Standard Weinberg-Salam Model Research Articles

Monopole configuration in Weinberg-Salam model

We present a new type of spherically symmetric monopole and dyon solutions with the magnetic charge 4π e in the standard Weinberg-Salam model. The monopole (and dyon) could be interpreted as a non-trivial hybrid between the abelian Dirac monopole and non-abelian 't Hooft-Polyakov monopole (with an electric charge). We discuss the possible physical implications of the electroweak dyon.

THE HIGGS BOSON MASS IN SUPERSYMMETRIC WEINBERG-SALAM MODEL BROKEN AT HIGH SCALE

We study the dependence of the Higgs boson mass on the scale of supersymmetry breaking in the minimal supersymmetric extension of the standard Weinberg-Salam model.

Electro-weak Corrections to the Hyperfine Structure of Positronium

Corrections coming from weak interactions to the hyperfine splitting of the ground level of positronium are calculated in the standard Weinberg-Salam model. We obtain a contribution of 1.15 × 10 −5 MHz from this effect.

Inverse muon decay in a steady external field

A standard Weinberg-Salam model has been used to calculate the cross section of υμ+e »ve+μ in steady crossed fields (EH=E2−H2=0). The asymptotic behavior of the cross section has been examined as a function of the kinematic and dynamic (field) invariant parameters.

Invisible scalars visible in Higgs decay

We consider an extended Weinberg-Salam model with an additional SU(3)⊗SU(2)⊗U(1) gauge singlet scalar field. For the light scalar field the dominant Higgs decay mode is into two scalars. LEP experiments on the Higgs search allow to distinguish between the standard Weinberg-Salam model and the model with additional light scalars. Namely, our model predicts the existence of acoplanar jets with missing energy and acoplanar lepton pairs with missing energy which come from the decays (Higgs→two light scalars; Z→hadrons; e + e −, μ +μ −,τ +τ −) and the absence of four jet events which are typical for both the standard Weinberg-Salam model and its minimal supersymmetric extension.

Possibility of measuring the coupling constants of heavy quarks

The electroweak asymmetries (the front-back angular asymmetry, the right-left asymmetry, the degree of longitudinal polarization of a quark, and the degree of circular polarization of a γ-ray) in the ordinary and radiative annihilation of an electron-positron pair into a pair of heavy quarks are analyzed in the standard Weinberg-Salam model. It is shown that these P-odd asymmetries are quite sensitive to the magnitude of the right-hand coupling constant of a quark.

On the high-energy behaviour of a minimal extension of the Weinberg-Salam model

The electron-positron annihilation cross section near the heavy neutral vector-boson (Z) mass is calculated in the standard Weinberg-Salam (WS) model as well as in an SU(2)*U(1)*U'(1) (primed) model. Simple analytic expressions are presented for different parity-violating and asymmetry parameters in both the WS and primed models. The numerical results for these parameters indicate that the two models might be distinguishable at higher energies if the forward-backward asymmetry parameter and the parity-violating asymmetry parameters are measured.

The partial width of the Higgs boson inH→W + W −γ decay

The partial width of the processH→W + W −γ is examined in the standard Weinberg-Salam model. The photon spectra are plotted with differentm H >2m w values. The decay ratioR=Γ(H→W + W −γ)/Γ(H→W + W −) is evaluated and found to be 0(.01). This process may be observed atm H ≈150 GeV.

Neutral-current effects in the standard and extended gauge models for spin polarization effects in e+e- → μ+μ-

We study various observables (the asymmetry due to the beam polarizations, the forward-backward asymmetry, etc.) in which the neutral-current effects appear in the reaction e+e- →μ +μ- induced by (longitudinally and transversely) polarized as well as unpolarized e+e- beams in combination with the measurements of the longitudinal polarizationP L(μ-) of the outgoing muon(s). We carry out the numerical calculation for these quantities at TRISTAN and LEP energies, adopting as examples of the electroweak gauge models the standard WeinbergSalam model, the ones based onSU 2× U1×[U1]′ and onSU 2× U1 ×[SU 2]′. We argue that at TRISTAN energies the angular distribution of PL(μ-) measurable in the experiment by the polarized beams is especially useful for the purpose of distinguishing between the models. At LEP energy range the measurements of the angular distribution and the energy dependence of PL(μ-) using polarized beams, in addition to the measurement of the total cross-section, can determine the correct model if any.

Polarization amplitudes for photoproduction of charged weak bosons

We perform a detailed analysis of high energy photoproduction of charged intermediate bosons with polarized initial and final state particles. We study the dependence of cross sections on the magnetic and electric quadrupole moments of the weak boson and define polarization asymmetries which may help to discriminate the standard Weinberg-Salam model from other alternatives.

Double-boson-exchange processes in high-energyνμe−collisions in the standard Weinberg-Salam model

In this paper, we shall study double-boson-exchange processes in the reactions ${\ensuremath{\nu}}_{\ensuremath{\mu}}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}{e}^{\ensuremath{-}}{\ensuremath{\nu}}_{e}$, ${\ensuremath{\nu}}_{\ensuremath{\mu}}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}{e}^{\ensuremath{-}}{\ensuremath{\nu}}_{\ensuremath{\mu}}$, and ${\ensuremath{\nu}}_{\ensuremath{\mu}}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}{\ensuremath{\mu}}^{\ensuremath{-}}{\ensuremath{\nu}}_{e}$, using the standard Weinberg-Salam SU(2)\ifmmode\times\else\texttimes\fi{}U(1) model of electroweak interactions. At neutrino laboratory energy \ensuremath{\sim} 100 GeV, the cross section for the first reaction is \ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}44}$ ${\mathrm{cm}}^{2}$. This reaction may be observable with experimental facilities in the near future. It could serve as a useful tool for distinguishing the Weinberg-Salam model from other models of electroweak interactions.

Angular distributions of hadronic jet from the decay of W-boson produced with finite transverse momentum

The angular distributions of the hadronic jet in the jet pair rest system from the decay of the W± produced in pp and pp collisions are calculated at large invariant mass and finite transverse momentum of the jet pair system, by using the lowest order of the quantum chromodynamics and the standard Weinberg-Salam model. The numerical evaluation for coefficients of the angular distributions is carried out for pp collisions at $$\sqrt s = 800$$ GreV in three different (helicity, Gottfried-Jackson and Collins-Soper) reference frames.

Parity violation in elastic N-N scattering at high energies

Calculates the asymmetry in nucleon-nucleon elastic scattering at high energies arising from heavy boson exchange in the standard Weinberg-Salam model. By neglecting the strong interaction enhancement effects, the authors' result for p-n scattering is one order of magnitude higher than for p-p scattering. Enhancement effects increase the p-p asymmetry, which may become comparable with the p-n asymmetry. Their asymmetries, however, are too small if compared with the total cross section asymmetry measured at Argonne at 6 GeV/c on a water target.

Parity-violating effects in electroproduction of theΔ(1232)by polarized electrons

Parity-violating effects in the (quasi)elastic scattering of longitudinally polarized electrons from spin-\textonehalf{} targets are discussed in the framework of the unified guage theories of weak and electromagnetic interactions. In particular, the $R\ensuremath{-}L$ asymmetry in electroproduction of the $\ensuremath{\Delta}(1232)$ is studied in considerable detail, taking into account the full spin-$\frac{3}{2}$ structure of this resonance. Our results are valid for all values of $E$ and the entire range of ${Q}^{2}$. Numerical predictions are given for the standard Weinberg-Salam model at several energies of the electron beam.

Fine-structure correction for atomic parity-violating amplitudes

Expressions for parity-violating (PV) amplitudes constructed for electron-quark scattering in an SU(2)\ifmmode\times\else\texttimes\fi{}U(1)\ifmmode\times\else\texttimes\fi{}U\ensuremath{'}(1) model up to fourth order in electroweak coupling constants are used to calculate PV amplitudes for electron-nucleon scattering. These results are compared with those obtained in the standard Weinberg-Salam model. It is found that the numbers in the two models differ at best by 1%. Thus PV interaction in electron-nucleon scattering is not sensitive enough to distinguish between these two models.

Propagation of a neutrino in a homogeneous magnetic field

A neutrino, although it has no electric charge, can interact with a magnetic field by virtue of self-energy processes in which the virtual particles are charged. In this note, we examine the one-loop correction to the neutrino propagator in the presence of a homogeneous magnetic field in the context of the standard Weinberg-Salam model for leptons, using a technique introduced by Sapirstein.

New currents at CHEER

Various variants on the standard Weinberg–Salam model are analysed in terms of current limits and possible rates at CHEER.

Radiative corrections to the neutral-current interactions in the Weinberg-Salam model

The neutral amplitudes for neutrino-quark scattering are calculated in the one-loop approximation of the standard Weinberg-Salam model of weak and electromagnetic interactions. A careful analysis of renormalization procedure in the 't Hooft-Feynman gauge is presented. Apart from the photonic corrections which are subject to the ordinary QED analysis, purely weak corrections are of the order of one per cent in the amplitudes expressed in terms of the Fermi coupling constant.

SU(2)×U(1)×U'(1) models which are slightly different from the Weinberg-Salam model

We discuss SU(2) x U(1) x U'(1) models by a uniform formula which is convenient for their comparison with the standard Weinberg-Salam model. As examples, we give three interesting models which are based on different grand unification models. In one model, U'(1) does not contribute to the electromagnetic interaction; in the other two, both U(1) and U'(1) do contribute to the electromagnetic interaction. Also, the first two models can approach the standard Weinberg-Salam model as close as one wants; but the third model has limitations on it.

Z0decay into three gluons

After pointing out that the two-gluon decay mode of the ${Z}^{0}$ vanishes, we calculate the differential and the total decay rates for ${Z}^{0}\ensuremath{\rightarrow}\mathrm{ggg}$. Using the standard Weinberg-Salam model and quantum chromodynamics, we find a branching ratio of 1.8\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}5}$. We also discuss ${Z}^{0}\ensuremath{\rightarrow}\mathrm{gg}\ensuremath{\gamma}$ and ${Z}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\gamma}$.