Searching for signatures of new physics in $B \to K \, \nu \, \overline{\nu}$ to distinguish between Dirac and Majorana neutrinos

TL;DR

This paper analyzes how new physics could affect the decay $B o K u ar{ u}$, aiming to distinguish whether neutrinos are Dirac or Majorana particles by studying decay signatures and distributions.

Contribution

It provides a model-independent framework analyzing decay signatures and form factors, constraining new physics parameters, and proposing methods to determine neutrino nature using upcoming experimental data.

Findings

Constraints on new physics parameters from Belle-II data

Analytical relations among form factors consistent with lattice QCD

Potential to distinguish Dirac and Majorana neutrinos with future measurements

Abstract

We conduct a model-independent analysis of the distinct signatures of various generic new physics possibilities in the decay $B \to K \, \nu \, \overline{\nu}$ by analyzing the branching ratio as well as the missing mass-square distribution. Considering the final neutrinos to be of the same flavor with non-zero mass, we discuss the new physics contributions for both Dirac and Majorana neutrino possibilities. In our study, we utilize the analytical relations among form factors in semi-leptonic $B \to K$ transitions, which are consistent with current lattice QCD predictions to a very high numerical accuracy. We provide constraints on different new physics parameters, taking into account the recent measurement of $B^+ \to K^+ \, \nu \, \overline{\nu}$ branching ratio by the Belle-II collaboration. In future, if the missing mass-square distribution for $B^+ \to K^+ \, \nu \, \overline{\nu}$ decay gets reported by Belle-II with analysis of more events than their present data set, one can not only investigate possible new physics effects in these decays, but also probe the Dirac/Majorana nature of the neutrinos using quantum statistics, since a difference between the two cases is known to exist in the presence of non-standard neutrino interactions.