Neutrino-Electron Scattering: General Constraints on Z' and Dark Photon Models

TL;DR

This paper derives general constraints on $U(1)_X$ models, including dark photons and light $Z'$ bosons, using neutrino-electron scattering data from multiple experiments, accounting for interference effects.

Contribution

It provides exact analytic formulas and comprehensive limits on $U(1)_X$ models with kinetic and mass mixing, applicable to dark photon and light $Z'$ scenarios.

Findings

TEXONO, CHARM-II, and GEMMA data set the most restrictive bounds on new vector boson masses.

Interference effects between new physics and Standard Model contributions are significant and included in the analysis.

Results are valid for both dark photon-like and light $Z'$ models.

Abstract

We study the framework of $U(1)_X$ models with kinetic mixing and/or mass mixing terms. We give general and exact analytic formulas and derive limits on a variety of $U(1)_X$ models that induce new physics contributions to neutrino-electron scattering, taking into account interference between the new physics and Standard Model contributions. Data from TEXONO, CHARM-II and GEMMA are analyzed and shown to be complementary to each other to provide the most restrictive bounds on masses of the new vector bosons. In particular, we demonstrate the validity of our results to dark photon-like as well as light $Z^\prime$ models.