Electroweak interaction

About: Electroweak interaction is a research topic. Over the lifetime, 16333 publications have been published within this topic receiving 468927 citations. The topic is also known as: electroweak force.

Beyond S, T, and U.

Abstract: The contribution to precision electroweak measurements due to TeV physics which couples primarily to the W ± and Z bosons may be parameterized in terms of the three ‘oblique correction’ parameters, S, T and U. We extend this parameterization to physics at much lower energies, > 100 GeV, and show that in this more general case neutral-current experiments are sensitive to only two additional parameters. A third new parameter enters into the W ± width. The standard electroweak theory has recently come of age, with experiments now probing its predictions with sufficient accuracy to test its r corrections in some detail. Besides providing a detailed test of the model, these precision measurements are also very useful for the constraints they impose on any potential new physics that might exist at energies higher than those that have been hitherto experimentally explored. A particularly interesting class of new physics that is constrained by these measure

Beautiful mirrors and precision electroweak data

Abstract: The standard model (SM) with a light Higgs boson provides a very good description of the precision electroweak observable data coming from the CERN LEP, SLD and Fermilab Tevatron experiments. Most of the observables, with the notable exception of the forward-backward asymmetry of the bottom quark, point towards a Higgs boson mass far below its current experimental bound. The disagreement, within the SM, between the values for the weak mixing angle as obtained from the measurement of the leptonic and hadronic asymmetries at lepton colliders, may be taken to indicate new physics contributions to the precision electroweak observables. In this article we investigate the possibility that the inclusion of additional bottomlike quarks could help resolve this discrepancy. Two inequivalent assignments for these new quarks are analyzed. The resultant fits to the electroweak data show a significant improvement when compared to that obtained in the SM. While in one of the examples analyzed the exotic quarks are predicted to be light, with masses below 300 GeV, and the Higgs boson tends to be heavy, in the second one the Higgs boson is predicted to be light, with a mass below 250 GeV, while the quarks tend to be heavy, with masses of about 800 GeV. The collider signatures associated with the new exotic quarks, as well as the question of unification of couplings within these models and a possible cosmological implication of the new physical degrees of freedom at the weak scale are also discussed.

Conformal phase transition in gauge theories

Abstract: The conception of the conformal phase transiton (CPT), which is relevant for the description of nonperturbative dynamics in gauge theories, is introduced and elaborated. The main features of such a phase transition are established. In particular, it is shown that in the CPT there is an abrupt change of the spectrum of light excitations at the critical point, though the phase transition is continuous. The structure of the effective action describing the CPT is elaborated and its connection with the dynamics of the partially conserved dilatation current is pointed out. The applications of these results to QCD, models of dynamical electroweak symmetry breaking, and to the description of the phase diagram in (3+1)-dimensional SU(N{sub c}) gauge theories are considered. {copyright} {ital 1997} {ital The American Physical Society}

Updated Status of the Global Electroweak Fit and Constraints on New Physics

Abstract: We present an update of the Standard Model fit to electroweak precision data. We include newest experimental results on the top quark mass, the W mass and width, and the Higgs boson mass bounds from LEP, Tevatron and the LHC. We also include a new determination of the electromagnetic coupling strength at the Z pole. We find for the Higgs boson mass (91 +30 -23) GeV and (120 +12 -5) GeV when not including and including the direct Higgs searches, respectively. From the latter fit we indirectly determine the W mass to be (80.360 +0.014 -0.013) GeV. We exploit the data to determine experimental constraints on the oblique vacuum polarisation parameters, and confront these with predictions from the Standard Model (SM) and selected SM extensions. By fitting the oblique parameters to the electroweak data we derive allowed regions in the BSM parameter spaces. We revisit and consistently update these constraints for a fourth fourth fermion generation, two Higgs doublet, inert Higgs and littlest Higgs models, models with large, universal or warped extra dimensions and technicolour. In most of the models studied a heavy Higgs boson can be made compatible with the electroweak precision data.