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.

Constraining the top-Higgs sector of the standard model effective field theory

Abstract: Working in the framework of the Standard Model effective field theory, we study chirality-flipping couplings of the top quark to Higgs and gauge bosons. We discuss in detail the renormalization-group evolution to lower energies and investigate direct and indirect contributions to high- and low-energy $CP$-conserving and $CP$-violating observables. Our analysis includes constraints from collider observables, precision electroweak tests, flavor physics, and electric dipole moments. We find that indirect probes are competitive or dominant for both $CP$-even and $CP$-odd observables, even after accounting for uncertainties associated with hadronic and nuclear matrix elements, illustrating the importance of including operator mixing in constraining the Standard Model effective field theory. We also study scenarios where multiple anomalous top couplings are generated at the high scale, showing that while the bounds on individual couplings relax, strong correlations among couplings survive. Finally, we find that enforcing minimal flavor violation does not significantly affect the bounds on the top couplings.

Flavor physics in the Randall-Sundrum model I. Theoretical setup and electroweak precision tests

Abstract: A complete discussion of tree-level flavor-changing effects in the Randall-Sundrum (RS) model with brane-localized Higgs sector and bulk gauge and matter fields is presented. The bulk equations of motion for the gauge and fermion fields, supplemented by boundary conditions taking into account the couplings to the Higgs sector, are solved exactly. For gauge fields the Kaluza-Klein (KK) decomposition is performed in a covariant Rξ gauge. For fermions the mixing between different generations is included in a completely general way. The hierarchies observed in the fermion spectrum and the quark mixing matrix are explained naturally in terms of anarchic five-dimensional Yukawa matrices and wave-function overlap integrals. Detailed studies of the flavor-changing couplings of the Higgs boson and of gauge bosons and their KK excitations are performed, including in particular the couplings of the standard W± and Z0 bosons. A careful analysis of electroweak precision observables including the S and T parameters and the Z0b couplings shows that the simplest RS model containing only Standard Model particles and their KK excitations is consistent with all experimental bounds for a KK scale as low as a few TeV, if one allows for a heavy Higgs boson (mh 1 TeV) and/or for an ultra-violet cutoff below the Planck scale. The study of flavor-changing effects includes analyses of the non-unitarity of the quark mixing matrix, anomalous right-handed couplings of the W± bosons, tree-level flavor-changing neutral current couplings of the Z0 and Higgs bosons, the rare decays t → c(u)Z0 and t → c(u)h, and the flavor mixing among KK fermions. The results obtained in this work form the basis for general calculations of flavor-changing processes in the RS model and its extensions.

Gluons and the quark sea at high energies: distributions, polarization, tomography

Abstract: This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics. This report is organized around four major themes: i) the spin and flavor structure of the proton, ii) three-dimensional structure of nucleons and nuclei in momentum and configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC.

How magnetic is the Dirac neutrino

Abstract: We derive model-independent, "naturalness" upper bounds on the magnetic moments µnu of Dirac neutrinos generated by physics above the scale of electroweak symmetry breaking. In the absence of fine-tuning of effective operator coefficients, we find that current information on neutrino mass implies that |µnu|<~10-14 bohr magnetons. This bound is several orders of magnitude stronger than those obtained from analyses of solar and reactor neutrino data and astrophysical observations.