Theoretical Bounds on New Four-Fermion Interactions and TeV Scale Physics

TL;DR

This paper reviews constraints on new four-fermion interactions at the TeV scale, highlighting current bounds from nuclear decays and collider searches, and discussing future prospects with neutron decay experiments and LHC data.

Contribution

It provides a comprehensive analysis of bounds on non-standard four-fermion interactions from various experiments and discusses future experimental sensitivities.

Findings

Current bounds from nuclear and pion decays are the most stringent.

Future neutron decay and LHC measurements will improve constraints.

Accurate calculation of neutron-to-proton matrix elements is crucial for future bounds.

Abstract

The standard model weak interactions can be described by four-fermion V-A operators at low energies. New physics at the TeV scale can, however, generate the other Lorentz structures. In this talk, we review the constraints on such interactions from nuclear and hadronic decays, as well as from collider searches. Currently the most stringent bounds come from the analysis of the 0+ to 0+ nuclear and the pi to e nu gamma radiative pion decays. In the near future, the ultracold neutron beta decay experiments and the direct LHC measurements will compete in setting the most stringent bounds, provided, however, that the neutron-to-proton non-perturbative transition matrix elements can be calculated to a level of 10-20% accuracy.