Impact of Beyond the Standard Model Physics in the Detection of the Cosmic Neutrino Background

TL;DR

This paper explores how physics beyond the Standard Model, especially right-chiral currents, can significantly alter the detection rate of the Cosmic Neutrino Background in experiments like PTOLEMY, potentially mimicking Majorana neutrino signals.

Contribution

It demonstrates that BSM interactions can modify the neutrino capture rate, making Dirac neutrinos appear as Majorana ones, and discusses implications for neutrino detection experiments.

Findings

BSM interactions can increase Dirac neutrino capture rates up to 2.2 times the Standard Model expectation.

Presence of right-handed neutrinos can further increase the capture rate by 30-90%.

Lower than expected capture rates could indicate new physics beyond the Standard Model.

Abstract

We discuss the effect of Beyond the Standard Model charged current interactions on the detection of the Cosmic Neutrino Background by neutrino capture on tritium in a PTOLEMY-like detector. We show that the total capture rate can be substantially modified for Dirac neutrinos if scalar or tensor right-chiral currents, with strength consistent with current experimental bounds, are at play. We find that the total capture rate for Dirac neutrinos, $\Gamma_{\rm D}^{\rm BSM}$, can be between 0.3 to 2.2 of what is expected for Dirac neutrinos in the Standard Model, $\Gamma_{\rm D}^{\rm SM}$, so that it can be made as large as the rate expected for Majorana neutrinos with only Standard Model interactions. A non-negligible primordial abundance of right-handed neutrinos can only worsen the situation, increasing $\Gamma_{\rm D}^{\rm BSM}$ by 30 to 90\%. On the other hand, if a much lower total rate is measured than what is expected for $\Gamma_{\rm D}^{\rm SM}$, it may be a sign of new physics.