Final results of nu-e-bar electron scattering cross-section measurements and constraints on new physics

TL;DR

This study measured the antineutrino-electron scattering cross-section using a large scintillating detector at a nuclear reactor, testing the Standard Model and setting bounds on new physics phenomena.

Contribution

It provides the first detailed measurement of the nu-e-bar scattering cross-section at low momentum transfer and constrains various beyond Standard Model physics scenarios.

Findings

Measured cross-section ratio R_{expt} = 1.08 ± 0.21(stat) ± 0.16(sys) times R_{SM}

Determined the weak mixing angle to be $ heta_W^2$ = 0.251 ± 0.031(stat) ± 0.024(sys)

Verified destructive interference in nu-e-bar+e processes

Abstract

The nu-e-bar electron elastic scattering cross-section was measured with a CsI(Tl) scintillating crystal detector array with a total mass of 187 kg at the Kuo-Sheng Nuclear Power Station. The detectors were exposed to a reactor nu-e-bar flux of 6.4 X 10^{12} cm^{-2}s^{-1} originated from a core with 2.9 GW thermal power. Using 29882/7369 kg-days of Reactor ON/OFF data, the Standard Model (SM) of electroweak interaction was probed at the 4-momentum transfer range of Q^2 ~ 3 X 10^{-6} GeV^2. A cross-section ratio of R_{expt} = [1.08 +- 0.21(stat) +- 0.16(sys)] X R_{SM} was measured. Constraints on the electroweak parameters (g_V,g_A) were placed, corresponding to a weak mixing angle measurement of $\s2tw$ = [0.251 +- 0.031(stat) +- 0.024(sys)]. Destructive interference in the SM nu-e-bar+e processes was verified. Bounds on neutrino anomalous electromagnetic properties (neutrino magnetic moment and neutrino charge radius), non-standard neutrino interactions, upparticle physics and non-commutative physics were placed. We summarize the experimental details and results, and discuss projected sensitivities with realistic and feasible hardware upgrades.