Reducing Hadronic Uncertainty in Low-Energy Neutral-Current Processes

TL;DR

This paper reduces the hadronic uncertainty in low-energy neutral-current neutrino scattering by analyzing quark current correlators using chiral perturbation theory, significantly improving precision in relevant measurements.

Contribution

It provides a detailed chiral perturbation theory analysis of charge-current correlators, leading to a substantial reduction in hadronic uncertainty for neutrino scattering processes.

Findings

Hadronic uncertainty reduced by a factor of ~35.

Charge-charge and charge-isospin correlators are identical in SU(2) ChPT.

Leading-order SU(3) ChPT calculation discusses relevant counterterms.

Abstract

We analyze the hadronic uncertainty from light-quark loops coupled to (anti)neutrino in low-energy neutral-current (anti)neutrino scattering, estimated at the $3$-$4$ permille level. This uncertainty arises from limited knowledge of the charge-isospin correlation function of quark currents. We study the charge-charge and charge-isospin correlators within $\mathrm{SU}(2)$ and $\mathrm{SU}(3)$ chiral perturbation theory (ChPT). In $\mathrm{SU}(2)$ ChPT, the two correlators are identical to all orders in the chiral and electromagnetic expansions. We further perform a leading-order $\mathrm{SU}(3)$ ChPT calculation and discuss the relevant counterterms. Our findings reduce the hadronic uncertainty in neutral-current processes such as (anti)neutrino-electron and coherent elastic (anti)neutrino-nucleus scattering by a factor $\sim 35$.