NASA Astrophysics Data System (ADS)
Agashe, Kaustubh; Azatov, Aleksandr; Han, Tao; Li, Yingchuan; Si, Zong-Guo; Zhu, Lijun
2010-05-01
The framework of a warped extra dimension with the standard model (SM) fields propagating in it is a very well-motivated extension of the SM since it can address both the Planck-weak and flavor hierarchy problems of the SM. Within this framework, solution to the little hierarchy problem motivates extending the SM electroweak (EW) 5D gauge symmetry in such a way that its breakdown to the SM delivers the SM Higgs boson. We study signals at the large hadron collider (LHC) for the extra EW (called coset) gauge bosons, a fundamental ingredient of this framework. The coset gauge bosons, due to their unique EW gauge quantum numbers [doublets of SU(2)L], do not couple at leading order to two SM particles. We find that, using the associated production of the charged coset gauge bosons via their coupling to bottom quark and a (light) Kaluza-Klein excitation of the top quark, the LHC can have a 3σ reach of ˜2(2.6)TeV for the coset gauge boson masses with ˜100(1000)fb-1 luminosity. Since current theoretical framework(s) suggest an indirect lower limit on coset gauge boson masses of ≳3TeV, luminosity or energy upgrade of LHC is likely to be crucial in observing these states.
Gauging nonrelativistic field theories using the coset construction
NASA Astrophysics Data System (ADS)
Karananas, Georgios K.; Monin, Alexander
2016-03-01
We discuss how nonrelativistic spacetime symmetries can be gauged in the context of the coset construction. We consider theories invariant under the centrally extended Galilei algebra as well as the Lifshitz one, and we investigate under what conditions they can be supplemented by scale transformations. We also clarify the role of torsion in these theories.
Coset construction of a D-brane gauge field
NASA Astrophysics Data System (ADS)
McArthur, I. N.
2016-04-01
D-branes have a world-volume U (1) gauge field A whose field strength F = dA gives rise to a Born-Infeld term in the D-brane action. Supersymmetry and kappa symmetry transformations of A are traditionally inferred by the requirement that the Born-Infeld term is consistent with both supersymmetry and kappa symmetry of the D-brane action. In this paper, we show that integrability of the assigned supersymmetry transformations leads to an extension of the standard supersymmetry algebra that includes a fermionic central charge. We construct a superspace one-form on an enlarged superspace related by a coset construction to this centrally extended algebra whose supersymmetry and kappa symmetry transformations are derived, rather than inferred. It is shown that under pullback, these transformations are of the form expected for the D-brane U (1) gauge field. We relate these results to manifestly supersymmetric approaches to construction of D-brane actions.
Electroweak Gauge-Higgs Unification Scenario
Hosotani, Yutaka
2008-11-23
In the gauge-Higgs unification scenario 4D Higgs fields are unified with gauge fields in higher dimensions. The electroweak model is constructed in the Randall-Sundrum warped space. The electroweak symmetry is dynamically broken by the Hosotani mechanism due to the top quark contribution. The Higgs mass is predicted to be around 50 GeV with the vanishing ZZH and WWH couplings so that the LEP2 bound for the Higgs mass is evaded.
Electroweak Gauge Models and Lepton Conservation Laws
NASA Astrophysics Data System (ADS)
Atsuji, N.; Ito, I.; Tsai, S. Y.; Kimura, T.; Furuya, K.
1982-04-01
We discuss, in the framework of the spontaneously broken electroweak gauge theory, the connection between the two non-standard lepton conservation laws, i.e., the Konopinski-Mahmoud (KM) scheme and the multiplicative scheme. For this purpose, we take SU(3) as a gauge group and start with KM triplets ({μ}^+,{ν},e^-)_L and (e^+,{ν}^c,{μ}^-)_L. We then point out that the idea of mass generation through the Higgs mechanism naturally gives rise to {μ}-e mixing which, supplemented by the requirement of a {μ}-e symmetry, results in a model of leptons which obeys the multiplicative scheme. This model also provides a mechanism for giving an asymmetrical masses to the electron and muon which otherwise behave symmetrically. An extension of the model to include the heavy lepton and quark sectors is suggested.
LHC signals for warped electroweak charged gauge bosons
NASA Astrophysics Data System (ADS)
Agashe, Kaustubh; Gopalakrishna, Shrihari; Han, Tao; Huang, Gui-Yu; Soni, Amarjit
2009-10-01
We study signals at the LHC for the Kaluza-Klein (KK) excitations of electroweak charged gauge bosons in the framework of the standard model (SM) fields propagating in the bulk of a warped extra dimension. Such a scenario can solve both the Planck-weak and flavor hierarchy problems of the SM. There are two such charged states in this scenario with couplings to light quarks and leptons being suppressed relative to those in the SM, whereas the couplings to top/bottom quarks are enhanced, similar to the case of electroweak neutral gauge bosons previously studied. However, unlike the case of electroweak neutral gauge bosons, there is no irreducible QCD background (including pollution from possibly degenerate KK gluons) for decays to top+bottom final states so that this channel is useful for the discovery of the charged states. Moreover, decays of electroweak charged gauge bosons to longitudinal W, Z and Higgs are enhanced just as for the neutral bosons. However, unlike for the neutral gauge bosons, the purely leptonic (and hence clean) decay mode of the WZ is fully reconstructible so that the ratio of the signal to the SM (electroweak) background can potentially be enhanced by restricting to the resonance region more efficiently. We show that such final states can give sensitivity to 2(3) TeV masses with an integrated luminosity of 100(300)fb-1. We emphasize that improvements in discriminating a QCD jet from a highly boosted hadronically decaying W, and a highly boosted top jet from a bottom jet will enhance the reach for these KK particles, and that the signals we study for the warped extra dimensional model might actually be applicable also to a wider class of nonsupersymmetric models of electroweak symmetry breaking.
Eboli, O.J.P.; Gonzalez-Garcia, M.C.
2004-10-01
We analyze the potential of the CERN Large Hadron Collider (LHC) to study anomalous trilinear vector-boson interactions W{sup +}W{sup -}{gamma} and W{sup +}W{sup -}Z through the single production of electroweak gauge bosons via the weak boson fusion processes qq{yields}qqW({yields}l{sup {+-}}{nu}) and qq{yields}qqZ({yields}l{sup +}l{sup -}) with l=e or {mu}. After a careful study of the standard model backgrounds, we show that the single production of electroweak bosons at the LHC can provide stringent tests on deviations of these vertices from the standard model prediction. In particular, we show that single gauge-boson production exhibits a sensitivity to the couplings {delta}{kappa}{sub Z,{gamma}} similar to that attainable from the analysis of electroweak boson pair production.
CERN LHC signals for warped electroweak neutral gauge bosons
NASA Astrophysics Data System (ADS)
Agashe, Kaustubh; Davoudiasl, Hooman; Gopalakrishna, Shrihari; Han, Tao; Huang, Gui-Yu; Perez, Gilad; Si, Zong-Guo; Soni, Amarjit
2007-12-01
We study signals at the Large Hadron Collider (LHC) for Kaluza-Klein (KK) excitations of the electroweak gauge bosons in the framework with the standard model (SM) gauge and fermion fields propagating in a warped extra dimension. Such a framework addresses both the Planck-weak and flavor hierarchy problems of the SM. Unlike the often studied Z' cases, in this framework, there are three neutral gauge bosons due to the underlying SU(2)L×SU(2)R×U(1)X gauge group in the bulk. Furthermore, couplings of these KK states to light quarks and leptons are suppressed, whereas those to top and bottom quarks are enhanced compared to the SM gauge couplings. Therefore, the production of light quark and lepton states is suppressed relative to other beyond the SM constructions, and the fermionic decays of these states are dominated by the top and bottom quarks, which are, though, overwhelmed by KK gluons dominantly decaying into them. However, as we emphasize in this paper, decays of these states to longitudinal W, Z and Higgs are also enhanced similarly to the case of top and bottom quarks. We show that the W, Z and Higgs final states can give significant sensitivity at the LHC to ˜2(3)TeV KK scale with an integrated luminosity of ˜100fb-1 (˜1ab-1). Since current theoretical framework(s) favor KK masses ≳3TeV, a luminosity upgrade of LHC is likely to be crucial in observing these states.
LHC Higgs signatures from extended electroweak gauge symmetry
NASA Astrophysics Data System (ADS)
Abe, Tomohiro; Chen, Ning; He, Hong-Jian
2013-01-01
We study LHC Higgs signatures from the extended electroweak gauge symmetry SU(2) ⊗ SU(2) ⊗ U(1). Under this gauge structure, we present an effective UV completion of the 3-site moose model with ideal fermion delocalization, which contains two neutral Higgs states ( h, H) plus three new gauge bosons ( W ' , Z '). We study the unitarity, and reveal that the exact E 2 cancellation in the longitudinal V L V L scattering amplitudes is achieved by the joint role of exchanging both spin-1 new gauge bosons W ' /Z ' and spin-0 Higgs bosons h/H. We identify the lighter Higgs state h with mass 125 GeV, and derive the unitarity bound on the mass of heavier Higgs boson H. The parameter space of this model is highly predictive. We study the production and decay signals of this 125 GeV Higgs boson h at the LHC. We demonstrate that the h Higgs boson can naturally have enhanced signals in the diphoton channel gg → h → γγ, while the event rates in the reactions gg → h → W W ∗ and gg → h → ZZ ∗ are generally suppressed relative to the SM expectation. Searching the h Higgs boson via the associated production and the vector boson fusions are also discussed for our model. We further analyze the LHC signals of the heavier Higgs boson H as a new physics discriminator from the SM. For wide mass-ranges of H, we derive constraints from the existing LHC searches, and study the discovery potential of H at the LHC (8 TeV) and LHC (14 TeV).
Natural limits of electroweak model as contraction of its gauge group
NASA Astrophysics Data System (ADS)
Gromov, N. A.
2015-06-01
The low and higher energy limits of the electroweak model are obtained from the first principles of gauge theory. Both limits are given by the same contraction of the gauge group, but for the different consistent rescalings of the field space. Mathematical contraction parameter in both cases is interpreted as energy. Very weak neutrino-matter interactions are explained by zero tending contraction parameter, which depends on neutrino energy. The second consistent rescaling corresponds to the higher energy limit of the electroweak model. At the infinite energy all particles lose mass, electroweak interactions become long-range and are mediated by neutral currents. The limit model represents the development of the early Universe from the big bang up to the end of the first second.
Stability of the Electroweak Vacuum: Gauge Independence and Advanced Precision.
Bednyakov, A V; Kniehl, B A; Pikelner, A F; Veretin, O L
2015-11-13
We perform a manifestly gauge-independent analysis of the vacuum stability in the standard model including two-loop matching, three-loop renormalization group evolution, and pure QCD corrections through four loops. All these ingredients are exact, except that light-fermion masses are neglected. We in turn apply the criterion of nullifying the Higgs self-coupling and its beta function in the modified minimal-subtraction scheme and a recently proposed consistent method for determining the true minimum of the effective Higgs potential that also avoids gauge dependence. Exploiting our knowledge of the Higgs-boson mass, we derive an upper bound on the pole mass of the top quark by requiring that the standard model be stable all the way up to the Planck mass scale and conservatively estimate the theoretical uncertainty. This bound is compatible with the Monte Carlo mass quoted by the Particle Data Group at the 1.3σ level. PMID:26613431
Polarisation of electroweak gauge bosons at the LHC
NASA Astrophysics Data System (ADS)
Stirling, James; Vryonidou, Eleni
2013-05-01
We present results for the polarisation of gauge bosons produced at the LHC. Polarisation effects for W bosons manifest themselves in the angular distributions of the lepton and in the distributions of lepton transverse momentum and missing transverse energy. The polarisation is discussed for a range of different processes producing W bosons such as W+jets and W from top production. The relative contributions of the different polarisation states vary from process to process, reflecting the dynamics of the underlying hardscattering process. We also calculate the polarisation of the Z boson produced in association with QCD jets at the LHC.
Toward electroweak scale cold dark matter with local dark gauge symmetry and beyond the DM EFT
NASA Astrophysics Data System (ADS)
Ko, Pyungwon
2016-06-01
In this talk, I describe a class of electroweak (EW) scale dark matter (DM) models where its stability or longevity are the results of underlying dark gauge symmetries: stable due to unbroken local dark gauge symmetry or topology, or long-lived due to the accidental global symmetry of dark gauge theories. Compared with the usual phenomenological dark matter models (including DM EFT or simplified DM models), DM models with local dark gauge symmetries include dark gauge bosons, dark Higgs bosons and sometimes excited dark matter. And dynamics among these fields are completely fixed by local gauge principle. The idea of singlet portals including the Higgs portal can thermalize these hidden sector dark matter very efficiently, so that these DM could be easily thermal DM. I also discuss the limitation of the usual DM effective field theory or simplified DM models without the full SM gauge symmetry, and emphasize the importance of the full SM gauge symmetry and renormalizability especially for collider searches for DM.
Electroweak gauge-boson production in association with b jets at Hadron Colliders
NASA Astrophysics Data System (ADS)
Febres Cordero, F.; Reina, L.
2015-06-01
The production of both charged and neutral electroweak gauge bosons in association with b jets has attracted a lot of experimental and theoretical attention in recent years because of its central role in the physics programs of both the Fermilab Tevatron and the CERN Large Hadron Collider. The improved level of accuracy achieved both in the theoretical predictions and experimental measurements of these processes can promote crucial developments in modeling b-quark jets and b-quark parton distribution functions, and can provide a more accurate description of some of the most important backgrounds to the measurement of Higgs-boson couplings and several new physics searches. In this paper, we review the status of theoretical predictions for cross sections and kinematic distributions of processes in which an electroweak gauge boson is produced in association with up to two b jets in hadronic collisions, namely p\\bar {p}, pp → V + 1b jet and p\\bar {p}, pp → V + 2b jets with V = W±, Z/γ*, γ. Available experimental measurements at both the Fermilab Tevatron and the CERN Large Hadron Collider are also reviewed and their comparison with theoretical predictions is discussed.
Gamma-ray constraints on dark-matter annihilation to electroweak gauge and Higgs bosons
Fedderke, Michael A.; Kolb, Edward W.; Lin, Tongyan; Wang, Lian-Tao E-mail: Rocky.Kolb@uchicago.edu E-mail: liantaow@uchicago.edu
2014-01-01
Dark-matter annihilation into electroweak gauge and Higgs bosons results in γ-ray emission. We use observational upper limits on the fluxes of both line and continuum γ-rays from the Milky Way Galactic Center and from Milky Way dwarf companion galaxies to set exclusion limits on allowed dark-matter masses. (Generally, Galactic Center γ-ray line search limits from the Fermi-LAT and the H.E.S.S. experiments are most restrictive.) Our limits apply under the following assumptions: a) the dark matter species is a cold thermal relic with present mass density equal to the measured dark-matter density of the universe; b) dark-matter annihilation to standard-model particles is described in the non-relativistic limit by a single effective operator O∝J{sub DM}⋅J{sub SM}, where J{sub DM} is a standard-model singlet current consisting of dark-matter fields (Dirac fermions or complex scalars), and J{sub SM} is a standard-model singlet current consisting of electroweak gauge and Higgs bosons; and c) the dark-matter mass is in the range 5 GeV to 20 TeV. We consider, in turn, the 34 possible operators with mass dimension 8 or lower with non-zero s-wave annihilation channels satisfying the above assumptions. Our limits are presented in a large number of figures, one for each of the 34 possible operators; these limits can be grouped into 13 classes determined by the field content and structure of the operators. We also identify three classes of operators (coupling to the Higgs and SU(2){sub L} gauge bosons) that can supply a 130 GeV line with the desired strength to fit the putative line signal in the Fermi-LAT data, while saturating the relic density and satisfying all other indirect constraints we consider.
Dark matter coupling to electroweak gauge and Higgs bosons: An effective field theory approach
NASA Astrophysics Data System (ADS)
Chen, Jing-Yuan; Kolb, Edward W.; Wang, Lian-Tao
2013-12-01
If dark matter is a new species of particle produced in the early universe as a cold thermal relic (a weakly-interacting massive particle-WIMP), its present abundance, its scattering with matter in direct-detection experiments, its present-day annihilation signature in indirect-detection experiments, and its production and detection at colliders, depend crucially on the WIMP coupling to standard-model (SM) particles. It is usually assumed that the WIMP couples to the SM sector through its interactions with quarks and leptons. In this paper we explore the possibility that the WIMP coupling to the SM sector is via electroweak gauge and Higgs bosons. In the absence of an ultraviolet-complete particle-physics model, we employ effective field theory to describe the WIMP-SM coupling. We consider both scalars and Dirac fermions as possible dark-matter candidates. Starting with an exhaustive list of operators up to dimension 8, we present detailed calculation of dark-matter annihilations to all possible final states, including γγ, γZ, γh, ZZ, Zh, W+W-, hh, and ffbar, and demonstrate the correlations among them. We compute the mass scale of the effective field theory necessary to obtain the correct dark-matter mass density, and well as the resulting photon line signals.
QCD and electroweak interference in Higgs production by gauge boson fusion
Andersen, Jeppe R.; Smillie, Jennifer M.
2007-02-01
We explicitly calculate the contribution to Higgs production at the LHC from the interference between gluon fusion and weak vector boson fusion, and compare it to the pure QCD and pure electroweak result. While the effect is small at tree level, we speculate it will be significantly enhanced by loop effects.
Thermal corrections to Electroweak Decays
NASA Astrophysics Data System (ADS)
Masood, Samina
2016-03-01
We study the electroweak processes at finite temperatures. This includes the decay rates of electroweak gauge bosons and beta decays. Major thermal corrections come from QED type radiative corrections. Heavy mass of the electroweak gauge bosons helps to suppress the radiative corrections due to the electroweak gauge boson loops. Therefore, dominant thermal corrections are due to the photon loops. We also discuss the relevance of our results to astrophysics and cosmology.
NASA Astrophysics Data System (ADS)
Cook, Paul P.; Fleming, Michael
2014-07-01
The algebra A {/D - 3 + + +} dimensionally reduces to the E D-1 symmetry algebra of (12 - D)-dimensional supergravity. An infinite set of five-dimensional gravitational objects embedded in D-dimensions is constructed by identifying the null geodesic motion on cosets embedded in the generalised Kac-Moody algebra A {/D - 3 + + +}. By analogy with super-gravity these are bound states of dual gravitons. The metric interpolates continuously between exotic gravitational solutions generated by the action of an affine sub-group. We investigate mixed-symmetry fields in the brane sigma model, identify actions for the full interpolating bound state and investigate the dualisation of the bound state to a solution of the Einstein-Hilbert action via the Hodge dual on multiforms. We conclude that the Hodge dual is insufficient to reconstruct solutions to the Einstein-Hilbert action from mixed-symmetry tensors.
Electroweak theory based on S U (4 )L⊗U (1 )X gauge group
NASA Astrophysics Data System (ADS)
Long, H. N.; Hue, L. T.; Loi, D. V.
2016-07-01
This paper includes two main parts. In the first part, we present generalized gauge models based on the S U (3 )C⊗S U (4 )L⊗U (1 )X (3-4-1) gauge group with arbitrary electric charges of exotic leptons. The mixing matrix of neutral gauge bosons is analyzed, and the eigenmasses and eigenstates are obtained. The anomaly-free as well as matching conditions are discussed precisely. In the second part, we present a new development of the original 3-4-1 model [R. Foot, H. N. Long, and T. A. Tran, Phys. Rev. D 50, R34 (1994), F. Pisano and V. Pleitez, Phys. Rev. D 51, 3865 (1995).]. Different from previous works, in this paper the neutrinos, with the help of the scalar decuplet H , get the Dirac masses at the tree level. The vacuum expectation value (VEV) of the Higgs boson field in the decuplet H acquiring the VEV responsible for neutrino Dirac mass leads to mixing in separated pairs of singly charged gauge bosons, namely the Standard Model (SM) W boson and K , the new gauge boson acting in the right-handed lepton sector, as well as the singly charged bileptons X and Y . Due to the mixing, there occurs a right-handed current carried by the W boson. From the expression of the electromagnetic coupling constant, ones get the limit of the sine-squared of the Weinberg angle, sin2θW<0.25 , and a constraint on electric charges of extra leptons. In the limit of lepton number conservation, the Higgs sector contains all massless Goldstone bosons for massive gauge bosons and the SM-like Higgs boson. Some phenomenology is discussed.
Signals for new spin-1 resonances in electroweak gauge boson pair production at the LHC
Alves, A.; Eboli, O. J. P.; Netto, D. Goncalves; Gonzalez-Garcia, M. C.; Mizukoshi, J. K.
2009-10-01
The mechanism of electroweak symmetry breaking (EWSB) will be directly scrutinized soon at the CERN Large Hadron Collider. We analyze the LHC potential to look for new vector bosons associated with the EWSB sector, presenting a possible model independent approach to search for these new spin-1 resonances. We show that the analyses of the processes pp{yields}l{sup +}l{sup '-}Ee{sub T}, l{sup {+-}}jjEe{sub T}, l{sup '{+-}}l{sup +}l{sup -}Ee{sub T}, l{sup {+-}}jjEe{sub T}, and l{sup +}l{sup -}jj (with l, l{sup '}=e or {mu} and j=jet) have a large reach at the LHC and can lead to the discovery or exclusion of many EWSB scenarios such as Higgsless models.
Neutral triple electroweak gauge boson production in the large extra-dimension model at the LHC
NASA Astrophysics Data System (ADS)
Kumar, M. C.; Mathews, Prakash; Ravindran, V.; Seth, Satyajit
2012-05-01
We study the prospects of probing large extra-dimension models at the LHC through neutral triple gauge boson production processes. In theories with extra dimensions these processes result from the exchange of a tower of massive graviton modes between the SM particles. We consider γγγ, γγZ, γZZ, and ZZZ production processes, and present our results for various kinematic distributions at the LHC for S=14TeV.
Determination of the spin of new resonances in electroweak gauge boson pair production at the LHC
Eboli, O. J. P.; Fong, Chee Sheng; Gonzalez-Fraile, J.; Gonzalez-Garcia, M. C.
2011-05-01
The appearance of spin-1 resonances associated with the electroweak symmetry breaking sector is expected in many extensions of the standard model. We analyze the CERN Large Hadron Collider potential to probe the spin of possible new charged and neutral vector resonances through the purely leptonic processes pp{yields}Z{sup '{yields}}l{sup +}l{sup '-}Ee{sub T}, and pp{yields}W{sup '{yields}}l{sup '{+-}l+}l{sup -}Ee{sub T}, with l, l{sup '}=e or {mu}. We perform a model-independent analysis and demonstrate that the spin of the new states can be determined with 99% C.L. in a large fraction of the parameter space where these resonances can be observed with 100 fb{sup -1}. We show that the best sensitivity to the spin is obtained by directly studying correlations between the final state leptons, without the need of reconstructing the events in their center-of-mass frames.
Integrable λ-deformations: squashing coset CFTs and AdS5 × S 5
NASA Astrophysics Data System (ADS)
Demulder, Saskia; Sfetsos, Konstantinos; Thompson, Daniel C.
2015-07-01
We examine integrable λ-deformations of SO( n + 1) /SO( n) coset CFTs and their analytic continuations. We provide an interpretation of the deformation as a squashing of the corresponding coset σ-model's target space. We realise the λ-deformation for n = 5 case as a solution to supergravity supported by non-vanishing five-form and dilaton. This interpolates between the coset CFT SO(4 , 2) /SO(4 , 1) × SO(6) /SO(5) constructed as a gauged WZW model and the non-Abelian T-dual of the AdS5 × S 5 spacetime.
Large N reduction on coset spaces
Kawai, Hikaru; Shimasaki, Shinji; Tsuchiya, Asato
2010-04-15
As an extension of our previous work concerning the large N reduction on group manifolds, we study the large N reduction on coset spaces. We show that large N field theories on coset spaces are described by certain corresponding matrix models. We also construct Chern-Simons-like theories on group manifolds and coset spaces, and give their reduced models.
Accomando, E.; Kaiser, A.
2006-05-01
We have analyzed the production of WZ and WW vector-boson pairs at the LHC. These processes give rise to four-fermion final states, and are particularly sensitive to possible nonstandard trilinear gauge-boson couplings. We have studied the interplay between the influence of these anomalous couplings and the effect of the complete logarithmic electroweak O({alpha}) corrections. Radiative corrections to the standard model processes in double-pole approximation and nonstandard terms due to trilinear couplings are implemented into a Monte Carlo program for pp{yields}4f(+{gamma}) with final states involving four or two charged leptons. We numerically investigate purely leptonic final states and find that electroweak corrections can fake new-physics signals, modifying the observables by the same amount and shape, in kinematical regions of statistical significance.
NASA Technical Reports Server (NTRS)
Deng, Robert H.; Herro, Mark A.
1988-01-01
A class of block coset codes with disparity and run-length constraints are studied. They are particularly well suited for high-speed optical fiber links and similar channels, where dc-free pulse formats, channel error control, and low-complexity encoder-decoder implementations are required. The codes are derived by partitioning linear block codes. The encoder and decoder structures are the same as those of linear block codes with only slight modifications. A special class of dc-free coset block codes are derived from BCH codes with specified bounds on minimum distance, disparity, and run length. The codes have low disparity levels (a small running digital sum) and good error-correcting capabilities.
Pangilinan, Monica
2010-05-01
The top quark produced through the electroweak channel provides a direct measurement of the V_{tb} element in the CKM matrix which can be viewed as a transition rate of a top quark to a bottom quark. This production channel of top quark is also sensitive to different theories beyond the Standard Model such as heavy charged gauged bosons termed W'. This thesis measures the cross section of the electroweak produced top quark using a technique based on using the matrix elements of the processes under consideration. The technique is applied to 2.3 fb^{-1} of data from the D0 detector. From a comparison of the matrix element discriminants between data and the signal and background model using Bayesian statistics, we measure the cross section of the top quark produced through the electroweak mechanism σ(p$\\bar{p}$ → tb + X, tqb + X) = 4.30_{-1.20}^{+0.98} pb. The measured result corresponds to a 4.9σ Gaussian-equivalent significance. By combining this analysis with other analyses based on the Bayesian Neural Network (BNN) and Boosted Decision Tree (BDT) method, the measured cross section is 3.94 ± 0.88 pb with a significance of 5.0σ, resulting in the discovery of electroweak produced top quarks. Using this measured cross section and constraining |V_{tb}| < 1, the 95% confidence level (C.L.) lower limit is |V_{tb}| > 0.78. Additionally, a search is made for the production of W' using the same samples from the electroweak produced top quark. An analysis based on the BDT method is used to separate the signal from expected backgrounds. No significant excess is found and 95% C.L. upper limits on the production cross section are set for W' with masses within 600-950 GeV. For four general models of W{prime} boson production using decay channel W' → t$\\bar{p}$, the lower mass limits are the following: M(W'_{L} with SM couplings) > 840 GeV; M(W'_{R}) > 880 GeV or 890 GeV if the right-handed neutrino is
Electroweak results from the tevatron
Wood, D.
1997-01-01
Electroweak results are presented from the CDF and DO experiments based on data collected in recent runs of the Fermilab Tevatron Collider. The measurements include the mass and width of the W boson, the production cross sections of the W and Z bosons, and the W charge asymmetry. Additional results come from studies of events with pairs of electroweak gauge bosons and include limits on anomalous couplings.
Coset Codes Viewed as Terminated Convolutional Codes
NASA Technical Reports Server (NTRS)
Fossorier, Marc P. C.; Lin, Shu
1996-01-01
In this paper, coset codes are considered as terminated convolutional codes. Based on this approach, three new general results are presented. First, it is shown that the iterative squaring construction can equivalently be defined from a convolutional code whose trellis terminates. This convolutional code determines a simple encoder for the coset code considered, and the state and branch labelings of the associated trellis diagram become straightforward. Also, from the generator matrix of the code in its convolutional code form, much information about the trade-off between the state connectivity and complexity at each section, and the parallel structure of the trellis, is directly available. Based on this generator matrix, it is shown that the parallel branches in the trellis diagram of the convolutional code represent the same coset code C(sub 1), of smaller dimension and shorter length. Utilizing this fact, a two-stage optimum trellis decoding method is devised. The first stage decodes C(sub 1), while the second stage decodes the associated convolutional code, using the branch metrics delivered by stage 1. Finally, a bidirectional decoding of each received block starting at both ends is presented. If about the same number of computations is required, this approach remains very attractive from a practical point of view as it roughly doubles the decoding speed. This fact is particularly interesting whenever the second half of the trellis is the mirror image of the first half, since the same decoder can be implemented for both parts.
Quantum groups, braiding matrices and coset models
Itoyama, H.
1989-07-01
We discuss a few results on quantum groups in the context of rational conformal field theory with underlying affine Lie algebras. A vertex-height correspondence - a well-known procedure in solvable lattice models - is introduced in the WZW theory. This leads to a new definition of chiral vertex operator in which the zero mode is given by the q-Clebsch Gordan coefficients. Braiding matrices of coset models are found to factorize into those of the WZW theories. We briefly discuss the construction of the generators of the universal enveloping algebra in Toda field theories. 21 refs., 2 figs.
Unanswered Questions in the Electroweak Theory
Quigg, Chris
2009-11-01
This article is devoted to the status of the electroweak theory on the eve of experimentation at CERN's Large Hadron Collider. A compact summary of the logic and structure of the electroweak theory precedes an examination of what experimental tests have established so far. The outstanding unconfirmed prediction of the electroweak theory is the existence of the Higgs boson, a weakly interacting spin-zero particle that is the agent of electroweak symmetry breaking, the giver of mass to the weak gauge bosons, the quarks, and the leptons. General arguments imply that the Higgs boson or other new physics is required on the TeV energy scale. Indirect constraints from global analyses of electroweak measurements suggest that the mass of the standard-model Higgs boson is less than 200 GeV. Once its mass is assumed, the properties of the Higgs boson follow from the electroweak theory, and these inform the search for the Higgs boson. Alternative mechanisms for electroweak symmetry breaking are reviewed, and the importance of electroweak symmetry breaking is illuminated by considering a world without a specific mechanism to hide the electroweak symmetry. For all its triumphs, the electroweak theory has many shortcomings.
Renton, P.
1990-01-01
The central part of the book consists of a comprehensive discussion of many scattering and decay processes involving electromagnetic, weak and strong interactions. A list of topics includes electron-proton scattering, Compton scattering, muon decay, electron-positron annihilation, photon and hadron structure functions, neutrino-nucleus scattering, Cabibbo theory, tau-lepton decays, W and Z boson decays, mixing phenomena and many others. For most processes, the author presents the appropriate Feynman diagrams, first-order matrix elements and the resulting cross sections or decay rates. The last section of Electroweak Interactions discusses some of the open or unanswered questions in the standard model, including the undiscovered top quark, the Higgs mechanism of electroweak symmetry breaking and detailed tests involving radiative effects. The book concludes with a brief account of ideas that extend beyond the standard model, such as left-right symmetric models, grand unified theories, compositeness, supersymmetry and string theory.
Electroweak Baryogenesis with Anomalous Higgs Couplings
NASA Astrophysics Data System (ADS)
Kobakhidze, Archil; Wu, Lei; Yue, Jason
2016-07-01
In non-linear realisation of the electroweak gauge symmetry, the LHC Higgs boson can be assumed to be a singlet under SU(2)L ⊗ U(1)Y. In such scenario, the Standard Model particle content can be kept but new sets of couplings are allowed. We identify a range of anomalous Higgs cubic and the 𝒞𝒫-violating Higgs-top quark couplings that leads to first order phase transition and successful baryogenesis at the electroweak scale.
Precision Electroweak Physics at the LHC
NASA Astrophysics Data System (ADS)
Freitas, Ayres
2015-04-01
The current status of precision tests of the electroweak Standard Model is summarized, and a short review of the theory input from higher-order loop corrections is given. The most constraining quantities are the masses and couplings of the W and Z bosons, and it is shown how these put strong bounds on various examples of new physics. Furthermore, the impact of current and future LHC data on electroweak precision tests is described in some detail. It is also briefly discussed how measurements of anomalous gauge boson couplings provide complementary information about the electroweak theory.
Demarteau, M.; D0 Collaboration
1993-05-01
Preliminary results from D0 are presented on properties of the W{sup {plus_minus}} and Z{sup 0} electroweak gauge bosons, using final states containing electrons and muons. In particular, preliminary measurements of the W{sup {plus_minus}} and Z{sup 0} production cross sections with decay into final states containing electrons are shown and a status report on the determination of M{sub w}/M{sub z} is given.
Electroweak measurements at the Tevatron
Garcia, Jose E.; /INFN, Pisa
2006-06-01
Recent Electroweak measurements by the CDF and D0 collaborations in p{bar p} collisions {radical}s = 1.96 TeV are presented here. Measurements of W, Z and diboson production cross sections as well as W asymmetry using integrated luminosities up to 800 pb{sup -1} are reviewed. Limits on triple gauge anomalous couplings on diboson production are discussed elsewhere.
NASA Astrophysics Data System (ADS)
Paschos, E. A.
2005-01-01
The electroweak theory unifies two basic forces of nature: the weak force and electromagnetism. This book is a concise introduction to the structure of the electroweak theory and its applications. It describes the structure and properties of field theories with global and local symmetries, leading to the construction of the standard model. It describes the new particles and processes predicted by the theory, and compares them with experimental results. It also covers neutral currents, the properties of W and Z bosons, the properties of quarks and mesons containing heavy quarks, neutrino oscillations, CP-asymmetries in K, D, and B meson decays, and the search for Higgs particles. Each chapter contains problems, stemming from the long teaching experience of the author, to supplement the text. This will be of great interest to graduate students and researchers in elementary particle physics. Password protected solutions are available to lecturers at www.cambridge.org/9780521860987. Each chapter has an introduction highlighting its contents and giving a historical perspective. Chapters are cross-referenced, interrelating concepts and sections of the book. Contains 49 exercises
Electroweak baryogenesis from exotic electroweak symmetry breaking
NASA Astrophysics Data System (ADS)
Blinov, Nikita; Kozaczuk, Jonathan; Morrissey, David E.; Tamarit, Carlos
2015-08-01
We investigate scenarios in which electroweak baryogenesis can occur during an exotic stage of electroweak symmetry breaking in the early Universe. This transition is driven by the expectation value of a new electroweak scalar instead of the standard Higgs field. A later, second transition then takes the system to the usual electroweak minimum, dominated by the Higgs boson, while preserving the baryon asymmetry created in the first transition. We discuss the general requirements for such a two-stage electroweak transition to be suitable for electroweak baryogenesis and present a toy model that illustrates the necessary ingredients. We then apply these results to construct an explicit realization of this scenario within the inert two Higgs doublet model. Despite decoupling the Higgs from the symmetry-breaking transition required for electroweak baryogenesis, we find that this picture generically predicts new light states that are accessible experimentally.
Models of little Higgs and electroweak precision tests
Chen, Mu-Chun; /Fermilab
2006-01-01
The little Higgs idea is an alternative to supersymmetry as a solution to the gauge hierarchy problem. In this note, the author reviews various little Higgs models and their phenomenology with emphasis on the precision electroweak constraints in these models.
Theory and phenomenology of electroweak phase transitions
NASA Astrophysics Data System (ADS)
Patel, Hiren H.
An open problem in cosmology is to explain the origin of baryon abundance implied by observational cosmology. Among the many proposed explanations, electroweak baryogenesis is particularly attractive in that its ingredients is discoverable by modern experiments. The analysis of the electroweak phase transition in the early universe comprises an integral component within the larger study of electroweak baryogenesis. In this work, I make a detailed investigation of the conventional analysis of the electroweak phase transition commonly found in literature, and explicitly demonstrate that results are not independent of the choice of gauge. In its place, I provide a manifestly gauge-independent method for the analysis, review sources of theoretical and numerical uncertainties, and explore avenues for further development. Next, I explore the dynamics of the electroweak phase transition in two minimal extensions of the Standard Model of particle physics. Within these simple models, I describe a novel pattern of electroweak symmetry breaking favorable for baryogenesis that can serve as a paradigm for phase transition analysis in more complicated models.
Electroweak physics results from the Tevatron
Demarteau, M.
1996-11-01
An overview of recent electroweak physics results from the Tevatron is given. Properties of the W{sup {+-}} and Z{sup 0} gauge bosons using final states containing electrons and muons based on large integrated luminosities are presented. In particular, measurements of the W{sup {+-}} and Z{sup 0} production cross sections, the W-charge asymmetry and the measurement of the W-mass are summarized. Gauge boson self interactions are measured by studying gauge boson pair production and Emits on anomalous gauge boson couplings are discussed.
Cosets of meromorphic CFTs and modular differential equations
NASA Astrophysics Data System (ADS)
Gaberdiel, Matthias R.; Hampapura, Harsha R.; Mukhi, Sunil
2016-04-01
Some relations between families of two-character CFTs are explained using a slightly generalised coset construction, and the underlying theories (whose existence was only conjectured based on the modular differential equation) are constructed. The same method also gives rise to interesting new examples of CFTs with three and four characters.
History of electroweak symmetry breaking
NASA Astrophysics Data System (ADS)
Kibble, T. W. B.
2015-07-01
In this talk, I recall the history of the development of the unified electroweak theory, incorporating the symmetry-breaking Higgs mechanism, as I saw it from my standpoint as a member of Abdus Salam's group at Imperial College. I start by describing the state of physics in the years after the Second World War, explain how the goal of a unified gauge theory of weak and electromagnetic interactions emerged, the obstacles encountered, in particular the Goldstone theorem, and how they were overcome, followed by a brief account of more recent history, culminating in the historic discovery of the Higgs boson in 2012.
(Re-)inventing the relativistic wheel: gravity, cosets, and spinning objects
NASA Astrophysics Data System (ADS)
Delacrétaz, Luca V.; Endlich, Solomon; Monin, Alexander; Penco, Riccardo; Riva, Francesco
2014-11-01
Space-time symmetries are a crucial ingredient of any theoretical model in physics. Unlike internal symmetries, which may or may not be gauged and/or spontaneously broken, space-time symmetries do not admit any ambiguity: they are gauged by gravity, and any conceivable physical system (other than the vacuum) is bound to break at least some of them. Motivated by this observation, we study how to couple gravity with the Goldstone fields that non-linearly realize spontaneously broken space-time symmetries. This can be done in complete generality by weakly gauging the Poincaré symmetry group in the context of the coset construction. To illustrate the power of this method, we consider three kinds of physical systems coupled to gravity: superfluids, relativistic membranes embedded in a higher dimensional space, and rotating point-like objects. This last system is of particular importance as it can be used to model spinning astrophysical objects like neutron stars and black holes. Our approach provides a systematic and unambiguous parametrization of the degrees of freedom of these systems.
Inequivalence of coset constructions for spacetime symmetries: Coupling with gravity
NASA Astrophysics Data System (ADS)
Baratella, Pietro; Creminelli, Paolo; Serone, Marco; Trevisan, Gabriele
2016-02-01
We study how the coupling with gravity of theories with nonlinearly realized spacetime symmetries is modified when one changes the parametrization of the coset. As an example, we focus on the so-called Galileon duality: a reparametrization which maps a Galilean invariant action into another one which enjoys the same symmetry. Starting with a standard coupling with gravity, with a parametric separation between the Planck scale and the typical scale of the coset, one ends up with a theory without such a separation. In particular an infinite set of higher-dimension operators are relevant when the superluminality of the Galileon is measurable in the effective theory. This addresses an apparent paradox since superluminality arises in the dual theory even when absent in the original one.
Electroweak corrections and unitarity in linear moose models
Chivukula, R. Sekhar; Simmons, Elizabeth H.; He, H.-J.; Kurachi, Masafumi; Tanabashi, Masaharu
2005-02-01
We calculate the form of the corrections to the electroweak interactions in the class of Higgsless models which can be deconstructed to a chain of SU(2) gauge groups adjacent to a chain of U(1) gauge groups, and with the fermions coupled to any single SU(2) group and to any single U(1) group along the chain. The primary advantage of our technique is that the size of corrections to electroweak processes can be directly related to the spectrum of vector bosons ('KK modes'). In Higgsless models, this spectrum is constrained by unitarity. Our methods also allow for arbitrary background 5D geometry, spatially dependent gauge-couplings, and brane kinetic energy terms. We find that, due to the size of corrections to electroweak processes in any unitary theory, Higgsless models with localized fermions are disfavored by precision electroweak data. Although we stress our results as they apply to continuum Higgsless 5D models, they apply to any linear moose model including those with only a few extra vector bosons. Our calculations of electroweak corrections also apply directly to the electroweak gauge sector of 5D theories with a bulk scalar Higgs boson; the constraints arising from unitarity do not apply in this case.
Electroweak Physics at the Tevatron
Sekaric, J.; /Kansas U.
2011-06-08
The most recent Electroweak results from the Tevatron are presented. The importance of precise Standard Model measurements in the Higgs sector, quantum chromodynamics and searches for new physics is emphasized. Analyzed data correspond to 1-7 fb{sup -1} of integrated luminosity recorded by the CDF and D0 detectors at the Tevatron Collider at {radical}s = 1.96 TeV during the period between 2002-2010. The main goal of the Electroweak (EW) physics is to probe the mechanism of the EW symmetry breaking. An important aspect of these studies is related to precise measurements of the Standard Model (SM) parameters and tests of the SU(2) x U(1) gauge symmetry. Deviations from the SM may be indicative of new physics. Thus, the interplay between the tests of the 'standard' physics and searches for a 'nonstandard' physics is an important aspect of the EW measurements. The observables commonly used in these measurements are cross sections, gauge boson couplings, differential distributions, asymmetries, etc. Besides, many EW processes represent a non-negligible background in a Higgs boson and top quark production, and production of supersymmetric particles. Therefore, the complete and detailed understanding of EW processes is a mandatory precondition for early discoveries of very small new physics signals. Furthermore, several EW analyses represent a proving ground for analysis techniques and statistical treatments used in the Tevatron Higgs searches.
Electroweak fragmentation functions for dark matter annihilation
Cavasonza, Leila Ali; Krämer, Michael; Pellen, Mathieu
2015-02-18
Electroweak corrections can play a crucial role in dark matter annihilation. The emission of gauge bosons, in particular, leads to a secondary flux consisting of all Standard Model particles, and may be described by electroweak fragmentation functions. To assess the quality of the fragmentation function approximation to electroweak radiation in dark matter annihilation, we have calculated the flux of secondary particles from gauge-boson emission in models with Majorana fermion and vector dark matter, respectively. For both models, we have compared cross sections and energy spectra of positrons and antiprotons after propagation through the galactic halo in the fragmentation function approximation and in the full calculation. Fragmentation functions fail to describe the particle fluxes in the case of Majorana fermion annihilation into light fermions: the helicity suppression of the lowest-order cross section in such models cannot be lifted by the leading logarithmic contributions included in the fragmentation function approach. However, for other classes of models like vector dark matter, where the lowest-order cross section is not suppressed, electroweak fragmentation functions provide a simple, model-independent and accurate description of secondary particle fluxes.
Recent Electroweak Results from the Tevatron
Zhu, Junjie; /SUNY, Stony Brook
2009-07-01
W and Z bosons are mainly produced via quark-antiquark annihilations at the Fermilab Tevatron collider. Precision measurements with these gauge bosons provide us with high precision tests of the Standard Model (SM) as well as indirect search for possible new physics beyond the SM. I present the recent electroweak measurements related to single W, Z boson and diboson productions from the CDF and D0 experiments at the Fermilab Tevatron collider.
Electroweak Sudakov Corrections using Effective Field Theory
Chiu Juiyu; Golf, Frank; Kelley, Randall; Manohar, Aneesh V.
2008-01-18
Electroweak Sudakov corrections of the form {alpha}{sup n}log{sup m}s/M{sub W,Z}{sup 2} are summed using renormalization group evolution in soft-collinear effective theory. Results are given for the scalar, vector, and tensor form factors for fermion and scalar particles. The formalism for including massive gauge bosons in soft-collinear effective theory is developed.
Precision experiments in electroweak interactions
Swartz, M.L.
1990-03-01
The electroweak theory of Glashow, Weinberg, and Salam (GWS) has become one of the twin pillars upon which our understanding of all particle physics phenomena rests. It is a brilliant achievement that qualitatively and quantitatively describes all of the vast quantity of experimental data that have been accumulated over some forty years. Note that the word quantitatively must be qualified. The low energy limiting cases of the GWS theory, Quantum Electrodynamics and the V-A Theory of Weak Interactions, have withstood rigorous testing. The high energy synthesis of these ideas, the GWS theory, has not yet been subjected to comparably precise scrutiny. The recent operation of a new generation of proton-antiproton (p{bar p}) and electron-positron (e{sup +}e{sup {minus}}) colliders has made it possible to produce and study large samples of the electroweak gauge bosons W{sup {plus minus}} and Z{sup 0}. We expect that these facilities will enable very precise tests of the GWS theory to be performed in the near future. In keeping with the theme of this Institute, Physics at the 100 GeV Mass Scale, these lectures will explore the current status and the near-future prospects of these experiments.
Chris Quigg
2001-08-10
After a short essay on the current state of particle physics, the author reviews the antecedents of the modern picture of the weak and electromagnetic interactions and then undertakes a brief survey of the SU(2){sub L} {circle_times} U(1){sub Y} electroweak theory. The authors reviews the features of electroweak phenomenology at tree level and beyond, presents an introduction to the Higgs boson and the 1-TeV scale, and examines arguments for enlarging the electroweak theory. The author concludes with a brief look at low-scale gravity.
Precision electroweak measurements
Demarteau, M.
1996-11-01
Recent electroweak precision measurements fro {ital e}{sup +}{ital e}{sup -} and {ital p{anti p}} colliders are presented. Some emphasis is placed on the recent developments in the heavy flavor sector. The measurements are compared to predictions from the Standard Model of electroweak interactions. All results are found to be consistent with the Standard Model. The indirect constraint on the top quark mass from all measurements is in excellent agreement with the direct {ital m{sub t}} measurements. Using the world`s electroweak data in conjunction with the current measurement of the top quark mass, the constraints on the Higgs` mass are discussed.
D. S. Waters
2004-06-02
Inclusive W and Z production cross-sections have been measured by CDF and certain electroweak parameters extracted with high precision from these measurements. New results on diboson production at the Tevatron are also presented.
A. Sidoti
2003-11-03
The CDF experiment at the Tevatron has used p{bar p} collisions at {radical}s = 1.96 TeV to perform electroweak physics measurements. A program of precision electroweak tests of SM started measuring W and Z bosons cross section using different leptonic final states, evaluating dielectron Forward-Backward Asymmetry A{sub FB} and di-boson cross section production.
Crucial role of neutrinos in the electroweak symmetry breaking
NASA Astrophysics Data System (ADS)
Smetana, Adam
2013-12-01
Not only the top-quark condensate appears to be the natural significant source of dynamical electroweak symmetry breaking. Provided the seesaw scenario, the neutrinos can have their Dirac masses large enough so that their condensates contribute significantly to the electroweak scale as well. We address the question of a phenomenological feasibility of the top-quark and neutrino condensation conspiracy against the electroweak symmetry within the simplifying two-composite-Higgs-doublet model. Mandatory is to reproduce the masses of electroweak gauge bosons, the top-quark mass and the recently observed scalar mass of 125 GeV, and to satisfy the upper limits on absolute value of active neutrino masses. To accomplish that, the number of right-handed neutrinos participating on the seesaw mechanism turns out to be rather large, O(100-1000).
Crucial role of neutrinos in the electroweak symmetry breaking
Smetana, Adam
2013-12-30
Not only the top-quark condensate appears to be the natural significant source of dynamical electroweak symmetry breaking. Provided the seesaw scenario, the neutrinos can have their Dirac masses large enough so that their condensates contribute significantly to the electroweak scale as well. We address the question of a phenomenological feasibility of the top-quark and neutrino condensation conspiracy against the electroweak symmetry within the simplifying two-composite-Higgs-doublet model. Mandatory is to reproduce the masses of electroweak gauge bosons, the top-quark mass and the recently observed scalar mass of 125 GeV, and to satisfy the upper limits on absolute value of active neutrino masses. To accomplish that, the number of right-handed neutrinos participating on the seesaw mechanism turns out to be rather large, O(100–1000)
Nodulman, L.; CDF Collaboration
1996-06-01
The CDF collaboration is engaged in a broad program of electroweak measurements. The production of WW, WZ, ZZ, W{sub {gamma}}, Z{sub {gamma}} and the high mass Drell Yan charge asymmetry will be discussed, along with a status report on extracting a new W mass from the most recent 90 pb{sup {minus}1} data sample.
Electroweak asymmetries from SLD
Bellodi, G.
2002-06-01
We present a summary of the results on electroweak asymmetries performed by the SLD experiment at the Stanford Linear Collider (SLC). Most of these results are final and are based, unless otherwise stated, on the full 1993-1998 data set of approximately 550,000 hadronic decays of Z{sup 0} bosons, produced with an average electron beam polarization of 73%.
Review of Physics Results from the Tevatron. Electroweak Physics
Kotwal, Ashutosh V.; Schellman, Heidi; Sekaric, Jadranka
2015-02-17
We summarize an extensive Tevatron (1984–2011) electroweak physics program that involves a variety of W and Z boson precision measurements. The relevance of these studies using single and associated gauge boson production to our understanding of the electroweak sector, quantum chromodynamics and searches for new physics is emphasized. Furthermore,we discuss the importance of the W boson mass measurement, the W/Z boson distributions and asymmetries, and diboson studies. We also highlight the recent Tevatron measurements and prospects for the final Tevatron measurements.
Electroweak standard model with very special relativity
NASA Astrophysics Data System (ADS)
Alfaro, Jorge; González, Pablo; Ávila, Ricardo
2015-05-01
The very special relativity electroweak Standard Model (VSR EW SM) is a theory with SU (2 )L×U (1 )R symmetry, with the same number of leptons and gauge fields as in the usual Weinberg-Salam model. No new particles are introduced. The model is renormalizable and unitarity is preserved. However, photons obtain mass and the massive bosons obtain different masses for different polarizations. Besides, neutrino masses are generated. A VSR-invariant term will produce neutrino oscillations and new processes are allowed. In particular, we compute the rate of the decays μ →e +γ . All these processes, which are forbidden in the electroweak Standard Model, put stringent bounds on the parameters of our model and measure the violation of Lorentz invariance. We investigate the canonical quantization of this nonlocal model. Second quantization is carried out, and we obtain a well-defined particle content. Additionally, we do a counting of the degrees of freedom associated with the gauge bosons involved in this work, after spontaneous symmetry breaking has been realized. Violations of Lorentz invariance have been predicted by several theories of quantum gravity [J. Alfaro, H. Morales-Tecotl, and L. F. Urrutia, Phys. Rev. Lett. 84, 2318 (2000); Phys. Rev. D 65, 103509 (2002)]. It is a remarkable possibility that the low-energy effects of Lorentz violation induced by quantum gravity could be contained in the nonlocal terms of the VSR EW SM.
Electroweak baryogenesis with anomalous Higgs couplings
NASA Astrophysics Data System (ADS)
Kobakhidze, Archil; Wu, Lei; Yue, Jason
2016-04-01
We investigate feasibility of efficient baryogenesis at the electroweak scale within the effective field theory framework based on a non-linear realisation of the electroweak gauge symmetry. In this framework the LHC Higgs boson is described by a singlet scalar field, which, therefore, admits new interactions. Assuming that Higgs couplings with the eletroweak gauge bosons are as in the Standard Model, we demonstrate that the Higgs cubic coupling and the CP-violating Higgs-top quark anomalous couplings alone may drive the a strongly first-order phase transition. The distinguished feature of this transition is that the anomalous Higgs vacuum expectation value is generally non-zero in both phases. We identify a range of anomalous couplings, consistent with current experimental data, where sphaleron rates are sufficiently fast in the `symmetric' phase and are suppressed in the `broken' phase and demonstrate that the desired baryon asymmetry can indeed be generated in this framework. This range of the Higgs anomalous couplings can be further constrained from the LHC Run 2 data and be probed at high luminosity LHC and beyond.
Higgs couplings and electroweak phase transition
NASA Astrophysics Data System (ADS)
Katz, Andrey; Perelstein, Maxim
2014-07-01
We argue that extensions of the Standard Model (SM) with a strongly first-order electroweak phase transition generically predict significant deviations of the Higgs couplings to gluons, photons, and Z bosons from their SM values. Precise experimental measurements of the Higgs couplings at the LHC and at the proposed next-generation facilities will allow for a robust test of the phase transition dynamics. To illustrate this point, in this paper we focus on the scenario in which loops of a new scalar field are responsible for the first-order phase transition, and study a selection of benchmark models with various SM gauge quantum numbers of the new scalar. We find that the current LHC measurement of the Higgs coupling to gluons already excludes the possibility of a first-order phase transition induced by a scalar in a sextet, or larger, representation of the SU(3) c . Future LHC experiments (including HL-LHC) will be able to definitively probe the case when the new scalar is a color triplet. If the new scalar is not colored, an electron-positron Higgs factory, such as the proposed ILC or TLEP, would be required to test the nature of the phase transition. The extremely precise measurement of the Higgsstrahlung cross section possible at such machines will allow for a comprehensive and definitive probe of the possibility of a first-order electroweak phase transition in all models we considered, including the case when the new scalar is a pure gauge singlet.
Optical multi-coset sampling of GHz-band chirped signals
NASA Astrophysics Data System (ADS)
Valley, George C.; Sefler, George A.; Shaw, T. J.; Smith, Stephen L.
2015-03-01
Direct digitization of long, wideband chirped RF signals in the GHz band requires power hungry ADCs and produces large data sets. Here we present an optical scheme to perform multi-coset sampling of such signals with reduced power consumption and smaller data sets. In our scheme a repetitively pulsed femtosecond laser is dispersed to the interpulse time, the RF is modulated on the optical field, and the field is directed to a pair of wavelength-division demultiplexers (WDM). The channels of the WDM are attenuated with a pseudo-random sequence to form a coset pattern that repeats at the laser repetition rate. After a photodiode, the photocurrent is integrated for the duration of the dispersed optical pulse so that the coset pattern non-uniformly samples the RF signal. Since the laser repetition rate is uncorrelated with the RF, each coset provides an independent measurement of the RF. Experimental and numerical results show that 4 properties of the RF chirp pulse can be determined from the multiple coset samples: carrier frequency, chirp rate, start time, and pulse duration. Results are presented for a 20MHz chirp on a 13 microsecond pulse at a carrier of 2.473 GHz.
Mass of the electroweak monopole
NASA Astrophysics Data System (ADS)
Kimm, Kyoungtae; Yoon, J. H.; Oh, S. H.; Cho, Y. M.
2016-03-01
We present three independent methods to estimate the mass of the electroweak monopole. Our result strongly implies the existence of a genuine electroweak monopole of mass around 4-10 TeV, which could be detected by MoEDAL at present Large Hadron Collider (LHC). We emphasize that the discovery of the electroweak monopole should be the final test of the Standard Model.
NASA Astrophysics Data System (ADS)
He, Hong-Jian
1998-08-01
We review the recent progress in studying the anomalous electroweak quartic gauge boson couplings (QGBCs) at the LHC and the next generation high energy e±e- linear colliders (LCs). The main focus is put onto the strong electroweak symmetry breaking scenario in which the non-decoupling guarantees sizable new physics effects for the QGBCs. After commenting upon the current low energy indirect bounds and summarizing the theoretical patterns of QGBCs predicted by the typical resonance/non-resonance models, we review our systematic model-independent analysis on bounding them via WW-fusion and WWZ/ZZZ-production. The interplay of the two production mechanisms and the important role of the beam-polarization at the LCs are emphasized. The same physics may be similarly and better studied at a multi-TeV muon collider with high luminosity.
Eboli, O. J. P.; Gonzalez-Garcia, M. C.; Mizukoshi, J. K.
2006-10-01
We analyze the potential of the CERN Large Hadron Collider (LHC) to study the structure of quartic vector-boson interactions through the pair production of electroweak gauge bosons via weak boson fusion qq{yields}qqWW. In order to study these couplings we have performed a partonic level calculation of all processes pp{yields}jje{sup {+-}}{mu}{sup {+-}}{nu}{nu} and pp{yields}jje{sup {+-}}{mu}{sup {+-}}{nu}{nu} at the LHC using the exact matrix elements at O({alpha}{sub em}{sup 6}) and O({alpha}{sub em}{sup 4}{alpha}{sub s}{sup 2}) as well as a full simulation of the tt plus 0 to 2 jets backgrounds. A complete calculation of the scattering amplitudes is necessary not only for a correct description of the process but also to preserve all correlations between the final-state particles which can be used to enhance the signal. Our analyses indicate that the LHC can improve by more than 1 order of magnitude the bounds arising at the present from indirect measurements.
Fused RSOS lattice models as higher-level nonunitary minimal cosets
NASA Astrophysics Data System (ADS)
Tartaglia, Elena; Pearce, Paul A.
2016-05-01
We consider the Forrester-Baxter RSOS lattice models with crossing parameter λ = (m‧-m)π/m‧ in Regime III. In the continuum scaling limit, these models are described by the minimal models { M }(m,{m}\\prime ). We conjecture that, for λ < π/n, the n × n fused RSOS models with n≥slant 2 are described by the higher-level coset {({A}1(1))}k\\otimes {({A}1(1))}n/{({A}1(1))}k+n at fractional level k = nM/(M‧-M)-2 with (M,{M}\\prime )=({nm}-(n-1){m}\\prime ,{m}\\prime ). To support this conjecture, we investigate the one-dimensional sums arising from Baxter’s off-critical corner transfer matrices. In unitary cases (m = m‧-1) it is known that, up to leading powers of q, these coincide with the branching functions {b}r,s,{\\ell }{m\\prime -n,{m}\\prime ,n}(q). For general nonunitary cases (m < m‧-1), we identify the ground state one-dimensional RSOS paths and relate them to the quantum numbers (r, s, ℓ) in the various sectors. For n = 1, 2, 3, we obtain the local energy functions H(a, b, c) in a suitable gauge and verify that the associated one-dimensional sums produce finitized forms that converge, as N becomes large, to the fractional level branching functions {b}r,s,{\\ell }M,{M\\prime ,n}(q). Extending the work of Schilling, we also conjecture finitized bosonic branching functions {b}r,s,{\\ell }M,{M\\prime ,n;(N)}(q) for general n and check that these agree with the one-dimensional sums for n = 1, 2, 3 out to system sizes N = 14. Lastly, the finitized Kac characters {χ }r,s,{\\ell }P,{P\\prime ,n;(N)}(q) of the n × n fused logarithmic minimal models { L }{ M }(p,{p}\\prime ) are obtained by taking the logarithmic limit m,{m}\\prime \\to ∞ with m‧/m→p‧/p+.
FAST TRACK COMMUNICATION: Symmetry breaking, conformal geometry and gauge invariance
NASA Astrophysics Data System (ADS)
Ilderton, Anton; Lavelle, Martin; McMullan, David
2010-08-01
When the electroweak action is rewritten in terms of SU(2) gauge-invariant variables, the Higgs can be interpreted as a conformal metric factor. We show that asymptotic flatness of the metric is required to avoid a Gribov problem: without it, the new variables fail to be nonperturbatively gauge invariant. We also clarify the relations between this approach and unitary gauge fixing, and the existence of similar transformations in other gauge theories.
Canonical coset parametrization and the Bures metric of the three-level quantum systems
Akhtarshenas, S. J.
2007-01-15
An explicit parametrization for the state space of an n-level density matrix is given. The parametrization is based on the canonical coset decomposition of unitary matrices. We also compute, explicitly, the Bures metric tensor over the state space of two- and three-level quantum systems.
Introduction to Electroweak Symmetry Breaking
Dawson,S.
2008-10-02
The Standard Model (SM) is the backbone of elementary particle physics-not only does it provide a consistent framework for studying the interactions of quark and leptons, but it also gives predictions which have been extensively tested experimentally. In these notes, I review the electroweak sector of the Standard Model, discuss the calculation of electroweak radiative corrections to observables, and summarize the status of SM Higgs boson searches. Despite the impressive experimental successes, however, the electroweak theory is not completely satisfactory and the mechanism of electroweak symmetry breaking is untested. I will discuss the logic behind the oft-repeated statement: 'There must be new physics at the TeV scale'. These lectures reflect my strongly held belief that upcoming results from the LHC will fundamentally change our understanding of electroweak symmetry breaking. In these lectures, I review the status of the electroweak sector of the Standard Model, with an emphasis on the importance of radiative corrections and searches for the Standard Model Higgs boson. A discussion of the special role of the TeV energy scale in electroweak physics is included.
Anderson, G.W.
1991-09-16
An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, {l angle}{phi}{r angle}{sub T} is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of {l angle}{phi}{r angle}{sub T}. In very minimal extensions of the standard model it is quite easy to increase {l angle}{phi}{r angle}{sub T} so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value {l angle}{phi}{r angle} = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state {l angle}{phi}{r angle} = 246 GeV unstable. The requirement that the state {l angle}{phi}{r angle} = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field.
Anderson, G.W.
1991-09-16
An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, {l_angle}{phi}{r_angle}{sub T} is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of {l_angle}{phi}{r_angle}{sub T}. In very minimal extensions of the standard model it is quite easy to increase {l_angle}{phi}{r_angle}{sub T} so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value {l_angle}{phi}{r_angle} = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state {l_angle}{phi}{r_angle} = 246 GeV unstable. The requirement that the state {l_angle}{phi}{r_angle} = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field.
NASA Astrophysics Data System (ADS)
Anderson, Gregory Wayne
An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles, and completes at a temperature where the order parameter,
Electroweak symmetry breaking: Higgs/whatever
Chanowitz, M.S.
1989-10-16
In the first of these two lectures the Higgs mechanism is reviewed in its most general form, which does not necessarily require the existence of Higgs bosons. The general consequences of the hypothesis that electroweak symmetry breaking is due to the Higgs mechanism are deduced just from gauge invariance and unitarity. In the second lecture the general properties are illustrated with three specific models: the Weinberg-Salam model, its minimal supersymmetric extension, and technicolor. The second lecture concludes with a discussion of the experiment signals for strong WW scattering, whose presence or absence will allow us to determine whether the symmetry breaking sector lies above or below 1 TeV. 57 refs.
Gedanken Worlds without Higgs: QCD-Induced Electroweak Symmetry Breaking
Quigg, Chris; Shrock, Robert; /YITP, Stony Brook
2009-01-01
To illuminate how electroweak symmetry breaking shapes the physical world, we investigate toy models in which no Higgs fields or other constructs are introduced to induce spontaneous symmetry breaking. Two models incorporate the standard SU(3){sub c} {circle_times} SU(2){sub L} {circle_times} U(1){sub Y} gauge symmetry and fermion content similar to that of the standard model. The first class--like the standard electroweak theory--contains no bare mass terms, so the spontaneous breaking of chiral symmetry within quantum chromodynamics is the only source of electroweak symmetry breaking. The second class adds bare fermion masses sufficiently small that QCD remains the dominant source of electroweak symmetry breaking and the model can serve as a well-behaved low-energy effective field theory to energies somewhat above the hadronic scale. A third class of models is based on the left-right-symmetric SU(3){sub c} {circle_times} SU(2){sub L} {circle_times} SU(2){sub R} {circle_times} U(1)B?L gauge group. In a fourth class of models, built on SU(4){sub PS} {circle_times} SU(2){sub L} {circle_times} SU(2){sub R} gauge symmetry, lepton number is treated as a fourth color. Many interesting characteristics of the models stem from the fact that the effective strength of the weak interactions is much closer to that of the residual strong interactions than in the real world. The Higgs-free models not only provide informative contrasts to the real world, but also lead us to consider intriguing issues in the application of field theory to the real world.
Strong and Electroweak Matter 2004
NASA Astrophysics Data System (ADS)
Eskola, Kari J.; Kainulainen, Kimmo; Kajantie, Keijo; Rummukainen, Kari
results confront models / M. D'Elia and M. P. Lombardo -- Singlet free energies of a static quark-antiquark pair / K. Petrov -- Contributions to transport theory from multi-particle interactions and production processes / M. E. Carrington -- Transport coefficients and the 2PI effective action in the large N limit / G. Aarts and J. M. Martinez Resco -- Thermal features far from equilibrium: prethermalization / S. Borsányi -- QCD phase diagram at small Baryon densities from imaginary [symbol]: status report / O. Philipsen and Ph. de Forcrand -- Two loop renormalisation of the magnetic coupling in hot QCD and spatial Wilson loop / P. Giovannangeli -- Thermodynamics of deconfined QCD at small and large chemical potential / A. Ipp -- Evading the infrared problem of thermal QCD / Y. Schroder -- Chiral mesons in hot matter / A. Gómez Nicola, F. J. Llanes-Estrada and J. R. Peláez -- Thermal production of axinos in the early universe / A. Brandenburg and F. D. Steffen -- The 2-PI-1/N approximation applied to tachyonic preheating / A. Tranberg, A. Arrizabalaga and J. Smit -- Nonequilibrium dynamics in scalar hybrid models / J. Baacke and A. Heinen -- Photon mass in inflation and nearly minimal magnetogenesis / T. Prokopec -- Transport equations for chiral fermions to order [symbol] and electroweak Baryogenesis / S. Weinstock, M. G. Schmidt and T. Prokopec -- The gapless 2SC phase / M. Huang and I. A. Shovkovy -- Gapless CFL and its competition with mixed phases / M. Alford, C. Kouvaris and K. Rajagopal -- Transport coefficients in color superconducting quark matter / C. Manuel -- Renormalization and resummation in finite temperature field theories / A. Jakovác and Zs. Szép -- Renormalization and gauge symmetry for 2PI effective actions / U. Reinosa -- Out-of-equilibrium massless Schwinger model / R. F. Alvarez-Estrada -- Selfconsistent calculations of hadrons at finite temperature / C. Beckmann -- Fermion production in classical fields / D. D. Dietrich -- Numerical study of
The gauge-Higgs legacy of the LHC Run I
NASA Astrophysics Data System (ADS)
Butter, Anja; Éboli, Oscar J. P.; Gonzalez-Fraile, J.; Gonzalez-Garcia, M. C.; Plehn, Tilman; Rauch, Michael
2016-07-01
The effective Lagrangian expansion provides a framework to study effects of new physics at the electroweak scale. To make full use of LHC data in constraining higher-dimensional operators we need to include both the Higgs and the electroweak gauge sector in our study. We first present an analysis of the relevant di-boson production LHC results to update constraints on triple gauge boson couplings. Our bounds are several times stronger than those obtained from LEP data. Next, we show how in combination with Higgs measurements the triple gauge vertices lead to a significant improvement in the entire set of operators, including operators describing Higgs couplings.
Electroweak Baryogenesis and Higgs Properties
Cohen, Timothy; Morrissey, David E.; Pierce, Aaron; /Michigan U., MCTP
2012-03-13
We explore the connection between the strength of the electroweak phase transition and the properties of the Higgs boson. Our interest is in regions of parameter space that can realize electroweak baryogenesis. We do so in a simplified framework in which a single Higgs field couples to new scalar fields charged under SU(3){sub c} by way of the Higgs portal. Such new scalars can make the electroweak phase transition more strongly first-order, while contributing to the effective Higgs boson couplings to gluons and photons through loop effects. For Higgs boson masses in the range 115 {approx}< m{sub h} {approx}< 130 GeV, whenever the phase transition becomes strong enough for successful electroweak baryogenesis, we find that Higgs boson properties are modified by an amount observable by the LHC. We also discuss the baryogenesis window of the minimal supersymmetric standard model (MSSM), which appears to be under tension. Furthermore, we argue that the discovery of a Higgs boson with standard model-like couplings to gluons and photons will rule out electroweak baryogenesis in the MSSM.
Three-point functions in the 𝒩 = 4 orthogonal coset theory
NASA Astrophysics Data System (ADS)
Ahn, Changhyun; Kim, Hyunsu; Paeng, Jinsub
2016-06-01
We construct the lowest higher spin-2 current in terms of the spin-1 and the spin-1 2 currents living in the orthogonal SO(N+4) SO(N)×SO(4) Wolf space coset theory for general N. The remaining 15 higher spin currents are determined. We obtain the three-point functions of bosonic (higher) spin currents with two scalars for finite N and k (the level of the spin-1 current). By multiplying SU(2) × U(1) into the above Wolf space coset theory, the other 15 higher spin currents together with the above lowest higher spin-2 current are realized in the extension of the large 𝒩 = 4 linear superconformal algebra. Similarly, the three-point functions of bosonic (higher) spin currents with two scalars for finite N and k are obtained. Under the large N ’t Hooft limit, the two types of three-point functions in the nonlinear and linear versions coincide as in the unitary coset theory found previously.
Studies of strong electroweak symmetry breaking at future e{sup +}e{sup {minus}} linear colliders
Barklow, T.L.
1994-08-01
Methods of studying strong electroweak symmetry breaking at future e{sup +}e{sup {minus}} linear colliders are reviewed. Specifically, we review precision measurements of triple gauge boson vertex parameters and the rescattering of longitudinal W bosons in the process e{sup +}e{sup {minus}} {yields} W{sup +}W{sup {minus}}. Quantitative estimates of the sensitivity of each technique to strong electroweak symmetry breaking are included.
Electroweak symmetry breaking via QCD.
Kubo, Jisuke; Lim, Kher Sham; Lindner, Manfred
2014-08-29
We propose a new mechanism to generate the electroweak scale within the framework of QCD, which is extended to include conformally invariant scalar degrees of freedom belonging to a larger irreducible representation of SU(3)c. The electroweak symmetry breaking is triggered dynamically via the Higgs portal by the condensation of the colored scalar field around 1 TeV. The mass of the colored boson is restricted to be 350 GeV≲mS≲3 TeV, with the upper bound obtained from perturbative renormalization group evolution. This implies that the colored boson can be produced at the LHC. If the colored boson is electrically charged, the branching fraction of the Higgs boson decaying into two photons can slightly increase, and moreover, it can be produced at future linear colliders. Our idea of nonperturbative electroweak scale generation can serve as a new starting point for more realistic model building in solving the hierarchy problem. PMID:25215976
Chanowitz, M.S.
1990-09-01
The Higgs mechanism is reviewed in its most general form, requiring the existence of a new symmetry-breaking force and associated particles, which need not however be Higgs bosons. The first lecture reviews the essential elements of the Higgs mechanism, which suffice to establish low energy theorems for the scattering of longitudinally polarized W and Z gauge bosons. An upper bound on the scale of the symmetry-breaking physics then follows from the low energy theorems and partial wave unitarity. The second lecture reviews particular models, with and without Higgs bosons, paying special attention to how the general features discussed in lecture 1 are realized in each model. The third lecture focuses on the experimental signals of strong WW scattering that can be observed at the SSC above 1 TeV in the WW subenergy, which will allow direct measurement of the strength of the symmetry-breaking force. 52 refs., 10 figs.
Unparticles and electroweak symmetry breaking
Lee, Jong-Phil
2008-11-23
We investigate a scalar potential inspired by the unparticle sector for the electroweak symmetry breaking. The scalar potential contains the interaction between the standard model fields and unparticle sector. It is described by the non-integral power of fields that originates from the nontrivial scaling dimension of the unparticle operator. It is found that the electroweak symmetry is broken at tree level when the interaction is turned on. The scale invariance of unparticle sector is also broken simultaneously, resulting in a physical Higgs and a new lighter scalar particle.
Fluctuation driven electroweak phase transition
NASA Technical Reports Server (NTRS)
Gleiser, Marcelo; Kolb, Edward W.
1991-01-01
We examine the dynamics of the electroweak phase transition in the early Universe. For Higgs masses in the range 46 less than or = M sub H less than or = 150 GeV and top quark masses less than 200 GeV, regions of symmetric and asymmetric vacuum coexist to below the critical temperature, with thermal equilibrium between the two phases maintained by fluctuations of both phases. We propose that the transition to the asymmetric vacuum is completed by percolation of these subcritical fluctuations. Our results are relevant to scenarios of baryogenesis that invoke a weakly first-order phase transition at the electroweak scale.
Two-step electroweak baryogenesis
NASA Astrophysics Data System (ADS)
Inoue, Satoru; Ovanesyan, Grigory; Ramsey-Musolf, Michael J.
2016-01-01
We analyze electroweak baryogenesis during a two-step electroweak symmetry-breaking transition, wherein the baryon asymmetry is generated during the first step and preserved during the second. Focusing on the dynamics of C P violation required for asymmetry generation, we discuss general considerations for successful two-step baryogenesis. Using a concrete model realization, we illustrate in detail the viability of this scenario and the implications for present and future electric dipole moment (EDM) searches. We find that C P violation associated with a partially excluded sector may yield the observed baryon asymmetry while evading present and future EDM constraints.
Electroweak Theory: Proceedings of the Advanced School on Electroweak Theory
NASA Astrophysics Data System (ADS)
Espriu, D.; Pich, A.
1998-04-01
The Table of Contents for the full book PDF is as follows: * Foreword * Quark Mixing and CP Violation * Heavy Quark Effective Theory * Introduction to Low-Energy Supersymmetry * An Introduction to Dynamical Electroweak Symmetry Breaking * Hadron Colliders, the Top Quark, and the Higgs Sector * Physics Potential of LEP2 and NLC * List of Participants
A supersymmetric extension of quantum gauge theory
NASA Astrophysics Data System (ADS)
Grigore, D. R.; Scharf, G.
2003-01-01
We consider a supersymmetric extension of quantum gauge theory based on a vector multiplet containing supersymmetric partners of spin 3/2 for the vector fields. The constructions of the model follows closely the usual construction of gauge models in the Epstein-Glaser framework for perturbative field theory. Accordingly, all the arguments are completely of quantum nature without reference to a classical supersymmetric theory. As an application we consider the supersymmetric electroweak theory. The resulting self-couplings of the gauge bosons agree with the standard model up to a divergence.
Electroweak and b-physics at the Tevatron collider
Hara, K.
1994-04-01
The CDF and D0 experiments have collected integrated luminosities of 21 pb{sup {minus}1} and 16 pb{sup {minus}1}, respectively, in the 1992--1993 run (Run Ia) at the Fermilab Tevatron. Preliminary results on electroweak physics are reported from both experiments: the W mass, the leptonic branching ratios {Tau}(W {yields} {ell}{nu}), the total W width, gauge boson couplings, W decay asymmetry and W{prime}/Z{prime} search. Preliminary new results on b physics are presented: B{sup o} {minus} {bar B}{sup o} mixing from D0, and masses and lifetimes of B{minus}mesons from CDF.
Strong coupling electroweak symmetry breaking
Barklow, T.L.; Burdman, G.; Chivukula, R.S.
1997-04-01
The authors review models of electroweak symmetry breaking due to new strong interactions at the TeV energy scale and discuss the prospects for their experimental tests. They emphasize the direct observation of the new interactions through high-energy scattering of vector bosons. They also discuss indirect probes of the new interactions and exotic particles predicted by specific theoretical models.
Latest Electroweak Results from CDF
Lancaster, Mark
2010-05-01
The latest results in electroweak physics from proton anti-proton collisions at the Fermilab Tevatron recorded by the CDF detector are presented. The results provide constraints on parton distribution functions, the mass of the Higgs boson and beyond the Standard Model physics.
Moriond Electroweak 2006: Theory summary
Lykken, Joseph D.; /Fermilab
2006-07-01
A concise look at the big picture of particle physics, including the status of the Standard Model, neutrinos, supersymmetry, extra dimensions and cosmology. Based upon the theoretical summary presented at the XLIst Rencontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile, 11-18 March 2006.
Spin and precision electroweak physics
Marciano, W.J.
1993-12-31
A perspective on fundamental parameters and precision tests of the Standard Model is given. Weak neutral current reactions are discussed with emphasis on those processes involving (polarized) electrons. The role of electroweak radiative corrections in determining the top quark mass and probing for ``new physics`` is described.
Insensitive unification of gauge couplings with three vector-like families
Dermisek, Radovan
2013-05-23
The standard model extended by three vector-like families with masses of order 1 TeV - 100 TeV allows for unification of gauge couplings. The values of gauge couplings at the electroweak scale are highly insensitive to fundamental parameters. The grand unification scale is large enough to avoid the problem with fast proton decay. The electroweak minimum of the Higgs potential is stable.
Radiative electroweak symmetry breaking model perturbative all the way to the Planck scale.
Chway, Dongjin; Dermíšek, Radovan; Jung, Tae Hyun; Kim, Hyung Do
2014-08-01
We discuss an extension of the standard model by fields not charged under standard model gauge symmetry in which the electroweak symmetry breaking is driven by the Higgs quartic coupling itself without the need for a negative mass term in the potential. This is achieved by a scalar field S with a large coupling to the Higgs field at the electroweak scale which is driven to very small values at high energies by the gauge coupling of a hidden symmetry under which S is charged. This model can remain perturbative all the way to the Planck scale. The Higgs boson is fully standard-model-like in its couplings to fermions and gauge bosons. However, the effective cubic and quartic self-couplings of the Higgs boson are significantly enhanced. PMID:25126909
Gaussian effective potential for the standard model SU(2)xU(1) electroweak theory
Siringo, Fabio; Marotta, Luca
2008-07-01
The Gaussian effective potential is derived for the non-Abelian SU(2)xU(1) gauge theory of electroweak interactions. At variance with naive derivations, the Gaussian effective potential is proven to be a genuine variational tool in any gauge. The role of ghosts is discussed and the unitarity gauge is shown to be the only choice which allows calculability without insertion of further approximations. The full non-Abelian calculation confirms the existence of a light Higgs boson in the nonperturbative strong coupling regime of the Higgs sector.
NASA Astrophysics Data System (ADS)
Cvetič, M.; Gubser, S. S.; Lü, H.; Pope, C. N.
2000-10-01
A class of conformally flat and asymptotically anti-de Sitter geometries involving profiles of scalar fields is studied from the point of view of gauged supergravity. The scalars involved in the solutions parametrize the SL(N,R)/SO(N) submanifold of the full scalar coset of the gauged supergravity, and are described by a symmetric potential with a universal form. These geometries descend via consistent truncation from distributions of D3-branes, M2-branes, or M5-branes in ten or eleven dimensions. We exhibit analogous solutions asymptotic to AdS6 which descend from the D4-D8-brane system. We obtain the related six-dimensional theory by consistent reduction from massive type IIA supergravity. All our geometries correspond to states in the Coulomb branch of the dual conformal field theories. We analyze linear fluctuations of minimally coupled scalars and find both discrete and continuous spectra, but always bounded below.
Cvetic, M.; Gubser, S. S.; Lu'', H.; Pope, C. N.
2000-10-15
A class of conformally flat and asymptotically anti--de Sitter geometries involving profiles of scalar fields is studied from the point of view of gauged supergravity. The scalars involved in the solutions parametrize the SL(N,R)/SO(N) submanifold of the full scalar coset of the gauged supergravity, and are described by a symmetric potential with a universal form. These geometries descend via consistent truncation from distributions of D3-branes, M2-branes, or M5-branes in ten or eleven dimensions. We exhibit analogous solutions asymptotic to AdS{sub 6} which descend from the D4-D8-brane system. We obtain the related six-dimensional theory by consistent reduction from massive type IIA supergravity. All our geometries correspond to states in the Coulomb branch of the dual conformal field theories. We analyze linear fluctuations of minimally coupled scalars and find both discrete and continuous spectra, but always bounded below.
Electroweak constraints on warped geometry in five dimensions and beyond
NASA Astrophysics Data System (ADS)
Archer, Paul R.; Huber, Stephan J.
2010-10-01
Here we consider the tree level corrections to electroweak (EW) observables from standard model (SM) particles propagating in generic warped extra dimensions. The scale of these corrections is found to be dominated by three parameters, the Kaluza-Klein (KK) mass scale, the relative coupling of the KK gauge fields to the Higgs and the relative coupling of the KK gauge fields to fermion zero modes. It is found that 5D spaces that resolve the hierarchy problem through warping typically have large gauge-Higgs coupling. It is also found in D> 5 where the additional dimensions are warped the relative gauge-Higgs coupling scales as a function of the warp factor. If the warp factor of the additional spaces is contracting towards the IR brane, both the relative gauge-Higgs coupling and resulting EW corrections will be large. Conversely EW constraints could be reduced by finding a space where the additional dimension’s warp factor is increasing towards the IR brane. We demonstrate that the Klebanov Strassler solution belongs to the former of these possibilities.
A few words about resonances in the electroweak effective Lagrangian
NASA Astrophysics Data System (ADS)
Rosell, Ignasi; Pich, Antonio; Santos, Joaquín; Sanz-Cillero, Juan José
2016-01-01
Contrary to a widely spread believe, we have demonstrated that strongly coupled electroweak models including both a light Higgs-like boson and massive spin-1 resonances are not in conflict with experimental constraints on the oblique S and T parameters. We use an effective Lagrangian implementing the chiral symmetry breaking SU (2)L ⊗ SU (2)R → SU (2)L + R that contains the Standard Model gauge bosons coupled to the electroweak Goldstones, one Higgs-like scalar state h with mass mh = 126 GeV and the lightest vector and axial-vector resonance multiplets V and A. We have considered the one-loop calculation of S and T in order to study the viability of these strongly-coupled scenarios, being short-distance constraints and dispersive relations the main ingredients of the calculation. Once we have constrained the resonance parameters, we do a first approach to the determination of the low energy constants of the electroweak effective theory at low energies (without resonances). We show this determination in the case of the purely Higgsless bosonic Lagrangian.
Standard Model Gauge Couplings from Gauge-Dilatation Symmetry Breaking
NASA Astrophysics Data System (ADS)
Odagiri, Kosuke
2014-09-01
It is well known that the self-energy of the gauge bosons is quadratically divergent in the Standard Model when a simple cutoff is imposed. We demonstrate phenomenologically that the quadratic divergences in fact unify. The unification occurs at a surprisingly low scale, GeV. Suppose now that there is a spontaneously broken rotational symmetry between the space-time coordinates and gauge theoretical phases. The symmetry-breaking pattern is such that the gauge bosons arise as the massless Goldstone bosons, whereas the dilatonic mode acts as the massive (Higgs) boson, whose vacuum expectation value determines the gauge couplings. In this case, the quadratic divergences or the tadpoles of the gauge boson self-energy should indeed unify because these divergences need to be cancelled by a universal dilatonic contribution, assuming dynamical symmetry breaking. If there is dynamical symmetry breaking, we are in principle able to calculate the value of the gauge couplings as well as the scale hierarchy . We perform this calculation by adopting a naive quartic symmetry-breaking potential which unfortunately violates local gauge invariance. Using tadpole-cancellation and dilatonic self-energy conditions, the value of is then found to be approximately GeV in the Feynman gauge and GeV in the Landau gauge. The cancellation of an anomaly in the dilaton self-energy requires that the number of fermionic generations equals three. The symmetry-breaking needs to be driven by some other mass-generating mechanism such as electroweak symmetry breaking. Our estimation for is of the correct order if GeV.
Electroweak results from the Tevatron
Demarteau, M.
1995-10-01
Results from the CDF and D{O} experiments are presented on properties of the W{plus_minus} and Z{sup 0} gauge bosons using final states containing electrons and muons based on large integrated luminosities. In particular, measurements of the W{plus_minus} and Z{sup 0} production cross sections, the W-charge asymmetry and the CDF measurement of the W-mass are summarized. Gauge boson self interactions axe measured by studying di-gauge boson production and limits on anomalous gauge boson couplings axe discussed.
Strong Electroweak Symmetry Breaking in the Large Hadron Collider Era
NASA Astrophysics Data System (ADS)
Evans, Jared Andrew
2011-12-01
With the Large Hadron Collider collecting data, both the pursuit of novel detection techniques and the exploration of new ideas are more important than ever. Novel detection techniques are essential in order for the community to garner the most worth from the machine. New ideas are needed both to expand the boundaries of what could be observed and to foster the creative mindset of the community that moves particle physics into fascinating, and often unexpected, directions. Discovering whether electroweak symmetry is broken strongly or weakly is one of the most pressing questions to be answered. Exploring the possibility of strong electroweak symmetry breaking is the topic of this work. The first of two major sectors in this work concerns the theory of conformal technicolor. We present the low energy minimal model for conformal technicolor and verify that it can satisfy current constraints from experiment. We will also provide a UV completion for this model, which realistically extends the sector with high-energy supersymmetry. Two complete models of flavor are presented. This is the first example of a complete, consistent model of strong electroweak symmetry breaking. The second of the two sectors discusses experimental signatures arising in a large class of general technicolor models at the Large Hadron Collider. The possible existence of narrow scalar states that can be produced via gluon-gluon fusion is first discussed. These states can decay into exotic final states of multiple electroweak gauge bosons, third generation particles and even light composite Higgs particles. A two Higgs doublet model is proposed as an effective way to model these exciting states. Lastly, we discuss the array of possible final states and their possible discovery.
Yang-Mills solutions and Spin(7)-instantons on cylinders over coset spaces with G 2-structure
NASA Astrophysics Data System (ADS)
Haupt, Alexander S.
2016-03-01
We study {g} -valued Yang-Mills fields on cylinders Zleft(G/Hright)={R}× G/H , where G/H is a compact seven-dimensional coset space with G 2-structure, {g} is the Lie algebra of G, and Z(G/H) inherits a Spin(7)-structure. After imposing a general G-invariance condition, Yang-Mills theory with torsion on Z(G/H) reduces to Newtonian mechanics of a point particle moving in {{R}}^n under the influence of some quartic potential and possibly additional constraints. The kinematics and dynamics depends on the chosen coset space. We consider in detail three coset spaces with nearly parallel G 2-structure and four coset spaces with SU(3)-structure. For each case, we analyze the critical points of the potential and present a range of finite-energy solutions. We also study a higher-dimensional analog of the instanton equation. Its solutions yield G-invariant Spin(7)-instanton configurations on Z(G/H), which are special cases of Yang-Mills configurations with torsion.
NASA Astrophysics Data System (ADS)
Cohen, Timothy; Craig, Nathaniel; Knapen, Simon
2016-03-01
We propose a simple model of split supersymmetry from gauge mediation. This model features gauginos that are parametrically a loop factor lighter than scalars, accommodates a Higgs boson mass of 125 GeV, and incorporates a simple solution to the μ- b μ problem. The gaugino mass suppression can be understood as resulting from collective symmetry breaking. Imposing collider bounds on μ and requiring viable electroweak symmetry breaking implies small a-terms and small tan β — the stop mass ranges from 105 to 108 GeV. In contrast with models with anomaly + gravity mediation (which also predict a one-loop loop suppression for gaugino masses), our gauge mediated scenario predicts aligned squark masses and a gravitino LSP. Gluinos, electroweakinos and Higgsinos can be accessible at the LHC and/or future colliders for a wide region of the allowed parameter space.
ELECTROWEAK PHYSICS AND PRECISION STUDIES.
MARCIANO, W.
2005-10-24
The utility of precision electroweak measurements for predicting the Standard Model Higgs mass via quantum loop effects is discussed. Current values of m{sub W}, sin{sup 2} {theta}{sub W}(m{sub Z}){sub {ovr MS}} and m{sub t} imply a relatively light Higgs which is below the direct experimental bound but possibly consistent with Supersymmetry expectations. The existence of Supersymmetry is further suggested by a 2{sigma} discrepancy between experiment and theory for the muon anomalous magnetic moment. Constraints from precision studies on other types of ''New Physics'' are also briefly described.
Inflation at the electroweak scale
NASA Technical Reports Server (NTRS)
Knox, Lloyd; Turner, Michael S.
1993-01-01
We present a model for slow-rollover inflation where the vacuum energy that drives inflation is of the order of G(F) exp -2; unlike most models, the conversion of vacuum energy to radiation ('reheating') is moderately efficient. The scalar field responsible for inflation is a standard-model singlet, develops a vacuum expectation value of 4 x 10 exp 6 GeV, has a mass of about 1 GeV, and can play a role in electroweak phenomena. We also discuss models where the energy scale of inflation is somewhat larger, but still well below the unification scale.
Electroweak interactions at the SSC
Cahn, R.N.
1985-08-01
Production of the gauge bosons, W/sup +/, W/sup -/, and Z/sup 0/ in various combinations at the Superconducting Super Collider is considered. Possibilities for producing Higgs bosons and detecting them are then evaluated. 18 refs. (LEW)
Precision electroweak physics at future collider experiments
Baur, U.; Demarteau, M.
1996-11-01
We present an overview of the present status and prospects for progress in electroweak measurements at future collider experiments leading to precision tests of the Standard Model of Electroweak Interactions. Special attention is paid to the measurement of the {ital W} mass, the effective weak mixing angle, and the determination of the top quark mass. Their constraints on the Higgs boson mass are discussed.
13. The su(2|1) Model of Electroweak Interactions and Its Connection to NC Geometry
NASA Astrophysics Data System (ADS)
Häussling, R.
I review the su(2|1) model of electroweak interactions which is essentially based on the super Lie algebra su(2|1), thus incorporating both usual gauge fields and Higgs fields in one generalized Yang-Mills field. Special emphasis is put on the natural appearance of spontaneous symmetry breaking and other appealing features of the model like generation mixing. Also the connection of the model to noncommutative geometry is briefly discussed.
Electroweak corrections to W+W-Z and ZZZ production at the linear collider
NASA Astrophysics Data System (ADS)
Boudjema, F.; Le, D. N.; Sun, H.; Weber, M. M.
2010-07-01
We calculate the electroweak corrections to the production of WWZ and ZZZ at the linear collider in the Standard Model. These processes are important for the extraction of the quartic couplings of the massive gauge bosons which can be a window on the mechanism of spontaneous symmetry breaking. We find that the weak corrections to some kinematic distributions show new features and hence cannot be explained by an overall scale factor.
Progressive gauge U(1) family symmetry for quarks and leptons
NASA Astrophysics Data System (ADS)
Ma, Ernest
2016-08-01
The pattern of quark and lepton mass matrices is unexplained in the standard model of particle interactions. I propose the novel idea of a progressive gauge U (1 ) symmetry where it is a reflection of the regressive electroweak symmetry breaking pattern, caused by an extended Higgs scalar sector. Phenomenological implications of this new hypothesis are discussed.
Electroweak relaxation from finite temperature
NASA Astrophysics Data System (ADS)
Hardy, Edward
2015-11-01
We study theories which naturally select a vacuum with parametrically small Electroweak Scale due to finite temperature effects in the early universe. In particular, there is a scalar with an approximate shift symmetry broken by a technically natural small coupling to the Higgs, and a temperature dependent potential. As the temperature of the universe drops, the scalar follows the minimum of its potential altering the Higgs mass squared parameter. The scalar also has a periodic potential with amplitude proportional to the Higgs expectation value, which traps it in a vacuum with a small Electroweak Scale. The required temperature dependence of the potential can occur through strong coupling effects in a hidden sector that are suppressed at high temperatures. Alternatively, it can be generated perturbatively from a one-loop thermal potential. In both cases, for the scalar to be displaced, a hidden sector must be reheated to temperatures significantly higher than the visible sector. However this does not violate observational constraints provided the hidden sector energy density is transferred to the visible sector without disrupting big bang nucleosynthesis. We also study how the mechanism can be implemented when the visible sector is completed to the Minimal Supersymmetric Standard Model at a high scale. Models with a UV cutoff of 10 TeV and no fields taking values over a range greater than 1012 GeV are possible, although the scalar must have a range of order 108 times the effective decay constant in the periodic part of its potential.
Flavor from the electroweak scale
Bauer, Martin; Carena, Marcela; Gemmler, Katrin
2015-11-04
We discuss the possibility that flavor hierarchies arise from the electroweak scale in a two Higgs doublet model, in which the two Higgs doublets jointly act as the flavon. Quark masses and mixing angles are explained by effective Yukawa couplings, generated by higher dimensional operators involving quarks and Higgs doublets. Modified Higgs couplings yield important effects on the production cross sections and decay rates of the light Standard Model like Higgs. In addition, flavor changing neutral currents arise at tree-level and lead to strong constraints from meson-antimeson mixing. Remarkably, flavor constraints turn out to prefer a region in parameter space that is in excellent agreement with the one preferred by recent Higgs precision measurements at the Large Hadron Collider (LHC). Direct searches for extra scalars at the LHC lead to further constraints. Precise predictions for the production and decay modes of the additional Higgs bosons are derived, and we present benchmark scenarios for searches at the LHC Run II. As a result, flavor breaking at the electroweak scale as well as strong coupling effects demand a UV completion at the scale of a few TeV, possibly within the reach of the LHC.
Flavor from the electroweak scale
Bauer, Martin; Carena, Marcela; Gemmler, Katrin
2015-11-04
We discuss the possibility that flavor hierarchies arise from the electroweak scale in a two Higgs doublet model, in which the two Higgs doublets jointly act as the flavon. Quark masses and mixing angles are explained by effective Yukawa couplings, generated by higher dimensional operators involving quarks and Higgs doublets. Modified Higgs couplings yield important effects on the production cross sections and decay rates of the light Standard Model like Higgs. In addition, flavor changing neutral currents arise at tree-level and lead to strong constraints from meson-antimeson mixing. Remarkably, flavor constraints turn out to prefer a region in parameter spacemore » that is in excellent agreement with the one preferred by recent Higgs precision measurements at the Large Hadron Collider (LHC). Direct searches for extra scalars at the LHC lead to further constraints. Precise predictions for the production and decay modes of the additional Higgs bosons are derived, and we present benchmark scenarios for searches at the LHC Run II. As a result, flavor breaking at the electroweak scale as well as strong coupling effects demand a UV completion at the scale of a few TeV, possibly within the reach of the LHC.« less
Electroweak-scale resonant leptogenesis
Pilaftsis, Apostolos; Underwood, Thomas E.J.
2005-12-01
We study minimal scenarios of resonant leptogenesis near the electroweak phase transition. These models offer a number of testable phenomenological signatures for low-energy experiments and future high-energy colliders. Our study extends previous analyses of the relevant network of Boltzmann equations, consistently taking into account effects from out of equilibrium sphalerons and single lepton flavors. We show that the effects from single lepton flavors become very important in variants of resonant leptogenesis, where the observed baryon asymmetry in the Universe is created by lepton-to-baryon conversion of an individual lepton number, for example, that of the {tau}-lepton. The predictions of such resonant {tau}-leptogenesis models for the final baryon asymmetry are almost independent of the initial lepton-number and heavy neutrino abundances. These models accommodate the current neutrino data and have a number of testable phenomenological implications. They contain electroweak-scale heavy Majorana neutrinos with appreciable couplings to electrons and muons, which can be probed at future e{sup +}e{sup -} and {mu}{sup +}{mu}{sup -} high-energy colliders. In particular, resonant {tau}-leptogenesis models predict sizable 0{nu}{beta}{beta} decay, as well as e- and {mu}-number-violating processes, such as {mu}{yields}e{gamma} and {mu}{yields}e conversion in nuclei, with rates that are within reach of the experiments proposed by the MEG and MECO collaborations.
Higher spin currents with arbitrary N in the = 1 stringy coset minimal model
NASA Astrophysics Data System (ADS)
Ahn, Changhyun
2013-07-01
In the = 1 supersymmetric coset model based on at level ( k, N), the lowest = 1 higher spin supercurrent with , in terms of two independent numerator WZW currents, is reviewed. By calculating the operator product expansions (OPE) between this = 1 higher spin supercurrent and itself, the next two =1 higher spin supercurrents can be generated with and . These four currents are polynomials of degree 3 , 4 , 4 , 4 in the first numerator WZW currents with level k. The complete nonlinear OPE of the lowest = 1 higher spin supercurrent for general N is obtained. The three-point functions involving two scalar primaries with one spin-2 current or spin-3 current are calculated in the large N limit for all values of the 't Hooft coupling. In particular, the light states that appeared in the case when the second level was fixed by 1 are no longer light ones because the eigenvalues are finite in the large N limit.
Coset construction and character sum rules for the doubly extended N = 4 superconformal algebras
NASA Astrophysics Data System (ADS)
Petersen, Jens Lyng; Taormina, Anne
1993-06-01
Character sum rules associated with the realization of the N = 4 superconformal algebra Ãγ on manifolds corresponding to the group cosets SU(3) k˜+ / U(1) are derived and developed as an important tool in obtaining the modular properties of Ãγ characters as well as information on certain extensions of that algebra. Their structure strongly suggests the existence of rational conformal field theories with central charges in the range 1 ⪕ c ⪕ 4. The corresponding characters appear in the massive sector of the sum rules and are completely specified in terms of the characters for the parafermionic theory SU(3)/(SU(2)×U(1)) and in terms of the branching functions of massless Ãγ characters into SU(2) k˜+× SU(2) 1 characters.
Mills, R.
1989-06-01
This article is a survey of the history and ideas of gauge theory. Described here are the gradual emergence of symmetry as a driving force in the shaping of physical theory; the elevation of Noether's theorem, relating symmetries to conservation laws, to a fundamental principle of nature; and the force of the idea (''the gauge principle'') that the symmetries of nature, like the interactions themselves, should be local in character. The fundamental role of gauge fields in mediating the interactions of physics springs from Noether's theorem and the gauge principle in a remarkably clean and elegant way, leaving, however, some tantalizing loose ends that might prove to be the clue to a future deeper level of understanding. The example of the electromagnetic field as the prototype gauge theory is discussed in some detail and serves as the basis for examining the similarities and differences that emerge in generalizing to non-Abelian gauge theories. The article concludes with a brief examination of the dream of total unification: all the forces of nature in a single unified gauge theory, with the differences among the forces due to the specific way in which the fundamental symmetries are broken in the local environment.
A pedagogical review of electroweak symmetry breaking scenarios
NASA Astrophysics Data System (ADS)
Bhattacharyya, Gautam
2011-02-01
We review different avenues of electroweak symmetry breaking explored over the years. This constitutes a timely exercise as the world's largest and the highest energy particle accelerator, namely, the Large Hadron Collider (LHC) at CERN near Geneva, has started running whose primary mission is to find the Higgs or some phenomena that mimic the effects of the Higgs, i.e. to unravel the mysteries of electroweak phase transition. In the beginning, we discuss the Standard Model Higgs mechanism. After that we review the Higgs sector of the minimal supersymmetric Standard Model. Then we take up three relatively recent ideas: little Higgs, gauge-Higgs unification and Higgsless scenarios. For the latter three cases, we first present the basic ideas and restrict our illustration to some instructive toy models to provide an intuitive feel of the underlying dynamics, and then discuss, for each of the three cases, how more realistic scenarios are constructed and how to decipher their experimental signatures. Wherever possible, we provide pedagogical details, which beginners might find useful.
A gravitating electroweak bag model
NASA Astrophysics Data System (ADS)
Burinskii, Alexander
2016-02-01
Gravitational and electromagnetic (EM) field of electron is described by the Kerr-Newman (KN) black hole solution with a topological defect. Regularization of this defect by the Higgs field leads to the smooth source which shares much in common with the known MIT- and SLAC- bag models, but has the advantage, of matching gravitational and electromagnetic fields of the electron. This model is flexible, and the rotating KN bag takes the shape of a thin disk with a circular string positioned on the sharp border of the disk. We consider the lowest excitations of the KN solution and the corresponding deformations of the bag surface, setting a preliminary correspondence with electroweak sector of the SM.
Electroweak Baryogenesis and Colored Scalars
Cohen, Timothy; Pierce, Aaron; /Michigan U., MCTP
2012-02-15
We consider the 2-loop finite temperature effective potential for a Standard Model-like Higgs boson, allowing Higgs boson couplings to additional scalars. If the scalars transform under color, they contribute 2-loop diagrams to the effective potential that include gluons. These 2-loop effects are perhaps stronger than previously appreciated. For a Higgs boson mass of 115 GeV, they can increase the strength of the phase transition by as much as a factor of 3.5. It is this effect that is responsible for the survival of the tenuous electroweak baryogenesis window of the Minimal Supersymmetric Standard Model. We further illuminate the importance of these 2-loop diagrams by contrasting models with colored scalars to models with singlet scalars. We conclude that baryogenesis favors models with light colored scalars. This motivates searches for pair-produced di-jet resonances or jet(s) + = E{sub T}.
On a model of dynamical breaking of the electroweak symmetry
NASA Astrophysics Data System (ADS)
Arbuzov, B. A.
1992-08-01
A model of dynamical breaking of the symmetry of the electroweak interaction is proposed. It is based on a self-consistent mechanism of the appearance of an additional gauge invariant vertex. The conditions of spontaneous symmetry breaking in the mass operators of W, Z and in the form factor of the vertex give a set of equations. There exist solutions breaking the symmetry which bear no contradiction to the existing data. The model defines the Weinberg mixing angle sin 2θw ≈ 0.34 with the possible accuracy of (20-30)%. The mechanism predicts strong W and Z multiple production in e+e- reactions at TeV energies.
NASA Astrophysics Data System (ADS)
Cheng, Michael
2012-03-01
The Standard Model provides an elegant mechanism for electroweak symmetry breaking (EWSB) via the introduction of a scalar Higgs field. However, the Standard Model Higgs mechanism is not the only way to explain EWSB. A class of models, broadly known as Technicolor, postulates the existence of a new strongly-interacting gauge sector at the TeV scale, coupled to the Standard Model through technifermions charged under electroweak. In technicolor, the spontaneous breaking of chiral symmetry triggers EWSB, with the resulting Goldstone bosons ``eaten'' by the massive W, Z gauge bosons. Because they are strongly-coupled and inherently non-perturbative, numerical lattice gauge theory provides an ideal arena in which technicolor can be explored. The maturation of lattice methods and availability of sufficient computing power has spurred the investigation of technicolor using lattice gauge theory techniques, in particular one variant known as ``walking'' technicolor. A technicolor model that resembles QCD is problematic that it does not satisfy the constraints of precision electro-weak observables, most notably those encapsulated by the Peskin-Takeuchi parameters, as well as the contraints on flavor-changing neutral currents. Walking technicolor is a class of models where the theory is near-conformal, i.e. the gauge coupling runs very slowly (``walks'') over some large range of energy scales. This walking behavior produces a large separation of scales between the natural cut-off for the theory and the EWSB scale, allowing one to naturally generate fermion masses without violating contrainsts on flavor-changing neutral currents. The dynamics of walking theories may also allow it to satisfy the bounds on the Peskin-Takeuchi parameters. We discuss the results of recent lattice calculations that explore the properties of walking technicolor models and the its implications on possible physics beyond the Standard Model.
Cosmological properties of a gauged axion
Coriano, Claudio; Mariano, Antonio; Guzzi, Marco; Lazarides, George
2010-09-15
We analyze the most salient cosmological features of axions in extensions of the standard model with a gauged anomalous extra U(1) symmetry. The model is built by imposing the constraint of gauge invariance in the anomalous effective action, which is extended with Wess-Zumino counterterms. These generate axionlike interactions of the axions to the gauge fields and a gauged shift symmetry. The scalar sector is assumed to acquire a nonperturbative potential after inflation, at the electroweak phase transition, which induces a mixing of the Stueckelberg field of the model with the scalars of the electroweak sector, and at the QCD phase transition. We discuss the possible mechanisms of sequential misalignments which could affect the axions of these models, and generated, in this case, at both transitions. We compute the contribution of these particles to dark matter, quantifying their relic densities as a function of the Stueckelberg mass. We also show that models with a single anomalous U(1) in general do not account for the dark energy, due to the presence of mixed U(1)-SU(3) anomalies.
Illuminating new electroweak states at hadron colliders
NASA Astrophysics Data System (ADS)
Ismail, Ahmed; Izaguirre, Eder; Shuve, Brian
2016-07-01
In this paper, we propose a novel powerful strategy to perform searches for new electroweak states. Uncolored electroweak states appear in generic extensions of the Standard Model (SM) and yet are challenging to discover at hadron colliders. This problem is particularly acute when the lightest state in the electroweak multiplet is neutral and all multiplet components are approximately degenerate. In this scenario, production of the charged fields of the multiplet is followed by decay into nearly invisible states; if this decay occurs promptly, the only way to infer the presence of the reaction is through its missing energy signature. Our proposal relies on emission of photon radiation from the new charged states as a means of discriminating the signal from SM backgrounds. We demonstrate its broad applicability by studying two examples: a pure Higgsino doublet and an electroweak quintuplet field.
CP-Violating Sources for Electroweak Baryogenesis
Lee, Christopher
2008-11-23
In this talk I derive the CP-violating sources for the squark number density in the MSSM generated by interactions with the spacetime-varying Higgs vev during a first-order electroweak phase transition.
New strong interactions above the electroweak scale
White, A.R.
1994-08-09
Theoretical arguments for a new higher-color quark sector, based on Pomeron physics in QCD, are briefly described. The electroweak symmetry-breaking, Strong CP conservation, and electroweak scale CP violation, that is naturally produced by this sector is also outlined. A further consequence is that above the electroweak scale there will be a radical change in the strong interaction. Electroweak states, in particular multiple W`s and Z`s, and new, semi-stable, very massive, baryons, will be commonly produced. The possible correlation of expected phenomena with a wide range of observed Cosmic Ray effects at and above the primary spectrum knee is described. Related phenomena that might be seen in the highest energy hard scattering events at the Fermilab Tevatron, some of which could be confused with top production, are also briefly discussed.
An electroweak enigma: Hyperon radiative decays
Vorobyov, A.,; Jastrzembski, E.; Lach, J.; Marriner, J.; Golovtsov, V.; Krivshich, A.; Schegelsky, V.; Smirnov, N.; Terentiev, N.K.; Uvarov, L.; McCliment, E.; Newsom, C.; Norbeck, E.; Cooper, P.S.; /Yale U.
1985-04-03
The main thrust of this experiment will be to measure the asymmetry parameter for the electroweak decay {Sigma}{sup +} {yields} p{gamma} and verify its branching ratio. As a secondary goal they will measure, or set new upper limits for, the branching ratio of the electroweak decay {Xi}{sup -} {yields} {Sigma}{sup -}{gamma}. Since the {Xi}{sup -} are expected to be polarized, information on the asymmetry parameter may also be available.
Betts, Robert E.; Crawford, John F.
1989-04-04
An aging gauge comprising a container having a fixed or a variable sized t opening with a cap which can be opened to control the sublimation rate of a thermally sublimational material contained within the container. In use, the aging gauge is stored with an item to determine total heat the item is subjected to and also the maximum temperature to which the item has been exposed. The aging gauge container contains a thermally sublimational material such as naphthalene or similar material which has a low sublimation rate over the temperature range from about 70.degree. F. to about 160.degree. F. The aging products determined by analyses of a like item aged along with the aging gauge for which the sublimation amount is determined is employed to establish a calibration curve for future aging evaluation. The aging gauge is provided with a means for determining the maximum temperature exposure (i.e., a thermally indicating material which gives an irreversible color change, Thermocolor pigment). Because of the relationship of doubling reaction rates for increases of 10.degree. C., equivalency of item used in accelerated aging evaluation can be obtained by referring to a calibration curve depicting storage temperature on the abscissa scale and multiplier on the ordinate scale.
Betts, Robert E.; Crawford, John F.
1989-01-01
An aging gauge comprising a container having a fixed or a variable sized t opening with a cap which can be opened to control the sublimation rate of a thermally sublimational material contained within the container. In use, the aging gauge is stored with an item to determine total heat the item is subjected to and also the maximum temperature to which the item has been exposed. The aging gauge container contains a thermally sublimational material such as naphthalene or similar material which has a low sublimation rate over the temperature range from about 70.degree. F. to about 160.degree. F. The aging products determined by analyses of a like item aged along with the aging gauge for which the sublimation amount is determined is employed to establish a calibration curve for future aging evaluation. The aging gauge is provided with a means for determining the maximum temperature exposure (i.e., a thermally indicating material which gives an irreversible color change, Thermocolor pigment). Because of the relationship of doubling reaction rates for increases of 10.degree. C., equivalency of item used in accelerated aging evaluation can be obtained by referring to a calibration curve depicting storage temperature on the abscissa scale and multiplier on the ordinate scale.
Singlet-catalyzed electroweak phase transitions and precision Higgs boson studies
NASA Astrophysics Data System (ADS)
Profumo, Stefano; Ramsey-Musolf, Michael J.; Wainwright, Carroll L.; Winslow, Peter
2015-02-01
We update the phenomenology of gauge-singlet extensions of the Standard Model scalar sector and their implications for the electroweak phase transition. Considering the introduction of one real scalar singlet to the scalar potential, we analyze present constraints on the potential parameters from Higgs coupling measurements at the Large Hadron Collider (LHC) and electroweak precision observables for the kinematic regime in which no new scalar decay modes arise. We then show how future precision measurements of Higgs boson signal strengths and the Higgs self-coupling could probe the scalar potential parameter space associated with a strong first-order electroweak phase transition. We illustrate using benchmark precision for several future collider options, including the high-luminosity LHC, the International Linear Collider, Triple-Large Electron-Positron collider, the China Electron-Positron Collider, and a 100 TeV proton-proton collider, such as the Very High Energy LHC or the Super Proton-Proton Collider. For the regions of parameter space leading to a strong first-order electroweak phase transition, we find that there exists considerable potential for observable deviations from purely Standard Model Higgs properties at these prospective future colliders.
Vacuum stability and radiative electroweak symmetry breaking in an SO(10) dark matter model
NASA Astrophysics Data System (ADS)
Mambrini, Yann; Nagata, Natsumi; Olive, Keith A.; Zheng, Jiaming
2016-06-01
Vacuum stability in the Standard Model is problematic as the Higgs quartic self-coupling runs negative at a renormalization scale of about 1010 GeV . We consider a nonsupersymmetric SO(10) grand unification model for which gauge coupling unification is made possible through an intermediate scale gauge group, Gint=SU (3 )C⊗SU (2 )L⊗SU (2 )R⊗U (1 )B -L . Gint is broken by the vacuum expectation value of a 126 of SO(10) which not only provides for neutrino masses through the seesaw mechanism but also preserves a discrete Z2 that can account for the stability of a dark matter candidate, here taken to be the Standard Model singlet component of a bosonic 16 . We show that in addition to these features the model insures the positivity of the Higgs quartic coupling through its interactions to the dark matter multiplet and 126 . We also show that the Higgs mass squared runs negative, triggering electroweak symmetry breaking. Thus, the vacuum stability is achieved along with radiative electroweak symmetry breaking and captures two more important elements of supersymmetric models without low-energy supersymmetry. The conditions for perturbativity of quartic couplings and for radiative electroweak symmetry breaking lead to tight upper and lower limits on the dark matter mass, respectively, and this dark matter mass region (1.35-2 TeV) can be probed in future direct detection experiments.
Electroweak interactions and dark baryons in the sextet BSM model with a composite Higgs particle
NASA Astrophysics Data System (ADS)
Fodor, Zoltan; Holland, Kieran; Kuti, Julius; Mondal, Santanu; Nogradi, Daniel; Wong, Chik Him
2016-07-01
The electroweak interactions of a strongly coupled gauge theory are discussed with an outlook beyond the Standard Model (BSM) under global and gauge anomaly constraints. The theory is built on a minimal massless fermion doublet of the SU(2) BSM flavor group (bsm-flavor) with a confining gauge force at the TeV scale in the two-index symmetric (sextet) representation of the BSM SU(3) color gauge group (bsm-color). The intriguing possibility of near-conformal sextet gauge dynamics could lead to the minimal realization of the composite Higgs mechanism with a light 0++ scalar, far separated from strongly coupled resonances of the confining gauge force in the 2-3 TeV range, distinct from Higgsless technicolor. In previous publications we have presented results for the meson spectrum of the theory, including the light composite scalar, which is perhaps the emergent Higgs impostor. Here we discuss the critically important role of the baryon spectrum in the sextet model investigating its compatibility with what we know about thermal evolution of the early Universe including its galactic and terrestrial relics. For an important application, we report the first numerical results on the baryon spectrum of this theory from nonperturbative lattice simulations with baryon correlators in the staggered fermion implementation of the strongly coupled gauge sector. The quantum numbers of composite baryons and their spectroscopy from lattice simulations are required inputs for exploring dark matter contributions of the sextet BSM model, as outlined for future work.
NASA Astrophysics Data System (ADS)
Das, Arindam; Oda, Satsuki; Okada, Nobuchika; Takahashi, Dai-suke
2016-06-01
We consider the minimal U(1 ) ' extension of the standard model (SM) with the classically conformal invariance, where an anomaly-free U(1 ) ' gauge symmetry is introduced along with three generations of right-handed neutrinos and a U(1 ) ' Higgs field. Since the classically conformal symmetry forbids all dimensional parameters in the model, the U(1 ) ' gauge symmetry is broken by the Coleman-Weinberg mechanism, generating the mass terms of the U(1 ) ' gauge boson (Z' boson) and the right-handed neutrinos. Through a mixing quartic coupling between the U(1 ) ' Higgs field and the SM Higgs doublet field, the radiative U(1 ) ' gauge symmetry breaking also triggers the breaking of the electroweak symmetry. In this model context, we first investigate the electroweak vacuum instability problem in the SM. Employing the renormalization group equations at the two-loop level and the central values for the world average masses of the top quark (mt=173.34 GeV ) and the Higgs boson (mh=125.09 GeV ), we perform parameter scans to identify the parameter region for resolving the electroweak vacuum instability problem. Next we interpret the recent ATLAS and CMS search limits at the LHC Run-2 for the sequential Z' boson to constrain the parameter region in our model. Combining the constraints from the electroweak vacuum stability and the LHC Run-2 results, we find a bound on the Z' boson mass as mZ'≳3.5 TeV . We also calculate self-energy corrections to the SM Higgs doublet field through the heavy states, the right-handed neutrinos and the Z' boson, and find the naturalness bound as mZ'≲7 TeV , in order to reproduce the right electroweak scale for the fine-tuning level better than 10%. The resultant mass range of 3.5 TeV ≲mZ'≲7 TeV will be explored at the LHC Run-2 in the near future.
Workshop on electroweak symmetry breaking: proceedings
Hinchliffe, I.
1984-10-01
A theoretical workshop on electroweak symmetry breaking at the Superconducting Supercollider was held at Lawrence Berkeley Laboratory, June 4-22, 1984. The purpose of the workshop was to focus theoretical attention on the ways in which experimentation at the SSC could reveal manifestations of the phenomenon responsible for electroweak symmetry breaking. This issue represents, at present, the most compelling scientific argument for the need to explore the energy region to be made accessible by the SSC, and a major aim of the workshop was to involve a broad cross section of particle theorists in the ongoing process of sharpening the requirements for both accelerator and detector design that will ensure detection and identification of meaningful signals, whatever form the electroweak symmetry breaking phenomenon should actually take. Separate entries were prepared for the data base for the papers presented.
Anomaly nucleation constrains SU(2) gauge theories.
Halverson, James
2013-12-27
We argue for the existence of additional constraints on SU(2) gauge theories in four dimensions when realized in ultraviolet completions admitting an analog of D-brane nucleation. In type II string compactifications these constraints are necessary and sufficient for the absence of cubic non-Abelian anomalies in certain nucleated SU(N>2) theories. It is argued that they appear quite broadly in the string landscape. Implications for particle physics are discussed; most realizations of the standard model in this context are inconsistent, unless extra electroweak fermions are added. PMID:24483790
Electroweak naturalness and deflected mirage mediation
NASA Astrophysics Data System (ADS)
Barger, Vernon; Everett, Lisa L.; Garon, Todd S.
2016-04-01
We investigate the question of electroweak naturalness within the deflected mirage mediation (DMM) framework for supersymmetry breaking in the minimal supersymmetric standard model. The class of DMM models considered are nine-parameter theories that fall within the general classification of the 19-parameter phenomenological minimal supersymmetric standard model. Our results show that these DMM models have regions of parameter space with very low electroweak fine-tuning, at levels comparable to the phenomenological minimal supersymmetric standard model. These parameter regions should be probed extensively in the current LHC run.
Radiative and Electroweak Penguins at Belle
Hyun, Hyo Jung
2010-02-10
Radiative and electroweak penguin decays of B mesons are a sensitive probe of new physics beyond the Standard Model. We study the inclusive and exclusive radiative and electroweak penguin decays of B meson and also search an exotic particle seen by the HyperCP experiment. The measurements are based on a large data sample of 605 fb{sup -1} containing 657 millions BB-bar pairs collected at the UPSILON(4S) with the Belle detector at the KEKB energy asymmetric e{sup +}e{sup -} collider.
Quadratic electroweak corrections for polarized Moller scattering
A. Aleksejevs, S. Barkanova, Y. Kolomensky, E. Kuraev, V. Zykunov
2012-01-01
The paper discusses the two-loop (NNLO) electroweak radiative corrections to the parity violating electron-electron scattering asymmetry induced by squaring one-loop diagrams. The calculations are relevant for the ultra-precise 11 GeV MOLLER experiment planned at Jefferson Laboratory and experiments at high-energy future electron colliders. The imaginary parts of the amplitudes are taken into consideration consistently in both the infrared-finite and divergent terms. The size of the obtained partial correction is significant, which indicates a need for a complete study of the two-loop electroweak radiative corrections in order to meet the precision goals of future experiments.
Top and Electroweak Measurements at the Tevatron
Bartos, P.
2016-01-01
In this report, we summarize the latest results of the top-quark mass and electroweak measurements from the Tevatron. Since the world combination of top-quark mass measurements was done, CDF and D0 experiments improved the precision of several results. Some of them reach the relative precition below 1% for a single measurement. From the electroweak results, we report on the WW and WZ production cross section, measurements of the weak mixing angle and indirect measurements of W boson mass. The Tevatron results of the weak mixing angle are still the most precise ones of hadron colliders.
Electroweak corrections to Bs,d→ℓ+ℓ-
NASA Astrophysics Data System (ADS)
Bobeth, Christoph; Gorbahn, Martin; Stamou, Emmanuel
2014-02-01
We calculate the full two-loop electroweak matching corrections to the operator governing the decay Bq→ℓ+ℓ- in the standard model. Their inclusion removes an electroweak scheme and scale uncertainty of about ±7% of the branching ratio. Using different renormalization schemes of the involved electroweak parameters, we estimate residual perturbative electroweak and QED uncertainties to be less than ±1% at the level of the branching ratio.
Fermions and gauge bosons in SU(4){sub L}xU(1){sub X} models with little Higgs
Nam, Soo-hyeon
2008-11-23
We discuss the aspects of the little Higgs model with the SU(4){sub L}xU(1){sub X} electroweak gauge group as an alternative solution to the naturalness and fine-tuning issues. We introduce anomaly-free fermion spectra, and present their interactions with the physical gauge bosons. We also discuss some phenomenological implications of these fermions and the extra gauge bosons based on recent experimental results.
Bulk Randall-Sundrum models, electroweak precision tests, and the 125 GeV Higgs
NASA Astrophysics Data System (ADS)
Iyer, Abhishek M.; Sridhar, K.; Vempati, Sudhir K.
2016-04-01
We present up-to-date electroweak fits of various Randall-Sundrum (RS) models. We consider the bulk RS, deformed RS, and the custodial RS models. For the bulk RS case we find the lightest Kaluza-Klein (KK) mode of the gauge boson to be ˜8 TeV , while for the custodial case it is ˜3 TeV . The deformed model is the least fine-tuned of all which can give a good fit for KK masses <2 TeV depending on the choice of the model parameters. We also comment on the fine-tuning in each case.
Electroweak Symmetry Breaking from Monopole Condensation
Csaki, Csaba; Shirman, Yuri; Terning, John
2011-01-28
We argue that the electroweak symmetry of the standard model (SM) could be broken via condensation of magnetic monopole bilinears. We present an extension of the SM where this could indeed happen, and where the heavy top mass is also a consequence of the magnetic interactions.
On the Ambjorn-Olesen electroweak condensates
NASA Astrophysics Data System (ADS)
Bartolucci, Daniele; De Marchis, Francesca
2012-07-01
We obtain sufficient conditions for the existence of the Ambjorn-Olesen ["On electroweak magnetism," Nucl. Phys. B315, 606-614 (1989), 10.1016/0550-3213(89)90004-7] electroweak N-vortices in case N ⩾ 1 and therefore generalize earlier results [D. Bartolucci and G. Tarantello, "Liouville type equations with singular data and their applications to periodic multivortices for the electroweak theory," Commun. Math. Phys. 229, 3-47 (2002), 10.1007/s002200200664; J. Spruck and Y. Yang, "On multivortices in the electroweak theory I: Existence of periodic solutions," Commun. Math. Phys. 144, 1-16 (1992), 10.1007/BF02099188] which handled the cases N ∈ {1, 2, 3, 4}. The variational argument provided here has its own independent interest as it generalizes the one adopted by Ding et al. ["Existence results for mean field equations," Ann. Inst. Henri Poincare, Anal. Non Lineaire 16, 653-666 (1999), 10.1016/S0294-1449(99)80031-6] to obtain solutions for Liouville-type equations on closed 2-manifolds. In fact, we obtain at once a second proof of the existence of supercritical conformal metrics on surfaces with conical singularities and prescribed Gaussian curvature recently established by Bartolucci, De Marchis and Malchiodi [Int. Math. Res. Not. 24, 5625-5643 (2011), 10.1093/imrn/rnq285].
Theory of precision electroweak measurements
Peskin, M.E.
1990-03-01
In these lectures, I will review the theoretical concepts needed to understand the goals and implications of experiments in this new era of weak interactions. I will explain how to compute the most important order-{alpha} radiative corrections to weak interaction processes and discuss the physical implications of these correction terms. I hope that this discussion will be useful to those --- experimentalists and theorists --- who will try to interpret the new data that we will soon receive. This paper is organized as follows: I will review the structure of the standard weak interaction model at zeroth order. I will discuss the measurement of the Z{sup 0} boson mass in e{sup +}e{sup {minus}} annihilation. This measurement is affected by radiative correction to the form of the Z{sup 0} resonance, and so I will review the theory of the resonance line shape. I will briefly review the modifications of the properties of the Z{sup 0} which would be produced by additional neutral gauge bosons. I will review the theory of the renormalization of weak interaction parameters such as sin{sup 2} {theta}{sub {omega}}, concentrating especially on the contributions of the top quark and other heavy, undiscovered particles.
Approximate gauge symemtry of composite vector bosons
Suzuki, Mahiko
2010-06-01
It can be shown in a solvable field theory model that the couplings of the composite vector mesons made of a fermion pair approach the gauge couplings in the limit of strong binding. Although this phenomenon may appear accidental and special to the vector bosons made of a fermion pair, we extend it to the case of bosons being constituents and find that the same phenomenon occurs in more an intriguing way. The functional formalism not only facilitates computation but also provides us with a better insight into the generating mechanism of approximate gauge symmetry, in particular, how the strong binding and global current conservation conspire to generate such an approximate symmetry. Remarks are made on its possible relevance or irrelevance to electroweak and higher symmetries.
Approximate gauge symmetry of composite vector bosons
NASA Astrophysics Data System (ADS)
Suzuki, Mahiko
2010-08-01
It can be shown in a solvable field theory model that the couplings of the composite vector bosons made of a fermion pair approach the gauge couplings in the limit of strong binding. Although this phenomenon may appear accidental and special to the vector bosons made of a fermion pair, we extend it to the case of bosons being constituents and find that the same phenomenon occurs in a more intriguing way. The functional formalism not only facilitates computation but also provides us with a better insight into the generating mechanism of approximate gauge symmetry, in particular, how the strong binding and global current conservation conspire to generate such an approximate symmetry. Remarks are made on its possible relevance or irrelevance to electroweak and higher symmetries.
Implications of Gauge Invariance on a Heavy Diphoton Resonance
Low, Ian; Lykken, Joseph
2015-12-30
Assuming a heavy electroweak singlet scalar, which couples to the Standard Model gauge bosons only through loop-induced couplings, SU(2)_L x U(1)_Y gauge invariance imposes interesting patterns on its decays into electroweak gauge bosons, which are dictated by only two free parameters. Therefore experimental measurements on any two of the four possible electroweak channels would determine the remaining two decay channels completely. Furthermore, searches in the WW/ZZ channels probe a complimentary region of parameter space from searches in the gamma-gamma/Z-gamma channels. We derive a model-independent upper bound on the branching fraction in each decay channel, which for the diphoton channel turns out to be about 61%. Including the coupling to gluons, the upper bound on the diphoton branching fraction implies an upper bound on the mass scale of additional colored particles mediating the gluon-fusion production. Using an event rate of about 5 fb for the reported 750 GeV diphoton excess, we find the new colored particle must be lighter than O(1.7 TeV) and O(2.6 TeV) for a pure CP-even and a pure CP-odd singlet scalar, respectively.
Determining triple gauge boson couplings from Higgs data.
Corbett, Tyler; Éboli, O J P; Gonzalez-Fraile, J; Gonzalez-Garcia, M C
2013-07-01
In the framework of effective Lagrangians with the SU(2)(L)×U(1)(Y) symmetry linearly realized, modifications of the couplings of the Higgs field to the electroweak gauge bosons are related to anomalous triple gauge couplings (TGCs). Here, we show that the analysis of the latest Higgs boson production data at the LHC and Tevatron give rise to strong bounds on TGCs that are complementary to those from direct TGC analysis. We present the constraints on TGCs obtained by combining all available data on direct TGC studies and on Higgs production analysis. PMID:23862992
A little more gauge mediation and the light Higgs mass
NASA Astrophysics Data System (ADS)
Suryanarayana Mummidi, V.; Vempati, Sudhir K.
2014-04-01
We consider minimal models of gauge mediated supersymmetry breaking with an extra U(1) factor in addition to the Standard Model gauge group. A U(1) charged, Standard Model singlet is assumed to be present which allows for an additional NMSSM like coupling, λHuHdS. The U(1) is assumed to be flavour universal. Anomaly cancellation in the MSSM sector requires additional coloured degrees of freedom. The S field can get a large vacuum expectation value along with consistent electroweak symmetry breaking. It is shown that the lightest CP even Higgs boson can attain mass of the order of 125 GeV.
NASA Astrophysics Data System (ADS)
Neretin, Yu A.
2015-06-01
We construct p-adic analogues of operator colligations and their characteristic functions. Consider a p-adic group \\mathbf G={GL}(α+k∞, Q_p), a subgroup L= O(k∞, Z_p) of \\mathbf G and a subgroup \\mathbf K= O(∞, Z_p) which is diagonally embedded in L. We show that the space Γ=\\mathbf K\\setminus\\mathbf G/\\mathbf K of double cosets admits the structure of a semigroup and acts naturally on the space of \\mathbf K-fixed vectors of any unitary representation of \\mathbf G. With each double coset we associate a `characteristic function' that sends a certain Bruhat-Tits building to another building (the buildings are finite-dimensional) in such a way that the image of the distinguished boundary lies in the distinguished boundary. The second building admits the structure of a (Nazarov) semigroup, and the product in Γ corresponds to the pointwise product of characteristic functions.
Higgs decays in gauge extensions of the standard model
NASA Astrophysics Data System (ADS)
Bunk, Don; Hubisz, Jay; Jain, Bithika
2014-02-01
We explore the phenomenology of virtual spin-1 contributions to the h→γγ and h→Zγ decay rates in gauge extensions of the standard model. We consider generic Lorentz and gauge-invariant vector self-interactions, which can have nontrivial structure after diagonalizing the quadratic part of the action. Such features are phenomenologically relevant in models where the electroweak gauge bosons mix with additional spin-1 fields, such as occurs in little Higgs models, extra dimensional models, strongly coupled variants of electroweak symmetry breaking, and other gauge extensions of the standard model. In models where nonrenormalizable operators mix field strengths of gauge groups, the one-loop Higgs decay amplitudes can be logarithmically divergent, and we provide power counting for the size of the relevant counterterm. We provide an example calculation in a four-site moose model that contains degrees of freedom that model the effects of vector and axial-vector resonances arising from TeV scale strong dynamics.
Marginal deformations of WZNW and coset models from O( d, d) transformations
NASA Astrophysics Data System (ADS)
Hassan, S. F.; Sen, Ashoke
1993-09-01
We show that the O(2, 2) transformation of the SU(2) WZNW model gives rise to marginal deformation of this model by the operator ∫ d2zJ(z) overlineJ( overlinez) where J, overlineJareU(1) currents in the Cartan subalgebra. Generalization of this result to other WZNW theories is discussed. We also consider the O(3, 3) transformation of the product of an SU(2) WZNW model and a gauged SU(2) WZNW model. The three-parameter set of models obtained after the transformation is shown to be the result of first deforming the product of two SU(2) WZNW theories by marginal operators of the form Σ i,j = 12 C ijJ ioverlineJj, and then gauging an appropriate U(1) subgroup of the theory. Our analysis leads to a general conjecture that O( d, d) transformations of any WZNW model correspond to marginal deformation of the WZNW theory by an appropriate combination of left and right moving currents belonging to the Cartan subalgebra; and O( d, d) transformations of a gauged WZNW model can be identified to the gauged version of such marginally deformed WZNW models.
Generalizing twisted gauge invariance
Duenas-Vidal, Alvaro; Vazquez-Mozo, Miguel A.
2009-05-01
We discuss the twisting of gauge symmetry in noncommutative gauge theories and show how this can be generalized to a whole continuous family of twisted gauge invariances. The physical relevance of these twisted invariances is discussed.
A UV-complete Composite Higgs model for Electroweak Symmetry Breaking: Minimal Conformal Technicolor
NASA Astrophysics Data System (ADS)
Tacchi, Ruggero Altair
The Large Hadron Collider is currently collecting data. One of the main goals of the experiment is to find evidence of the mechanism responsible for the breaking of the electroweak symmetry. There are many different models attempting to explain this breaking and traditionally most of them involve the use of supersymmetry near the scale of the breaking. This work is focused on exploring a viable model that is not based on a weakly coupled low scale supersymmetry sector to explain the electroweak symmetry breaking. We build a model based on a new strong interaction, in the fashion of theories commonly called "technicolor", name that is reminiscent of one of the first attempts of explaining the electroweak symmetry breaking using a strong interaction similar to the one whose charges are called colors. We explicitly study the minimal model of conformal technicolor, an SU(2) gauge theory near a strongly coupled conformal fixed point, with conformal symmetry softly broken by technifermion mass terms. Conformal symmetry breaking triggers chiral symmetry breaking in the pattern SU(4) → Sp (4), which gives rise to a pseudo-Nambu-Goldstone boson that can act as a composite Higgs boson. There is an additional composite pseudoscalar A with mass larger than mh and suppressed direct production at LHC. We discuss the electroweak fit in this model in detail. A good fit requires fine tuning at the 10% level. We construct a complete, realistic, and natural UV completion of the model, that explains the origin of quark and lepton masses and mixing angles. We embed conformal technicolor in a supersymmetric theory, with supersymmetry broken at a high scale. The effective theory below the supersymmetry breaking scale is minimal conformal technicolor with an additional light technicolor gaugino that might give rise to an additional pseudo Nambu-Goldstone boson that is observable at the LHC.
Electroweak Symmetry Breaking in Historical Perspective
NASA Astrophysics Data System (ADS)
Quigg, Chris
2015-10-01
The discovery of the Higgs boson is a major milestone in our progress toward understanding the natural world. A particular aim of this review is to show how diverse ideas came together in the conception of electroweak symmetry breaking that led up to the discovery. I also survey what we know now that we did not know before, what properties of the Higgs boson remain to be established, and what new questions we may now hope to address.
Electroweak Symmetry Breaking in Historical Perspective
Quigg, Chris
2015-10-01
The discovery of the Higgs boson is a major milestone in our progress toward understanding the natural world. A particular aim of my review is to show how diverse ideas came together in the conception of electroweak symmetry breaking that led up to the discovery. Furthermore, I survey what we know now that we did not know before, what properties of the Higgs boson remain to be established, and what new questions we may now hope to address.
Tevatron Measurements of Electroweak Boson Production
Hooper, Ryan J.; /Lewis U.
2011-08-01
With a large and still increasing dataset, W and Z boson physics studies at the Tevatron p{bar p} collider are particularly useful for testing many aspects of the Standard Model. In this proceeding, we present measurements of electroweak boson properties, distributions, and charge asymmetries. We examine both solitary W and Z production as well as production in association with jets. These measurements are compared to NLO QCD predictions, are used to extract fundamental Standard Model parameters, and constrain parton distribution functions.
Strong dynamics and lattice gauge theory
NASA Astrophysics Data System (ADS)
Schaich, David
In this dissertation I use lattice gauge theory to study models of electroweak symmetry breaking that involve new strong dynamics. Electroweak symmetry breaking (EWSB) is the process by which elementary particles acquire mass. First proposed in the 1960s, this process has been clearly established by experiments, and can now be considered a law of nature. However, the physics underlying EWSB is still unknown, and understanding it remains a central challenge in particle physics today. A natural possibility is that EWSB is driven by the dynamics of some new, strongly-interacting force. Strong interactions invalidate the standard analytical approach of perturbation theory, making these models difficult to study. Lattice gauge theory is the premier method for obtaining quantitatively-reliable, nonperturbative predictions from strongly-interacting theories. In this approach, we replace spacetime by a regular, finite grid of discrete sites connected by links. The fields and interactions described by the theory are likewise discretized, and defined on the lattice so that we recover the original theory in continuous spacetime on an infinitely large lattice with sites infinitesimally close together. The finite number of degrees of freedom in the discretized system lets us simulate the lattice theory using high-performance computing. Lattice gauge theory has long been applied to quantum chromodynamics, the theory of strong nuclear interactions. Using lattice gauge theory to study dynamical EWSB, as I do in this dissertation, is a new and exciting application of these methods. Of particular interest is non-perturbative lattice calculation of the electroweak S parameter. Experimentally S ≈ -0.15(10), which tightly constrains dynamical EWSB. On the lattice, I extract S from the momentum-dependence of vector and axial-vector current correlators. I created and applied computer programs to calculate these correlators and analyze them to determine S. I also calculated the masses
Towards a scale free electroweak baryogenesis
NASA Astrophysics Data System (ADS)
Ishikawa, Kazuya; Kitahara, Teppei; Takimoto, Masahiro
2015-03-01
We propose a new electroweak baryogenesis scenario in high-scale supersymmetric (SUSY) models. We consider a singlet extension of the minimal SUSY standard model introducing additional vectorlike multiplets. We show that the strongly first-order phase transition can occur at a high temperature comparable to the soft SUSY breaking scale. In addition, the proper amount of the baryon asymmetry of the Universe can be generated via the lepton number violating process in the vectorlike multiplet sector. The typical scale of our scenario, the soft SUSY breaking scale, can be any value. Thus our new electroweak baryogenesis scenario can be realized at arbitrary scales, and we call this scenario scale free electroweak baryogenesis. This soft SUSY breaking scale is determined by other requirements. If the soft SUSY breaking scale is O (10 ) TeV , our scenario is compatible with the observed mass of the Higgs boson and the constraints by electric dipole moment measurements and flavor experiments. Furthermore, the singlino can be a good candidate for dark matter.
SU(2/1) gauge-Higgs unification
NASA Astrophysics Data System (ADS)
Loginov, E. K.
2016-06-01
We discuss a question whether the observed Weinberg angle and Higgs mass are calculable in the formalism based on a construction in which the electroweak gauge group SU(2) × U(1)Y is embedded in the graded Lie group SU(2/1). Here, we follow original works of Ne’eman and Fairlie believing that bosonic fields take their values in the Lie superalgebra and fermionic fields take their values in its representation space. At the same time, our approach differs significantly. The main one is that while for them the gauge symmetry group is SU(2/1), here we consider only symmetries generated by its even subgroup, i.e. symmetries of the standard electroweak model. The reason is that such formalism fixes the quartic Higgs coupling and at the same time removes the sign and statistics problems. The main result is that the presented model predicts values of the Weinberg angle and the Higgs mass correctly up to the two-loop level. Moreover, the model sets the unification scale coinciding with the electroweak scale and automatically describes the fermions correctly with the correct quark and lepton charges.
Towards the natural gauge mediation
NASA Astrophysics Data System (ADS)
Ding, Ran; Li, Tianjun; Wang, Liucheng; Zhu, Bin
2015-10-01
The sweet spot supersymmetry (SUSY) solves the μ/ B μ problem in the Minimal Supersymmetric Standard Model (MSSM) with gauge mediated SUSY breaking (GMSB) via the generalized Giudice-Masiero (GM) mechanism where only the μ-term and soft Higgs masses are generated at the unification scale of the Grand Unified Theory (GUT) due to the approximate PQ symmetry. Because all the other SUSY breaking soft terms are generated via the GMSB below the GUT scale, there exists SUSY electroweak (EW) fine-tuning problem to explain the 125 GeV Higgs boson mass due to small trilinear soft term. Thus, to explain the Higgs boson mass, we propose the GMSB with both the generalized GM mechanism and Higgs-messenger interactions. The renormalization group equations are runnings from the GUT scale down to EW scale. So the EW symmetry breaking can be realized easier. We can keep the gauge coupling unification and solution to the flavor problem in the GMSB, as well as solve the μ/ B μ -problem. Moreover, there are only five free parameters in our model. So we can determine the characteristic low energy spectra and explore its distinct phenomenology. The fine-tuning measure can be as low as 100. For some benchmark points, the stop mass can be as low as 1.7 TeV while the glunio mass is around 2.5 TeV. The gravitino dark matter can come from a thermal production with the correct relic density and be consistent with the thermal leptogenesis. Because gluino and stop can be relatively light in our model, how to search for such GMSB at the upcoming run II of the LHC experiment could be very interesting.
Gaugings of four-dimensional N =3 supergravity and AdS4/CFT3 holography
NASA Astrophysics Data System (ADS)
Karndumri, Parinya; Upathambhakul, Khem
2016-06-01
We study matter-coupled N =3 gauged supergravity in four dimensions with various semisimple gauge groups. When coupled to n vector multiplets, the gauged supergravity contains 3 +n vector fields and 3 n complex scalars parametrized by S U (3 ,n )/S U (3 )×S U (n )×U (1 ) coset manifold. Semisimple gauge groups take the form of G0×H ⊂S O (3 ,n )⊂S U (3 ,n ) with H being a compact subgroup of S O (n +3 -dim (G0)). The G0 groups considered in this paper are of the form S O (3 ), S O (3 ,1 ), S O (2 ,2 ), S L (3 ,R ) and S O (2 ,1 )×S O (2 ,2 ). We find that S O (3 )×S O (3 ), S O (3 ,1 ) and S L (3 ,R ) gauge groups admit a maximally supersymmetric AdS4 critical point. The S O (2 ,1 )×S O (2 ,2 ) gauge group admits a supersymmetric Minkowski vacuum while the remaining gauge groups admit both half-supersymmetric domain wall vacua and AdS4 vacua with completely broken supersymmetry. For the S O (3 )×S O (3 ) gauge group, there exists another supersymmetric N =3 AdS4 critical point with S O (3 )diag symmetry. We explicitly give a detailed study of various holographic RG flows between AdS4 critical points, flows to nonconformal theories, and supersymmetric domain walls in each gauge group. The results provide gravity duals of N =3 Chern-Simons-matter theories in three dimensions.
Quartic gauge boson couplings at linear colliders. Interplay of WWZ/ZZZ production and WW-fusion
NASA Astrophysics Data System (ADS)
Han, Tao; He, Hong-Jian; Yuan, C.-P.
1998-03-01
We study new physics effects to the quartic gauge boson couplings formulated by the electroweak chiral Lagrangian. Five next-to-leading order operators characterize the anomalous quartic gauge interactions which involve pure Goldstone boson dynamics for the electroweak symmetry breaking. We estimate the typical size of these couplings in different strongly-interacting models and examine the sensitivity to directly probing them via the WWZ/ZZZ triple gauge boson production at the high energy linear colliders. The important roles of polarized e- and e+ beams are stressed. We then compare the results with those from the W-pair production of the WW-fusion processes, and analyze the interplay of these two production mechanisms for an improved probe of the quartic gauge boson interactions.
PRECISION ELECTROWEAK MEASUREMENTS AND THE HIGGS MASS.
MARCIANO, W.J.
2004-08-02
The utility of precision electroweak measurements for predicting the Standard Model Higgs mass via quantum loop effects is discussed. Current constraints from m{sub w} and sin{sup 2} {theta}{sub w} (m{sub z}){sub {ovr MS}} imply a relatively light Higgs {approx}< 154 GeV which is consistent with Supersymmetry expectations. The existence of Supersymmetry is further suggested by a discrepancy between experiment and theory for the muon anomalous magnetic moment. Constraints from precision studies on other types of ''New Physics'' are also briefly described.
Electroweak Baryogenesis from a Classical Force
Joyce, M.; Prokopec, T.; Turok, N.
1995-08-28
We describe a new effect that produces baryons at a first order electroweak phase transition. It operates when there is a {ital CP}-violating field present on propagating bubble walls. The novel aspect is that it involves a purely classical force, which alters the motion of particles across the wall and through diffusion creates a chiral asymmetry in front of the wall. We develop a technique for computing the baryon asymmetry using the Boltzmann equation, and a fluid approximation which allows us to model strong scattering effects. The final formula for the baryon asymmetry has a remarkably simple form.
Minimal electroweak model for monopole annihilation
Farris, T.H. ); Kephart, T.W.; Weiler, T.J. ); Yuan, T.C. )
1992-02-03
We construct the minimal (most economical in fields) extension of the standard model implementing the Langacker-Pi mechanism for reducing the grand unified theory (GUT) monopole cosmic density to an allowed level. The model contains just a single charged scalar field in addition to the standard Higgs doublet, and is easily embeddable in any GUT. We identify the region of parameter space where monopoles annihilate in the higher temperature early Universe. A particularly alluring possibility is that the demise of monopoles at the electroweak scale is in fact the origin of the Universe's net baryon number.
Electroweak boson production in double parton scattering
NASA Astrophysics Data System (ADS)
Golec-Biernat, Krzysztof; Lewandowska, Emilia
2014-11-01
We study the W+W- and Z0Z0 electroweak boson production in double parton scattering using QCD evolution equations for double parton distributions. In particular, we analyze the impact of splitting terms in the evolution equations on the double parton scattering cross sections. Unlike the standard terms, the splitting terms are not suppressed for large values of the relative momentum of two partons in the double parton scattering. Thus, they play an important role which we discuss in detail for the single splitting contribution to the cross sections under the study.
Strong Coupling Gauge Theories in LHC ERA
NASA Astrophysics Data System (ADS)
Fukaya, H.; Harada, M.; Tanabashi, M.; Yamawaki, K.
2011-01-01
Higgs, or techni-dilaton - composite Higgs near conformality / Koichi Yamawaki -- Phase diagram of strongly interacting theories / Francesco Sannino -- Resizing conformal windows / O. Antipin and K. Tuominen -- Nearly conformal gauge theories on the lattice / Zoltan Fodor ... [et al.] -- Going beyond QCD in lattice gauge theory / G. T. Fleming -- Phases of QCD from small to large N[symbol]: (some) lattice results / A. Deuzeman, E. Pallante and M. P. Lombardo -- Lattice gauge theory and (quasi)-conformal technicolor / D. K. Sinclair and J. B. Kogut -- Study of the running coupling constant in 10-flavor QCD with the Schrodinger functional method / N. Yamada ... [et al.] -- Study of the running coupling in twisted Polyakov scheme / T. Aoyama ... [et al.].Running coupling in strong gauge theories via the lattice / Zoltan Fodor ... [et al.] -- Higgsinoless supersymmetry and hidden gravity / Michael L. Graesser, Ryuichiro Kitano and Masafumi Kurachi -- The latest status of LHC and the EWSB physics / S. Asai -- Continuum superpartners from supersymmetric unparticles / Hsin-Chia Cheng -- Review of minimal flavor constraints for technicolor / Hidenori S. Fukano and Francesco Sannino -- Standard model and high energy Lorentz violation / Damiano Anselmi -- Dynamical electroweak symmetry breaking and fourth family / Michio Hashimoto -- Holmorphic supersymmetric Nambu-Jona-Lasino model and dynamical electroweak symmetry breaking / Dong-Won Jung, Otto C. W. Kong and Jae Sik Lee -- Ratchet model of Baryogenesis / Tatsu Takeuchi, Azusa Minamizaki and Akio Sugamoto -- Classical solutions of field equations in Einstein Gauss-Bonnet gravity / P. Suranyi, C. Vaz and L. C. R. Wijewardhana -- Black holes constitute all dark matter / Paul H. Frampton -- Electroweak precision test and Z [symbol] in the three site Higgsless model / Tomohiro Abe -- Chiral symmetry and BRST symmetry breaking, quaternion reality and the lattice simulation / Sadataka Furui -- Holographic techni-dilaton, or
Holographic RG flows in six dimensional F(4) gauged supergravity
NASA Astrophysics Data System (ADS)
Karndumri, Parinya
2013-01-01
We study critical points of F (4) gauged supergravity in six dimensions coupled to three vector multiplets. Scalar fields are described by {{mathbb{R}}+}× {SOleft( {4,3} right)}/{SO(4)× SO(3)} coset space, and the gauge group is given by SO(3)R × SO(3) with SO(3)R being the R-symmetry. We identify new non-supersymmetric critical points of the scalar potential. One of these new critical points is shown to be stable with all scalar masses above the BF bound and should correspond to a new non-supersymmetric CFT in five dimensions. On the other hand, the maximally supersymmetric critical point with all scalars vanishing is dual to an SCFT5 arising from a near horizon geometry of the D4-D8 brane system in type I' theory with an enhanced global symmetry E 1 SU(2). We give a numerical RG flow solution interpolating between this SCFT and the new stable critical point. The flow describes a non-supersymmetric deformation driven by relevant operators of dimension 3. We identify the dual operators with the mass terms for hypermultiplet scalars in the dual field theory. The solution provides another example of holographic RG flows in AdS6/CFT5 correspondence.
Strain gauge installation tool
Conard, Lisa Marie
1998-01-01
A tool and a method for attaching a strain gauge to a test specimen by maaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.
Strain gauge installation tool
Conard, Lisa Marie
1997-12-01
A tool and a method for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.
Light-Front Quantization of Gauge Theories
Brodskey, Stanley
2002-12-01
Light-front wavefunctions provide a frame-independent representation of hadrons in terms of their physical quark and gluon degrees of freedom. The light-front Hamiltonian formalism provides new nonperturbative methods for obtaining the QCD spectrum and eigensolutions, including resolvant methods, variational techniques, and discretized light-front quantization. A new method for quantizing gauge theories in light-cone gauge using Dirac brackets to implement constraints is presented. In the case of the electroweak theory, this method of light-front quantization leads to a unitary and renormalizable theory of massive gauge particles, automatically incorporating the Lorentz and 't Hooft conditions as well as the Goldstone boson equivalence theorem. Spontaneous symmetry breaking is represented by the appearance of zero modes of the Higgs field leaving the light-front vacuum equal to the perturbative vacuum. I also discuss an ''event amplitude generator'' for automatically computing renormalized amplitudes in perturbation theory. The importance of final-state interactions for the interpretation of diffraction, shadowing, and single-spin asymmetries in inclusive reactions such as deep inelastic lepton-hadron scattering is emphasized.
Enabling electroweak baryogenesis through dark matter
NASA Astrophysics Data System (ADS)
Lewicki, Marek; Rindler-Daller, Tanja; Wells, James D.
2016-06-01
We study the impact on electroweak baryogenesis from a swifter cosmological expansion induced by dark matter. We detail the experimental bounds that one can place on models that realize it, and we investigate the modifications of these bounds that result from a non-standard cosmological history. The modifications can be sizeable if the expansion rate of the Universe increases by several orders of magnitude. We illustrate the impact through the example of scalar field dark matter, which can alter the cosmological history enough to enable a strong-enough first-order phase transition in the Standard Model when it is supplemented by a dimension six operator directly modifying the Higgs boson potential. We show that due to the modified cosmological history, electroweak baryogenesis can be realized, while keeping deviations of the triple Higgs coupling below HL-LHC sensitivies. The required scale of new physics to effectuate a strong-enough first order phase transition can change by as much as twenty percent as the expansion rate increases by six orders of magnitude.
Modified magnetohydrodynamics around the electroweak transition
NASA Astrophysics Data System (ADS)
Pavlović, Petar; Leite, Natacha; Sigl, Günter
2016-06-01
We analyse solutions of the MHD equations around the electroweak transition taking into account the effects of the chiral anomaly. It is shown that a transition that is not of the first order has direct consequences on the evolution of the asymmetry between left- and right-handed leptons. Assuming an initial chiral asymmetry in the symmetric phase at temperatures higher than the transition temperature, as well as the existence of magnetic fields, it is demonstrated that the asymmetry typically grows with time, until it undergoes a fast decrease at the transition, and then eventually gets damped at lower temperatures in the broken phase. We argue that it is unlikely to have any significant magnetic field amplification as a consequence of the electroweak transition in the Standard model, even when the chiral anomaly is introduced. The presence of a chiral asymmetry between left- and right-handed charge carriers naturally leads to the creation of helical magnetic fields from non-helical fields and this can have consequences on their subsequent evolution. Similarly, an initially vanishing chiral asymmetry is naturally created in the presence of a helical magnetic field.
Electroweak Baryogenesis in R-symmetric Supersymmetry
Fok, R.; Kribs, Graham D.; Martin, Adam; Tsai, Yuhsin
2013-03-01
We demonstrate that electroweak baryogenesis can occur in a supersymmetric model with an exact R-symmetry. The minimal R-symmetric supersymmetric model contains chiral superfields in the adjoint representation, giving Dirac gaugino masses, and an additional set of "R-partner" Higgs superfields, giving R-symmetric \\mu-terms. New superpotential couplings between the adjoints and the Higgs fields can simultaneously increase the strength of the electroweak phase transition and provide additional tree-level contributions to the lightest Higgs mass. Notably, no light stop is present in this framework, and in fact, we require both stops to be above a few TeV to provide sufficient radiative corrections to the lightest Higgs mass to bring it up to 125 GeV. Large CP-violating phases in the gaugino/higgsino sector allow us to match the baryon asymmetry of the Universe with no constraints from electric dipole moments due to R-symmetry. We briefly discuss some of the more interesting phenomenology, particularly of the of the lightest CP-odd scalar.
CP nonconservation in dynamically broken gauge theories
Lane, K.
1981-01-01
The recent proposal of Eichten, Lane, and Preskill for CP nonconservation in electroweak gauge theories with dynamical symmetry breaking is reviewed. Through the alignment of the vacuum with the explicit chiral symmetry breaking Hamiltonian, these theories provide a natural way to understand the dynamical origin of CP nonconservation. Special attention is paid to the problem of strong CP violation. Even through all vacuum angles are zero, this problem is not automatically avoided. In the absence of strong CP violation, the neutron electric dipole moment is expected to be 10/sup -24/-10/sup -26/ e-cm. A new class of models is proposed in which both strong CP violation and large /..delta..S/ = 2 effects may be avoided. In these models, /..delta..C/ = 2 processes such as D/sup o/ D/sup -o/ mixing may be large enough to observe.
General gauge mediation at the weak scale
NASA Astrophysics Data System (ADS)
Knapen, Simon; Redigolo, Diego; Shih, David
2016-03-01
We completely characterize General Gauge Mediation (GGM) at the weak scale by solving all IR constraints over the full parameter space. This is made possible through a combination of numerical and analytical methods, based on a set of algebraic relations among the IR soft masses derived from the GGM boundary conditions in the UV. We show how tensions between just a few constraints determine the boundaries of the parameter space: electroweak symmetry breaking (EWSB), the Higgs mass, slepton tachyons, and left-handed stop/sbottom tachyons. While these constraints allow the left-handed squarks to be arbitrarily light, they place strong lower bounds on all of the right-handed squarks. Meanwhile, light EW superpartners are generic throughout much of the parameter space. This is especially the case at lower messenger scales, where a positive threshold correction to m h coming from light Higgsinos and winos is essential in order to satisfy the Higgs mass constraint.
Precision Electroweak Measurements on the Z Presonance
Aleph,Delphi,L3,Opal,SLD , Collaborations
2005-09-08
The authors report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. the data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLD experiment using a polarized beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarized asymmetries. The mass and width of the Z boson, m{sub Z} and {Lambda}{sub Z}, and its couplings to fermions, for example the {rho} parameter and the effective electroweak mixing angle for leptons, are precisely measured: m{sub Z} = 91.1875 {+-} 0.0021 GeV; {Lambda}{sub Z} = 2.4952 {+-} 0.0023 GeV; {rho}{sub {ell}} = 1.0050 {+-} 0.0010; sin{sup 2} {theta}{sub eff}{sup lept} = 0.23153 {+-} 0.00016. The number of light neutrino species is determined to be 2.9840 {+-} 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model. At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its Standard Model expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m{sub t} = 173{sub -10}{sup +13} GeV, and the mass of the W boson, m{sub W} = 80.363 {+-} 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the Standard Model. Using in addition the direct measurements of m{sub t} and m{sub W}, the mass of the as yet unobserved Standard Model Higgs boson is predicted with a
Research on Electroweak and Flavor Symmetry Breaking
Lane, Kenneth Douglas
2013-05-01
Abstract of Project Summary, as written in August 2012: The objective of this research is the primary one of the Large Hadron Collider (LHC) at CERN in Geneva: the discovery and study of the origin of electroweak symmetry breaking (EWSB). This is the mission of the LHC's two large general-purpose detectors, ATLAS and CMS. Lane's approach to this goal assumes that a new strong interaction at the electroweak energy scale of 100's of GeV, called ``technicolor'' (TC), is responsible for triggering EWSB. He is one of the developers of technicolor, particularly of its flavor-physics component, called extended technicolor (ETC). The TC/ETC theory of this physics provides not only the dynamics of EWSB, but also an understanding of the types (flavors) of quarks and leptons and of their masses and mixing. The main thrust of this research involves close collaboration with members of ATLAS and CMS to search for the signatures of TC/ETC that are most accessible experimentally. These are new, rather heavy, spin-one particles --- technivector bosons ($\\tro$, $\\tom$, $\\ta$) --- readily produced at the LHC and decaying into electroweak bosons, $\\gamma, W, Z$, and spin-zero bosons called technipions, $\\tpi$. If these particles exist, they hold the key to understanding flavor physics. A very important recent development at the LHC is the discovery of a new 125-GeV boson decaying into $\\gamma\\gamma$, $ZZ$ and $WW$. This particle is widely suspected to be the long-sought Higgs boson, a basic component of the so-called standard model of EWSB. But, from a purely theoretical standpoint, this resolution to the origin of EWSB is very unsatisfactory. Moreover, there are interesting and possibly significant discrepancies of the data with this interpretation. Lane and collaborators are proposing that this boson is, in fact, a special kind of technipion. He is also working with ATLAS experimentalists to test this hypothesis. The LHC data to be collected and analyzed by ATLAS and CMS over
Light dark matter, naturalness, and the radiative origin of the electroweak scale
Altmannshofer, Wolfgang; Bardeen, William A.; Bauer, Martin; Carena, Marcela; Lykken, Joseph D.
2015-01-09
We study classically scale invariant models in which the Standard Model Higgs mass term is replaced in the Lagrangian by a Higgs portal coupling to a complex scalar field of a dark sector. We focus on models that are weakly coupled with the quartic scalar couplings nearly vanishing at the Planck scale. The dark sector contains fermions and scalars charged under dark SU(2) × U(1) gauge interactions. Radiative breaking of the dark gauge group triggers electroweak symmetry breaking through the Higgs portal coupling. Requiring both a Higgs boson mass of 125.5 GeV and stability of the Higgs potential up tomore » the Planck scale implies that the radiative breaking of the dark gauge group occurs at the TeV scale. We present a particular model which features a long-range abelian dark force. The dominant dark matter component is neutral dark fermions, with the correct thermal relic abundance, and in reach of future direct detection experiments. The model also has lighter stable dark fermions charged under the dark force, with observable effects on galactic-scale structure. Collider signatures include a dark sector scalar boson with mass ≲ 250 GeV that decays through mixing with the Higgs boson, and can be detected at the LHC. As a result, the Higgs boson, as well as the new scalar, may have significant invisible decays into dark sector particles.« less
Light dark matter, naturalness, and the radiative origin of the electroweak scale
Altmannshofer, Wolfgang; Bardeen, William A.; Bauer, Martin; Carena, Marcela; Lykken, Joseph D.
2015-01-09
We study classically scale invariant models in which the Standard Model Higgs mass term is replaced in the Lagrangian by a Higgs portal coupling to a complex scalar field of a dark sector. We focus on models that are weakly coupled with the quartic scalar couplings nearly vanishing at the Planck scale. The dark sector contains fermions and scalars charged under dark SU(2) × U(1) gauge interactions. Radiative breaking of the dark gauge group triggers electroweak symmetry breaking through the Higgs portal coupling. Requiring both a Higgs boson mass of 125.5 GeV and stability of the Higgs potential up to the Planck scale implies that the radiative breaking of the dark gauge group occurs at the TeV scale. We present a particular model which features a long-range abelian dark force. The dominant dark matter component is neutral dark fermions, with the correct thermal relic abundance, and in reach of future direct detection experiments. The model also has lighter stable dark fermions charged under the dark force, with observable effects on galactic-scale structure. Collider signatures include a dark sector scalar boson with mass ≲ 250 GeV that decays through mixing with the Higgs boson, and can be detected at the LHC. As a result, the Higgs boson, as well as the new scalar, may have significant invisible decays into dark sector particles.
The Electroweak Phase Transition: Corralling the Higgs with Colliders & Cosmology
NASA Astrophysics Data System (ADS)
Long, Andrew J.
Through this thesis, I investigate the way in which the electroweak phase transition, and therefore the Higgs boson, bridges high energy particle physics and early universe cosmology; moreover, I argue that it is particularly interesting to explore this bridge today as experiments such as the Large Hadron Collider begin to uncover the nature of physics at the electroweak scale. I will discuss how measurements of the properties of the Higgs boson at the Large Hadron Collider allow one to determine the nature of the phase transition that was responsible for electroweak symmetry breaking in the early universe. That information in turn will allow one to assess whether the asymmetry between the abundances of matter and anti-matter in the universe may have been generated during the electroweak phase transition. Additionally, I will discuss the impact of the electroweak phase transition on another cosmological relic: namely, the dark matter. Precise measurements of the mass and abundance of dark matter today yield further information about the nature of the electroweak phase transition, in some scenarios. This information may be used to test the hypothesis that the cosmological constant, assumed to be a good model of dark energy, is finely tuned. In this way, I hope to demonstrate the importance of the electroweak phase transition as a bridge between terrestrial tests of high energy physics and cosmological tests of the physics of the early universe.
Neutrino dynamics below the electroweak crossover
NASA Astrophysics Data System (ADS)
Ghiglieri, J.; Laine, M.
2016-07-01
We estimate the thermal masses and damping rates of active (m < eV) and sterile (M ~ GeV) neutrinos with thermal momenta k~ 3T at temperatures below the electroweak crossover (5 GeV < T < 160 GeV) . These quantities fix the equilibration or ``washout'' rates of Standard Model lepton number densities. Sterile neutrinos interact via direct scatterings mediated by Yukawa couplings, and via their overlap with active neutrinos. Including all leading-order reactions we find that the washout rate generally exceeds the Hubble rate for 5 GeV < T < 30 GeV . Therefore it is challenging to generate a large lepton asymmetry facilitating dark matter computations operating at T < 5 GeV, whereas the generation of a baryon asymmetry at T > 130 GeV remains an option. Our differential rates are tabulated in a form suitable for studies of specific scenarios with given neutrino Yukawa matrices.
Radiative And Electroweak Penguin Decays of B
Richman, Jeffrey D.; /UC, Santa Barbara
2007-11-09
Radiative and electroweak penguin decays of B mesons are flavor-changing-neutral-current processes that provide powerful ways to test the Standard Model at the one-loop level, to search for the effects of new physics, and to extract Standard Model parameters such as CKM matrix elements and quark masses. The large data samples obtained by the B-factory experiments BaBar and Belle, together with an intensive theoretical effort, have led to significant progress towards understanding these rare decays. Recent experimental results include the measurements of the b {yields} d{gamma} decays B {yields} {rho}({omega}){gamma}, the observation of B {yields} K(*){ell}{sup +}{ell}{sup -} decays (together with studies of the associated kinematic distributions), and improved measurements of the inclusive B {yields} Xs{gamma} rate and photon energy spectrum.
Standard electroweak interactions and Higgs bosons
Cox, B.; Gilman, F.J.
1984-09-01
In the standard model, only one basic component remains to be found: the Higgs boson. The specifics of Higgs boson production and detection, with decay to t anti t and a particular t quark mass range in mind, have not been examined in detail. As such, the working group on Standard Electroweak Interactions and Higgs Bosons at this meeting decided to concentrate on Higgs boson production and detection at SSC energies in the particular case where the Higgs mass is in the range so as to make t anti t quark-antiquark pairs the dominant decay mode. The study of this case, that of the so-called intermediate mass Higgs, had already been launched in the Berkeley PSSC Workshop on Electroweak Symmetry Breaking, and was continued and extended here. The problems of t quark jet identification and detection efficiency and the manner of rejection of background (especially from b quark jets) with realistic detectors then occupied much of the attention of the group. The subject of making precise measurements of parameters in the standard model at SSC energies is briefly examined. Then we delve into the Higgs sector, with an introduction to the neutral Higgs of the standard model together with its production cross-sections in various processes and the corresponding potential backgrounds. A similar, though briefer, discussion for a charged Higgs boson (outside the Standard Model) follows. The heart of the work on identifying and reconstructing the t and then the Higgs boson in the face of backgrounds is discussed. The problems with semileptonic decays, low energy jet fragments, mass resolution, and b-t discrimination all come to the fore. We have tried to make a serious step here towards a realistic assessment of the problems entailed in pulling a signal out of the background, including a rough simulation of calorimeter-detector properties. 25 references.
Next-to-leading order QCD corrections to electroweak Zjj production in the POWHEG BOX
NASA Astrophysics Data System (ADS)
Jäger, Barbara; Schneider, Steven; Zanderighi, Giulia
2012-09-01
We present an implementation of electroweak Z-boson production in association with two jets at hadron colliders in the POWHEG framework, a method that allows the interfacing of NLO-QCD calculations with parton-shower Monte Carlo programs. We focus on the leptonic decays of the weak gauge boson, and take photonic and non-resonant contributions to the matrix elements fully into account. We provide results for observables of particular importance for the suppression of QCD backgrounds to vector-boson fusion processes by means of central-jet-veto techniques. While parton-shower effects are small for most observables associated with the two hardest jets, they can be more pronounced for distributions that are employed in central-jet-veto studies.
A consistent model of electroweak data including Z → b overlineb and Z → c overlinec
NASA Astrophysics Data System (ADS)
Agashe, K.; Graesser, M.; Hinchliffe, I.; Suzuki, M.
1996-02-01
We have performed an overall fit to the electroweak data with the generation blind U(1) extension of the Standard Model. As input data for fitting we have included the asymmetry parameters, the partial decay widths of Z, neutrino scattering, and atomic parity violation. The QCD coupling αs has been constrained to the world average obtained from all data except the Z width. On the basis of our fit we have constructed a viable gauge model that not only explains Rb and Rc but also provides a much better overall fit to the data than the Standard Model. Despite its phenomenological viability, our model is unfortunately not simple from the theoretical viewpoint. Atomic parity violation experiments strongly disfavor more aesthetically appealing alternatives that can be grand unified.
Lower bound on the electroweak wall velocity from hydrodynamic instability
Mégevand, Ariel; Membiela, Federico Agustín; Sánchez, Alejandro D.
2015-03-27
The subsonic expansion of bubbles in a strongly first-order electroweak phase transition is a convenient scenario for electroweak baryogenesis. For most extensions of the Standard Model, stationary subsonic solutions (i.e., deflagrations) exist for the propagation of phase transition fronts. However, deflagrations are known to be hydrodynamically unstable for wall velocities below a certain critical value. We calculate this critical velocity for several extensions of the Standard Model and compare with an estimation of the wall velocity. In general, we find a region in parameter space which gives stable deflagrations as well as favorable conditions for electroweak baryogenesis.
Classically conformal radiative neutrino model with gauged B - L symmetry
NASA Astrophysics Data System (ADS)
Okada, Hiroshi; Orikasa, Yuta
2016-09-01
We propose a classically conformal model in a minimal radiative seesaw, in which we employ a gauged B - L symmetry in the standard model that is essential in order to work the Coleman-Weinberg mechanism well that induces the B - L symmetry breaking. As a result, nonzero Majorana mass term and electroweak symmetry breaking simultaneously occur. In this framework, we show a benchmark point to satisfy several theoretical and experimental constraints. Here theoretical constraints represent inert conditions and Coleman-Weinberg condition. Experimental bounds come from lepton flavor violations (especially μ → eγ), the current bound on the Z‧ mass at the CERN Large Hadron Collider, and neutrino oscillations.
NASA Astrophysics Data System (ADS)
Huang, Fa Peng; Gu, Pei-Hong; Yin, Peng-Fei; Yu, Zhao-Huan; Zhang, Xinmin
2016-05-01
We study the collider phenomenology of the electroweak phase transition and electroweak baryogenesis in the framework of the effective field theory. Our study shows that the effective theory using the dimension-6 operators can enforce strong first order phase transition and provide sizable C P violation to realize a successful electroweak baryogenesis. Such dimension-6 operators can induce interesting Higgs phenomenology that can be verified at colliders such as the LHC and the planning CEPC. We then demonstrate that this effective theory can originate from vectorlike quarks and the triplet Higgs.
Behavior of Tachyon in String Cosmology Based on Gauged WZW Model
NASA Astrophysics Data System (ADS)
Lee, Sunggeun; Nam, Soonkeon
We investigate a string theoretic cosmological model in the context of the gauged Wess-Zumino-Witten model. Our model is based on a product of non-compact coset space and a spectator flat space; [SL(2, R)/U(1)]k × ℝ2. We extend the formerly studied semiclassical consideration with infinite Kac-Moody level k to a finite one. In this case, the tachyon field appears in the effective action, and we solve the Einstein equation to determine the behavior of tachyon as a function of time. We find that tachyon field dominates over dilaton field in early times. In particular, we consider the energy conditions of the matter fields consisting of the dilaton and the tachyon which affect the initial singularity. We find that not only the strong energy but also the null energy condition is violated.
Strongly first-order electroweak phase transition and classical scale invariance
NASA Astrophysics Data System (ADS)
Farzinnia, Arsham; Ren, Jing
2014-10-01
In this work, we examine the possibility of realizing a strongly first-order electroweak phase transition within the minimal classically scale-invariant extension of the standard model (SM), previously proposed and analyzed as a potential solution to the hierarchy problem. By introducing one complex gauge-singlet scalar and three (weak scale) right-handed Majorana neutrinos, the scenario was successfully rendered capable of achieving a radiative breaking of the electroweak symmetry (by means of the Coleman-Weinberg mechanism), inducing nonzero masses for the SM neutrinos (via the seesaw mechanism), presenting a pseudoscalar dark matter candidate (protected by the CP symmetry of the potential), and predicting the existence of a second CP-even boson (with suppressed couplings to the SM content) in addition to the 125 GeV scalar. In the present treatment, we construct the full finite-temperature one-loop effective potential of the model, including the resummed thermal daisy loops, and demonstrate that finite-temperature effects induce a first-order electroweak phase transition. Requiring the thermally driven first-order phase transition to be sufficiently strong at the onset of the bubble nucleation (corresponding to nucleation temperatures TN˜100-200 GeV) further constrains the model's parameter space; in particular, an O(0.01) fraction of the dark matter in the Universe may be simultaneously accommodated with a strongly first-order electroweak phase transition. Moreover, such a phase transition disfavors right-handed Majorana neutrino masses above several hundreds of GeV, confines the pseudoscalar dark matter masses to ˜1-2 TeV, predicts the mass of the second CP-even scalar to be ˜100-300 GeV, and requires the mixing angle between the CP-even components of the SM doublet and the complex singlet to lie within the range 0.2≲sinω ≲0.4. The obtained results are displayed in comprehensive exclusion plots, identifying the viable regions of the parameter space
Electroweak contributions to squark pair production at the LHC
Germer, Jan; Hollik, Wolfgang; Mirabella, Edoardo; Trenkel, Maike
2010-02-10
We present the tree-level and next-to-leading order (NLO) electroweak (EW) contributions to squark - squark production at the Large Hadron Collider (LHC) within the framework of the Minimal Supersymmetric Standard Model (MSSM).
Matching of gauge invariant dimension-six operators for b → s and b → c transitions
NASA Astrophysics Data System (ADS)
Aebischer, Jason; Crivellin, Andreas; Fael, Matteo; Greub, Christoph
2016-05-01
New physics realized above the electroweak scale can be encoded in a model independent way in the Wilson coefficients of higher dimensional operators which are in-variant under the Standard Model gauge group. In this article, we study the matching of the SU(3) C × SU(2) L × U(1) Y gauge invariant dimension-six operators on the standard B physics Hamiltonian relevant for b → s and b → c transitions. The matching is performed at the electroweak scale (after spontaneous symmetry breaking) by integrating out the top quark, W , Z and the Higgs particle. We first carry out the matching of the dimension-six operators that give a contribution at tree level to the low energy Hamiltonian. In a second step, we identify those gauge invariant operators that do not enter b → s transitions already at tree level, but can give relevant one-loop matching effects.
Constraints on C P -violating gauge-Higgs operators
NASA Astrophysics Data System (ADS)
Dwivedi, Siddharth; Ghosh, Dilip Kumar; Mukhopadhyaya, Biswarup; Shivaji, Ambresh
2015-11-01
We consider the most general set of S U (2 )×U (1 ) invariant C P -violating operators of dimension six, which contribute to V V h interactions (V =W , Z , γ ). Our aim is to constrain any C P -violating new physics above the electroweak scale via the effective couplings that arise when such physics is integrated out. For this purpose, we use, in turn, electroweak precision data, global fits of Higgs data at the Large Hadron Collider and the electric dipole moments of the neutron and the electron. We thus impose constraints mainly on two-parameter and three-parameter spaces. We find that the constraints from the electroweak precision data are the weakest. Among the existing Higgs search channels, considerable constraints come from the diphoton signal strength. We note that potential contribution to h →γ Z may in principle be a useful constraining factor, but it can be utilized only in the high energy run. The contributions to electric dipole moments mostly lead to the strongest constraints, though somewhat fine-tuned combinations of more than one parameter with large magnitudes are allowed. We also discuss constraints on gauge boson trilinear couplings which depend on the parameters of the C P -violating operators.
Generalized higher gauge theory
NASA Astrophysics Data System (ADS)
Ritter, Patricia; Sämann, Christian; Schmidt, Lennart
2016-04-01
We study a generalization of higher gauge theory which makes use of generalized geometry and seems to be closely related to double field theory. The local kinematical data of this theory is captured by morphisms of graded manifolds between the canonical exact Courant Lie 2-algebroid T M ⊕ T ∗ M over some manifold M and a semistrict gauge Lie 2-algebra. We discuss generalized curvatures and infinitesimal gauge transformations. Finite gauge transformation as well as global kinematical data are then obtained from principal 2-bundles over 2-spaces. As dynamical principle, we consider first the canonical Chern-Simons action for such a gauge theory. We then show that a previously proposed 3-Lie algebra model for the six-dimensional (2,0) theory is very naturally interpreted as a generalized higher gauge theory.
NASA Astrophysics Data System (ADS)
Fujita, T.; Jalil, M. B. A.; Tan, S. G.; Murakami, S.
2011-12-01
We present an overview of gauge fields in spintronics, focusing on their origin and physical consequences. Important topics, such as the Berry gauge field associated with adiabatic quantum evolution as well as gauge fields arising from other non-adiabatic considerations, are discussed. We examine the appearance and effects of gauge fields across three spaces, namely real-space, momentum-space, and time, taking on a largely semiclassical approach. We seize the opportunity to study other "spin-like" systems, including graphene, topological insulators, magnonics, and photonics, which emphasize the ubiquity and importance of gauge fields. We aim to provide an intuitive and pedagogical insight into the role played by gauge fields in spin transport.
Strain gauge installation tool
Conard, L.M.
1998-06-16
A tool and a method are disclosed for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool. 6 figs.
Triple gauge vertices at one-loop level in two-Higgs-doublet model
NASA Astrophysics Data System (ADS)
Malinský, M.; Hořejší, J.
2004-05-01
Renormalized triple gauge vertices (TGV) are examined within the two-Higgs-doublet model of the electroweak interactions. Deviations of the TGV from their standard-model values are calculated at the one-loop level, in the on-shell renormalization scheme. As a consistency check, UV divergence cancellations anticipated on symmetry grounds are verified explicitly. The dependence of the TGV finite parts on the masses of possible heavy Higgs scalars is discussed briefly.
Electroweak Physics (diboson production) measurements with ATLAS
NASA Astrophysics Data System (ADS)
Bachas, K.; Atlas Collaboration
2016-07-01
This paper is intended to give an overview of the ATLAS results on the production cross sections of gauge boson pairs using data from pp collisions at √{{s}} = 7 TeV for W γ, Z γ, W± W±, ZZ, W± Z and WV , where V = W± or Z decaying hadronically and √{{s}} = 8 TeV for ZZ, W± W±, W± Z and W± W± at the LHC at CERN. The cross sections are found to be in agreement with the expectations from the Standard Model within the estimated uncertainties. The production cross section measurements also allow for studies of anomalous triple and quartic gauge couplings for which 95% confidence limits are set.
High temperature pressure gauge
Echtler, J. Paul; Scandrol, Roy O.
1981-01-01
A high temperature pressure gauge comprising a pressure gauge positioned in fluid communication with one end of a conduit which has a diaphragm mounted in its other end. The conduit is filled with a low melting metal alloy above the diaphragm for a portion of its length with a high temperature fluid being positioned in the remaining length of the conduit and in the pressure gauge.
Spontaneous parity violation and SUSY strong gauge theory
Haba, Naoyuki; Ohki, Hiroshi
2012-07-27
We suggest simple models of spontaneous parity violation in supersymmetric strong gauge theory. We focus on left-right symmetric model and investigate vacuum with spontaneous parity violation. Non-perturbative effects are calculable in supersymmetric gauge theory, and we suggest new models. Our models show confinement, so that we try to understand them by using a dual description of the theory. The left-right symmetry breaking and electroweak symmetry breaking are simultaneously occurred with the suitable energy scale hierarchy. This structure has several advantages compared to the MSSM. The scale of the Higgs mass (left-right breaking scale) and that of VEVs are different, so the SUSY little hierarchy problems are absent. The second model also induces spontaneous supersymmetry breaking.
Gauge coupling unification in a classically scale invariant model
NASA Astrophysics Data System (ADS)
Haba, Naoyuki; Ishida, Hiroyuki; Takahashi, Ryo; Yamaguchi, Yuya
2016-02-01
There are a lot of works within a class of classically scale invariant model, which is motivated by solving the gauge hierarchy problem. In this context, the Higgs mass vanishes at the UV scale due to the classically scale invariance, and is generated via the Coleman-Weinberg mechanism. Since the mass generation should occur not so far from the electroweak scale, we extend the standard model only around the TeV scale. We construct a model which can achieve the gauge coupling unification at the UV scale. In the same way, the model can realize the vacuum stability, smallness of active neutrino masses, baryon asymmetry of the universe, and dark matter relic abundance. The model predicts the existence vector-like fermions charged under SU(3) C with masses lower than 1 TeV, and the SM singlet Majorana dark matter with mass lower than 2.6 TeV.
Geometric phase and gauge connection in polyatomic molecules.
Wittig, Curt
2012-05-14
group applicable in the immediate vicinity of a two-state intersection is U(2), which factors to U(1) × SU(2). Gauging SU(2) yields three fields, whereas U(1) is not gauged, as the result cannot be brought into registry with electronic structure theory, and there are other problems as well. A parallel with spontaneous symmetry breaking in electroweak theory is noted. Loss of SU(2) symmetry as the energy gap between adiabats increases yields the inter-related U(1) symmetries of the upper and lower adiabats, with spinor character imprinted in the vicinity of the degeneracy. PMID:22314331
Indications for an extra neutral gauge boson in electroweak precision data
Erler; Langacker
2000-01-10
A new analysis of the hadronic peak cross section at LEP 1 implies a small amount of missing invisible width in Z decays, while the effective weak charge in atomic parity violation has been determined recently to 0.6% accuracy, indicating a significantly negative S parameter. As a consequence, the data are described well if the presence of an extra Z' boson, such as predicted in grand unified theories, is assumed. Moreover, the data are now rich enough to study an arbitrary extra Z' boson and to determine its couplings in a model independent way. An excellent fit to the data is obtained in this case, suggestive of a family nonuniversal Z' similar to those predicted in a class of superstring theories. PMID:11015875
Low energy strong electroweak sector with decoupling
Casalbuoni, R.; Dominici, D. |; Deandrea, A.; Gatto, R.; De Curtis, S.; Grazzini, M. |
1996-05-01
We discuss possible symmetries of effective theories describing spinless and spin-1 bosons, mainly to concentrate on an intriguing phenomenological possibility: that of a hardly noticeable strong electroweak sector at relatively low energies. Specifically, a model with both vector and axial vector strong interacting bosons may possess a discrete symmetry imposing degeneracy of the two sets of bosons (degenerate BESS model). In such a case its effects at low energies become almost invisible and the model easily passes all low energy precision tests. The reason lies essentially in the fact that the model automatically satisfies decoupling, contrary to models with only vectors. For large mass of the degenerate spin-one bosons the model becomes identical at the classical level to the standard model taken in the limit of infinite Higgs boson mass. For these reasons we have thought it worthwhile to fully develop the model, together with its possible generalizations, and to study the expected phenomenology. For instance, just because of its invisibility at low energy, it is conceivable that degenerate BESS has low mass spin-one states and gives quite visible signals at existing or forthcoming accelerators. {copyright} {ital 1996 The American Physical Society.}
Gravitational waves from the electroweak phase transition
Leitao, Leonardo; Mégevand, Ariel; Sánchez, Alejandro D. E-mail: megevand@mdp.edu.ar
2012-10-01
We study the generation of gravitational waves in the electroweak phase transition. We consider a few extensions of the Standard Model, namely, the addition of scalar singlets, the minimal supersymmetric extension, and the addition of TeV fermions. For each model we consider the complete dynamics of the phase transition. In particular, we estimate the friction force acting on bubble walls, and we take into account the fact that they can propagate either as detonations or as deflagrations preceded by shock fronts, or they can run away. We compute the peak frequency and peak intensity of the gravitational radiation generated by bubble collisions and turbulence. We discuss the detectability by proposed spaceborne detectors. For the models we considered, runaway walls require significant fine tuning of the parameters, and the gravitational wave signal from bubble collisions is generally much weaker than that from turbulence. Although the predicted signal is in most cases rather low for the sensitivity of LISA, models with strongly coupled extra scalars reach this sensitivity for frequencies f ∼ 10{sup −4} Hz, and give intensities as high as h{sup 2}Ω{sub GW} ∼ 10{sup −8}.
MSSM Electroweak Baryogenesis and LHC Data
Carena, Marcela; Nardini, Germano; Quiros, Mariano; Wagner, Carlos E.M.
2013-02-01
Electroweak baryogenesis is an attractive scenario for the generation of the baryon asymmetry of the universe as its realization depends on the presence at the weak scale of new particles which may be searched for at high energy colliders. In the MSSM it may only be realized in the presence of light stops, and with moderate or small mixing between the left- and right-handed components. Consistency with the observed Higgs mass around 125 GeV demands the heavier stop mass to be much larger than the weak scale. Moreover the lighter stop leads to an increase of the gluon-gluon fusion Higgs production cross section which seems to be in contradiction with indications from current LHC data. We show that this tension may be considerably relaxed in the presence of a light neutralino with a mass lower than about 60 GeV, satisfying all present experimental constraints. In such a case the Higgs may have a significant invisible decay width and the stop decays through a three or four body decay channel, including a bottom quark and the lightest neutralino in the final state. All these properties make this scenario testable at a high luminosity LHC.
Nonperturbative QCD corrections to electroweak observables
Dru B Renner, Xu Feng, Karl Jansen, Marcus Petschlies
2011-12-01
Nonperturbative QCD corrections are important to many low-energy electroweak observables, for example the muon magnetic moment. However, hadronic corrections also play a significant role at much higher energies due to their impact on the running of standard model parameters, such as the electromagnetic coupling. Currently, these hadronic contributions are accounted for by a combination of experimental measurements and phenomenological modeling but ideally should be calculated from first principles. Recent developments indicate that many of the most important hadronic corrections may be feasibly calculated using lattice QCD methods. To illustrate this, we will examine the lattice computation of the leading-order QCD corrections to the muon magnetic moment, paying particular attention to a recently developed method but also reviewing the results from other calculations. We will then continue with several examples that demonstrate the potential impact of the new approach: the leading-order corrections to the electron and tau magnetic moments, the running of the electromagnetic coupling, and a class of the next-to-leading-order corrections for the muon magnetic moment. Along the way, we will mention applications to the Adler function, the determination of the strong coupling constant and QCD corrections to muonic-hydrogen.
Gravitational waves from the electroweak phase transition
NASA Astrophysics Data System (ADS)
Leitao, Leonardo; Mégevand, Ariel; Sánchez, Alejandro D.
2012-10-01
We study the generation of gravitational waves in the electroweak phase transition. We consider a few extensions of the Standard Model, namely, the addition of scalar singlets, the minimal supersymmetric extension, and the addition of TeV fermions. For each model we consider the complete dynamics of the phase transition. In particular, we estimate the friction force acting on bubble walls, and we take into account the fact that they can propagate either as detonations or as deflagrations preceded by shock fronts, or they can run away. We compute the peak frequency and peak intensity of the gravitational radiation generated by bubble collisions and turbulence. We discuss the detectability by proposed spaceborne detectors. For the models we considered, runaway walls require significant fine tuning of the parameters, and the gravitational wave signal from bubble collisions is generally much weaker than that from turbulence. Although the predicted signal is in most cases rather low for the sensitivity of LISA, models with strongly coupled extra scalars reach this sensitivity for frequencies f ~ 10-4 Hz, and give intensities as high as h2ΩGW ~ 10-8.
Electroweak Corrections at the LHC with MCFM
Campbell, John M.; Wackeroth, Doreen; Zhou, Jia
2015-07-10
Electroweak (EW) corrections at the LHC can be enhanced at high energies due to soft/collinear radiation of W and Z bosons, being dominated by Sudakov-like corrections in the form of $\\alpha_W^l\\log^n(Q^2/M_W^2)$ $(n \\le 2l, \\alpha_W = \\alpha/(4\\pi\\sin\\theta_W^2))$ when the energy scale $Q$ enters the TeV regime. Thus, the inclusion of EW corrections in LHC predictions is important for the search of possible signals of new physics in tails of kinematic distributions. EW corrections should also be taken into account in virtue of their comparable size ($\\mathcal{O}(\\alpha)$) to that of higher order QCD corrections ($\\mathcal{O}(\\alpha_s^2)$). We calculated the next-to-leading-order (NLO) weak corrections to the neutral-current (NC) Drell-Yan process, top-quark pair production and di-jet producion, and implemented them in the Monte-Carlo program MCFM. This enables a combined study with the corresponding NLO QCD corrections. We provide both the full NLO weak corrections and their weak Sudakov approximation valid at high energies. The latter is often used for a fast evaluation of weak effects, and having the exact result available as well allows to quantify the validity of the Sudakov approximation.
Bartholomew, M. J.
2016-01-01
To improve the quantitative description of precipitation processes in climate models, the Atmospheric Radiation Measurement (ARM) Climate Research Facility deployed rain gauges located near disdrometers (DISD and VDIS data streams). This handbook deals specifically with the rain gauges that make the observations for the RAIN data stream. Other precipitation observations are made by the surface meteorology instrument suite (i.e., MET data stream).
Quaternion gauge fields. Pseudocolor
Govorkov, A.B.
1987-03-01
A simplified Guenaydin-Guersey model, in which a Majorana field constructed using quaternions combines a lepton and a color quark, is considered. Formulation of the gauge principle directly in the quaternions leads to the appearance of two vector quaternion gauge fields, these corresponding to the decomposition SO(4) approx. SO(3) x SO(3) of the invariance group. The diagonal subgroup SO(3) of automorphisms of the quarternions appears as a pseudocolor symmetry of the quarks, and the gauge field corresponding to it as the field of three color gluons. The other gauge field corresponds to lepton-quark transitions and in the presence of spontaneous breaking of the SO(4) gauge symmetry by the scalar quaternion field acquires a (large) finite mass.
Electroweak Boson Production in Association with Jets
NASA Astrophysics Data System (ADS)
Focke, Christfried Hermann
The high energies involved in modern collider experiments lead to hadronic final states that are often boosted inside collimated jets and surrounded by soft radiation. Together with tracking and energy information from leptons and photons, these jets contain essential information about a collision event. A good theoretical understanding is vital for measurements within the Standard Model (SM) as well as for background modeling required for new physics searches. Often one is interested in hadronic final states with cuts on jets in order to reduce backgrounds. For example, by imposing a central jet veto pcut in H → WW → lnulnu one can greatly reduce contamination from tt¯ → WW bb¯. Imposing such a jet veto comes at the cost of introducing potentially large logarithms L = ln pcut/Q into the cross section (Q is the hard scale), since the cuts restrict the cancellation of soft and collinear divergences between real and virtual diagrams. There are at most two powers of L for each power of the strong coupling constant alphas and this can spoil the convergence of the perturbative series when alpha sL2 ˜ 1 . We resume these logarithmically enhanced terms to all orders within the framework of Soft-Collinear Effective Theory (SCET) in order to recover the convergence and obtain reliable predictions for several processes. Another focus of this dissertation is the application of SCET in fixed order predictions of electroweak boson production in association with an exclusive number of final state jets. We employ the N-jettiness event-shape TN to resolve the infrared singularity structure of QCD in the presence of N signal jets. This allows us to obtain the first complete next-to-next-to leading order predictions for W, Z and Higgs boson production in association with one jet.
Gauge invariants and bosonization
NASA Astrophysics Data System (ADS)
Kijowski, J.; Rudolph, G.; Rudolph, M.
1998-12-01
We present some results, which are part of our program of analyzing gauge theories with fermions in terms of local gauge invariant fields. In a first part the classical Dirac-Maxwell system is discussed. Next we develop a procedure which leads to a reduction of the functional integral to an integral over (bosonic) gauge invariant fields. We apply this procedure to the case of QED and the Schwinger model. In a third part we go some steps towards an analysis of the considered models. We construct effective (quantum) field theories which can be used to calculate vacuum expectation values of physical quantities.
Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.
1991-01-01
A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator, wherein each thermographic layer comprises a plurality of respective thermographic sensors in a juxtaposed relationship with respect to each other. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.
Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.
1991-01-01
A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator wherein each thermographic layer comprises a plurality of respective thermographic phosphors. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.
Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MaCarthur, Charles D.; Cala, Gregory C.
1991-01-01
A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.
Bacvinskas, W.S.; Bayer, J.E.; Davis, W.W.; Fodor, G.; Kikta, T.J.; Matchett, R.L.; Nilsen, R.J.; Wilczynski, R.
1991-12-31
The present invention is directed to a semi-automatic rod examination gauge for performing a large number of exacting measurements on radioactive fuel rods. The rod examination gauge performs various measurements underwater with remote controlled machinery of high reliability. The rod examination gauge includes instruments and a closed circuit television camera for measuring fuel rod length, free hanging bow measurement, diameter measurement, oxide thickness measurement, cladding defect examination, rod ovality measurement, wear mark depth and volume measurement, as well as visual examination. A control system is provided including a programmable logic controller and a computer for providing a programmed sequence of operations for the rod examination and collection of data.
Inert scalars and vacuum metastability around the electroweak scale
NASA Astrophysics Data System (ADS)
Świeżewska, Bogumiła
2015-07-01
We analyse effective potential around the electroweak (EW) scale in the Standard Model (SM) extended with a heavy scalar doublet. We show that the additional scalars can have a strong impact on vacuum stability. Although the additional heavy scalars may improve the behaviour of running Higgs self-coupling at large field values, we prove that they can destabilise the vacuum due to EW-scale effects. A new EW symmetry conserving minimum of the effective potential can appear rendering the electroweak symmetry breaking (EWSB) minimum meta- or unstable. However, for the case of the inert doublet model (IDM) with a 125 GeV Higgs boson we demonstrate that the parameter space region where the vacuum is meta- or unstable cannot be reconciled with the constraints from perturbative unitarity, electroweak precision tests (EWPT) and dark matter relic abundance measurements.
The electroweak phase transition in the Inert Doublet Model
Blinov, Nikita; Profumo, Stefano; Stefaniak, Tim
2015-07-21
We study the strength of a first-order electroweak phase transition in the Inert Doublet Model (IDM), where particle dark matter (DM) is comprised of the lightest neutral inert Higgs boson. We improve over previous studies in the description and treatment of the finite-temperature effective potential and of the electroweak phase transition. We focus on a set of benchmark models inspired by the key mechanisms in the IDM leading to a viable dark matter particle candidate, and illustrate how to enhance the strength of the electroweak phase transition by adjusting the masses of the yet undiscovered IDM Higgs states. We argue that across a variety of DM masses, obtaining a strong enough first-order phase transition is a generic possibility in the IDM. We find that due to direct dark matter searches and collider constraints, a sufficiently strong transition and a thermal relic density matching the universal DM abundance is possible only in the Higgs funnel regime.
Combined QCD and electroweak analysis of HERA data
NASA Astrophysics Data System (ADS)
Abramowicz, H.; Abt, I.; Adamczyk, L.; Adamus, M.; Antonelli, S.; Aushev, V.; Behnke, O.; Behrens, U.; Bertolin, A.; Bhadra, S.; Bloch, I.; Boos, E. G.; Brock, I.; Brook, N. H.; Brugnera, R.; Bruni, A.; Bussey, P. J.; Caldwell, A.; Capua, M.; Catterall, C. D.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cooper-Sarkar, A. M.; Corradi, M.; Dementiev, R. K.; Devenish, R. C. E.; Dusini, S.; Foster, B.; Gach, G.; Gallo, E.; Garfagnini, A.; Geiser, A.; Gizhko, A.; Gladilin, L. K.; Golubkov, Yu. A.; Grzelak, G.; Guzik, M.; Gwenlan, C.; Hain, W.; Hlushchenko, O.; Hochman, D.; Hori, R.; Ibrahim, Z. A.; Iga, Y.; Ishitsuka, M.; Januschek, F.; Jomhari, N. Z.; Kadenko, I.; Kananov, S.; Karshon, U.; Kaur, P.; Kisielewska, D.; Klanner, R.; Klein, U.; Korzhavina, I. A.; Kotański, A.; Kötz, U.; Kovalchuk, N.; Kowalski, H.; Krupa, B.; Kuprash, O.; Kuze, M.; Levchenko, B. B.; Levy, A.; Limentani, S.; Lisovyi, M.; Lobodzinska, E.; Löhr, B.; Lohrmann, E.; Longhin, A.; Lontkovskyi, D.; Lukina, O. Yu.; Makarenko, I.; Malka, J.; Mastroberardino, A.; Mohamad Idris, F.; Mohammad Nasir, N.; Myronenko, V.; Nagano, K.; Nobe, T.; Nowak, R. J.; Onishchuk, Yu.; Paul, E.; Perlański, W.; Pokrovskiy, N. S.; Polini, A.; Przybycień, M.; Roloff, P.; Ruspa, M.; Saxon, D. H.; Schioppa, M.; Schneekloth, U.; Schörner-Sadenius, T.; Shcheglova, L. M.; Shevchenko, R.; Shkola, O.; Shyrma, Yu.; Singh, I.; Skillicorn, I. O.; Słomiński, W.; Solano, A.; Stanco, L.; Stefaniuk, N.; Stern, A.; Stopa, P.; Sztuk-Dambietz, J.; Tassi, E.; Tokushuku, K.; Tomaszewska, J.; Tsurugai, T.; Turcato, M.; Turkot, O.; Tymieniecka, T.; Verbytskyi, A.; Wan Abdullah, W. A. T.; Wichmann, K.; Wing, M.; Yamada, S.; Yamazaki, Y.; Zakharchuk, N.; Żarnecki, A. F.; Zawiejski, L.; Zenaiev, O.; Zhautykov, B. O.; Zotkin, D. S.; ZEUS Collaboration
2016-05-01
A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarization of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u - and d -type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.
Gauge coupling unification in gauge-Higgs grand unification
NASA Astrophysics Data System (ADS)
Yamatsu, Naoki
2016-04-01
We discuss renormalization group equations for gauge coupling constants in gauge-Higgs grand unification on five-dimensional Randall-Sundrum warped space. We show that all four-dimensional Standard Model gauge coupling constants are asymptotically free and are effectively unified in SO(11) gauge-Higgs grand unified theories on 5D Randall-Sundrum warped space.
The price of an electroweak monopole
NASA Astrophysics Data System (ADS)
Ellis, John; Mavromatos, Nick E.; You, Tevong
2016-05-01
In a recent paper, Cho, Kim and Yoon (CKY) have proposed a version of the SU (2) × U (1) Standard Model with finite-energy monopole and dyon solutions. The CKY model postulates that the effective U(1) gauge coupling →∞ very rapidly as the Englert-Brout-Higgs vacuum expectation value →0, but in a way that is incompatible with LHC measurements of the Higgs boson H → γγ decay rate. We construct generalisations of the CKY model that are compatible with the H → γγ constraint, and calculate the corresponding values of the monopole and dyon masses. We find that the monopole mass could be < 5.5 TeV, so that it could be pair-produced at the LHC and accessible to the MoEDAL experiment.
Electroweak absorptive parts in the matching conditions of nonrelativistic QCD
Hoang, Andre H.; Reisser, Christoph J.
2005-04-01
Electroweak corrections associated with the instability of the top quark to the next-to-next-to-leading logarithmic (NNLL) total top pair threshold cross section in e{sup +}e{sup -} annihilation are determined. Our method is based on absorptive parts in electroweak matching conditions of the operators of nonrelativistic QCD and the optical theorem. The corrections lead to ultraviolet phase space divergences that have to be renormalized and lead to NLL mixing effects. Numerically, the corrections can amount to several percent and are comparable to the known NNLL QCD corrections.
Electroweak and B physics results from the Fermilab Tevatron Collider
Pitts, K.T.
2001-01-30
This writeup is an introduction to some of the experimental issues involved in performing electroweak and b physics measurements at the Fermilab Tevatron. In the electroweak sector, we discuss W and Z boson cross section measurements as well as the measurement of the mass of the W boson. For b physics, we discuss measurements of B{sup 0}/{bar B}{sup 0} mixing and CP violation. This paper is geared towards nonexperts who are interested in understanding some of the issues and motivations for these measurements and how the measurements are carried out.
Recent results in electroweak physics at the Tevatron
Giulia Manca
2004-02-13
The Run II physics program of CDF and D0 has just begun with the first 72 pb{sup -1} of analysis quality data collected at the center-of-mass energy of 1.96 TeV. The Electroweak measurements are among the first and most important benchmarks for the best understanding of the detectors and testing the Standard Model. We present measurements of the W and Z inclusive cross sections and decays asymmetries, recent results in di-boson physics and searches for new physics which make use of distinct electroweak signatures.
Electroweak baryogenesis in the exceptional supersymmetric standard model
Chao, Wei
2015-08-28
We study electroweak baryogenesis in the E{sub 6} inspired exceptional supersymmetric standard model (E{sub 6}SSM). The relaxation coefficients driven by singlinos and the new gaugino as well as the transport equation of the Higgs supermultiplet number density in the E{sub 6}SSM are calculated. Our numerical simulation shows that both CP-violating source terms from singlinos and the new gaugino can solely give rise to a correct baryon asymmetry of the Universe via the electroweak baryogenesis mechanism.
Fluctuation-driven electroweak phase transition. [in early universe
NASA Technical Reports Server (NTRS)
Gleiser, Marcelo; Kolb, Edward W.
1992-01-01
We examine the dynamics of the electroweak phase transition in the early Universe. For Higgs masses in the range 46 less than or = M sub H less than or = 150 GeV and top quark masses less than 200 GeV, regions of symmetric and asymmetric vacuum coexist to below the critical temperature, with thermal equilibrium between the two phases maintained by fluctuations of both phases. We propose that the transition to the asymmetric vacuum is completed by percolation of these subcritical fluctuations. Our results are relevant to scenarios of baryogenesis that invoke a weakly first-order phase transition at the electroweak scale.
Radiative natural supersymmetry: Reconciling electroweak fine-tuning and the Higgs boson mass
NASA Astrophysics Data System (ADS)
Baer, Howard; Barger, Vernon; Huang, Peisi; Mickelson, Dan; Mustafayev, Azar; Tata, Xerxes
2013-06-01
Models of natural supersymmetry seek to solve the little hierarchy problem by positing a spectrum of light Higgsinos ≲200-300GeV and light top squarks ≲600GeV along with very heavy squarks and TeV-scale gluinos. Such models have low electroweak fine-tuning and satisfy the LHC constraints. However, in the context of the minimal supersymmetric standard model, they predict too low a value of mh, are frequently in conflict with the measured b→sγ branching fraction, and the relic density of thermally produced Higgsino-like weakly interacting massive particles (WIMPs) falls well below dark matter measurements. We propose a framework dubbed radiative natural supersymmetry (RNS), which can be realized within the minimal supersymmetric standard model (avoiding the addition of extra exotic matter) and which maintains features such as gauge coupling unification and radiative electroweak symmetry breaking. The RNS model can be generated from supersymmetry (SUSY) grand unified theory type models with nonuniversal Higgs masses. Allowing for high-scale soft SUSY breaking Higgs mass mHu>m0 leads to automatic cancellations during renormalization group running and to radiatively-induced low fine-tuning at the electroweak scale. Coupled with large mixing in the top-squark sector, RNS allows for fine-tuning at the 3%-10% level with TeV-scale top squarks and a 125 GeV light Higgs scalar h. The model allows for at least a partial solution to the SUSY flavor, CP, and gravitino problems since first-/second-generation scalars (and the gravitino) may exist in the 10-30 TeV regime. We outline some possible signatures for RNS at the LHC, such as the appearance of low invariant mass opposite-sign isolated dileptons from gluino cascade decays. The smoking gun signature for RNS is the appearance of light Higgsinos at a linear e+e- collider. If the strong CP problem is solved by the Peccei-Quinn mechanism, then RNS naturally accommodates mixed axion-Higgsino cold dark matter, where the
G2HDM: Gauged Two Higgs Doublet Model
NASA Astrophysics Data System (ADS)
Huang, Wei-Chih; Tsai, Yue-Lin Sming; Yuan, Tzu-Chiang
2016-04-01
A novel model embedding the two Higgs doublets in the popular two Higgs doublet models into a doublet of a non-abelian gauge group SU(2) H is presented. The Standard Model SU(2) L right-handed fermion singlets are paired up with new heavy fermions to form SU(2) H doublets, while SU(2) L left-handed fermion doublets are singlets under SU(2) H . Distinctive features of this anomaly-free model are: (1) Electroweak symmetry breaking is induced from spontaneous symmetry breaking of SU(2) H via its triplet vacuum expectation value; (2) One of the Higgs doublet can be inert, with its neutral component being a dark matter candidate as protected by the SU(2) H gauge symmetry instead of a discrete Z 2 symmetry in the usual case; (3) Unlike Left-Right Symmetric Models, the complex gauge fields ( W 1 ' ∓ W 2 ' ) (along with other complex scalar fields) associated with the SU(2) H do not carry electric charges, while the third component W 3 ' can mix with the hypercharge U(1) Y gauge field and the third component of SU(2) L ; (4) Absence of tree level flavour changing neutral current is guaranteed by gauge symmetry; and etc. In this work, we concentrate on the mass spectra of scalar and gauge bosons in the model. Constraints from previous Z' data at LEP and the Large Hadron Collider measurements of the Standard Model Higgs mass, its partial widths of γγ and Zγ modes are discussed.
Program Calibrates Strain Gauges
NASA Technical Reports Server (NTRS)
Okazaki, Gary D.
1991-01-01
Program dramatically reduces personnel and time requirements for acceptance tests of hardware. Data-acquisition system reads output from Wheatstone full-bridge strain-gauge circuit and calculates strain by use of shunt calibration technique. Program nearly instantaneously tabulates and plots strain data against load-cell outputs. Modified to acquire strain data for other specimens wherever full-bridge strain-gauge circuits used. Written in HP BASIC.
Gauging without initial symmetry
NASA Astrophysics Data System (ADS)
Kotov, Alexei; Strobl, Thomas
2016-01-01
The gauge principle is at the heart of a good part of fundamental physics: Starting with a group G of so-called rigid symmetries of a functional defined over space-time Σ, the original functional is extended appropriately by additional Lie(G) -valued 1-form gauge fields so as to lift the symmetry to Maps(Σ , G) . Physically relevant quantities are then to be obtained as the quotient of the solutions to the Euler-Lagrange equations by these gauge symmetries. In this article we show that one can construct a gauge theory for a standard sigma model in arbitrary space-time dimensions where the target metric is not invariant with respect to any rigid symmetry group, but satisfies a much weaker condition: It is sufficient to find a collection of vector fields va on the target M satisfying the extended Killing equationv a(i ; j) = 0 for some connection acting on the index a. For regular foliations this is equivalent to requiring the conormal bundle to the leaves with its induced metric to be invariant under leaf-preserving diffeomorphisms of M, which in turn generalizes Riemannian submersions to which the notion reduces for smooth leaf spaces M / ∼. The resulting gauge theory has the usual quotient effect with respect to the original ungauged theory: in this way, much more general orbits can be factored out than usually considered. In some cases these are orbits that do not correspond to an initial symmetry, but still can be generated by a finite-dimensional Lie group G. Then the presented gauging procedure leads to an ordinary gauge theory with Lie algebra valued 1-form gauge fields, but showing an unconventional transformation law. In general, however, one finds that the notion of an ordinary structural Lie group is too restrictive and should be replaced by the much more general notion of a structural Lie groupoid.
Aldrovandi, R.; Pereira, J.G.
1986-05-15
Because it acts on space-time and is not semisimple, the Poincare group cannot lead to a gauge theory of the usual kind. A candidate model is discussed which keeps itself as close as possible to the typical gauge scheme. Its field equations are the Yang-Mills equations for the Poincare group. It is shown that there exists no Lagrangian for these equations.
Implications of a heavy gauge boson
NASA Astrophysics Data System (ADS)
Kang, Junhai
We study the implications of neutral heavy gauge bosons to electroweak (EW) baryogenesis, neutrino physics and the discovery limits at the Tevatron and LHC. For baryogenesis, we construct two anomaly free supersymmetric U(1)' models with secluded U(1) '-breaking sectors. In the framework of the one with E6 embedding, we study the one-loop effective potential at finite temperature, and show that there exist strong enough first order EW phase transition (EWPT) because of the large trilinear terms in the tree-level Higgs potentials. Unlike the Minimal Supersymmetric Standard Model (MSSM), the stop masses can be very heavy. We discuss possible large tree-level CP violation associated with the Higgs sector. Numerical calculations show that the contribution purely from the thin wall regime is big enough to explain the observed baryon number asymmetry for some of the parameter space. Our model is free of domain wall problems and does not introduce new contributions to electric dipole moments (EDM). Secondly, we consider various possibilities for generating neutrino masses in supersymmetric models with an additional U(1)' gauge symmetry. One class of models involves two extra U (1)' x U(1)″ gauge symmetries, with U(1)″ breaking at an intermediate scale and yielding small Dirac masses through higher-dimensional operators. The right-handed neutrinos Nci can naturally decouple from the low energy U(1) ', avoiding cosmological constraints. We secondly consider models with a pair of heavy triplets which couple to left-handed neutrinos. After integrating out the heavy triplets, a small neutrino Majorana mass matrix can be generated by the induced non-renormalizable terms. We also study models involving the double-see-saw mechanism, in which heavy Majorana masses are associated with the TeV-scale of U(1)' breaking. We finally study how the exotic particles and supersymmetric partners would affect the discovery limit at the Tevatron and LHC for neutral gauge bosons in generic
Sakurai Prize Lecture: Thirty Years of Precision Electroweak Physics
NASA Astrophysics Data System (ADS)
Sirlin, Alberto
2002-04-01
We discuss the development of the theory of electroweak radiative corrections and its role in testing the Standard Model, predicting the top quark mass, constraining the Higgs boson mass, and searching for deviations that may signal the presence of new physics.
Measurement of Electroweak Top Quark Production at {D\\O}
Tsai, Yun-Tse
2013-01-01
We present a new model-independent measurement of the electroweak single top-quark production cross section in proton-antiproton (p- $\\bar{p}$) collisions at √s = 1.96 TeV in 9.7 fb^{-1} of integrated luminosity collected with the DØ detector.
Electroweak matching conditions for top pair production at threshold
Hoang, Andre H.; Reisser, Christoph J.
2006-08-01
We determine the real parts of electroweak matching conditions relevant for top quark pair production close to threshold in e{sup +}e{sup -} annihilation at next-to-next-to-leading logarithmic (NNLL) order. Numerically the corrections are comparable to the NNLL QCD corrections.
Natural cold baryogenesis from strongly interacting electroweak symmetry breaking
Konstandin, Thomas; Servant, Géraldine E-mail: geraldine.servant@cern.ch
2011-07-01
The mechanism of ''cold electroweak baryogenesis'' has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on any particular UV completion but only on a stage of supercooling ended by a first-order phase transition in the evolution of the universe, which can be natural if there is nearly conformal dynamics at the TeV scale. Besides, baryon-number violation originates from the Standard Model only.
EXECUTIVE SUMMARY OF THE SNOWMASS 2001 WORKING GROUP : ELECTROWEAK SYMMETRY BREAKING.
CARENA,M.; GERDES,D.W.; HABER,H.E.; TURCOT,A.S.; ZERWAS,P.M.
2001-06-30
In this summary report of the 2001 Snowmass Electroweak Symmetry Breaking Working Group, the main candidates for theories of electroweak symmetry breaking are surveyed, and the criteria for distinguishing among the different approaches are discussed. The potential for observing electroweak symmetry breaking phenomena at the upgraded Tevatron and the LHC is described. We emphasize the importance of a high-luminosity e{sup +}e{sup -} linear collider for precision measurements to clarify the underlying electroweak symmetry breaking dynamics. Finally, we note the possible roles of the {mu}{sup +} {mu}{sup -} collider and VLHC for further elucidating the physics of electroweak symmetry breaking.
Gauge/Gravity Duality (Gauge Gravity Duality)
Polchinski, Joseph
2010-02-24
Gauge theories, which describe the particle interactions, are well understood, while quantum gravity leads to many puzzles. Remarkably, in recent years we have learned that these are actually dual, the same system written in different variables. On the one hand, this provides our most precise description of quantum gravity, resolves some long-standing paradoxes, and points to new principles. On the other, it gives a new perspective on strong interactions, with surprising connections to other areas of physics. I describe these ideas, and discuss current and future directions.
Wright, B.L.; Alrick, K.R.; Fritz, J.N.
1994-05-01
Axisymmetric magnetic (ASM) gauges are useful diagnostic tools in the study of the conversion of energy from underground explosions to distant seismic signals. Requiring no external power, they measure the strength (particle velocity) of the emerging shock wave under conditions that would destroy most instrumentation. Shock pins are included with each gauge to determine the angle of the shock front. For the Non-Proliferation Experiment, two ASM gauges were installed in the ANFO mixture to monitor the detonation wave and 10 were grouted into boreholes at various ranges in the surrounding rock (10 to 64 m from the center of explosion). These gauges were of a standard 3.8-inch-diameter design. In addition, two unique Jumbo ASM gauges (3-ft by 3-ft in cross section) were grouted to the wall of a drift at a range of 65 m. We discuss issues encountered in data analysis, present the results of our measurements, and compare these results with those of model simulations of the experiment.
Diagrammatic analysis of QCD gauge transformations and gauge cancellations
NASA Astrophysics Data System (ADS)
Feng, Y. J.; Lam, C. S.
1996-02-01
Diagrammatic techniques are invented to implement QCD gauge transformations. These techniques can be used to discover how gauge-dependent terms are canceled among diagrams to yield gauge-invariant results in the sum. In this way a multiloop pinching technique can be developed to change ordinary vertices into background-gauge vertices. The techniques can also be used to design new gauges to simplify calculations by reducing the number of gauge-dependent terms present in the intermediate steps. Two examples are discussed to illustrate this aspect of the applications. ¢ 1996 The American Physical Society.
DeTrano, Alexander; Karimi, Naghmeh; Karri, Ramesh; Guo, Xiaofei; Carlet, Claude; Guilley, Sylvain
2015-01-01
Masking countermeasures, used to thwart side-channel attacks, have been shown to be vulnerable to mask-extraction attacks. State-of-the-art mask-extraction attacks on the Advanced Encryption Standard (AES) algorithm target S-Box recomputation schemes but have not been applied to scenarios where S-Boxes are precomputed offline. We propose an attack targeting precomputed S-Boxes stored in nonvolatile memory. Our attack targets AES implemented in software protected by a low entropy masking scheme and recovers the masks with 91% success rate. Recovering the secret key requires fewer power traces (in fact, by at least two orders of magnitude) compared to a classical second-order attack. Moreover, we show that this attack remains viable in a noisy environment or with a reduced number of leakage points. Eventually, we specify a method to enhance the countermeasure by selecting a suitable coset of the masks set. PMID:26491717
DeTrano, Alexander; Karimi, Naghmeh; Karri, Ramesh; Guo, Xiaofei; Carlet, Claude; Guilley, Sylvain
2015-01-01
Masking countermeasures, used to thwart side-channel attacks, have been shown to be vulnerable to mask-extraction attacks. State-of-the-art mask-extraction attacks on the Advanced Encryption Standard (AES) algorithm target S-Box recomputation schemes but have not been applied to scenarios where S-Boxes are precomputed offline. We propose an attack targeting precomputed S-Boxes stored in nonvolatile memory. Our attack targets AES implemented in software protected by a low entropy masking scheme and recovers the masks with 91% success rate. Recovering the secret key requires fewer power traces (in fact, by at least two orders of magnitude) compared to a classical second-order attack. Moreover, we show that this attack remains viable in a noisy environment or with a reduced number of leakage points. Eventually, we specify a method to enhance the countermeasure by selecting a suitable coset of the masks set. PMID:26491717
Electroweak top-quark pair production at the LHC with Z ' bosons to NLO QCD in POWHEG
NASA Astrophysics Data System (ADS)
Bonciani, Roberto; Ježo, Tomáš; Klasen, Michael; Lyonnet, Florian; Schienbein, Ingo
2016-02-01
We present the calculation of the NLO QCD corrections to the electroweak production of top-antitop pairs at the CERN LHC in the presence of a new neutral gauge boson. The corrections are implemented in the parton shower Monte Carlo program POWHEG. Standard Model (SM) and new physics interference effects are properly taken into account. QED singularities, first appearing at this order, are consistently subtracted. Numerical results are presented for SM and Z ' total cross sections and distributions in invariant mass, transverse momentum, azimuthal angle and rapidity of the top-quark pair. The remaining theoretical uncertainty from scale and PDF variations is estimated, and the potential of the charge asymmetry to distinguish between new physics models is investigated for the Sequential SM and a leptophobic topcolor model.