Year: 2026
Type: preprint
Abstract: The mono-photon process $e^+e^- \to γ+\mathrm{invisible}$ at Belle II probes both invisible new states and the electroweak couplings of neutrinos. In this work, we study the process $e^+e^- \to γν\barν$, finding that Belle II with the full expected dataset can determine the neutrino-sensitive effective weak mixing angle to a 3.6$\%$ relative statistical precision, competitive with existing neutrino probes at other energy scales. Polarized beams, as proposed for the Chiral Belle upgrade, separate the neutral- and charged-current contributions and provide independent access to each, giving a handle on the chiral structure of the neutrino gauge interactions. The same process is an irreducible background to dark boson searches, producing a neutrino fog once the luminosity exceeds 1 ab$^{-1}$.
Source: arXiv (Cornell University)
Institutions: TRIUMF, University of Victoria, Simon Fraser University
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7206207662