.-L. Qi, E. Witten, and S.-C. Zhang, Phys. Rev. B 87, 134519 (2013), 10.1103/PhysRevB.87.134519], we use the method of gauged Wess-Zumino-Witten functionals to construct an effective action for a Weyl fermion with a Majorana mass that arises from coupling to a charged condensate. We obtain expressions for the current induced by an external gauge field and observe that the topological part of the current is only one-third of that that might have been expected from the gauge anomaly. The anomaly is not changed by the induced mass gap, however. The topological current is supplemented by a conventional supercurrent that provides the remaining two-thirds of the anomaly once the equation of motion for the Goldstone mode is satisfied. We apply our formula for the current to resolve the apparent paradox and also to the chiral magnetic effect (CME), where it predicts a reduction of the CME current to one-third of its value for a free Weyl gas in thermal equilibrium. We attribute this reduction to a partial cancellation of the CME by a chiral vortical effect current arising from the persistent rotation of the fluid induced by the external magnetic field.
K →π semileptonic form factors with Nf=2 +1 +1 twisted mass fermions
NASA Astrophysics Data System (ADS)
Carrasco, N.; Lami, P.; Lubicz, V.; Riggio, L.; Simula, S.; Tarantino, C.; ETM Collaboration
2016-06-01
We present a lattice QCD determination of the vector and scalar form factors of the semileptonic K →π ℓν decay which are relevant for the extraction of the Cabibbo-Kobayashi-Maskawa matrix element |Vu s| from experimental data. Our results are based on the gauge configurations produced by the European Twisted Mass Collaboration with Nf=2 +1 +1 dynamical fermions, which include in the sea, besides two light mass degenerate quarks, also the strange and the charm quarks. We use data simulated at three different values of the lattice spacing and with pion masses as small as 210 MeV. Our final result for the vector form factor at zero momentum transfer is f+(0 )=0.9709 (46 ) , where the uncertainty is both statistical and systematic combined in quadrature. Using the latest experimental value of f+(0 )|Vu s| from Kℓ3 decays, we obtain |Vu s|=0.2230 (11 ) , which allows us to test the unitarity constraint of the Standard Model below the permille level once the determination of |Vu d| from superallowed nuclear β decays is adopted. A slight tension with unitarity at the level of ˜2 standard deviations is observed. Moreover, we present our results for the semileptonic scalar f0(q2) and vector f+(q2) form factors in the whole range of values of the squared four-momentum transfer q2 measured in Kℓ3 decays, obtaining a very good agreement with the momentum dependence of the experimental data. We provide a set of synthetic data points representing our results for the vector and scalar form factors at the physical point for several selected values of q2.
Effective mass of the four-flux composite fermion at {nu}=1/4
Pan, W.; National High Magnetic Field Laboratory, Tallahassee, Florida 32310 ; Stormer, H. L.; Department of Physics and Department of Applied Physics, Columbia University, New York, New York 10027 ; Tsui, D. C.; Pfeiffer, L. N.; Baldwin, K. W.; West, K. W.
2000-02-15
We have measured the effective mass (m{sup *}) of the four flux composite fermion at Landau-level filling factor {nu}=1/4 ({sup 4}CF), using the activation energy gaps at the fractional quantum Hall effect states {nu}=2/7, 3/11, and 4/15 and the temperature dependence of the Shubnikov-de Haas (SdH) oscillations around {nu}=1/4. We find that the energy gaps show a linear dependence on the effective magnetic field B{sub eff} ({identical_to}B-B{sub {nu}}{sub =1/4}), and from this linear dependence we obtain m{sup *}=1.0m{sub e} and a disorder broadening {gamma}{approx}1 K for a sample of density n=0.87x10{sup 11} cm{sup -2}. The m{sup *} deduced from the temperature dependence of the SdH effect shows large differences for {nu}>1/4 and {nu}<1/4. For {nu}>1/4, m{sup *}{approx}1.0m{sub e}. It scales as {radical}(B{sub {nu}}) with the mass derived from the data around {nu}=1/2 and shows an increase in m{sup *} as {nu}{yields}1/4, resembling the findings around {nu}=1/2. For {nu}<1/4, m{sup *} increases rapidly with increasing B{sub eff} and can be described by m{sup *}/m{sub e}=-3.3+5.7B{sub eff}. This anomalous dependence on B{sub eff} is precursory to the formation of the insulating phase at still lower filling. (c) 2000 The American Physical Society.
Quark masses, chiral symmetry, and the U(1) anomaly
Creutz, M.
1996-09-17
The author discusses the mass parameters appearing in the gauge theory of the strong interactions, concentrating on the two flavor case. He shows how the effect of the CP violating parameter {theta} is simply interpreted in terms of the state of the aether via an effective potential for meson fields. For degenerate flavors he shows that a first order phase transition is expected at {theta} = {pi}. The author speculates on the implications of this structure for Wilson`s lattice fermions.
Engelhardt, Michael; Musch, Bernhard; Bhattacharya, Tanmoy; Gupta, Rajan; Hagler, Phillip; Negele, John; Pochinsky, Andrew; Shafer, Andreas; Syritsyn, Sergey; Yoon, Boram
2014-12-01
Lattice QCD calculations of transverse momentum-dependent parton distributions (TMDs) in a nucleon are performed based on a definition of TMDs via hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for the lattice calculation. Using a RBC/UKQCD domain wall fermion ensemble corresponding to a pion mass of 297MeV, on a lattice with spacing 0.084fm, selected TMD observables are accessed and compared to previous explorations at heavier pion masses on coarser lattices.
Engelhardt, M.; Musch, B.; Bhattacharya, T.; Gupta, R.; Hagler, P.; Negele, J.; Pochinsky, A.; Schafer, A.; Syritsyn, S.; Yoon, B.
2014-06-23
Here, lattice QCD calculations of transverse momentum-dependent parton distributions (TMDs) in a nucleon are performed based on a definition of TMDs via hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for the lattice calculation. Using a RBC/UKQCD domain wall fermion ensemble corresponding to a pion mass of 297 MeV, on a lattice with spacing 0.084 fm, selected TMD observables are accessed and compared to previous exploration at heavier pion masses on coarser lattices.
NASA Astrophysics Data System (ADS)
Hoelbling, Christian; Zielinski, Christian
2016-07-01
We follow up on a suggestion by Adams and construct explicit domain wall fermion operators with staggered kernels. We compare different domain wall formulations, namely the standard construction as well as Boriçi's modified and Chiu's optimal construction, utilizing both Wilson and staggered kernels. In the process, we generalize the staggered kernels to arbitrary even dimensions and introduce both truncated and optimal staggered domain wall fermions. Some numerical investigations are carried out in the (1 +1 )-dimensional setting of the Schwinger model, where we explore spectral properties of the bulk, effective and overlap Dirac operators in the free-field case, on quenched thermalized gauge configurations and on smooth topological configurations. We compare different formulations using the effective mass, deviations from normality and violations of the Ginsparg-Wilson relation as measures of chirality.
Anderson, G.W.
1992-12-01
The effect of large third generation Yukawa couplings on radiative electroweak symmetry breaking in N = 1 SUSY-GUTS is reported. Limits on tan {beta}, and on the amount of fine tuning necessary for consistent symmetry breaking in the MSSM are derived. Predictions for fermion masses and mixing angles from GUT scale textures are also discussed. The effect of large Yukawa couplings on the running of the DHR texture is used to determine limits on the top quark valid for all values of tan {beta}.
NASA Astrophysics Data System (ADS)
Aaltonen, T.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Butti, P.; Buzatu, A.; Calamba, A.; Camarda, S.; Campanelli, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Cho, K.; Chokheli, D.; Clark, A.; Clarke, C.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Cremonesi, M.; Cruz, D.; Cuevas, J.; Culbertson, R.; d'Ascenzo, N.; Datta, M.; de Barbaro, P.; Demortier, L.; Deninno, M.; D'Errico, M.; Devoto, F.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; Donati, S.; D'Onofrio, M.; Dorigo, M.; Driutti, A.; Ebina, K.; Edgar, R.; Erbacher, R.; Errede, S.; Esham, B.; Farrington, S.; Fernández Ramos, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Franklin, M.; Freeman, J. C.; Frisch, H.; Funakoshi, Y.; Galloni, C.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González López, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gramellini, E.; Grosso-Pilcher, C.; Guimaraes da Costa, J.; Hahn, S. R.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, M.; Harr, R. F.; Harrington-Taber, T.; Hatakeyama, K.; Hays, C.; Heinrich, J.; Herndon, M.; Hocker, A.; Hong, Z.; Hopkins, W.; Hou, S.; Hughes, R. E.; Husemann, U.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kambeitz, M.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. H.; Kim, S. B.; Kim, Y. J.; Kim, Y. K.; Kimura, N.; Kirby, M.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Kruse, M.; Kuhr, T.; Kurata, M.; Laasanen, A. T.; Lammel, S.; Lancaster, M.; Lannon, K.; Latino, G.; Lee, H. S.; Lee, J. S.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lipeles, E.; Lister, A.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lucà, A.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Marchese, L.; Margaroli, F.; Marino, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Moon, C. S.; Moore, R.; Morello, M. J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Nigmanov, T.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagliarone, C.; Palencia, E.; Palni, P.; Papadimitriou, V.; Parker, W.; Pauletta, G.; Paulini, M.; Paus, C.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Pranko, A.; Prokoshin, F.; Ptohos, F.; Punzi, G.; Redondo Fernández, I.; Renton, P.; Rescigno, M.; Rimondi, F.; Ristori, L.; Robson, A.; Rodriguez, T.; Rolli, S.; Ronzani, M.; Roser, R.; Rosner, J. L.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Shreyber-Tecker, I.; Simonenko, A.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Song, H.; Sorin, V.; St. Denis, R.; Stancari, M.; Stentz, D.; Strologas, J.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thomson, E.; Thukral, V.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.; Vázquez, F.; Velev, G.; Vellidis, C.; Vernieri, C.; Vidal, M.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wallny, R.; Wang, S. M.; Waters, D.
2016-06-01
A search for a Higgs boson with suppressed couplings to fermions, hf, assumed to be the neutral, lower-mass partner of the Higgs boson discovered at the Large Hadron Collider, is reported. Such a Higgs boson could exist in extensions of the standard model with two Higgs doublets, and could be produced via p p ¯→H±hf→W*hfhf→4 γ +X , where H± is a charged Higgs boson. This analysis uses all events with at least three photons in the final state from proton-antiproton collisions at a center-of-mass energy of 1.96 TeV collected by the Collider Detector at Fermilab, corresponding to an integrated luminosity of 9.2 fb-1. No evidence of a signal is observed in the data. Values of Higgs-boson masses between 10 and 100 GeV /c2 are excluded at 95% Bayesian credibility.
Electronic structure and mass enhancement of the heavy fermion superconductor UPt 3
NASA Astrophysics Data System (ADS)
Wang, C. S.; Krakauer, H.; Pickett, W. E.
1985-12-01
The self-consistent general potential linearized augmented plane wave method has been applied to study the enegy bands of the heavy fermion superconductor UPt 3 within the local density approxination. We found 2.5 f-electrons per U atom and a f-band width of ≈1.9 eV pinned at the Fermi energy EF. An enhancement factor of 19 is deduced from the density of states at EF and the experimental linear coefficient of the specific heat. Possible sources of the renormalization are discussed based on available experimental information.
Fermionic-Bosonic Couplings in a Weakly Deformed Odd-Mass Nucleus ^{93}_{41}Nb
Orce, J. N.; Holt, J. D.; Linnemann, A.; McKay, C. J.; Fransen, C.; Jolie, J.; Kuo, T.T.S.; Lesher, S. R.; McEllistrem, M. T.; Pietralla, N.; Warr, N.; Werner, V.; Yates, S. W.
2010-01-01
A comprehensive level scheme of {sup 93}Nb below 2 MeV has been constructed from information obtained with the {sup 93}Nb(n,n{prime}{gamma}) and the {sup 94}Zr(p,2n{gamma}{gamma}){sup 93}Nb reactions. Branching ratios, lifetimes, transition multipolarities, and spin assignments have been determined. From M1 and E2 strengths, fermionic-bosonic excitations of isoscalar and isovector characters have been identified from the weak couplings of the {pi}1g{sub 9/2} {circle_times} {sub 40}{sup 92}Zr and {pi}2p{sub 1/2}{sup -1} {circle_times} {sub 42}{sup 94}Mo configurations. A microscopic interpretation of such excitations is obtained from shell-model calculations, which use low-momentum effective interactions.
NASA Astrophysics Data System (ADS)
Ziino, G.
2016-03-01
The idea of a `Majorana mass' to make a chiral neutrino really neutral is here reconsidered. It is pointed out that such an approach, unlike Majorana's (non-chiral) old one, does not strictly lead, in general, to a true self-conjugate particle. This can be seen on directly using the basic definition (or fundamental representation) of charge conjugation C in Quantum Field Theory, as an operation just acting on annihilation and creation operators and just expressing particle-antiparticle interchange. It is found, indeed, that the `active' and `sterile' whole fields which can be obtained from mixing the chiral components of two mutually charge-conjugate Dirac fields are themselves `charge conjugate' to each other (rather than individually self-conjugate). These fields, taken as mass eigenfields (as in the `Majorana mass' case), are shown to describe particles carrying pseudoscalar-type charges and being neutral relative to scalar-type charges only. For them, ` CP symmetry' would be nothing but pure mirror symmetry, and C violation (already implied in their respective `active' and `sterile' behaviors) should then involve time-reversal violation as well. The new (no longer strictly chargeless) `Majorana mass' neutrino model still proves, however, neither to affect the usual expectation for a neutrinoless double β-decay, nor to prevent `active' and `sterile' neutrino varieties from generally taking different mass values. One has, on the other hand, that any fermion being just a genuine (i.e. really self-conjugate) Majorana particle cannot truly exist in two distinct—`active' and `sterile'—versions, and it can further bear only a unified mass kind which may at once be said to be either a `Majorana-like' or a `Dirac-like' mass kind.
Four-fermion production in e+e- collisions at centre-of-mass energies of 130 and 136 GeV
NASA Astrophysics Data System (ADS)
Buskulic, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Nief, J.-Y.; Odier, P.; Pietrzyk, B.; Casado, M. P.; Chmeissani, M.; Crespo, J. M.; Delfino, M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll; Juste, A.; Martinez, M.; Orteu, S.; Padilla, C.; Park, I. C.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Girone, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Alemany, R.; Bazarko, A. O.; Cattaneo, M.; Comas, P.; Coyle, P.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Harvey, J.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Lutters, G.; Martin, E. B.; Mato, P.; Minten, A.; Miquel, R.; Mir, Ll. M.; Moneta, L.; Oest, T.; Pacheco, A.; Pusztaszeri, J.-F.; Ranjard, F.; Rensing, P.; Rolandi, L.; Schlatter, D.; Schmelling, M.; Schmitt, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Venturi, A.; Wachsmuth, H.; Wagner, A.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rosnet, P.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Rensch, B.; Wäänänen, A.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Brient, J. C.; Rougé, A.; Rumpf, M.; Valassi, A.; Videau, H.; Focardi, E.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Teixeira-Dias, P.; Thompson, A. S.; Thomson, F.; Thorn, S.; Turnbull, R. M.; Becker, U.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Schmidt, M.; Sommer, J.; Stenzel, H.; Tittel, K.; Werner, S.; Wunsch, M.; Abbaneo, D.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Morawitz, P.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Stacey, A. M.; Williams, M. D.; Dissertori, G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Betteridge, A. P.; Bowdery, C. K.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Sloan, T.; Whelan, E. P.; Williams, M. I.; Galla, A.; Greene, A. M.; Hoffmann, C.; Jacobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Konstantinidis, N.; Payre, P.; Rousseau, D.; Talby, M.; Sadouki, A.; Thulasidas, M.; Tilquin, A.; Trabelsi, K.; Aleppo, M.; Ragusa, F.; Bauer, C.; Berlich, R.; Blum, W.; Büscher, V.; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; Denis, R. St; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph; Höcker, A.; Jacholkowska, A.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nikolic, I.; Park, H. J.; Schune, M.-H.; Simion, S.; Veillet, J.-J.; Videau, I.; Zerwas, D.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Fantechi, R.; Ferrante, I.; Giassi, A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Verdini, P. G.; Walsh, J.; Blair, G. A.; Bryant, L. M.; Cerutti, F.; Chambers, J. T.; Gao, Y.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Maley, P.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Koksal, A.; Letho, M.; Newton, W. M.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Putz, J.; Rothberg, J.; Wasserbaech, S.; Williams, R. W.; Armstrong, S. R.; Elmer, P.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; González, S.; Grahl, J.; Greening, T. C.; Hayes, O. J.; Hu, H.; McNamara, P. A.; Nachtman, J. M.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Walsh, A. M.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zheng, M.; Zobernig, G.; Aleph Collaboration
1996-02-01
Four-fermion events have been selected in a data sample of 5.8 pb -1 collected with the ALEPH detector at centre-of-mass energies of 130 and 136 GeV. The final states ℓ +ℓ -q overlineq, ℓ +ℓ -ℓ +ℓ -, ν overlineνq overlineq, and ν overlineνℓ +ℓ - have been examined. Five events are observed in the data, in agreement with the Standard Model predictions of 6.67±0.38 events from four-fermion processes and 0.14 -0.05+0.19 from background processes.
Hadron Properties with FLIC Fermions
James Zanotti; Wolodymyr Melnitchouk; Anthony Williams; J Zhang
2003-07-01
The Fat-Link Irrelevant Clover (FLIC) fermion action provides a new form of nonperturbative O(a)-improvement in lattice fermion actions offering near continuum results at finite lattice spacing. It provides computationally inexpensive access to the light quark mass regime of QCD where chiral nonanalytic behavior associated with Goldstone bosons is revealed. The motivation and formulation of FLIC fermions, its excellent scaling properties and its low-lying hadron mass phenomenology are presented.
A streamlined method for chiral fermions on the lattice
Bodwin, G.T. . High Energy Physics Div.); Kovacs, E.V. )
1992-11-10
We discussed the use of renormalization counterterms to restore the chiral gauge symmetry in a lattice theory of Wilson fermions. We show that a large class of counterterms can be implemented automatically by making a simple modification to the fermion determinant.
Hachmöller, Oliver; Aichler, Michaela; Schwamborn, Kristina; Lutz, Lisa; Werner, Martin; Sperling, Michael; Walch, Axel; Karst, Uwe
2016-05-01
A laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) method is developed and applied for the analysis of paraffin-embedded liver needle biopsy specimens of patients with Wilson's disease (WD), a rare autosomal recessive disorder of the copper metabolism causing various hepatic, neurological and psychiatric symptoms due to a copper accumulation in the liver and the central nervous system. The sample set includes two WD liver samples and one negative control sample. The imaging analysis was performed with a spatial resolution of 10 μm. Besides copper, iron was monitored because an elevated iron concentration in the liver is known for WD. In addition to this, both elements were quantified using an external calibration based on matrix-matched gelatine standards. The presented method offers low limits of detection of 1 and 5 μg/g for copper and iron, respectively. The high detection power and good spatial resolution allow the analysis of small needle biopsy specimen using this method. The two analyzed WD samples can be well differentiated from the control sample due to their inhomogeneous copper distribution and high copper concentrations of up to 1200 μg/g. Interestingly, the WD samples show an inverse correlation of regions with elevated copper concentrations and regions with high iron concentrations. PMID:27049132
Revisiting Wilson's Moral Components.
ERIC Educational Resources Information Center
Straughan, Roger
2000-01-01
Discusses the reasons why educational researchers and teachers never embraced the ideas of John Wilson as they related to his components of morality in moral education. States that through this examination, the strengths and weaknesses of Wilson's approach can be appraised. (CMK)
Human Sociobiology: Wilson's Fallacy.
ERIC Educational Resources Information Center
Lehrman, Nathaniel S.
1981-01-01
Presents an introduction to and a critique of E.O. Wilson's new science of sociobiology, which focuses on explaining the social behavior of species as diverse as ants, apes, and humans. Suggests that Wilson has gone beyond his data in claiming that complex human behaviors such as altruism are caused to any extent by genetic, as opposed to…
Matrix flavor brane and dual Wilson line
NASA Astrophysics Data System (ADS)
Karch, Andreas; Sun, Sichun
2014-03-01
We study a novel non-Abelian matrix configuration of probe D-branes in AdS5. This configuration gives rise to a new D-brane phenomenon related to the known "Myers effect" in the context of holography. It is dual to a deformation of the field theory by a Wilson line threaded fermion bilinear. We study the two-point function of these short Wilson lines from both the non-Abelian Dirac-Born-Infeld action and a classical string world sheet calculation and identify the region where they agree. We also study a related configuration where the non-Abelian nature of the embedding functions is enhanced by a background flux as in the Myers effect.
An explicit SU(12) family and flavor unification model with natural fermion masses and mixings
Albright, Carl H.; Feger, Robert P.; Kephart, Thomas W.
2012-07-01
We present an SU(12) unification model with three light chiral families, avoiding any external flavor symmetries. The hierarchy of quark and lepton masses and mixings is explained by higher dimensional Yukawa interactions involving Higgs bosons that contain SU(5) singlet fields with VEVs about 50 times smaller than the SU(12) unification scale. The presented model has been analyzed in detail and found to be in very good agreement with the observed quark and lepton masses and mixings.
Universal SU(2/1) and the Higgs and fermion masses
Ne`eman, Y.
1992-12-31
We review the SU(2/1) internal supersymmetry suggested by D. Fairlie and the author in 1979. The initial apparent difficulties were resolved when, with J. Thierry-Mieg, we understood that the gauging of a supergroup implies taking the usual Yang-Mills-like Principal (Double) Fibre Bundle as a ``scaffold`` and using its Grassmann algebra as parameter manifold for the supergauge. SU(2/1) Universality fixes the masses of the Higgs scalar field and the ``top`` quark around 100--200 GeV, in the same region as the W and Z masses. A ``unified``` supergauge, enclosing SU(3)colour x SU(2) x U(l), predicts a fourth lepton generation in which the neutrino mass is of the same order.
[Samuel Alexander Kinnier Wilson].
Kikuchi, Raita
2014-11-01
Samuel Alexander Kinnier Wilson is considered a pioneer in extrapyramidal system research largely due to his dissertation on progressive lenticular degeneration, later known as "Wilson's Disease". His concept of neurological symptomatology was based on the clinical observations of Pierre Marie, Joseph Babinski and John Hughlings Jackson, who he observed when he was young. To keep focusing on the nature of actual symptoms while performing medical examinations is the essence of neurological symptomatology, which in turn form the spirit of neurology. This paper will discuss major events in Wilson's later life that would explain how his basic idea for neurological symptomatology was eventually formed. PMID:25407062
On the Locality and Scaling of Overlap Fermions at Coarse Lattice Spacings
Terrence Draper; Nilmani Mathur; Jianbo Zhang; Andrei Alexandru; Ying Chen; Shao-Jing Dong; Ivan Horvath; Frank X. Lee; Keh-Fei Liu; Sonali Tamhankar
2006-11-07
The overlap fermion offers the considerable advantage of exact chiral symmetry on the lattice, but is numerically intensive. This can be made affordable while still providing large lattice volumes, by using coarse lattice spacing, given that good scaling and localization properties are established. Here, using overlap fermions on quenched Iwasaki gauge configurations, we demonstrate directly that, with appropriate choice of negative Wilson's mass, the overlap Dirac operator's range is comfortably small in lattice units for each of the lattice spacings 0.20 fm, 0.17 fm, and 0.13 fm (and scales to zero in physical units in the continuum limit). In particular, our direct results contradict recent speculation that an inverse lattice spacing of 1 GeV is too low to have satisfactory localization. Furthermore, hadronic masses (available on the two coarser lattices) scale very well.
Boucaud, Ph.; Leroy, J.-P.; Le Yaouanc, A.; Micheli, J.; Pene, O.; Rodriguez-Quintero, J.
2010-05-01
We study the quark mass function on hypercubic lattices in a large range of physical volumes and cutoffs. To avoid the very large Wilson term artefact, we exploit the relation between the quark mass function and the pseudoscalar vertex in the continuum. We extrapolate to the chiral limit. In function of the physical volume, we observe a striking discontinuity in the properties of chiral extrapolation around a physical volume L{sub c{approx_equal}}6 GeV{sup -1}=1.2 fm. It is present in the quark mass function, which collapses to zero, as well as in the pion mass and the quark condensate as directly calculated from the pseudoscalar correlator. It is strongly reminiscent of the phenomenon of chiral symmetry restoration observed by Neuberger and Narayanan at N{sub C}={infinity} around the same physical length. In the case of spontaneous symmetry breaking, we confirm that the operator product expansion of the quark mass function, involving the quark condensate, is not operative at the available momenta, even taking into account the unusually large high order corrections to the Wilson coefficient calculated by Chetyrkin and Maier; the gap remains large, around a factor 2, even at the largest momenta available to us (p{approx_equal}6 GeV).
Wilson's Disease Association International
... Connect with Wilson Disease Association Send Email Physician Contacts List of Physicians and Institutions in Your Area View Contacts Support Contacts Individuals who can offer Support and Information View ...
Beyond-mean-field boson-fermion model for odd-mass nuclei
NASA Astrophysics Data System (ADS)
Nomura, K.; Nikšić, T.; Vretenar, D.
2016-05-01
A novel method for calculating spectroscopic properties of medium-mass and heavy atomic nuclei with an odd number of nucleons is introduced, based on the framework of nuclear energy density functional theory and the particle-core coupling scheme. The deformation energy surface of the even-even core, as well as the spherical single-particle energies and occupation probabilities of the odd particle(s), are obtained in a self-consistent mean-field calculation determined by the choice of the energy density functional and pairing interaction. This method uniquely determines the parameters of the Hamiltonian of the boson core, and only the strength of the particle-core coupling is specifically adjusted to selected data for a particular nucleus. The approach is illustrated in a systematic study of low-energy excitation spectra and transition rates of axially deformed odd-mass Eu isotopes.
Aoki phases in the lattice Gross-Neveu model with flavored mass terms
Creutz, Michael; Kimura, Taro; Misumi, Tatsuhiro
2011-05-01
We investigate the parity-broken phase structure for staggered and naive fermions in the Gross-Neveu model as a toy model of QCD. We consider a generalized staggered Gross-Neveu model including two types of four-point interactions. We use generalized mass terms to split the doublers for both staggered and naive fermions. The phase boundaries derived from the gap equations show that the mass splitting of tastes results in an Aoki phase both in the staggered and naive cases. We also discuss the continuum limit of these models and explore taking the chirally symmetric limit by fine-tuning a mass parameter and two-coupling constants. This supports the idea that in lattice QCD we can derive one- or two-flavor staggered fermions by tuning the mass parameter, which are likely to be less expensive than Wilson fermions in QCD simulation.
Blum, Thomas; Doi, Takumi; Hayakawa, Masashi; Izubuchi, Taku; Yamada, Norikazu
2007-12-01
We determine the light quark masses from lattice QCD simulations incorporating the electromagnetic interaction of valence quarks, using the splittings of charged and neutral pseudoscalar meson masses as inputs. The meson masses are calculated on lattice QCD configurations generated by the RBC Collaboration for two flavors of dynamical domain-wall fermions, which are combined with QED configurations generated via quenched noncompact lattice QED. The electromagnetic part of the pion mass splitting is found to be m{sub {pi}{sup +}}-m{sub {pi}{sup 0}}=4.12(21) MeV, where only the statistical error is quoted, and similarly for the kaon, 1.443(55) MeV. Our results for the light quark masses are m{sub u}{sup MS}(2 GeV)=3.02(27)(19) MeV, m{sub d}{sup MS}(2 GeV)=5.49(20)(34) MeV, and m{sub s}{sup MS}(2 GeV)=119.5(56)(74) MeV, where the first error is statistical and the second reflects the uncertainty in our nonperturbative renormalization procedure. By averaging over {+-}e to cancel O(e) noise exactly on each combined gauge field configuration, we are able to work at physical {alpha}=1/137 and obtain very small statistical errors. In our calculation, several sources of systematic error remain, including finite volume, nonzero lattice spacing, chiral extrapolation, quenched QED, and quenched strange quark, which may be more significant than the errors quoted above. We discuss these systematic errors and how to reduce or eliminate them.
Running coupling and fermion mass in strong coupling QED3+1
NASA Astrophysics Data System (ADS)
Sauli, Vladimír
2004-06-01
A simple toy model is used in order to exhibit the technique of extracting the non-perturbative information about Green's functions in Minkowski space. The effective charge and the dynamical electron mass are calculated in strong coupling 3+1 QED by solving the coupled Dyson-Schwinger equations for electron and photon propagators. The minimal Ball-Chiu vertex was used for simplicity and we impose the Landau gauge fixing on QED action. The solutions obtained separately in Euclidean and Minkowski space were compared. The latter one was extracted with the help of spectral technique.
Stabilities of Superfluid and Density Wave States in Fermionic Mass Imbalanced Optical Lattices
NASA Astrophysics Data System (ADS)
Takemori, Nayuta; Koga, Akihisa
We study the attractive Hubbard model with different masses by means of dynamical mean-field theory with continuous-time quantum Monte Carlo simulation. Calculating the internal energy and density of states, we discuss how the interaction affects the stabilities of superfluid and density wave states at half-filling. It is found that the density wave and superfluid states are almost degenerate in a certain region. On the other hand, the genuine density wave state is stable in a wide parameter space.
Grossman, Yuval; Harnik, Roni; Perez, Gilad; Schwartz, MatthewD.; Surujon, Ze'ev
2004-07-30
The observed flavor structure of the standard model arises naturally in ''split fermion'' models which localize fermions at different places in an extra dimension. It has, until now, been assumed that the bulk masses for such fermions can be chosen to be flavor diagonal simultaneously at every point in the extra dimension, with all the flavor violation coming from the Yukawa couplings to the Higgs. We consider the more natural possibility in which the bulk masses cannot be simultaneously diagonalized, that is, that they are twisted in flavor space. We show that, in general, this does not disturb the natural generation of hierarchies in the flavor parameters. Moreover, it is conceivable that all the flavor mixing and CP-violation in the standard model may come only from twisting, with the five-dimensional Yukawa couplings taken to be universal.
Grossman, Y
2004-07-24
The observed flavor structure of the standard model arises naturally in ''split fermion'' models which localize fermions at different places in an extra dimension. It has, until now, been assumed that the bulk masses for such fermions can be chosen to be flavor diagonal simultaneously at every point in the extra dimension, with all the flavor violation coming from the Yukawa couplings to the Higgs. We consider the more natural possibility in which the bulk masses cannot be simultaneously diagonalized, that is, that they are twisted in flavor space. We show that, in general, this does not disturb the natural generation of hierarchies in the flavor parameters. Moreover, it is conceivable that all the flavor mixing and CP-violation in the standard model may come only from twisting, with the five-dimensional Yukawa couplings taken to be universal.
Kenneth Wilson and Lattice QCD
NASA Astrophysics Data System (ADS)
Ukawa, Akira
2015-09-01
We discuss the physics and computation of lattice QCD, a space-time lattice formulation of quantum chromodynamics, and Kenneth Wilson's seminal role in its development. We start with the fundamental issue of confinement of quarks in the theory of the strong interactions, and discuss how lattice QCD provides a framework for understanding this phenomenon. A conceptual issue with lattice QCD is a conflict of space-time lattice with chiral symmetry of quarks. We discuss how this problem is resolved. Since lattice QCD is a non-linear quantum dynamical system with infinite degrees of freedom, quantities which are analytically calculable are limited. On the other hand, it provides an ideal case of massively parallel numerical computations. We review the long and distinguished history of parallel-architecture supercomputers designed and built for lattice QCD. We discuss algorithmic developments, in particular the difficulties posed by the fermionic nature of quarks, and their resolution. The triad of efforts toward better understanding of physics, better algorithms, and more powerful supercomputers have produced major breakthroughs in our understanding of the strong interactions. We review the salient results of this effort in understanding the hadron spectrum, the Cabibbo-Kobayashi-Maskawa matrix elements and CP violation, and quark-gluon plasma at high temperatures. We conclude with a brief summary and a future perspective.
Wilson loops from supergravity and string theory
NASA Astrophysics Data System (ADS)
Sonnenschein, J.
2000-03-01
We present a theorem that determines the value of the Wilson loop associated with a Nambu-Goto action which generalizes the action of the AdS 5 × S 5 model. In particular, we derive sufficient conditions for confining behaviour. We then apply this theorem to various string models. We go beyond the classical string picture by incorporating quadratic quantum fluctuations. We show that the bosonic determinant of Dp -branes with 16 supersymmetries yields a Lüscher term. We confirm that the free energy associated with a BPS configuration of a single quark is free from divergences. We show that unlike for a string in flat spacetime in the case of AdS 5 × S 5 the fermionic determinant does not cancel the bosonic one. For a set-up that corresponds to a confining gauge theory the correction to the potential is attractive. We determine the form of the Wilson loop for actions that include non-trivial B µicons/Journals/Common/nu" ALT="nu" ALIGN="TOP"/> field. The issue of an exact determination of the value of the stringy Wilson loop is discussed.
NASA Technical Reports Server (NTRS)
Strecker, Kevin; Truscott, Andrew; Partridge, Guthrie; Chen, Ying-Cheng
2003-01-01
Dual evaporation gives 50 million fermions at T = 0.1 T(sub F). Demonstrated suppression of interactions by coherent superposition - applicable to atomic clocks. Looking for evidence of Cooper pairing and superfluidity.
Effective fermion masses of order gT in high-temperature gauge theories with exact chiral invariance
Weldon, H.A.
1982-11-15
It is shown that, at finite temperature, chiral invariance does not imply that fermion propagators have poles at K/sup 2/ = 0. Instead, a zero-momentum fermion has energy K/sup 0/ = M, where M/sup 2/ = g/sup 2/C(R)T/sup 2//8 and C(R) is the quadratic Casimir of the fermion representation. The dispersion relation for Knot =0 is computed and can be crudely approximated (to within 10%) by K/sup 0/roughly-equal(M/sup 2/+K /sup 2/)/sup 1/2/. Applications to high-temperature QCD, SU(2) x U(1), and grand unified theories are discussed.
Fermionic pentagons and NMHV hexagon
NASA Astrophysics Data System (ADS)
Belitsky, A. V.
2015-05-01
We analyze the near-collinear limit of the null polygonal hexagon super Wilson loop in the planar N = 4 super-Yang-Mills theory. We focus on its Grassmann components which are dual to next-to-maximal helicity-violating (NMHV) scattering amplitudes. The kinematics in question is studied within a framework of the operator product expansion that encodes propagation of excitations on the background of the color flux tube stretched between the sides of Wilson loop contour. While their dispersion relation is known to all orders in 't Hooft coupling from previous studies, we find their form factor couplings to the Wilson loop. This is done making use of a particular tessellation of the loop where pentagon transitions play a fundamental role. Being interested in NMHV amplitudes, the corresponding building blocks carry a nontrivial charge under the SU(4) R-symmetry group. Restricting the current consideration to twist-two accuracy, we analyze two-particle contributions with a fermion as one of the constituents in the pair. We demonstrate that these nonsinglet pentagons obey bootstrap equations that possess consistent solutions for any value of the coupling constant. To confirm the correctness of these predictions, we calculate their contribution to the super Wilson loop demonstrating agreement with recent results to four-loop order in 't Hooft coupling.
Aryaeinejad, R.; Chou, W.; McHarris, W.C. )
1989-09-01
The interacting-boson-fermion-approximation and triaxial models were used to calculate excitation energies and mixing ratios for the {ital N}=80 nuclei, {sup 139}Pr, {sup 141}Pm, and {sup 143}Eu. For low-lying negative- and positive-parity states both models yield roughly the same numbers, in good agreement with experimental results. For high-lying states we find that the interacting-boson-fermion-approximation model describes the level structure considerably better than the triaxial model. On the other hand, the triaxial model gives more satisfactory results in predicting the mixing ratios.
NASA Technical Reports Server (NTRS)
Lee, Kimyeong; Holman, Richard; Kolb, Edward W.
1987-01-01
Wilson-loop symmetry breaking is considered on a space-time of the form M4 x K, where M4 is a four-dimensional space-time and K is an internal space with nontrivial and finite fundamental group. It is shown in a simple model that the different vacua obtained by breaking a non-Abelian gauge group by Wilson loops are separated in the space of gauge potentials by a finite energy barrier. An interpolating gauge configuration is then constructed between these vacua and shown to have minimum energy. Finally some implications of this construction are discussed.
Fermion frontiers in vector lattice gauge theories: Proceedings. Volume 8
1998-11-01
The inclusion of fermions into simulations of lattice gauge theories is very difficult both theoretically and numerically. With the presence of Teraflops-scale computers for lattice gauge theory, the authors wanted a forum to discuss new approaches to lattice fermions. The workshop concentrated on approaches which are ripe for study on such large machines. Although lattice chiral fermions are vitally important to understand, there is not technique at hand which is viable on these Teraflops-scale machines for real-world problems. The discussion was therefore focused on recent developments and future prospects for QCD-like theories. For the well-known fermion formulations, the Aoki phase in Wilson fermions, novelties of U{sub A}(1) symmetry and the {eta}{prime} for staggered fermions and new approaches for simulating the determinant for Wilson fermions were discussed. The newer domain-wall fermion formulation was reviewed, with numerical results given by many speakers. The fermion proposal of Friedberg, Lee and Pang was introduced. They also were able to compare and contrast the dependence of QCD and QCD-like SUSY theories on the number of quark flavors. These proceedings consist of several transparencies and a summary page from each speaker. This should serve to outline the major points made in each talk.
FLIC Fermions and Hadron Phenomenology
D. Leinweber; J.N. Hedditch; W. Melnitchouk; A.W. Thomas; A.G. Williams; R.D. Young; J.M. Zanotti; J.B. Zhang
2002-06-01
A pedagogical overview of the formulation of the Fat Link Irrelevant Clover (FLIC) fermion action and its associated phenomenology is described. The scaling analysis indicates FLIC fermions provide a new form of nonperturbative order (a) improvement where near-continuum results are obtained at finite lattice spacing. Spin-1/2 and spin-3/2, even and odd parity baryon resonances are investigated in quenched QCD, where the nature of the Roper resonance and Lambda (1405) are of particular interest. FLIC fermions allow efficient access to the light quark-mass regime, where evidence of chiral nonanalytic behavior in the Delta mass is observed.
An Interview with John Wilson.
ERIC Educational Resources Information Center
Halstead, J. Mark; McLaughlin, Terence H.
2000-01-01
Presents an interview with John Wilson covering topics such as: addressing the people who influenced him, highlighting Wilson's career and home background, and providing discussions on his opinions related to religion, morality, moral education, and the concept of authority. (CMK)
Wilson Disease: Frequently Asked Questions
... potentially hazardous for Wilson's disease patients? What copper levels in drinking water are potentially hazardous for Wilson's ... liver recovery can I expect with treatment? What level of liver recovery can I expect with treatment? ...
Fermion production during and after axion inflation
Adshead, Peter; Sfakianakis, Evangelos I.
2015-11-11
We study derivatively coupled fermions in axion-driven inflation, specifically m{sub ϕ}{sup 2}ϕ{sup 2} and monodromy inflation, and calculate particle production during the inflationary epoch and the post-inflationary axion oscillations. During inflation, the rolling axion acts as an effective chemical potential for helicity which biases the gravitational production of one fermion helicity over the other. This mechanism allows for efficient gravitational production of heavy fermion states that would otherwise be highly suppressed. Following inflation, the axion oscillates and fermions with both helicities are produced as the effective frequency of the fermion field changes non-adiabatically. For certain values of the fermion mass and axion-fermion coupling strength, the two helicity states are produced asymmetrically, resulting in unequal number-densities of left- and right-helicity fermions.
ERIC Educational Resources Information Center
Berlin, Isaiah
2012-01-01
In this 1960 article Isaiah Berlin compares Woodrow Wilson's emphasis on the need to educate university students for life in the real world with the difference between Oxford "realism" and Cambridge "idealism" in the nineteenth century. Oxford favoured a Wilsonian preference for general education over (but not to the exclusion of) pure…
ERIC Educational Resources Information Center
Gies, Joseph C.
1980-01-01
The aftermath of a Pennsylvania judge's overturning the trustees of Wilson College's decision to close is described. A new board and new president found themselves confronted with a public relations handicap--Judge Keller's decision was almost universally perceived as governmental intrusion. (MLW)
NASA Astrophysics Data System (ADS)
Javarone, Marco Alberto
2016-08-01
We study the structure of fermionic networks, i.e. a model of networks based on the behavior of fermionic gases, and we analyze dynamical processes over them. In this model, particle dynamics have been mapped to the domain of networks, hence a parameter representing the temperature controls the evolution of the system. In doing so, it is possible to generate adaptive networks, i.e. networks whose structure varies over time. As shown in previous works, networks generated by quantum statistics can undergo critical phenomena as phase transitions and, moreover, they can be considered as thermodynamic systems. In this study, we analyze fermionic networks and opinion dynamics processes over them, framing this network model as a computational model useful to represent complex and adaptive systems. Results highlight that a strong relation holds between the gas temperature and the structure of the achieved networks. Notably, both the degree distribution and the assortativity vary as the temperature varies, hence we can state that fermionic networks behave as adaptive networks. On the other hand, it is worth to highlight that we did not finding relation between outcomes of opinion dynamics processes and the gas temperature. Therefore, although the latter plays a fundamental role in gas dynamics, on the network domain, its importance is related only to structural properties of fermionic networks.
Hypersomnolence in Wilson Disease
Amann, Valerie C.; Maru, Neal K.; Jain, Vivek
2015-01-01
Wilson disease (WD) is an autosomal recessive disorder of copper metabolism resulting in copper accumulation in a number of organs including the liver, brain, and cornea, predominantly leading to hepatic, neurologic, and psychiatric manifestations. An association between WD and sleep problems is not commonly recognized, and sleep complaints are often overlooked. Daytime hypersomnolence is even more rarely reported in this population. We report a case of WD and hypersomnolence objectively confirmed by a multiple sleep latency test (MSLT). Consequently, we suggest that increased awareness, assessment, and treatment of sleep disorders, including daytime sleepiness, may help improve patients' quality of life. Citation: Amann VC, Maru NK, Jain V. Hypersomnolence in Wilson disease. J Clin Sleep Med 2015;11(11):1341–1343. PMID:25902827
Hypersialorrhea in Wilson's Disease.
Trocello, Jean-Marc; Osmani, Karima; Pernon, Michaela; Chevaillier, Gérard; de Brugière, Claire; Remy, Pascal; Wenisch, Emilie; Cousin, Catherine; Girardot-Tinant, Nadège; Woimant, France
2015-10-01
Hypersialorrhea, corresponding to excessive salivation is a symptom frequently reported in Wilson's disease, especially in its neurological form. The prevalence of this frequent complaint has not been often evaluated. During a 7-month period, 87 consecutive Wilson's disease patients answered to the simple question "do you have the sensation of excess saliva in your mouth?" to evaluate the frequency of this symptom. A sub-sample of 10 consecutive Wilson's disease patients with drooling was recruited to undergo quantitative and qualitative measures to evaluate the mechanism of hypersialorrhea. Excessive drooling or excess saliva was found in 46 % of patients followed at the French Reference Centre. Ninety-eight percent of them presented neurological symptoms and drooling was found in only one patient without neurological symptoms. Our study showed that patients with a complaint of excessive saliva produced significantly higher quantities of saliva at rest than controls. Endoscopic examination was abnormal in six patients. A significant decrease of swallowing frequency, longer swallow latencies, and poor swallowing capacities may partly explain the salivary stasis. Oropharyngeal sensitivity disorders were present in 50 % of our patients. The decrease of the swallowing frequency observed in all patients could be related to cognitive and behavioral abnormalities with initiation difficulties objectified by longer latencies triggered by all the ingested volumes. This study confirmed the hypothesis of a multifactorial origin of hypersialorrhea in patients who have been diagnosed in Wilson's disease. It was essential to evaluate drooling with a multidisciplinary consultation to better identify the underlying mechanisms and to implement strategies for speech therapy and therapeutic adaptation. PMID:26209285
NASA Astrophysics Data System (ADS)
Murdin, P.
2000-11-01
Mount Wilson Observatory, located in the San Gabriel Mountains near Pasadena, California, was founded in 1904 by George Ellery Hale with financial support from Andrew Carnegie. In the 1920s and 1930s, working at the 2.5 m Hooker telescope, Edwin Hubble made two of the most important discoveries in the history of astronomy: first, that `nebulae' are actually island universes—galaxies—each with bil...
Observing remnants by fermions' tunneling
Chen, D.Y.; Wu, H.W.; Yang, H. E-mail: iverwu@uestc.edu.cn
2014-03-01
The standard Hawking formula predicts the complete evaporation of black holes. In this paper, we introduce effects of quantum gravity into fermions' tunneling from Reissner-Nordstrom and Kerr black holes. The quantum gravity effects slow down the increase of Hawking temperatures. This property naturally leads to a residue mass in black hole evaporation. The corrected temperatures are affected by the quantum numbers of emitted fermions. Meanwhile, the temperature of the Kerr black hole is a function of θ due to the rotation.
Light quark simulations with FLIC fermions
J.M. Zanotti; D.B. Leinweber; W. Melnitchouk; A.G. Williams; J.B. Zhang
2002-06-01
Hadron masses are calculated in quenched lattice QCD in order to probe the scaling behavior of a novel fat-link clover fermion action in which only the irrelevant operators of the fermion action are constructed using APE-smeared links. Light quark masses corresponding to an m{sub pi}/m{sub p} ratio of 0.35 are considered to assess the exceptional configuration problem of clover-fermion actions. This Fat-Link Irrelevant Clover (FLIC) fermion action provides scaling which is superior to mean-field improvement and offers advantages over nonperturbative improvement, including reduced exceptional configurations.
NASA Astrophysics Data System (ADS)
Wang, Zhijun; Alexandradinata, A.; Cava, Robert J.; Bernevig, B. Andrei
Spatial symmetries in crystals are distinguished by whether they preserve the spatial origin. We show how this basic geometric property gives rise to a new topology in band insulators. We study spatial symmetries that translate the origin by a fraction of the lattice period, and find that these nonsymmorphic symmetries protect a novel surface fermion whose dispersion is shaped like an hourglass; surface bands connect one hourglass to the next in an unbreakable zigzag pattern. These exotic fermions are materialized in the large-gap insulators: KHg X (X = As,Sb,Bi), which we propose as the first material class whose topology relies on nonsymmorphic symmetries. Beside the hourglass fermion, a different surface of KHg X manifests a 3D generalization of the quantum spin Hall effect. To describe the bulk topology of nonsymmorphic crystals, we propose a non-Abelian generalization of the geometric theory of polarization. Our nontrivial topology originates not from an inversion of the parity quantum numbers, but rather of the rotational quantum numbers, which we propose as a fruitful in the search for topological materials. Finally, KHg X uniquely exemplifies a cohomological insulator, a concept that we will introduce in a companion work.
Wang, Zhijun; Alexandradinata, A; Cava, R J; Bernevig, B Andrei
2016-04-14
Spatial symmetries in crystals may be distinguished by whether they preserve the spatial origin. Here we study spatial symmetries that translate the origin by a fraction of the lattice period, and find that these non-symmorphic symmetries protect an exotic surface fermion whose dispersion relation is shaped like an hourglass; surface bands connect one hourglass to the next in an unbreakable zigzag pattern. These 'hourglass' fermions are formed in the large-gap insulators, KHgX (X = As, Sb, Bi), which we propose as the first material class whose band topology relies on non-symmorphic symmetries. Besides the hourglass fermion, another surface of KHgX manifests a three-dimensional generalization of the quantum spin Hall effect, which has previously been observed only in two-dimensional crystals. To describe the bulk topology of non-symmorphic crystals, we propose a non-Abelian generalization of the geometric theory of polarization. Our non-trivial topology originates from an inversion of the rotational quantum numbers, which we propose as a criterion in the search for topological materials. PMID:27075096
The Gaussian entropy of fermionic systems
Prokopec, Tomislav; Schmidt, Michael G.; Weenink, Jan
2012-12-15
We consider the entropy and decoherence in fermionic quantum systems. By making a Gaussian Ansatz for the density operator of a collection of fermions we study statistical 2-point correlators and express the entropy of a system fermion in terms of these correlators. In a simple case when a set of N thermalised environmental fermionic oscillators interacts bi-linearly with the system fermion we can study its time dependent entropy, which also represents a quantitative measure for decoherence and classicalization. We then consider a relativistic fermionic quantum field theory and take a mass mixing term as a simple model for the Yukawa interaction. It turns out that even in this Gaussian approximation, the fermionic system decoheres quite effectively, such that in a large coupling and high temperature regime the system field approaches the temperature of the environmental fields. - Highlights: Black-Right-Pointing-Pointer We construct the Gaussian density operator for relativistic fermionic systems. Black-Right-Pointing-Pointer The Gaussian entropy of relativistic fermionic systems is described in terms of 2-point correlators. Black-Right-Pointing-Pointer We explicitly show the growth of entropy for fermionic fields mixing with a thermal fermionic environment.
Green, Daniel; /SLAC /Stanford U., Dept. Phys.
2008-04-29
Gravitational theories do not admit gauge invariant local operators. We study the limits under which there exists a quasi-local description for a class of non-local gravitational observables where a sum over worldlines plays the role of the Wilson line for gauge theory observables. We study non-local corrections to the local description and circumstances where these corrections become large. We find that these operators are quasi-local in at space and AdS, but fail to be quasi-local in de Sitter space.
Many Masses on One Stroke:. Economic Computation of Quark Propagators
NASA Astrophysics Data System (ADS)
Frommer, Andreas; Nöckel, Bertold; Güsken, Stephan; Lippert, Thomas; Schilling, Klaus
The computational effort in the calculation of Wilson fermion quark propagators in Lattice Quantum Chromodynamics can be considerably reduced by exploiting the Wilson fermion matrix structure in inversion algorithms based on the non-symmetric Lanczos process. We consider two such methods: QMR (quasi minimal residual) and BCG (biconjugate gradients). Based on the decomposition M/κ = 1/κ-D of the Wilson mass matrix, using QMR, one can carry out inversions on a whole trajectory of masses simultaneously, merely at the computational expense of a single propagator computation. In other words, one has to compute the propagator corresponding to the lightest mass only, while all the heavier masses are given for free, at the price of extra storage. Moreover, the symmetry γ5M = M†γ5 can be used to cut the computational effort in QMR and BCG by a factor of two. We show that both methods then become — in the critical regime of small quark masses — competitive to BiCGStab and significantly better than the standard MR method, with optimal relaxation factor, and CG as applied to the normal equations.
Fermionic-bosonic couplings in a weakly deformed odd-mass nucleus, {sub 41}{sup 93}Nb
Orce, J. N.; Holt, J. D.; Linnemann, A.; Fransen, C.; Jolie, J.; Warr, N.; McKay, C. J.; McEllistrem, M. T.; Kuo, T. T. S.; Lesher, S. R.; Pietralla, N.; Werner, V.; Yates, S. W.
2010-10-15
A comprehensive level scheme of {sup 93}Nb below 2 MeV has been constructed from information obtained with the {sup 93}Nb(n,n{sup '{gamma}}) and the {sup 94}Zr(p,2n{gamma}{gamma}){sup 93}Nb reactions. Branching ratios, lifetimes, transition multipolarities, and spin assignments have been determined. From M1 and E2 strengths, fermionic-bosonic excitations of isoscalar and isovector characters have been identified from the weak couplings of the {pi}1g{sub 9/2} x {sub 40}{sup 92}Zr and {pi}2p{sub 1/2}{sup -1} x {sub 42}{sup 94}Mo configurations. A microscopic interpretation of such excitations is obtained from shell-model calculations, which use low-momentum effective interactions.
ee4fγ—A program for e+e-→4f,4f γ with nonzero fermion masses
NASA Astrophysics Data System (ADS)
Kołodziej, Karol; Jegerlehner, Fred
2004-05-01
A computer program ee4fγ for calculating cross-sections of any four fermion final state of e+e--annihilation at high energy and the corresponding bremsstrahlung reaction that is possible in the framework of the Standard Model is presented. As the fermion masses are arbitrary, the cross-sections for channels that do not contain e+ and/or e- in the final state can be computed without any collinear cut, the on-shell top quark production can be studied and the Higgs boson exchange can be incorporated in a consistent way. The program can be used as a Monte Carlo generator of unweighted events as well. Program summaryTitle of program:ee4fγ Version: 1.0 (February 2004) Catalogue identifier: ADTQ Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADTQ Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions: none Computers: all Operating systems: Unix/Linux Programming language used:FORTRAN 90 CPC Program Library subprograms used:RANLUX, ACPR RANLUX 79 (1994) 111—a random number generator Memory required to execute with typical data: 4.0 Mb No. of bits in a word: 32 No. of bytes in distributed program, including test data, etc.: 364 490 No. of lines in distributed program, including test data, etc.: 45 278 Distribution format: tar gzip file Nature of physical problem: Description of all e+e-→4 fermions and corresponding bremsstrahlung reactions that are possible in the Standard Model (SM) to lowest order and with nonzero fermion masses at center of mass energies typical for next generation linear colliders. Such reactions are relevant, typically, for W-pair or intermediate mass Higgs boson production and decay. Method of solution: Matrix elements are calculated with the helicity amplitude method. The phase space integration is performed numerically utilizing a multi-channel Monte Carlo method. Restrictions on complexity of the problem: No higher order effects are taken into account, except for assuming the fine
Wilson Loop Diagrams and Positroids
NASA Astrophysics Data System (ADS)
Agarwala, Susama; Marin-Amat, Eloi
2016-07-01
In this paper, we study a new application of the positive Grassmannian to Wilson loop diagrams (or MHV diagrams) for scattering amplitudes in N= 4 Super Yang-Mill theory (N = 4 SYM). There has been much interest in studying this theory via the positive Grassmannians using BCFW recursion. This is the first attempt to study MHV diagrams for planar Wilson loop calculations (or planar amplitudes) in terms of positive Grassmannians. We codify Wilson loop diagrams completely in terms of matroids. This allows us to apply the combinatorial tools in matroid theory used to identify positroids (non-negative Grassmannians) to Wilson loop diagrams. In doing so, we find that certain non-planar Wilson loop diagrams define positive Grassmannians. While non-planar diagrams do not have physical meaning, this finding suggests that they may have value as an algebraic tool, and deserve further investigation.
Emergent geometry from field theory: Wilson's renormalization group revisited
NASA Astrophysics Data System (ADS)
Kim, Ki-Seok; Park, Chanyong
2016-06-01
We find a geometrical description from a field theoretical setup based on Wilson's renormalization group in real space. We show that renormalization group equations of coupling parameters encode the metric structure of an emergent curved space, regarded to be an Einstein equation for the emergent gravity. Self-consistent equations of local order-parameter fields with an emergent metric turn out to describe low-energy dynamics of a strongly coupled field theory, analogous to the Maxwell equation of the Einstein-Maxwell theory in the AdSd +2 /CFTd +1 duality conjecture. We claim that the AdS3 /CFT2 duality may be interpreted as Landau-Ginzburg theory combined with Wilson's renormalization group, which introduces vertex corrections into the Landau-Ginzburg theory in the large-Ns limit, where Ns is the number of fermion flavors.
QCD hadron spectrum and the chiral limit with domain wall fermions
NASA Astrophysics Data System (ADS)
Wu, Lingling
We present the QCD hadron spectrum for the cases of both quenched and dynamical domain wall fermions. Quenched simulations at the lattice spacing a-1 ˜ 1--2 GeV with the Wilson gauge action demonstrate that the small induced effects of chiral symmetry breaking inherent in this formulation can be described by a residual mass ( mres) whose size decreases as the separation between the domain walls (Ls) is increased. However, at stronger couplings much larger values of Ls are required to achieve a given physical value of mres. Important effects of topological near-zero modes which should afflict an accurate quenched calculation are easily visible in the pion propagator. These effects can be controlled by working at an appropriately large volume. A non-linear behavior of m2p in the limit of small quark mass suggests the presence of additional infrared subtlety in the quenched approximation. In support of the thermodynamics studies, zero temperature dynamical simulations with the Wilson gauge action are performed to set the scale. The heavy pion mass obtained indicates the needs for much larger values of Ls to study the order of the transition. Simulations with the renormalization group improved gauge action exhibits an improved chiral behavior in our quenched study, nevertheless, this is not true for the dynamical case.
Scaling of fat-link irrelevant-clover fermions
Zanotti, J.M.; Lasscock, B.; Leinweber, D.B.; Williams, A.G.
2005-02-01
Hadron masses are calculated in quenched lattice QCD on a variety of lattices in order to probe the scaling behavior of the Fat-Link Irrelevant Clover (FLIC) fermion action, a fat-link clover fermion action in which the purely irrelevant operators of the fermion action are constructed using APE-smeared links. The scaling analysis indicates FLIC fermions provide a new form of nonperturbative O(a) improvement where near-continuum results are obtained at finite lattice spacing.
Aaltonen, T.; Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Adelman, J.; Aguilo, E.; Alexeev, G.D.; Alkhazov, G.; /Helsinki Inst. of Phys. /Dubna, JINR /Oklahoma U. /Michigan State U. /Tata Inst. /Illinois U., Chicago /Florida State U. /Chicago U., EFI /Simon Fraser U. /York U., Canada /St. Petersburg, INP /Illinois U., Urbana /Sao Paulo, IFT /Munich U. /University Coll. London /Oxford U. /St. Petersburg, INP /Duke U. /Kyungpook Natl. U. /Chonnam Natl. U. /Florida U. /Osaka City U.
2010-05-01
We combine results from searches by the CDF and D0 collaborations for a standard model Higgs boson (H) in the process gg {yields} H {yields} W{sup +}W{sup -} in p{bar p} collisions at the Fermilab Tevatron Collider at {radical}s = 1.o6 TeV. With 4.8 fb{sup -1} of itnegrated luminosity analyzed at CDF and 5.4 fb{sup -1} at D0, the 95% Confidence Level upper limit on {sigma}(gg {yields} H) x {Beta}(H {yields} W{sup +}W{sup -}) is 1.75 pb at m{sub H} = 120 GeV, 0.38 pb at m{sub H} = 165 GeV, and 0.83 pb at m{sub H} = 200 GeV. Assuming the presence of a fourth sequential generation of fermions with large masses, they exclude at the 95% Confidence Level a standard-model-like Higgs boson with a mass between 131 and 204 Gev.
How Is Wilson Disease Diagnosed?
... Connect with Wilson Disease Association Send Email Physician Contacts List of Physicians and Institutions in Your Area View Contacts Support Contacts Individuals who can offer Support and Information View ...
How Is Wilson Disease Inherited?
... Connect with Wilson Disease Association Send Email Physician Contacts List of Physicians and Institutions in Your Area View Contacts Support Contacts Individuals who can offer Support and Information View ...
NASA Technical Reports Server (NTRS)
Burke, Kevin
1987-01-01
The main activity relating to the study during this half year was a three week field trip to study Chinese sedimentary basins (June 10 to July 3, 1986) at no cost to the project. This study, while of a reconnaissance character, permitted progress in understanding how the processes of island arc-collision and micro-continental collision operated during the Paleozoic in far western China (especially the Junggar and Tarim basins and in the intervening Tien Shan Mountains). These effects of the continuing collision of India and Asia on the area were also studied. Most specifically, these result in the elevation of the Tien Shan to more than 4 km above sea level and the depression of Turfan to move 150m below sea level. Both thrusting and large-scale strike-slip motion are important in producing these elevation changes. Some effort during the half year was also devoted to the study of greenstone-belts in terms of the Wilson Cycle.
Garavelli, Livia; Mainardi, Paola Cerruti
2007-01-01
Mowat-Wilson syndrome (MWS) is a multiple congenital anomaly syndrome characterized by a distinct facial phenotype (high forehead, frontal bossing, large eyebrows, medially flaring and sparse in the middle part, hypertelorism, deep set but large eyes, large and uplifted ear lobes, with a central depression, saddle nose with prominent rounded nasal tip, prominent columella, open mouth, with M-shaped upper lip, frequent smiling, and a prominent but narrow and triangular pointed chin), moderate-to-severe intellectual deficiency, epilepsy and variable congenital malformations including Hirschsprung disease (HSCR), genitourinary anomalies (in particular hypospadias in males), congenital heart defects, agenesis of the corpus callosum and eye anomalies. The prevalence of MWS is currently unknown, but 171 patients have been reported so far. It seems probable that MWS is under-diagnosed, particularly in patients without HSCR. MWS is caused by heterozygous mutations or deletions in the Zinc finger E-box-binding homeobox 2 gene, ZEB2, previously called ZFHX1B (SIP1). To date, over 100 deletions/mutations have been reported in patients with a typical phenotype; they are frequently whole gene deletions or truncating mutations, suggesting that haploinsufficiency is the main pathological mechanism. Studies of genotype-phenotype analysis show that facial gestalt and delayed psychomotor development are constant clinical features, while the frequent and severe congenital malformations are variable. In a small number of patients, unusual mutations can lead to an atypical phenotype. The facial phenotype is particularly important for the initial clinical diagnosis and provides the hallmark warranting ZEB2 mutational analysis, even in the absence of HSCR. The majority of MWS cases reported so far were sporadic, therefore the recurrence risk is low. Nevertheless, rare cases of sibling recurrence have been observed. Congenital malformations and seizures require precocious clinical
Ginsparg-Wilson relation on a fuzzy 2-sphere for adjoint matter
Aoki, Hajime
2010-10-15
We formulate a Ginsparg-Wilson relation on a fuzzy 2-sphere for matter in the adjoint representation of the gauge group. Because of the Ginsparg-Wilson relation, an index theorem is satisfied. Our formulation is applicable to topologically nontrivial configurations as monopoles. It gives a solid basis for obtaining chiral fermions, which are an important ingredient of the standard model, from matrix model formulations of the superstring theory, such as the IIB matrix model, by considering topological configurations in the extra dimensions. We finally discuss whether this mechanism really works.
Playing with fermion couplings in Higgsless models
Casalbuoni, R.; De Curtis, S.; Dolce, D.; Dominici, D.
2005-04-01
We discuss the fermion couplings in a four dimensional SU(2) linear moose model by allowing for direct couplings between the left-handed fermions on the boundary and the gauge fields in the internal sites. This is realized by means of a product of nonlinear {sigma}-model scalar fields which, in the continuum limit, is equivalent to a Wilson line. The effect of these new nonlocal couplings is a contribution to the {epsilon}{sub 3} parameter which can be of opposite sign with respect to the one coming from the gauge fields along the string. Therefore, with some fine-tuning, it is possible to satisfy the constraints from the electroweak data.
Fermion masses and neutrino mixing in an SU(5)/sub GUT/ x SU(8)/sub ETC/ model
Aubrecht, G.J. II; Matsuki, T.; Tanaka, K.
1983-01-01
We extend the SU(3) x SU(2) x U(1) model without scalars to SU(5)/sub GUT/ x SU(8)/sub ETC/. In our model, the mixing in the leptons is identical to that for the quarks, so that the Cabibbo angle determines the mixing of nu/sub e/ and nu/sub ..mu../. The quark masses and mixing angles are studied for two and three generations of quarks.
Charmonium Spectrum from Quenched QCD with Overlap Fermions
S. Tamhankar; A. Alexandru; Y. Chen; S.J. Dong; T. Draper; I. Horvath; F.X. Lee; K.F. Liu; N. Mathur; J.B. Zhang
2005-07-20
We present the first study of the charmonium spectrum using overlap fermions, on quenched configurations. Simulations are performed on 16{sup 3} x 72 lattices, with Wilson gauge action at {beta} = 6.3345. We demonstrate that we have discretization errors under control at about 5%. We obtain 88(4) MeV for hyperfine splitting using the {sub 0} scale, and 121(6) MeV using the (1{bar P}-1{bar S}) scale. This paper raises the possibility that the discrepancy between the lattice results and the experimental value for charmonium hyperfine splitting can be resolved using overlap fermions to simulate the charm quark on lattice.
Scaling analysis of fat-link irrelevant clover fermion actions
Kamleh, Waseem; Lasscock, Ben; Leinweber, Derek B.; Williams, Anthony G.
2008-01-01
The fat-link irrelevant clover fermion action is a variant of the O(a)-improved Wilson action where the irrelevant operators are constructed using smeared links. While the use of such smearing allows for the use of highly improved definitions of the field strength tensor F{sub {mu}}{sub {nu}}, we show that the standard 1-loop clover term with a mean field improved coefficient c{sub sw} is sufficient to remove the O(a) errors, avoiding the need for nonperturbative tuning. This result enables efficient dynamical simulations in QCD with the fat-link irrelevant clover fermion action.
NASA Astrophysics Data System (ADS)
Khan, Saki
2016-06-01
We present a minimal renormalizable non-supersymmetric S O(10) grand unified model with a symmetry breaking sector consisting of Higgs fields in the 54H + 126H + 10H representations. This model admits a single intermediate scale associated with Pati-Salam symmetry along with a discrete parity. Spontaneous symmetry breaking, the unification of gauge couplings and proton lifetime estimates are studied in detail in this framework. Including threshold corrections self-consistently, obtained from a full analysis of the Higgs potential, we show that the model is compatible with the current experimental bound on proton lifetime. The model generally predicts an upper bound of few times 1035 yrs for proton lifetime, which is not too far from the present Super-Kamiokande limit of τp ≳ 1.29 × 1034 yrs. With the help of a Pecci-Quinn symmetry and the resulting axion, the model provides a suitable dark matter candidate while also solving the strong CP problem. The intermediate scale, MI ≈ (1013 - 1014) GeV which is also the B - L scale, is of the right order for the right-handed neutrino mass which enables a successful description of light neutrino masses and oscillations. The Yukawa sector of the model consists of only two matrices in family space and leads to a predictive scenario for quark and lepton masses and mixings. The branching ratios for proton decay are calculable with the leading modes being p → e+π0 and p →v ¯π+ . Even though the model predicts no new physics within the reach of LHC, the next generation proton decay detectors and axion search experiments have the capability to pass verdict on this minimal scenario.
Searches for Fourth Generation Fermions
Ivanov, A.; /Fermilab
2011-09-01
We present the results from searches for fourth generation fermions performed using data samples collected by the CDF II and D0 Detectors at the Fermilab Tevatron p{bar p} collider. Many of these results represent the most stringent 95% C. L. limits on masses of new fermions to-date. A fourth chiral generation of massive fermions with the same quantum numbers as the known fermions is one of the simplest extensions of the SM with three generations. The fourth generation is predicted in a number of theories, and although historically have been considered disfavored, stands in agreement with electroweak precision data. To avoid Z {yields} {nu}{bar {nu}} constraint from LEP I a fourth generation neutrino {nu}{sub 4} must be heavy: m({nu}{sub 4}) > m{sub Z}/2, where m{sub Z} is the mass of Z boson, and to avoid LEP II bounds a fourth generation charged lepton {ell}{sub 4} must have m({ell}{sub 4}) > 101 GeV/c{sup 2}. At the same time due to sizeable radiative corrections masses of fourth generation fermions cannot be much higher the current lower bounds and masses of new heavy quarks t' and b' should be in the range of a few hundred GeV/c{sup 2}. In the four-generation model the present bounds on the Higgs are relaxed: the Higgs mass could be as large as 1 TeV/c{sup 2}. Furthermore, the CP violation is significantly enhanced to the magnitude that might account for the baryon asymmetry in the Universe. Additional chiral fermion families can also be accommodated in supersymmetric two-Higgs-doublet extensions of the SM with equivalent effect on the precision fit to the Higgs mass. Another possibility is heavy exotic quarks with vector couplings to the W boson Contributions to radiative corrections from such quarks with mass M decouple as 1/M{sup 2} and easily evade all experimental constraints. At the Tevatron p{bar p} collider 4-th generation chiral or vector-like quarks can be either produced strongly in pairs or singly via electroweak production, where the latter can be
SUSY SU(5)× S 4 GUT flavor model for fermion masses and mixings with adjoint, large θ 13 PMNS
NASA Astrophysics Data System (ADS)
Zhao, Ya; Zhang, Peng-Fei
2016-06-01
We propose an S 4 flavor model based on supersymmetric (SUSY) SU(5) GUT. The first and third generations of 10 dimensional representations in SU(5) are all assigned to be 11 of S 4. The second generation of 10 is to be 12 of S 4. Right-handed neutrinos of singlet 1 and three generations of overline{mathbf{5}} are all assigned to be 31 of S 4. The VEVs of two sets of flavon fields are allowed a moderate hierarchy, that is <Φ ν > ˜ λ c <Φ e >. Tri-Bimaximal (TBM) mixing can be produced at both leading order (LO) and next to next to leading order (NNLO) in neutrino sector. All the masses of up-type quarks are obtained at LO. We also get the bottom-tau unification m τ = m b and the popular Georgi-Jarlskog relation m μ = 3 m s as well as a new mass relation {m}_e=8/27{m}_d in which the novel Clebsch-Gordan (CG) factor arises from the adjoint field H 24. The GUT relation leads to a sizable mixing angle θ 12 e ˜ θ c and the correct quark mixing matrix V CKM can also be realised in the model. The resulting CKM-like mixing matrix of charged leptons modifies the vanishing θ 13 ν in TBM mixing to a large {θ}_{13}^{PMNS}˜eq {θ}_c/√{2} , in excellent agreement with experimental results. A Dirac CP violation phase ϕ 12 ≃ ±π /2 is required to make the deviation from θ 12 ν small. We also present some phenomenological numerical results predicted by the model.
Fermionic influence on inflationary fluctuations
NASA Astrophysics Data System (ADS)
Boyanovsky, Daniel
2016-04-01
Motivated by apparent persistent large scale anomalies in the cosmic microwave background we study the influence of fermionic degrees of freedom on the dynamics of inflaton fluctuations as a possible source of violations of (nearly) scale invariance on cosmological scales. We obtain the nonequilibrium effective action of an inflaton-like scalar field with Yukawa interactions (YD ,M) to light fermionic degrees of freedom both for Dirac and Majorana fields in de Sitter space-time. The effective action leads to Langevin equations of motion for the fluctuations of the inflaton-like field, with self-energy corrections and a stochastic Gaussian noise. We solve the Langevin equation in the super-Hubble limit implementing a dynamical renormalization group resummation. For a nearly massless inflaton its power spectrum of super-Hubble fluctuations is enhanced, P (k ;η )=(H/2 π )2eγt[-k η ] with γt[-k η ]=1/6 π2 [∑i =1 NDYi,D 2+2 ∑j =1 NMYj,M 2]{ln2[-k η ]-2 ln [-k η ]ln [-k η0]} for ND Dirac and NM Majorana fermions, and η0 is the renormalization scale at which the inflaton mass vanishes. The full power spectrum is shown to be renormalization group invariant. These corrections to the super-Hubble power spectrum entail a violation of scale invariance as a consequence of the coupling to the fermionic fields. The effective action is argued to be exact in the limit of a large number of fermionic fields. A cancellation between the enhancement from fermionic degrees of freedom and suppression from light scalar degrees of freedom conformally coupled to gravity suggests the possibility of a finely tuned supersymmetry among these fields.
NASA Astrophysics Data System (ADS)
Jin, Xiao-Yong; Kuramashi, Yoshinobu; Nakamura, Yoshifumi; Takeda, Shinji; Ukawa, Akira
2015-12-01
We investigate the phase structure of three-flavor QCD in the presence of finite quark chemical potential μ /T ≲1.2 by using the nonperturbatively O (a ) improved Wilson fermion action on lattices with a fixed temporal extent Nt=6 and varied spatial linear extents Ns=8 , 10, 12. Especially, we focus on locating the critical end point that characterizes the phase structure, and extracting the curvature of the critical line on the μ -mπ plane. For Wilson-type fermions, the correspondence between bare parameters and physical parameters is indirect. Hence we present a strategy to transfer the bare parameter phase structure to the physical one, in order to obtain the curvature. Our conclusion is that the curvature is positive. This implies that, if one starts from a quark mass in the region of crossover at zero chemical potential, one would encounter a first-order phase transition when one raises the chemical potential.
NLO Hierarchy of Wilson Lines Evolution
Balitsky, Ian
2015-03-01
The high-energy behavior of QCD amplitudes can be described in terms of the rapidity evolution of Wilson lines. I present the hierarchy of evolution equations for Wilson lines in the next-to-leading order.
ERIC Educational Resources Information Center
Harrison, John L.
1977-01-01
The work of John Wilson, now teaching at Oxford University, as moral educator is summarized and evaluated. His rationalist humanistic approach is based on a componential characterization of the morally educated person. The rationale and conceptual status of the components is discussed. His position is compared to that of Peter McPhail, R. S.…
John Wilson on Moral Education.
ERIC Educational Resources Information Center
McLaughlin, Terence H.; Halstead, J. Mark
2000-01-01
Describes the approach to moral education utilized by John Wilson focusing on his claims, arguments, and conclusions. Explores eight specific topics, such as his general perspective on moral education and the meaning and nature of moral. Reports on the areas of difficulty and criticism in relation to his approach. (CMK)
Robert Wilson's Invitation to Insanity.
ERIC Educational Resources Information Center
Stephens, Judith L.
The plays of stage director Robert Wilson are devices presenting alternative modes of perception to theatre audiences accustomed to verbal/aural structures of experience. Uniting his interests in the arts and therapy, his plays create a theatrical event promoting empathy with the perceptions of the mentally or physically handicapped and…
Fermionization and Hubbard models
NASA Astrophysics Data System (ADS)
Dargis, P.; Maassarani, Z.
1998-12-01
We introduce a transformation which allows the fermionization of operators of any one-dimensional spin-chain. This fermionization procedure is independent of any eventual integrable structure and is compatible with it. We illustrate this method on various integrable and non-integrable chains, and deduce some general results. In particular, we fermionize XXC spin-chains and study their symmetries. Fermionic realizations of certain Lie algebras and superalgebras appear naturally as symmetries of some models. We also fermionize recently obtained Hubbard models, and obtain for the first time multispecies analogues of the Hubbard model, in their fermionic form. We comment on the conflict between symmetry enhancement and integrability of these models. Finally, the fermionic versions of the non-integrable spin-1 and spin- {3}/{2} Heisenberg chains are obtained.
Domain wall fermion quenched spectroscopy
NASA Astrophysics Data System (ADS)
Malureanu, Catalin Ionut
We measure y and the hadron spectrum on quenched ensembles using the domain wall fermion formulation. For the first time a 1/mf behavior of y for small valence masses has been observed. Our measurements of y on two different volumes of 83 x 32 and 163 x 32 at β = 5.85 suggest the behavior goes away on large enough volumes. Extensive spectrum calculations were done on 8 3 x 32 lattices at β = 5.7 and 5.85 corresponding roughly to a box size of 1.6 fm and 1.0 fm respectively. We have investigated five values of the extent of the fifth dimension Ls = 10, 16, 24, 32 and 48 with valence masses in the range 0.02 to 0.2 for the β = 5.7 ensemble and two values of Ls = 10 and 16 with valence masses in the range 0.02 to 0.08 for the β = 5.85 ensemble. Our pion remains massive in the infinite Ls extrapolation. This may be a finite volume effect. The nucleon to rho mass ratio stays constant at 1.4(1). Scaling violations for domain wall fermions are smaller roughly by a factor of four compared to the scaling violations in similar calculations done with staggered fermions.
Dynamical symmetries for fermions
Guidry, M.
1989-01-01
An introduction is given to the Fermion Dynamical Symmetry Model (FDSM). The analytical symmetry limits of the model are then applied to the calculation of physical quantities such as ground-state masses and B(E{sub 2}) values in heavy nuclei. These comparisons with data provide strong support for a new principle of collective motion, the Dynamical Pauli Effect, and suggest that dynamical symmetries which properly account for the pauli principle are much more persistent in nuclear structure than the corresponding boson symmetries. Finally, we present an assessment of criticisms which have been voiced concerning the FDSM, and a discussion of new phenomena and exotic spectroscopy'' which may be suggested by the model. 14 refs., 8 figs., 4 tabs.
Creutz fermions on an orthogonal lattice
Borici, Artan
2008-10-01
In a recent paper, Creutz has given a new action describing two species of Dirac fermions with exact chiral symmetry on the lattice. This action depends on parameters which may be fixed at certain values in order to get the right continuum limit. In this letter, we elaborate more on this idea and present an action which is free of any other parameter except the fermion mass.
Dual of QCD with one adjoint fermion
Mojaza, Matin; Nardecchia, Marco; Pica, Claudio; Sannino, Francesco
2011-03-15
We construct the magnetic dual of QCD with one adjoint Weyl fermion. The dual is a consistent solution of the 't Hooft anomaly matching conditions, allows for flavor decoupling, and remarkably constitutes the first nonsupersymmetric dual valid for any number of colors. The dual allows to bound the anomalous dimension of the Dirac fermion mass operator to be less than one in the conformal window.
Dephasing time of composite fermions
Lee, P.A.; Mucciolo, E.R.
1996-09-01
We study the dephasing of fermions interacting with a fluctuating transverse-gauge field. The divergence of the imaginary part of the fermion self-energy at finite temperatures is shown to result from a breakdown of Fermi{close_quote}s golden rule due to a faster than exponential decay in time. The strong dephasing affects experiments where phase coherence is probed. This result is used to describe the suppression of Shubnikov{endash}de Haas (SdH) oscillations of composite fermions (oscillations in the conductivity near the half-filled Landau level). We find that it is important to take into account both the effect of dephasing and the mass renormalization. We conclude that while it is possible to use the conventional theory to extract an effective mass from the temperature dependence of the SdH oscillations, the resulting effective mass differs from the {ital m}{sup {asterisk}} of the quasiparticle in Fermi-liquid theory. {copyright} {ital 1996 The American Physical Society.}
Chiral perturbation theory for the Wilson lattice action
Rupak, Gautam; Shoresh, Noam
2002-01-25
The authors extend chiral perturbation theory to include linear dependence on the lattice spacing a for the Wilson action. The perturbation theory is written as a double expansion in the small quark mass m{sub q} and lattice spacing a. They present formulae for the mass and decay constant of a flavor-non-singlet meson in this scheme to order a and m{sub q}{sup 2}. The extension to the partially quenched theory is also described.
Strong Wilson polygons from the lodge of free and bound mesons
NASA Astrophysics Data System (ADS)
Bonini, Alfredo; Fioravanti, Davide; Piscaglia, Simone; Rossi, Marco
2016-04-01
Previously predicted by the S-matrix bootstrap of the excitations over the GKP quantum vacuum, the appearance of a new particle at strong coupling — formed by one fermion and one anti-fermion — is here confirmed: this two-dimensional meson shows up, along with its infinite tower of bound states, while analysing the fermionic contributions to the Operator Product Expansion (collinear regime) of the Wilson null polygon loop. Moreover, its existence, free (This term is used here as opposite to bound, thus as unbound) and bound, turns out to be a powerful idea in re-summing all the contributions (at large coupling) for a general n-gon ( n ≥ 6) to a Thermodynamic Bethe Ansatz, which is proven to be equivalent to the known one and suggests new structures for a special Y-system.
Wilson's disease: An endocrine revelation
Kapoor, Nitin; Shetty, Sahana; Thomas, Nihal; Paul, Thomas Vizhalil
2014-01-01
Wilson's disease is an inherited disorder of copper metabolism. The affected patients, who otherwise have a near normal life span, may often suffer from some potentially treatable and under recognized endocrine disorders that may hinder their quality of life. We explored previously published literature on the various endocrine aspects of this disease with their probable underlying mechanisms, highlighting the universal need of research in this area. PMID:25364683
Haplotype studies in Wilson disease
Thomas, G.R.; Bull, P.C.; Roberts, E.A.; Cox, D.W.; Walshe, J.M. )
1994-01-01
In 51 families with Wilson disease, the authors have studied DNA haplotypes of dinucleotide repeat polymorphisms (CA repeats) in the 13q14.3 region, to examine these markers for association with the Wilson disease gene (WND). In addition to a marker (D13S133) described elsewhere, the authors have developed three new highly polymorphic markers (D13S314, D13S315, and D13S316) close to the WND locus. The authors have examined the distribution of marker alleles at the loci studied and have found that D13S314, D13S133, and D13S316 each show nonrandom distribution on chromosomes carrying the WND mutation. The authors have studied haplotypes of these three markers and have found that there are highly significant differences between WND and normal haplotypes in northern European families. These findings have important implications for mutation detection and molecular diagnosis in families with Wilson disease. 25 refs., 2 figs., 5 tabs.
[Wilson's disease - a case report].
Karwowska, Kornelia; Skrzypek, Julita; Chabik, Grzegorz; Członkowska, Anna; Zaborowska, Marzena; Wawrzyniak, Sławomir
2016-01-01
Wilson's disease (WD) or hepatolenticular degeneration, is a rare autosomal recessive genetic disorder caused by mutations in the Wilson disease protein (ATP7B) gene. It is characterized by impaired copper metabolism leading to its accumulation in various tissues and organs, including the liver and central nervous system, this results in the development of characteristic liver disease and neuropsychiatric symptoms. Liver symptoms usually appear during first three decades of life, while psychiatric symptoms are observed in people who are in their twenties or older. WD is one of few genetic diseases that can be effectively treated with pharmacotherapy. However, some cases, especially diagnosed late in the course of the disease, may not respond well to treatment. Here we present a case of a 22-year-old male with neurological, psychiatric and liver disease symptoms as an example of diagnostic and therapeutic challenges in patients. Wilson's disease (WD) should be considered in all patients presenting with neurological, psychiatric and liver disease symptoms especially those of young age. PMID:26891433
Chiral fermions in asymptotically safe quantum gravity
NASA Astrophysics Data System (ADS)
Meibohm, J.; Pawlowski, J. M.
2016-05-01
We study the consistency of dynamical fermionic matter with the asymptotic safety scenario of quantum gravity using the functional renormalisation group. Since this scenario suggests strongly coupled quantum gravity in the UV, one expects gravity-induced fermion self-interactions at energies of the Planck scale. These could lead to chiral symmetry breaking at very high energies and thus to large fermion masses in the IR. The present analysis which is based on the previous works (Christiansen et al., Phys Rev D 92:121501, 2015; Meibohm et al., Phys Rev D 93:084035, 2016), concludes that gravity-induced chiral symmetry breaking at the Planck scale is avoided for a general class of NJL-type models. We find strong evidence that this feature is independent of the number of fermion fields. This finding suggests that the phase diagram for these models is topologically stable under the influence of gravitational interactions.
Lifetime of a one-dimensional fermion
NASA Astrophysics Data System (ADS)
Khodas, Maxim; Ussishkin, Iddo; Pustilnik, Michael; Kamenev, Alex; Glazman, Leonid
2007-03-01
Interaction between fermions in one dimension is usually accounted for within the exactly solvable Tomonaga-Luttinger model. The crucial simplification made in this model is the linearization of the fermionic spectrum. That simplification leads to an infinite lifetime of a fermion at the mass shell, i.e., the corresponding Green function G(,k) diverges at ɛ=ξk. We find that inclusion of the curvature of electron spectrum, ξk=vFk+k^2/2m, yields a finite decay rate of a fermion, 1/τ(ξk)θ(k)k^8/m^3; here for definiteness we consider right-moving particles, and k is measured from the Fermi wave vector. The found finite lifetime allows one to assess the limitations of the Luttinger liquid paradigm.
Fermion hierarchy from sfermion anarchy
Altmannshofer, Wolfgang; Frugiuele, Claudia; Harnik, Roni
2014-12-31
We present a framework to generate the hierarchical flavor structure of Standard Model quarks and leptons from loops of superpartners. The simplest model consists of the minimal supersymmetric standard model with tree level Yukawa couplings for the third generation only and anarchic squark and slepton mass matrices. Agreement with constraints from low energy flavor observables, in particular Kaon mixing, is obtained for supersymmetric particles with masses at the PeV scale or above. In our framework both the second and the first generation fermion masses are generated at 1-loop. Despite this, a novel mechanism generates a hierarchy among the first andmore » second generations without imposing a symmetry or small parameters. A second-to-first generation mass ratio of order 100 is typical. The minimal supersymmetric standard model thus includes all the necessary ingredients to realize a fermion spectrum that is qualitatively similar to observation, with hierarchical masses and mixing. The minimal framework produces only a few quantitative discrepancies with observation, most notably the muon mass is too low. Furthermore, we discuss simple modifications which resolve this and also investigate the compatibility of our model with gauge and Yukawa coupling Unification.« less
Fermion hierarchy from sfermion anarchy
NASA Astrophysics Data System (ADS)
Altmannshofer, Wolfgang; Frugiuele, Claudia; Harnik, Roni
2014-12-01
We present a framework to generate the hierarchical flavor structure of Standard Model quarks and leptons from loops of superpartners. The simplest model consists of the minimal supersymmetric standard model with tree level Yukawa couplings for the third generation only and anarchic squark and slepton mass matrices. Agreement with constraints from low energy flavor observables, in particular Kaon mixing, is obtained for supersymmetric particles with masses at the PeV scale or above. In our framework both the second and the first generation fermion masses are generated at 1-loop. Despite this, a novel mechanism generates a hierarchy among the first and second generations without imposing a symmetry or small parameters. A second-to-first generation mass ratio of order 100 is typical. The minimal supersymmetric standard model thus includes all the necessary ingredients to realize a fermion spectrum that is qualitatively similar to observation, with hierarchical masses and mixing. The minimal framework produces only a few quantitative discrepancies with observation, most notably the muon mass is too low. We discuss simple modifications which resolve this and also investigate the compatibility of our model with gauge and Yukawa coupling Unification.
Fermion hierarchy from sfermion anarchy
Altmannshofer, Wolfgang; Frugiuele, Claudia; Harnik, Roni
2014-12-31
We present a framework to generate the hierarchical flavor structure of Standard Model quarks and leptons from loops of superpartners. The simplest model consists of the minimal supersymmetric standard model with tree level Yukawa couplings for the third generation only and anarchic squark and slepton mass matrices. Agreement with constraints from low energy flavor observables, in particular Kaon mixing, is obtained for supersymmetric particles with masses at the PeV scale or above. In our framework both the second and the first generation fermion masses are generated at 1-loop. Despite this, a novel mechanism generates a hierarchy among the first and second generations without imposing a symmetry or small parameters. A second-to-first generation mass ratio of order 100 is typical. The minimal supersymmetric standard model thus includes all the necessary ingredients to realize a fermion spectrum that is qualitatively similar to observation, with hierarchical masses and mixing. The minimal framework produces only a few quantitative discrepancies with observation, most notably the muon mass is too low. Furthermore, we discuss simple modifications which resolve this and also investigate the compatibility of our model with gauge and Yukawa coupling Unification.
Plutonium-Based Heavy-Fermion Systems
NASA Astrophysics Data System (ADS)
Bauer, E. D.; Thompson, J. D.
2015-03-01
An effective mass of charge carriers that is significantly larger than the mass of a free electron develops at low temperatures in certain lanthanide- and actinide-based metals, including those formed with plutonium, owing to strong electron-electron interactions. This heavy-fermion mass is reflected in a substantially enhanced electronic coefficient of specific heat Î³, which for elemental Pu is much larger than that of normal metals. By our definition, there are twelve Pu-based heavy-fermion compounds, most discovered recently, whose basic properties are known and discussed. Relative to other examples, these Pu-based heavy-fermion systems are particularly complex owing in part to the possible simultaneous presence of multiple, nearly degenerate 5fn configurations. This complexity poses significant opportunities as well as challenges, including understanding the origin of unconventional superconductivity in some of these materials.
Entanglement in fermionic systems
Banuls, Mari-Carmen; Cirac, J. Ignacio; Wolf, Michael M.
2007-08-15
The anticommuting properties of fermionic operators, together with the presence of parity conservation, affect the concept of entanglement in a composite fermionic system. Hence different points of view can give rise to different reasonable definitions of separable and entangled states. Here we analyze these possibilities and the relationship between the different classes of separable states. The behavior of the various classes when taking multiple copies of a state is also studied, showing that some of the differences vanish in the asymptotic regime. In particular, in the case of only two fermionic modes all the classes become equivalent in this limit. We illustrate the differences and relations by providing a complete characterization of all the sets defined for systems of two fermionic modes. The results are applied to Gibbs states of infinite chains of fermions whose interaction corresponds to a XY Hamiltonian with transverse magnetic field.
Supercycles, Wilson cycles and the future of Earth's oceans
NASA Astrophysics Data System (ADS)
Duarte, Joao; Schellart, Wouter; Rosas, Filipe
2014-05-01
At the dawn of the 20th Century Alfred Wegener proposed the existence of a supercontinent - Pangaea - gathering all the continental masses on Earth. Five decades later, while seeding the theory of plate tectonics, Tuzo Wilson introduced a new concept that would become known as Wilson cycles, which describes the evolution of oceans: 1) opening and spreading, 2) foundering of the passive margins and development of new subduction zones and 3) consumption and closure. Later on, in the 70's evidences for the existence of a number of other supercontinents and ancient oceans on Earth's history started to emerge. Today, concepts like supercycles, supercontinents, superoceans and Wilson cycles are loosely used. However, several important questions remain. How do subduction zones initiate in pristine oceans? Which major ocean on Earth will close to form the next supercontinent? The Atlantic (introversion), the Pacific (extroversion), or both? Are Wilson cycles of lower order than Supercycles? Are we in an abnormally long supercycle? Is there any cyclicity at all? These are some of the questions that we will tentatively address together with the proposal of several future scenarios for the evolution of Earth's oceans and continents.
Fermion-fermion interaction in a dilute gas-mixture Bose condensate
Mogilyuk, T. I.
2011-11-15
A mixture of a one-component Bose gas and two-component Fermi gas is considered at temperatures at which the Bose gas is completely condensed. Two fermions in such a mixture can interact with each other exchanging bosons from the condensate or supercondensate. The interaction potential, a change in the effective mass, the decay, and fermion spectrum are calculated in this quantum Fermi-Bose mixture.
Nucleon Axial Charge in (2+1)-Flavor Dynamical-Lattice QCD with Domain-Wall Fermions
Yamazaki, T.; Aoki, Y.; Blum, T.; Lin, H. W.; Lin, M. F.; Ohta, S.; Sasaki, S.; Tweedie, R. J.; Zanotti, J. M.
2008-05-02
We present results for the nucleon axial charge g{sub A} at a fixed lattice spacing of 1/a=1.73(3) GeV using 2+1 flavors of domain wall fermions on size 16{sup 3}x32 and 24{sup 3}x64 lattices (L=1.8 and 2.7 fm) with length 16 in the fifth dimension. The length of the Monte Carlo trajectory at the lightest m{sub {pi}} is 7360 units, including 900 for thermalization. We find finite volume effects are larger than the pion mass dependence at m{sub {pi}}=330 MeV. We also find a scaling with the single variable m{sub {pi}}L which can also be seen in previous two-flavor domain wall and Wilson fermion calculations. Using this scaling to eliminate the finite-volume effect, we obtain g{sub A}=1.20(6)(4) at the physical pion mass, m{sub {pi}}=135 MeV, where the first and second errors are statistical and systematic. The observed finite-volume scaling also appears in similar quenched simulations, but disappear when V{>=}(2.4 fm){sup 3}. We argue this is a dynamical quark effect.
Quark seesaw, vectorlike fermions and diphoton excess
NASA Astrophysics Data System (ADS)
Dev, P. S. Bhupal; Mohapatra, Rabindra N.; Zhang, Yongchao
2016-02-01
We present a possible interpretation of the recent diphoton excess reported by the early √{s}=13 TeV LHC data in quark seesaw left-right models with vectorlike fermions proposed to solve the strong CP problem without the axion. The gauge singlet real scalar field responsible for the mass of the vectorlike fermions has the right production cross section and diphoton branching ratio to be identifiable with the reported excess at around 750 GeV diphoton invariant mass. Various ways to test this hypothesis as more data accumulates at the LHC are proposed.
Condensation of gauge interacting massless fermions
Siringo, Fabio
2004-09-15
A single massless fermionic field with an Abelian U(1) gauge interaction (electrodynamics of a massless Dirac fermion) is studied by a variational method. Even without the insertion of any extra interaction the vacuum is shown to be unstable towards a particle-antiparticle condensate. The single particle excitations do acquire a mass and behave as massive Fermi particles. An explicit low-energy gap equation has been derived and numerically solved. Some consequences of condensation and mass generation are discussed in the framework of the standard model.
Implementation of the Duality between Wilson Loops and Scattering Amplitudes in QCD
Makeenko, Yuri; Olesen, Poul
2009-02-20
We generalize modern ideas about the duality between Wilson loops and scattering amplitudes in N=4 super Yang-Mills theory to large-N (or quenched) QCD. We show that the area-law behavior of asymptotically large Wilson loops is dual to the Regge-Veneziano behavior of scattering amplitudes at high energies and fixed momentum transfer, when the quark mass is small and/or the number of particles is large. We elaborate on this duality for string theory in flat space, identifying the asymptotes of the disk amplitude and the Wilson loop of large-N QCD.
Bold Diagrammatic Monte Carlo for Fermionic and Fermionized Systems
NASA Astrophysics Data System (ADS)
Svistunov, Boris
2013-03-01
In three different fermionic cases--repulsive Hubbard model, resonant fermions, and fermionized spins-1/2 (on triangular lattice)--we observe the phenomenon of sign blessing: Feynman diagrammatic series features finite convergence radius despite factorial growth of the number of diagrams with diagram order. Bold diagrammatic Monte Carlo technique allows us to sample millions of skeleton Feynman diagrams. With the universal fermionization trick we can fermionize essentially any (bosonic, spin, mixed, etc.) lattice system. The combination of fermionization and Bold diagrammatic Monte Carlo yields a universal first-principle approach to strongly correlated lattice systems, provided the sign blessing is a generic fermionic phenomenon. Supported by NSF and DARPA
A possible connection between massive fermions and dark energy
Goldman, Terrance; Stephenson, G J; Alsing, P M; Mckellar, B H J
2009-01-01
In a dense cloud of massive fermions interacting by exchange of a light scalar field, the effective mass of the fermion can become negligibly small. As the cloud expands, the effective mass and the total energy density eventually increase with decreasing density. In this regime, the pressure-density relation can approximate that required for dark energy. They apply this phenomenon to the expansion of the Universe with a very light scalar field and infer relations between the parameters available and cosmological observations. Majorana neutrinos at a mass that may have been recently determined, and fermions such as the Lightest Supersymmetric Particle (LSP) may both be consistent with current observations of dark energy.
Chiral perturbation theory for staggered sea quarks and Ginsparg-Wilson valence quarks
Baer, Oliver; Bernard, Claude; Rupak, Gautam; Shoresh, Noam
2005-09-01
We study lattice QCD with staggered sea and Ginsparg-Wilson valence quarks. The Symanzik effective action for this mixed lattice theory, including the lattice spacing contributions of O(a{sup 2}), is derived. Using this effective theory we construct the leading-order chiral Lagrangian. The masses and decay constants of pseudoscalars containing two Ginsparg-Wilson valence quarks are computed at one-loop order.
NASA Astrophysics Data System (ADS)
Iliesiu, Luca; Kos, Filip; Poland, David; Pufu, Silviu S.; Simmons-Duffin, David; Yacoby, Ran
2016-03-01
We study the conformal bootstrap for a 4-point function of fermions < ψψψψ> in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge C T . We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N . We also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.
GENERAL VIEW OF THE WILSON DAM, LOOKING SOUTHEAST, GENERATING PLANT ...
GENERAL VIEW OF THE WILSON DAM, LOOKING SOUTHEAST, GENERATING PLANT IN THE BACKGROUND. - Wilson Dam & Hydroelectric Plant, Spanning Tennessee River at Wilson Dam Road (Route 133), Muscle Shoals, Colbert County, AL
GENERAL VIEW LOOKING NORTHEAST SHOWING THE SWITCHYARD OF THE WILSON ...
GENERAL VIEW LOOKING NORTHEAST SHOWING THE SWITCHYARD OF THE WILSON DAM HYDROELECTRIC GENERATING PLANT. - Wilson Dam & Hydroelectric Plant, Spanning Tennessee River at Wilson Dam Road (Route 133), Muscle Shoals, Colbert County, AL
Reflections on Wilson's "The Quiet Evolution."
ERIC Educational Resources Information Center
Greer, W. Dwaine
1999-01-01
Explores Brent Wilson's report "The Quiet Evolution: Changing the Face of Arts Education," focusing on Wilson's reformulation of discipline-based art education and the methodology of the evaluation. Examines the findings and refers to "The Quiet Evolution Executive Summary." (CMK)
Wilson's disease in an Australian aborigine.
Crawford, D H; Shepherd, R; Cooksley, W G; Patrick, M; Powell, L W
1990-01-01
Wilson's disease is due to a genetically determined defect inherited as an autosomal recessive trait. Most reported cases have been caucasoid. This report describes a case of Wilson's disease in an Australian Aboriginal girl, only the second such case reported. PMID:2129845
John Wilson on the Necessity of Punishment.
ERIC Educational Resources Information Center
Marshall, James D.
1984-01-01
According to John Wilson, the punishment of children is logically necessary, or inevitable, and punishment is the necessary concommitant of serious education. It is argued here that Wilson has not successfully established his case for the necessity of the punishment of children. (RM)
Wilson on Kohlberg and Understanding Reasons.
ERIC Educational Resources Information Center
Nesbitt, Winston
1983-01-01
John Wilson recently criticized Kohlberg's view that at certain stages of their development children are unable to understand moral reasoning of certain kinds. It is argued here that Wilson fails to cast doubt on Kohlberg's view, because his account of what it is to understand a reason is inadequate. (Author/RM)
E. O. Wilson: Toward a Humanistic Biology.
ERIC Educational Resources Information Center
Humanist, 1982
1982-01-01
Contains speeches presented at the 1982 American Humanist Association Annual Conference. The author describes E.O. Wilson's contributions to the development of sociobiology. E.O. Wilson discusses the relationship of sociobiology to the biological and social sciences and to humanism. (AM)
LATTICE QCD THERMODYNAMICS WITH WILSON QUARKS.
EJIRI,S.
2007-11-20
We review studies of QCD thermodynamics by lattice QCD simulations with dynamical Wilson quarks. After explaining the basic properties of QCD with Wilson quarks at finite temperature including the phase structure and the scaling properties around the chiral phase transition, we discuss the critical temperature, the equation of state and heavy-quark free energies.
Power divergences in overlapping Wilson lines
NASA Astrophysics Data System (ADS)
Berwein, Matthias
2016-01-01
We discuss the divergence structure of Wilson line operators with partially overlapping segments on the basis of the cyclic Wilson loop as an explicit example. The generalized exponentiation theorem is used to show the exponentiation and factorization of power divergences for certain linear combinations of associated loop functions.
STS-120 Astronaut Stephanie D. Wilson
NASA Technical Reports Server (NTRS)
2007-01-01
Attired in a training version of her shuttle launch and entry suit, astronaut Stephanie D. Wilson, STS-120 mission specialist, awaits the start of a training session in the Space Vehicle Mockup Facility at Johnson Space Center. Wilson was preparing for her launch aboard Space Shuttle Discovery which occurred on October 23, 2007.
NASA Astrophysics Data System (ADS)
Weiner, Richard M.
2010-05-01
It is conjectured that all known fermions are topological solitons. This could explain the non-observation of bosonic leptons and baryons and provide a physical mechanism for the Pauli exclusion principle.
Fermions from classical statistics
Wetterich, C.
2010-12-15
We describe fermions in terms of a classical statistical ensemble. The states {tau} of this ensemble are characterized by a sequence of values one or zero or a corresponding set of two-level observables. Every classical probability distribution can be associated to a quantum state for fermions. If the time evolution of the classical probabilities p{sub {tau}} amounts to a rotation of the wave function q{sub {tau}}(t)={+-}{radical}(p{sub {tau}}(t)), we infer the unitary time evolution of a quantum system of fermions according to a Schroedinger equation. We establish how such classical statistical ensembles can be mapped to Grassmann functional integrals. Quantum field theories for fermions arise for a suitable time evolution of classical probabilities for generalized Ising models.
Ab initio calculation of the neutron-proton mass difference.
Borsanyi, Sz; Durr, S; Fodor, Z; Hoelbling, C; Katz, S D; Krieg, S; Lellouch, L; Lippert, T; Portelli, A; Szabo, K K; Toth, B C
2015-03-27
The existence and stability of atoms rely on the fact that neutrons are more massive than protons. The measured mass difference is only 0.14% of the average of the two masses. A slightly smaller or larger value would have led to a dramatically different universe. Here, we show that this difference results from the competition between electromagnetic and mass isospin breaking effects. We performed lattice quantum-chromodynamics and quantum-electrodynamics computations with four nondegenerate Wilson fermion flavors and computed the neutron-proton mass-splitting with an accuracy of 300 kilo-electron volts, which is greater than 0 by 5 standard deviations. We also determine the splittings in the Σ, Ξ, D, and Ξcc isospin multiplets, exceeding in some cases the precision of experimental measurements. PMID:25814578
Canonical gravity with fermions
Bojowald, Martin; Das, Rupam
2008-09-15
Canonical gravity in real Ashtekar-Barbero variables is generalized to allow for fermionic matter. The resulting torsion changes several expressions in Holst's original vacuum analysis, which are summarized here. This in turn requires adaptations to the known loop quantization of gravity coupled to fermions, which is discussed on the basis of the classical analysis. As a result, parity invariance is not manifestly realized in loop quantum gravity.
In Brief: Mount Wilson centennial
NASA Astrophysics Data System (ADS)
Showstack, Randy
2008-11-01
The 60-inch reflecting telescope at Mount Wilson Observatory, in southern California, which helped scientists measure the Milky Way and determine our solar system's position within it, celebrates its 100th anniversary in December. ``The 60-inch continued the Copernican Revolution by dethroning the Sun from the center of our galaxy,'' noted observatory director Harold McAlister. The telescope, with its silver-on-glass reflectors, also established the basic design for observatory telescopes on Earth. Capable of operating in several different optical configurations, the telescope was the first one built primarily for photographic and spectrographic use. With its 5-foot-diameter mirror, the telescope was the largest in the world until 1917. The telescope is retired from active science but is made available to groups for viewing astronomical objects. The observatory was founded by astronomer George Ellery Hale under the auspices of the Carnegie Institution of Washington. For more information, visit http://www.mtwilson.edu.
Wilson's disease: An Indian perspective.
Taly, A B; Prashanth, L K; Sinha, S
2009-01-01
Wilson's disease (WD) is an autosomal recessive disease involving a defect of copper transport by the hepatic lysosomes. It leads to excess copper deposition in the liver, the brain, the kidneys and the skeletal system, affecting most commonly children or young adults and running an invariably fatal course if not adequately treated by de-coppering therapy. The last century has witnessed several changes, notable among these are: Increased awareness, improved diagnostic facilities leading to earlier recognition even in the pre-symptomatic phase, clear distinction from its mimics, aggressive therapeutic approaches owing to availability of effective treatment and an overall reduction in the morbidity and mortality. It is widely acknowledged that the disease is not as rare as once believed. Sir SAK Wilson published his landmark article in 1912, but it was only in 1968 that the first patient of WD was reported from our country. Publications from India on WD have focused on phenotypic characterization, documentations of lesser recognized aspects of the disease e.g. seizures, behavior abnormality, speech and cognitive impairment, sub-clinical affection of visual pathway, heart and autonomic function and pre-symptomatic detection. Attempts have been made to understand the clinical heterogeneity of the disease through identification of biochemical and immunological markers, magnetic resonance imaging, neuropathological study and genetic analysis for novel and/or known mutations. Assessment of impairment and severity and effect of various therapeutic interventions namely zinc sulphate on the long-term outcome and quality of life have also been studied. Nevertheless, clinicians often face difficulties in long-term care of these patients. Diagnostic errors leading to delay in diagnosis and initiation of treatment are common, even in patients with positive family history. There is no consensus regarding therapeutic protocols since the use of penicillamine, once a 'gold standard
Heavy fermion behavior explained by bosons
NASA Technical Reports Server (NTRS)
Kallio, A.; Poykko, S.; Apaja, V.
1995-01-01
Conventional heavy fermion (HF) theories require existence of massive fermions. We show that heavy fermion phenomena can also be simply explained by existence of bosons with moderate mass but temperature dependent concentration below the formation temperature T(sub B), which in turn is close to room temperature. The bosons B(++) are proposed to be in chemical equilibrium with a system of holes h(+): B(++) = h(+) + h(+). This equilibrium is governed by a boson breaking function f(T), which determines the decreasing boson density and the increasing fermion density with increasing temperature. Since HF-compounds are hybridized from minimum two elements, we assume in addition existence of another fermion component h(sub s)(+) with temperature independent density. This spectator component is thought to be the main agent in binding the bosons in analogy with electronic or muonic molecules. Using a linear boson breaking function we can explain temperature dependence of the giant linear specific heat coefficient gamma(T) coming essentially from bosons. The maxima in resistivity, Hall coefficient, and susceptibility are explained by boson localization effects due to the Wigner crystallization. The antiferromagnetic transitions in turn are explained by similar localization of the pairing fermion system when their density n(sub h)(T(sub FL)) becomes lower than n(sub WC), the critical density of Wigner crystallization. The model applies irrespective whether a compound is superconducting or not. The same model explains the occurrence of low temperature antiferromagnetism also in high-T(sub c) superconductors. The double transition in UPt3 is proposed to be due to the transition of the pairing fermion liquid from spin polarized to unpolarized state.
Novel Fat-Link Fermion Actions
J. M. Zanotti; S. Bilson-Thompson; F. D. R. Bonnet; P. D. Coddington; D. B. Leinweber; A. G. Williams; J. B. Zhang; W. Melnitchouk; F. X. Lee
2001-07-01
The hadron mass spectrum is calculated in lattice QCD using a novel fat-link clover fermion action in which only the irrelevant operators in the fermion action are constructed using smeared links. The simulations are performed on a 16{sup 3} x 32 lattice with a lattice spacing of a=0.125 fm. We compare actions with n=4 and 12 smearing sweeps with a smearing fraction of 0.7. The n=4 Fat-Link Irrelevant Clover (FLIC) action provides scaling which is superior to mean-field improvement, and offers advantages over nonperturbative 0(a) improvement.
Fermions on one or fewer kinks
Chu Yizen; Vachaspati, Tanmay
2008-01-15
We find the full spectrum of fermion bound states on a Z{sub 2} kink. In addition to the zero mode, there are int[2m{sub f}/m{sub s}] bound states, where m{sub f} is the fermion and m{sub s} the scalar mass. We also study fermion modes on the background of a well-separated kink-antikink pair. Using a variational argument, we prove that there is at least one bound state in this background, and that the energy of this bound state goes to zero with increasing kink-antikink separation, 2L, and faster than e{sup -a2L} where a=min(m{sub s},2m{sub f}). By numerical evaluation, we find some of the low lying bound states explicitly.
The Virtues in John Wilson's Approach to Moral Education.
ERIC Educational Resources Information Center
Tobin, Bernadette
2000-01-01
Explores John Wilson's ideas on moral education, arguing against Wilson's criticism of virtue theory. Evaluates Wilson's account of moral education from the perspective of a neo-Aristotelian sense of morality and moral development. Focuses on a part of Wilson's work, "A New Introduction to Moral Education." (CMK)
NASA Planetary Scientist Profile Emily Wilson
NASA scientist Emily Wilson discusses her work developing miniaturized instruments that measure greenhouse gases in the atmosphere. Her latest instrument, the mini-LHR, works in tandem with AERONET...
Cusped Wilson lines in symmetric representations
NASA Astrophysics Data System (ADS)
Correa, Diego H.; Massolo, Fidel I. Schaposnik; Trancanelli, Diego
2015-08-01
We study the cusped Wilson line operators and Bremsstrahlung functions associated to particles transforming in the rank- k symmetric representation of the gauge group U( N) for super Yang-Mills. We find the holographic D3-brane description for Wilson loops with internal cusps in two different limits: small cusp angle and . This allows for a non-trivial check of a conjectured relation between the Bremsstrahlung function and the expectation value of the 1/2 BPS circular loop in the case of a representation other than the fundamental. Moreover, we observe that in the limit of k ≫ N, the cusped Wilson line expectation value is simply given by the exponential of the 1-loop diagram. Using group theory arguments, this eikonal exponentiation is conjectured to take place for all Wilson loop operators in symmetric representations with large k, independently of the contour on which they are supported.
NASA Astrophysics Data System (ADS)
Marino, Eduardo
The electron, discovered by Thomson by the end of the nineteenth century, was the first experimentally observed particle. The Weyl fermion, though theoretically predicted since a long time, was observed in a condensed matter environment in an experiment reported only a few weeks ago. Is there any linking thread connecting the first and the last observed fermion (quasi)particles? The answer is positive. By generalizing the method known as bosonization, the first time in its full complete form, for a spacetime with 3+1 dimensions, we are able to show that both electrons and Weyl fermions can be expressed in terms of the same boson field, namely the Kalb-Ramond anti-symmetric tensor gauge field. The bosonized form of the Weyl chiral currents lead to the angle-dependent magneto-conductance behavior observed in these systems.
Bonus symmetry for super Wilson loops
NASA Astrophysics Data System (ADS)
Münkler, Hagen
2016-05-01
The Yangian level-one hypercharge generator for the super Wilson loop in { N }=4 supersymmetric Yang-Mills theory is constructed. Moreover, evidence for the presence of a corresponding symmetry generator at all higher levels is provided. The derivation is restricted to the strong-coupling description of the super Wilson loop and based on the construction of novel conserved charges for type IIB superstrings on {{AdS}}5× {{{S}}}5.
Renormalization constants for 2-twist operators in twisted mass QCD
Alexandrou, C.; Constantinou, M.; Panagopoulos, H.; Stylianou, F.; Korzec, T.
2011-01-01
Perturbative and nonperturbative results on the renormalization constants of the fermion field and the twist-2 fermion bilinears are presented with emphasis on the nonperturbative evaluation of the one-derivative twist-2 vector and axial-vector operators. Nonperturbative results are obtained using the twisted mass Wilson fermion formulation employing two degenerate dynamical quarks and the tree-level Symanzik improved gluon action. The simulations have been performed for pion masses in the range of about 450-260 MeV and at three values of the lattice spacing a corresponding to {beta}=3.9, 4.05, 4.20. Subtraction of O(a{sup 2}) terms is carried out by performing the perturbative evaluation of these operators at 1-loop and up to O(a{sup 2}). The renormalization conditions are defined in the RI{sup '}-MOM scheme, for both perturbative and nonperturbative results. The renormalization factors, obtained for different values of the renormalization scale, are evolved perturbatively to a reference scale set by the inverse of the lattice spacing. In addition, they are translated to MS at 2 GeV using 3-loop perturbative results for the conversion factors.
Fermion boson metamorphosis in field theory
Ha, Y.K.
1982-01-01
In two-dimensional field theories many features are especially transparent if the Fermi fields are represented by non-local expressions of the Bose fields. Such a procedure is known as boson representation. Bilinear quantities appear in the Lagrangian of a fermion theory transform, however, as simple local expressions of the bosons so that the resulting theory may be written as a theory of bosons. Conversely, a theory of bosons may be transformed into an equivalent theory of fermions. Together they provide a basis for generating many interesting equivalences between theories of different types. In the present work a consistent scheme for constructing a canonical Fermi field in terms of a real scalar field is developed and such a procedure is valid and consistent with the tenets of quantum field theory is verified. A boson formulation offers a unifying theme in understanding the structure of many theories. This is illustrated by the boson formulation of a multifermion theory with chiral and internal symmetries. The nature of dynamical generation of mass when the theory undergoes boson transmutation and the preservation of continuous chiral symmetry in the massive case are examined. The dynamics of the system depends to a great extent on the specific number of fermions and different models of the same system can have very different properties. Many unusual symmetries of the fermion theory, such as hidden symmetry, duality and triality symmetries, are only manifest in the boson formulation. The underlying connections between some models with U(N) internal symmetry and another class of fermion models built with Majorana fermions which have O(2N) internal symmetry are uncovered.
Polarization of massive fermions in a vortical fluid
NASA Astrophysics Data System (ADS)
Fang, Ren-hong; Pang, Long-gang; Wang, Qun; Wang, Xin-nian
2016-08-01
Fermions become polarized in a vortical fluid due to spin-vorticity coupling. Such a polarization can be calculated from the Wigner function in a quantum kinetic approach. By extending previous results for chiral fermions, we derive the Wigner function for massive fermions up to next-to-leading order in spatial gradient expansion. The polarization density of fermions can be calculated from the axial vector component of the Wigner function and is found to be proportional to the local vorticity ω . The polarizations per particle for fermions and antifermions decrease with the chemical potential and increase with energy (mass). Both quantities approach the asymptotic value ℏ ω /4 in the large energy (mass) limit. The polarization per particle for fermions is always smaller than that for antifermions, whose ratio of fermions to antifermions also decreases with the chemical potential. The polarization per particle on the Cooper-Frye freeze-out hypersurface can also be formulated and is consistent with the previous result of Becattini et al.
Two-dimensional thermofield bosonization II: Massive fermions
Amaral, R.L.P.G.
2008-11-15
We consider the perturbative computation of the N-point function of chiral densities of massive free fermions at finite temperature within the thermofield dynamics approach. The infinite series in the mass parameter for the N-point functions are computed in the fermionic formulation and compared with the corresponding perturbative series in the interaction parameter in the bosonized thermofield formulation. Thereby we establish in thermofield dynamics the formal equivalence of the massive free fermion theory with the sine-Gordon thermofield model for a particular value of the sine-Gordon parameter. We extend the thermofield bosonization to include the massive Thirring model.
Burger, Florian; Feng, Xu; Hotzel, Grit; Jansen, Karl; Petschlies, Marcus; Renner, Dru B.
2013-11-01
We present results for the leading order QCD correction to the anomalous magnetic moment of the muon including the first two generations of quarks as dynamical degrees of freedom. Several light quark masses are examined in order to yield a controlled extrapolation to the physical pion mass. We analyse ensembles for three different lattice spacings and several volumes in order to investigate lattice artefacts and finite-size effects, respectively. We also provide preliminary results for this quantity for two flavours of mass-degenerate quarks at the physical value of the pion mass.
Benjamin, Doug; /Tufts U.
2011-08-01
We combine results from searches by the CDF and D0 Collaborations for a standard model Higgs boson (H) in the processes gg {yields} H {yields} W{sup +}W{sup -} and gg {yields} H {yields} ZZ in p{bar p} collisions at the Fermilab Tevatron Collider at {radical}s = 1.96 TeV. With 8.2 fb{sup -1} of integrated luminosity analyzed at CDF and 8.1 fb{sup -1} at D0, the 95% C.L. upper limit on {sigma}(gg {yields} H) x {Beta}(H {yields} W{sup +}W{sup -}) is 1.01 pb at m{sub H} = 120 GeV, 0.40 pb at m{sub H} = 165 GeV, and 0.47 pb at m{sub H} = 200 GeV. Assuming the presence of a fourth sequential generation of fermions with large masses, we exclude at the 95% Confidence Level a standard-model-like Higgs boson with a mass between 124 and 286 GeV.
NASA Astrophysics Data System (ADS)
Coakley, B.
2001-12-01
While the steady state tectonics of subduction are reasonably well understood, the initiation of subduction is not. Theoretical and modeling studies of subduction initiation require large, sustained in-plane stresses to break the continuous oceanic plate and drive the slab into the mantle before a new subduction zone can be self-sustaining. These studies have identified sediment loading and old, dense oceanic lithosphere associated with passive margins as factors favoring the localization of subduction. Old oceanic lithosphere is also quite strong, increasing the stress necessary to break the plate, making passive margins less appealing as a locale for initiation. In contrast to breaking the plate in-plane, a subduction zone could grow laterally, by crack propagation, extending to join a passive margin. "Primed" by the bouyancy flux of the pre-existing subduction zone, progressive failure along a passive continental margin would disrupt the oceanic lithosphere and become self-sustaining as the dense plate sank into the mantle, accelerating the tear. The Caribbean plate provides an example of how a micro-plate might nucleate a subduction zone through stress concentration. As the Caribbean plate advanced, the subduction zone at its leading, eastern edge was progressively channeled to the south as first Cuba and then Hispanola were jammed against the Bahamas platform. The Antilles arc is the current site of active subduction. The Caribbean plate is being over-ridden at the Muertos trough, south of Puerto Rico, and at the northern limit of South America and is over-riding the Pacific plate on the west and the North American plate on the east. The Caribbean plate is pinned between the three surrounding plates, which may provide the necessary stress concentration which could lead to the development of a new active margin on the East coast of North America. Wilson cycle tectonics, as seen in the Phanerozoic history of North Atlantic passive margins, require that passive
Fermion tunneling from dynamical horizons
NASA Astrophysics Data System (ADS)
Di Criscienzo, R.; Vanzo, L.
2008-06-01
The instability against emission of fermionic particles by the trapping horizon of an evolving black hole is analyzed and confirmed using the Hamilton-Jacobi tunneling method. This method automatically selects one special expression for the surface gravity of a changing horizon. The results also apply to point masses embedded in an expanding universe. As a bonus of the tunneling method, we gain the insight that the surface gravity still defines a temperature parameter as long as the evolution is sufficiently slow that the black-hole pass through a sequence of quasi-equilibrium states, and that black holes should be semi-classically unstable even in a hypothetical world without bosonic fields.
Wilson loops in supersymmetric gauge theories
NASA Astrophysics Data System (ADS)
Pestun, Vasily
This thesis is devoted to several exact computations in four-dimensional supersymmetric gauge field theories. In the first part of the thesis we prove conjecture due to Erickson-Semenoff-Zarembo and Drukker-Gross which relates supersymmetric circular Wilson loop operators in the N = 4 supersymmetric Yang-Mills theory with a Gaussian matrix model. We also compute the partition function and give a new matrix model formula for the expectation value of a supersymmetric circular Wilson loop operator for the pure N = 2 and the N* = 2 supersymmetric Yang-Mills theory on a four-sphere. Circular supersymmetric Wilson loops in four-dimensional N = 2 superconformal gauge theory are treated similarly. In the second part we consider supersymmetric Wilson loops of arbitrary shape restricted to a two-dimensional sphere in the four-dimensional N = 4 supersymmetric Yang-Mills theory. We show that expectation value for these Wilson loops can be exactly computed using a two-dimensional theory closely related to the topological two-dimensional Higgs-Yang-Mills theory, or two-dimensional Yang-Mills theory for the complexified gauge group.
Observation of Weyl fermions in condensed matter
NASA Astrophysics Data System (ADS)
Ding, Hong
In 1929, a German mathematician and physicist Hermann Weyl proposed that a massless solution of the Dirac equation represents a pair of new type of particles, the so-called Weyl fermions. However, their existence in particle physics remains elusive after more than eight decades, e.g., neutrino has been regarded as a Weyl fermion in the Standard Model until it was found to have mass. Recently, significant advances in topological materials have provided an alternative way to realize Weyl fermions in condensed matter as an emergent phenomenon. Weyl semimetals are predicted as a class of topological materials that can be regarded as three-dimensional analogs of graphene breaking time reversal or inversion symmetry. Electrons in a Weyl semimetal behave exactly as Weyl fermions, which have many exotic properties, such as chiral anomaly, magnetic monopoles in the crystal momentum space, and open Fermi arcs on the surface. In this talk I will report our experimental discovery of a Weyl semimetal in TaAs by observing Fermi arcs with a characteristic spin texture in the surface states and Weyl nodes in the bulk states using angle-resolved photoemission spectroscopy.
Xu Feng, Grit Hotzel, Karl Jansen, Marcus Petschlies, Dru B. Renner
2012-12-01
We present the first four-flavour lattice calculation of the leading-order hadronic vacuum polarisation contribution to the anomalous magnetic moment of the muon, a{sub {mu}}{sup hvp}, and the hadronic running of the QED coupling constant, {Delta}{alpha}{sup hvp}{sub QED}(Q{sup 2}). In the heavy sector a mixed-action setup is employed. The bare quark masses are determined from matching the K- and D-meson masses to their physical values. Several light quark masses are used in order to yield a controlled extrapolation to the physical pion mass by utilising a recently proposed improved method. We demonstrate that this method also works in the four-flavour case.
Schaefer, Mark; Schellenberg, Mavi; Merle, Uta; Weiss, Karl Heinz; Stremmel, Wolfgang
2008-01-01
Background In Wilson disease, copper is not sufficiently excreted into bile due to the absence or malfunction of the Wilson protein copper ATPase in the excretory pathway of hepatocytes. Copper is found in sweat. It is unknown if the Wilson protein plays a role in copper excretion into sweat. It is the aim of this study to investigate Wilson protein expression in sweat glands and analysing its effects on copper excretion into sweat in controls and patients with Wilson disease. Methods Immunofluorescent analysis of the Wilson protein in skin samples from normal rat, LEC rat and human skin biopsies were performed. Pilocarpin-induced sweat gland stimulation by iontophoretic transfer adapted from the methods used for cystic fibrosis sweat test was used for sweat induction. Sweat volume, sweat copper concentration, serum ceruloplasmin and serum copper were analysed in 28 Wilson patients and 21 controls. Results The Wilson protein is expressed in human and rat sweat gland epithelia. Copper concentration in sweat is not significantly different between controls and Wilson patients. Wilson patients produce significantly smaller volumes of sweat compared to controls. Sweat production is partially reversible in Wilson patients under medical treatment for Wilson disease or after liver transplantation Conclusion Wilson patients show a reduced sweat production with unaltered sweat copper concentration. The Wilson protein might play an important role in physiological sweat production. PMID:18637198
Mowat-Wilson syndrome affecting 3 siblings.
Ohtsuka, Motoko; Oguni, Hirokazu; Ito, Yasushi; Nakayama, Tomohiro; Matsuo, Mari; Osawa, Makiko; Saito, Kayoko; Yamada, Yasukazu; Wakamatsu, Nobuaki
2008-03-01
We herein report 3 cases of Mowat-Wilson syndrome, characterized by distinct facial features, severe psychomotor retardation, and epilepsy, recurring in 3 siblings from the same parents. The proband was a 15-month-old boy, the youngest of 3 children (2 elder sisters), who was referred to our hospital for the treatment of severe seizures. The clinical features and course of these 3 siblings were compatible with those of previously reported Mowat-Wilson syndrome patients, and all siblings had the same E87X nonsense mutation in ZFHX1B, whereas their mother did not show the mutation. Because Mowat-Wilson syndrome has been caused by de novo mutation in ZFHX1B, germ-line mosaicism should be considered if recurrence in siblings is observed. PMID:18230842
Torus Knot Polynomials and Susy Wilson Loops
NASA Astrophysics Data System (ADS)
Giasemidis, Georgios; Tierz, Miguel
2014-12-01
We give, using an explicit expression obtained in (Jones V, Ann Math 126:335, 1987), a basic hypergeometric representation of the HOMFLY polynomial of ( n, m) torus knots, and present a number of equivalent expressions, all related by Heine's transformations. Using this result, the symmetry and the leading polynomial at large N are explicit. We show the latter to be the Wilson loop of 2d Yang-Mills theory on the plane. In addition, after taking one winding to infinity, it becomes the Wilson loop in the zero instanton sector of the 2d Yang-Mills theory, which is known to give averages of Wilson loops in = 4 SYM theory. We also give, using matrix models, an interpretation of the HOMFLY polynomial and the corresponding Jones-Rosso representation in terms of q-harmonic oscillators.
Wilson surface observables from equivariant cohomology
NASA Astrophysics Data System (ADS)
Alekseev, Anton; Chekeres, Olga; Mnev, Pavel
2015-11-01
Wilson lines in gauge theories admit several path integral descriptions. The first one (due to Alekseev-Faddeev-Shatashvili) uses path integrals over coadjoint orbits. The second one (due to Diakonov-Petrov) replaces a 1-dimensional path integral with a 2-dimensional topological σ-model. We show that this σ-model is defined by the equivariant extension of the Kirillov symplectic form on the coadjoint orbit. This allows to define the corresponding observable on arbitrary 2-dimensional surfaces, including closed surfaces. We give a new path integral presentation of Wilson lines in terms of Poisson σ-models, and we test this presentation in the framework of the 2-dimensional Yang-Mills theory. On a closed surface, our Wilson surface observable turns out to be nontrivial for G non-simply connected (and trivial for G simply connected), in particular we study in detail the cases G=U(1) and G=SO(3).
Microscopic Spectrum of the Wilson Dirac Operator
Damgaard, P. H.; Splittorff, K.; Verbaarschot, J. J. M.
2010-10-15
We calculate the leading contribution to the spectral density of the Wilson Dirac operator using chiral perturbation theory where volume and lattice spacing corrections are given by universal scaling functions. We find analytical expressions for the spectral density on the scale of the average level spacing, and introduce a chiral random matrix theory that reproduces these results. Our work opens up a novel approach to the infinite-volume limit of lattice gauge theory at finite lattice spacing and new ways to extract coefficients of Wilson chiral perturbation theory.
Theoretical Foundation for the Index Theorem on the Lattice with Staggered Fermions
Adams, David H.
2010-04-09
A way to identify the would-be zero modes of staggered lattice fermions away from the continuum limit is presented. Our approach also identifies the chiralities of these modes, and their index is seen to be determined by gauge field topology in accordance with the index theorem. The key idea is to consider the spectral flow of a certain Hermitian version of the staggered Dirac operator. The staggered fermion index thus obtained can be used as a new way to assign the topological charge of lattice gauge fields. In a numerical study in U(1) backgrounds in two dimensions it is found to perform as well as the Wilson index while being computationally more efficient. It can also be expressed as the index of an overlap Dirac operator with a new staggered fermion kernel.