Probing Neutrino-Light-Quark Effective Scalar Interactions from Neutrino Masses

TL;DR

This work addresses how neutrino masses constrain scalar interactions between neutrinos and light quarks within a LEFT framework extended by light right-handed neutrinos. By combining perturbative loop corrections with nonperturbative quark-condensate contributions through a χPT matching, the authors derive robust bounds on the Wilson coefficients of scalar operators using neutrino-mass measurements, CEνNS data, and light pseudoscalar meson invisible decays. They demonstrate that for operators with $u$ and $d$ quarks both contributions are relevant, while for $s$ quarks perturbative effects dominate, and that electron-neutrino mass measurements yield the strongest constraints on these couplings. The results underline the importance of a complete treatment that includes both perturbative and nonperturbative effects and provide a framework for translating low-energy observables into UV-model implications for neutrino-mass generation scenarios. The methodology offers a path to connect high-scale theories to precision low-energy data, with potential impact on beyond-Standard-Model explorations of neutrino masses.

Abstract

In this work, we use neutrino masses as a probe of the neutrino-light-quark effective scalar interactions. It is found that neutrinos can acquire masses not only from the usual light quark loop corrections but also from the light quark condensates. The latter contribution has been overlooked in the literature. We show that both contributions are comparable for operators involving $u$ and $d$ quarks, while quark loop corrections dominate for operators involving the $s$ quark. Using the low-energy effective field theory extended with light right-handed neutrinos and matching to chiral perturbation theory, we systematically analyze these contributions, deriving constraints on the corresponding Wilson coefficients from neutrino mass bounds, coherent elastic neutrino-nucleus scattering, and light pseudoscalar meson invisible decays. Our analysis shows that electron neutrino mass measurements provide the most stringent constraints on these scalar couplings, significantly improving upon limits from other observables. The results highlight the importance of including both perturbative and nonperturbative contributions in complete phenomenological analyses of neutrino mass generation mechanisms.

Figures (1)

• Figure 1: One- and two-loop Feynman diagrams contributing to the Dirac neutrino masses, where the blob denote the neutrino-light-quark scalar effective interactions. Similar Fynman diagrams also apply to generate Majorana neutrino masses.