Showing papers on "Electroweak interaction published in 1990"
TL;DR: It is necessary that the Universe possess a nonzero value of B\ensuremath{-}L prior to the epoch of fermion-number violation if baryon and lepton asymmetries are to survive.
Abstract: In the presence of rapid fermion-number violation due to nonperturbative electroweak effects certain relations between the baryon number of the Universe and the lepton numbers of the Universe are predicted. In some cases the electron-neutrino asymmetry is exactly specified in terms of the baryon asymmetry. Without introducing new particles, beyond the usual quarks and leptons, it is necessary that the Universe possess a nonzero value of B - L prior to the epoch of fermion-number violation if baryon and lepton asymmetries are to survive. Contrary to intuition, even though electroweak processes violate B + L, a nonzero value of B + L persists after the epoch of rapid fermion-number violation. If the standard model is extended to include lepton-number violation, for example through Majorana neutrino masses, then electroweak processes will reduce the baryon number to zero even in the presence of an initial B - L unless 20 M(sub L) approximately greater than the square root of (T(sub B - L) m(sub P1)) where M(sub L) sets the scale of lepton number violation and T(sub B - L) is the temperature at which a B - L asymmetry is produced. In many models this implies that neutrinos must be so light that they cannot contribute appreciably to the mass density of the Universe.
707 citations
TL;DR: In this paper, a detailed description of the on-shell electroweak radiative corrections calculation together with a list of formulae for 4-fermion processes complete at the one-loop level and with the accuracy required for precision experiments at the e+e− colliders LEP and SLC.
Abstract: We present a detailed description of the on-shell electroweak radiative corrections calculation together with a list of formulae for 4-fermion processes complete at the one-loop level and with the accuracy required for precision experiments at the e+e− colliders LEP and SLC. Applications are discussed to the mass interdependence of the weak vector bosons, the weak mixing angle, and to the precisely measurable on-resonance observables Z mass, width, forward-backward and polarization asymmetries for leptonic and hadronic final states. Comparisons with the results of other calculations have been performed as far as possible with satisfactory agreement in the predictions for the measurable quantities.
350 citations
TL;DR: The effect of electroweak fermion number violation in the early universe is to distribute a fermanion number excess over all the electroweak doublets as discussed by the authors, which can result in the production of heavy stable particles in numbers comparable to the number of baryons.
312 citations
TL;DR: In this article, the leading radiative corrections to various weak interaction parameters due to new heavy particles were studied, using an effective chiral lagrangian and input from low energy QCD to confirm the large size of these effects in technicolor theories.
290 citations
TL;DR: In this article, the authors consider baryon and lepton number violating processes induced by instantons in an electroweak-type model and show semi-quantitatively that process of the type q + q → 7q + 3l are very much suppressed even at large energies.
271 citations
TL;DR: The phenomenology of a Higgs sector for the standard model which contains both doublet and triplet fields (under SU(2){sub {ital L}})}, which has many exotic features and surprising experimental signatures is explored.
Abstract: Even though the standard model of the strong and electroweak interactions has proven enormously successful, it need not be the case that a single Higgs-doublet field is responsible for giving masses to the weakly interacting vector bosons and the fermions In this paper we explore the phenomenology of a Higgs sector for the standard model which contains both doublet and triplet fields (under SU(2){sub {ital L}}) The resulting Higgs bosons have many exotic features and surprising experimental signatures Since a critical task of future accelerators will be to either discover or establish the nonexistence of Higgs bosons with mass below the TeV scale, it will be important to keep in mind the alternative possibilities characteristic of this and other nonminimal Higgs sectors
223 citations
TL;DR: A new mechanism through which a net baryon asymmetry could be generated at the electroweak phase transition is discussed, and appears capable of producing the observed asymmetry.
Abstract: A new mechanism through which a net baryon asymmetry could be generated at the electroweak phase transition is discussed. It works efficiently in ``nonminimal'' extensions of the standard model such as occur in supersymmetric theories, where the Higgs sector involves several fields. In these theories it appears capable of producing the observed asymmetry. Conversely, with more detailed calculations this mechanism could be used to put important constraints on nonminimal extensions of the standard model.
181 citations
TL;DR: In this paper, general IR-divergent scalar box integrals, as present in calculations of radiative corrections, using a photon mass λ as regulator, are calculated, and special “mass singular” cases and examples thereof occuring in the electroweak theory are listed.
175 citations
TL;DR: The one-loop electroweak radiative correction to the decay rate of the {tau} lepton into a neutrino plus hadrons is calculated and it is argued that modifications of this electroweak correction due to nonperturbative QCD effects are suppressed by powers of {ital M}{sub{tau}.
Abstract: The one-loop electroweak radiative correction to the decay rate of the {tau} lepton into a neutrino plus hadrons is calculated. The correction includes a large logarithm of {ital M}{sub {ital Z}}/{ital M}{sub {tau}} whose coefficient was calculated previously. The constant under the logarithm gives an additional electroweak correction of 0.1%. It is argued that modifications of this electroweak correction due to nonperturbative QCD effects are suppressed by powers of {ital M}{sub {tau}}.
154 citations
TL;DR: In this article, the baryon asymmetry generation within the extended electroweak model with two Higgs doublets was considered and the upper bound on the mass of the lightest Higgs boson was obtained.
150 citations
TL;DR: In this paper, the symmetry breakdown in the electroweak theory is dynamical and one should expect, in general, to have some nonuniversal interactions, given the present bounds on flavor mixing, this imposes rather strong restrictions on the dynamics and the pattern of spontaneous symmetry breaking.
TL;DR: In this paper, the authors investigated isosinglet neutrino production and decays within different models and concluded that these may discover the existence of singlets neutrinos and substantially improve and extend present limits on their mass and coupling strength.
TL;DR: It is pointed out that the baryon-number asymmetry in the Universe is erased by the sphaleron effect just below the electroweak phase transition irrespective of the primordial baryON- and lepton- number asymmetry, if there exists a Majorana-type interaction.
Abstract: We point out that the baryon-number asymmetry in the Universe is erased by the sphaleron effect just below the electroweak phase transition irrespective of the primordial baryon- and lepton-number asymmetry, if there exists a Majorana-type interaction. The requirement to avoid this happening leads to the condition that ${m}_{\ensuremath{
u}} (\mathrm{Majorana})l50$ keV for all species of neutrions, regardless of whether or not neutrinos are stable.
TL;DR: In this article, a magnetic type solution of the classical electroweak equations with the property that for fields larger than mw2/e a W- and Z-condensate is formed was discussed.
TL;DR: In this paper, the authors discuss possible extra U(1) gauge symmetries for extensions of the standard model, in connection with their Higgs boson sectors, and discuss the main physical implications of this analysis.
Book•
01 Jan 1990TL;DR: In this paper, the Glashow-Weinberg-Salam theory of the electroweak interaction was extended to the weak interaction in the framework of the grand unification theories of neutrinos.
Abstract: Notation elementary particles and interactions classical theory of the weak interaction and rudiments of nuclear beta decay nuclear structure and beta decay gauge theories the Glashow-Weinberg-Salam theory of the electroweak interaction the weak interaction in the framework of the grand unification theories neutrinos weak interaction and astrophysics GUT and cosmology.
TL;DR: In this article, a program package (DIZET) is developed to calculate the differential cross section for fermion pair production in e+e-annihilation processes, as a function of the energy of the process, the production angle, and the longitudinal polarization of the beam particles.
TL;DR: In this article, the authors review the theoretical motivation and phenomenological implications of mirror fermions and conclude that mirror neutrinos with masses in the ranges m N ≲ 1 eV and m N ≥ 18 GeV could mix appreciably with ordinary quarks and leptons.
CERN1
TL;DR: In this paper, a global analysis of all the electroweak data including precision measurements of the Z 0 mass and decays from LEP is presented, showing that the top quark mass m t ≈100−160 GeV.
TL;DR: In this paper, the authors performed a numerical analysis of high temperature transitions involving the change of topological charge in the electroweak theory and determined the rate of fermion number nonconservation in the phase with restored symmetry.
TL;DR: In this paper, the phenomenology of the flipped SU (5) × U (1) superstring model emphasizing the Higgs and fermion mass spectra is studied.
TL;DR: In this paper, the authors discuss the origin of magnetic instability and the peculiar anti-screening property of the W-condensate formed, which is closely related to the asymptotic freedom of the SU(2)w-fields.
Abstract: The classical electroweak theory is unstable for magnetic fields H satisfying , mw being the W mass. We discuss the origin of this instability and the peculiar anti-screening property of the W-condensate formed. The anti-screening is closely related to the asymptotic freedom of the SU(2)w-fields. Assuming that the Higgs mass mh>mw there will be a restoration of SU(2)w×Uy(1) symmetry for . By using Bogomol’nyi’s method in the special case where the mass of the Z-particle mz=mh we can find static magnetic solutions with a vacuum condensate of W- and Z-bosons. This class of non-perturbative solutions interpolate between the constant magnetic field in the broken phase and a constant Uy(1) field in the symmetric phase . The consequences of this magnetic instability are discussed in the cases of superconducting cosmic strings, high temperatures (the early universe) and high energy collisions.
TL;DR: In this article, the leading electroweak corrections to parity-violating, leptonic and semi-leptonic neutral current amplitudes in the framework of the standard model were calculated and additional contributions to lepton-nucleon amplitudes from mesonic intermediate states.
TL;DR: In this paper, the experimental consequences of the existence of a heavy neutral gauge vector boson may produce in e + e − measurements made at energies around the Z mass were analyzed using the new data from CDF, UA2 and SLC/LEP1 on W and Z masses.
TL;DR: In this article, it was shown that if extended technicolor interactions are to play a role in electroweak symmetry breaking and in particular if they are to enhance fermion masses above their values in the usual weak Extended Technicolor scenario, then the chiral symmetry breaking phase transition must be second order.
TL;DR: It is considered the possibility that multiple four-Fermi interactions are important in symmetry breaking, leading to an effective two-Higgs-doublet model at low energies, and Higgs-induced flavor-changing neutral currents are naturally suppressed in this model.
Abstract: Recently, there has been some interest in the possibility that electroweak symmetry breaking in the standard model is driven by attractive four-Fermi interactions among heavy quarks. In this paper, we consider the possibility that multiple four-Fermi interactions are important in symmetry breaking, leading to an effective two-Higgs-doublet model at low energies. Higgs-induced flavor-changing neutral currents are naturally suppressed in this model. We consider the case where there are three generations, as well as the case of a heavy fourth generation. Predictions are made for the heavy-quark and Higgs-boson masses.
TL;DR: In this article, the radiative corrections of the standard model with a light Higgs gave a lower bound on the corrections in the supersymmetric model, which may serve to distinguish between the two different theories.
TL;DR: In this paper, the authors explore the phenomenology of a nonstandard electroweak theory in which left-handed quarks and leptons transform as doublets under separate SU(2) gauge groups.
TL;DR: In this paper, it was shown that the (B + L )-violating instanton-induced interactions in the electroweak sector of the Standard Model and in the two-dimensional abelian Higgs model cannot suppress multiple gauge vector or Higgs scalar production below the threshold E 0 ≈ M H / α W.
Book•
01 Jan 1990
TL;DR: In this paper, the authors propose a quantum field theory for quantum electrodynamics, from Fermi theory to the standard model and beyond, with a focus on weak hadronic currents and electroweak interference effects.
Abstract: Preface 1. Introduction 2. Towards a quantum field theory 3. Wave equations, propagators and fields 4. Quantum electrodynamics 5. From Fermi theory to standard model 6. Purely leptonic interactions 7. Deep inelastic scattering and quantum chromodynamics 8. Weak hadronic currents, electroweak interference effects 9. Quark and lepton oscillations 10. The standard model and beyond Appendixes References Index.