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.

Comment on ``A Precise Determination of Electroweak Parameters in Neutrino-Nucleon Scattering''

Abstract: A systematic error in the extraction of $\sin^2 \theta_W$ from nuclear deep inelastic scattering of neutrinos and antineutrinos arises from higher-twist effects arising from nuclear shadowing. We explain that these effects cause a correction to the results of the recently reported significant deviation from the Standard Model that is potentially as large as the deviation claimed, and of a sign that cannot be determined without an extremely careful study of the data set used to model the input parton distribution functions.

Composite Higgses

Abstract: We present an overview of composite Higgs models in light of the discovery of the Higgs boson The small value of the physical Higgs mass suggests that the Higgs quartic is likely loop generated, thus models with tree-level quartics will generically be more tuned We classify the various models (including bona fide composite Higgs, little Higgs, holographic composite Higgs, twin Higgs and dilatonic Higgs) based on their predictions for the Higgs potential, review the basic ingredients of each of them, and quantify the amount of tuning needed, which is not negligible in any model We explain the main ideas for generating flavor structure and the main mechanisms for protecting against large flavor violating effects, and present a summary of the various coset models that can result in realistic pseudo-Goldstone Higgses We review the current experimental status of such models by discussing the electroweak precision, flavor and direct search bounds, and comment on UV completions and on ways to incorporate dark matter

How to use the Standard Model effective field theory

Abstract: We present a practical three-step procedure of using the Standard Model effective field theory (SM EFT) to connect ultraviolet (UV) models of new physics with weak scale precision observables. With this procedure, one can interpret precision measurements as constraints on a given UV model. We give a detailed explanation for calculating the effective action up to one-loop order in a manifestly gauge covariant fashion. This covariant derivative expansion method dramatically simplifies the process of matching a UV model with the SM EFT, and also makes available a universal formalism that is easy to use for a variety of UV models. A few general aspects of RG running effects and choosing operator bases are discussed. Finally, we provide mapping results between the bosonic sector of the SM EFT and a complete set of precision electroweak and Higgs observables to which present and near future experiments are sensitive. Many results and tools which should prove useful to those wishing to use the SM EFT are detailed in several appendices.

Primordial hypermagnetic fields and triangle anomaly

Abstract: The high-temperature plasma above the electroweak scale $\ensuremath{\sim}100\mathrm{GeV}$ may have contained a primordial hypercharge magnetic field whose anomalous coupling to the fermions induces a transformation of the hypermagnetic energy density into fermionic number. In order to describe this process, we generalize the ordinary magnetohydrodynamical equations to the anomalous case. We show that a not completely homogeneous hypermagnetic background induces fermion-number fluctuations, which can be expressed in terms of a generic hypermagnetic field configuration. We argue that, depending upon the various particle physics parameters involved in our estimate (electron Yukawa coupling, strength of the electroweak phase transition) and upon the hypermagnetic energy spectrum, sizable matter-antimatter fluctuations can be generated in the plasma. These fluctuations may modify the predictions of the standard big bang nucleosynthesis (BBN). We derive constraints on the magnetic fields from the requirement that the homogeneous BBN is not changed. We analyze the influence of primordial magnetic fields on the electroweak phase transition and show that some specific configurations of the magnetic field may be converted into net baryon number at the electroweak scale.

T parity and the littlest Higgs

Abstract: We construct T-parity invariant extensions of the littlest Higgs model, in which only linear representations of the full symmetry group are employed, without recourse to the non-linear representations introduced by Coleman, Callan, Wess, and Zumino (CCWZ). These models are based on the symmetry breaking pattern SU(5)l × Hr/SO(5), where Hr can be SO(5) or other larger symmetry groups. The structure of the models in the SU(5)l sector is identical to the littlest Higgs model based on SU(5)/SO(5). Since the full symmetry group is realized linearly, these models can be thought of as possible UV extensions of the T-invariant model using non-linear representations via CCWZ, with whom they share similar low energy phenomenology. We also comment on how to avoid constraints from four-fermion operators on T-invariant models with or without CCWZ construction. The electroweak data therefore place a very weak bound on the symmetry breaking scale, f ≥ 450 GeV.