Showing papers on "Electroweak interaction published in 1991"
TL;DR: In this paper, the DELPHI Collaboration data was used to show that in the minimal non-supersymmetric standard model with one Higgs doublet a single unification point is excluded by more than 7 standard deviations.
1,114 citations
Book•
01 Jan 1991
TL;DR: In this article, a comprehensive overview of the present understanding of neutrino mass in unified gauge theories, its phenomenological and cosmological implications, and its implications on the physics beyond the standard model is provided.
Abstract: Are neutrinos massless particles as predicted by the standard model of electroweak interactions? There are however many reasons to suspect that neutrinos may indeed be massive and understanding the neutrino mass may hold the key to our understanding of physics beyond the standard model.This book provides a comprehensive overview of our present understanding of neutrino mass in unified gauge theories, its phenomenological and cosmological implications. It is divided into four parts. The first part presents a model independent discussion of the properties of the neutrino and nature of the neutrino masses. Part 2 deals with neutrino masses in unified and grand unified theories. In Part 3, phenomenological implications of neutrino mass is discussed. This includes neutrino oscillations, neutrinoless double beta decay and electromagnetic properties of neutrinos. Part 4 considers the solar neutrino puzzle, SN1987A and cosmological constraints on the neutrino properties. The book is meant for beginning and advanced graduate students in particle physics as well as active researchers in the field. It contains an extensive list of references to the original literature.
678 citations
TL;DR: In this paper, the authors estimate the strength of the electromagnetic fields produced due to the electroweak phase transition in the early universe and show that the resulting electromagnetic fields can also produce magnetic fields of other unbroken gauge symmetries such as SU(3)c.
606 citations
TL;DR: In this paper, the effects of new physics on vacuum polarization corrections to electroweak processes can in general be parametrized in terms of six real constants, in the limit of neglecting terms which vanish for Λ→∞.
555 citations
TL;DR: In this paper, the authors performed a complete computation of the contributions to b → s + γ, B → s / + / −, b → S ν ν, b→ s ν + g, b d o − B d o, B s o − b s o−B s o, and B n − B n o − N = 1 supergravity with radiative breaking of the electroweak symmetry group.
526 citations
TL;DR: In this paper, a color embedding, SU(3) c → SU( 3) 1 × SU (3) 2, was proposed to break electroweak symmetries through top quark condensation.
376 citations
TL;DR: In this article, an effective field theory is presented for calculating corrections to electroweak parameters in models of technicolor, and the correction to the W-mass from the pseudo-goldstone boson states is calculated.
263 citations
TL;DR: In this paper, a new scenario for generating the baryon asymmetry in the universe within the framework of the inflationary cosmology was proposed, where decay of the weakly coupled inflaton field via the heavy Majorana neutrinos produces an asymmetry.
258 citations
TL;DR: In this article, a perturbative expansion that is exactly gauge invariant at each order and produces expressions that are particularly simple in form is proposed. But this definition differs from the traditional one based on the position of the pole of the scattering amplitude by 35 MeV or more than 1 σ of the present experimental accuracy.
253 citations
TL;DR: In this paper, a new mechanism through which a net baryon asymmetry could be generated at the electroweak phase transition is discussed, which works efficiently in minimal extensions of the standard model such as occur in supersymmetric theories, where the Higgs sector involves more than one doublet.
250 citations
TL;DR: In this article, an alternative class of models to the supersymmetric standard model (SSM) in which R -parity is extended to a continuous U(1) R symmetry is explored.
TL;DR: A consistent picture of the {ital q{bar q}} system emerges which should allow a reliable treatment of electroweak phenomena in the heavy-meson sector also.
Abstract: We investigate the predictive power of a relativistic constituent-quark model of electroweak properties of pseudoscalar and vector mesons in the {ital u}-, {ital d}-, {ital s}-quark sector. The rates for radiative and weak decay processes and electromagnetic form factors for charged and neutral pseudoscalar mesons are calculated and compared with experiment. This analysis determines the values of the angles for {eta}-{eta}{prime} and {omega}-{phi} mixing, and also the Kobayashi-Maskawa matrix element {ital V}{sub {ital u}{ital s}}. A consistent picture of the {ital q{bar q}} system emerges which should allow a reliable treatment of electroweak phenomena in the heavy-meson sector also.
TL;DR: In this paper, the impact of new physics associated with the Higgs sector on precision electroweak physics is examined, and it is shown that the new physics leaves a characteristic signature in the pattern of corrections to the standard model's contribution to precision EEG measurements.
TL;DR: In this paper, it is emphasized that if another quantum number conserved up to anomalies is present electroweak anomaly processes would not necessarily erase a primordial baryon asymmetry even if B-L=0.
Abstract: Processes involving the electroweak anomaly can erase completely a primordial baryon and lepton asymmetry if B-L=0. This has led to the search for plausible mechanisms for weak-scale baryogenesis, or for the generation of a primordial B-L asymmetry. Here it is emphasized that if another quantum number conserved up to anomalies is present electroweak anomaly processes would not necessarily erase a primordial baryon asymmetry even if B-L=0. Moreover, an asymmetry in the new quantum number that is comparable to the baryon asymmetry is generated concomitantly due to the electroweak anomaly. This asymmetry could be the origin of dark matter.
TL;DR: In this article, an effective lagrangian based framework for the inclusion of new heavy physics effects on gauge boson self-energies was developed, where various observables may be expressed in terms of the parameters S, T and U.
TL;DR: In this paper, the baryon and lepton number are violated at temperatures above the weak phase transition, and the asymmetry is proportional to a CP violating parameter, a large power of the gauge coupling and to factors which depend on the details of the transition.
TL;DR: In this article, the authors estimate the rate of sphaleron-like transitions in the electroweak theory in the phase with restored symmetry and show that Γ = k(αWT)4 with k ≈ 0.1-1.0.
TL;DR: It is shown that string theories allow interactions potentially leading to photon and graviton-mass terms when one or more scalar fields acquire vacuum expectation values, which provides a new constraint on model building for string theories.
Abstract: We show that string theories allow interactions potentially leading to photon and graviton-mass terms when one or more scalar fields acquire vacuum expectation values. A general analysis is presented for the case when one of these scalars is the electroweak Higgs-boson doublet. The results provide a new constraint on model building for string theories.
TL;DR: In this article, the convolution integral for fermion pair production in the electroweak standard theory was presented, including soft photon exponentiation, and the result was complete in the sense that it included initial-and final-state radiation and their interference.
TL;DR: The effective Lagrangian which exhibits explicitly the transmission of the CP-violating phases induced via the electroweak gaugino masses below the scale of the spontaneous breaking of SU is deduced.
Abstract: The effective Lagrangian which exhibits explicitly the transmission of the CP-violating phases induced via the electroweak gaugino masses below the scale of the spontaneous breaking of SU(2${)}_{\mathit{L}}$\ifmmode\times\else\texttimes\fi{}${\mathrm{U}}_{\mathit{y}}$(1) electroweak gauge symmetry is deduced. The formalism is used to compute the one-loop electric dipole moment of the electron including the full set of neutralino states. Contributions of neutralinos other than the photino are found to be significant. It is shown that the current data excludes maximal CP violation in the electroweak sector except for selectron masses \ensuremath{\gtrsim}200 GeV and photino masses \ensuremath{\gtrsim}750 GeV.
TL;DR: It is shown that the requirement that the vacuum survive the high temperatures of the early Universe places the strongest constraints from vacuum stability on the top-quark and Higgs-boson masses in the minimal standard model.
Abstract: The electroweak vacuum need not be absolutely stable. For certain top-quark and Higgs-boson masses in the minimal standard model, it is instead metastable with a lifetime exceeding the present age of the Universe. The decay of our vacuum may be nucleated at low temperature by quantum tunneling or at high temperature by thermal excitation. We show that the requirement that the vacuum survive the high temperatures of the early Universe places the strongest constraints from vacuum stability on the top-quark and Higgs-boson masses in the minimal standard model. If a single Higgs boson is found experimentally, these constraints may place an upper bound on the scale of new physics beyond the minimal standard model. In contrast with other work, we examine temperatures very large compared to the scale of weak symmetry restoration and find much stronger bounds. We also present a simple analytic approximation that directly relates the bounds to the running coupling constants of the minimal standard model.
01 Jan 1991
TL;DR: In this paper, the authors derived the unitarity and triviality bounds for the two Higgs doublet version of the standard model by investigating at tree level the elastic s-wave amplitudes of various Higgs and would-be Goldstone boson scatterings.
[...]
TL;DR: In this article, the first-order electroweak and QCD corrections to the top quark decay width Γ (t → W + b) were presented for the W-boson on shell.
CERN1
TL;DR: In this article, the instanton-induced contribution to the total cross section of vector boson scattering in SU (2) gauge theory with and without Higgs mechanism was investigated.
CERN1
TL;DR: In this article, the authors investigated the behavior of the total cross section for electroweak baryon and lepton number violation at low energies (√ s) at low energy.
TL;DR: In this article, an analytic expression for the one-loop radiative corrections to the HZZ vertex is derived within the minimal standard model of electroweak interactions and the influence of a fourth generation of heavy fermions is investigated.
TL;DR: In this paper, the decay rate for the rare radiative decays of the b quark hadrons was calculated in the standard theory of electroweak interactions, using theb quark decay model, in the framework of an effective low energy Lagrangian based on the gauge invariant operators of dimension 6.
Abstract: Inclusive photon energy spectrum and decay rate for the rare radiative decays of theB hadrons,B → γ+X
s
(hereX
s
denotes hadrons with total strangeness quantum numberS=−1), are calculated in the standard theory of electroweak interactions, using theb quark decay model. The calculations have been done in the framework of an effective low-energy Lagrangian based on the gauge invariant operators of dimension 6. The large QCD effects, contained in the Wilson coefficients of these operators, are included in our approach. The shape of the photon energy spectrum and the branching ratio BR (B→γ+X
s
) are sensitive to the top quark mass.
TL;DR: In this paper, the S -and T -parameters introduced by Peskin and Takeuchi to characterize the radiative corrections to the electroweak interactions were reinterpreted in an effective field theory language.
TL;DR: A dynamical generalization of the seesaw mechanism is proposed based upon the BCS theory in which a neutrino condensate gives rise to right-handed-neutrino Majorana masses and all associated spin-zero bosons are composite.
Abstract: We consider a new mechanism for dynamical symmetry breaking of the electroweak symmetries involving condensates of fourth-generation quarks and leptons A dynamical generalization of the seesaw mechanism is proposed based upon the BCS theory in which a neutrino condensate gives rise to right-handed-neutrino Majorana masses and all associated spin-zero bosons are composite The fourth-generation neutrino is naturally heavier than {ital M}{sub {ital Z}}/2 and the scale of new physics is bounded above The renormalization-group equations for the effective Lagrangian of this model are derived and used to solve the model Implications for neutrino masses are discussed