Right-handed Dirac and Majorana neutrinos at Belle II

Abstract

We assess the ability of the Belle II experiment to probe the Dirac or Majorana nature of a massive right-handed neutrino (RHN) $N$ in the MeV to GeV mass range. We consider the production and decay of RHNs to proceed via new interactions described by the standard model effective field theory (SMEFT) extended with right-handed neutrino fields (SMNEFT), and not via mass mixing with active neutrinos. We find that Belle II has the potential to discover $N$ if kinematically accessible. We perform detailed simulations of the angular distributions of lepton pairs from the decay of $N$ produced in two-body and three-body decays of $B$ mesons. We show that for $m_N$ above 100 MeV, Belle II can distinguish between Dirac and Majorana neutrinos at more than the 5$\sigma$ CL for most operators, and the combination of the production and decay operators can be identified from the subsequent decay of the heavy neutrino. Also, the production operators can be identified using three-body $B$ meson decay for any $m_N$ if the $B\to D\ell N$ and $B\to D^{\ast }\ell N$ events can be well separated.

28 pages, 13 figures, 12 tables

References in corpus (11)

• Heavy Majorana Neutrinos in the Effective Lagrangian Description: Application to Hadron Colliders
• Right-handed neutrino magnetic moments
• Constraints on Sterile Neutrinos in the MeV to GeV Mass Range
• Operator Bases in Effective Field Theories with Sterile Neutrinos: $d\le 9$
• Long-lived Sterile Neutrinos at Belle II in Effective Field Theory
• Anomalous dimensions from gauge couplings in SMEFT with right-handed neutrinos
• Three-Body Decays of Heavy Dirac and Majorana Fermions
• Long-lived heavy neutral leptons from mesons in effective field theory
• Neutrino mass constraints on beta decay
• Anomalous dimensions from Yukawa couplings in SMNEFT: four-fermion operators
• Majorana neutrinos with effective interactions in B decays

Cited by in corpus (2)

• When Energy Goes Missing: New Physics in $b\to s\nu \nu$ with Sterile Neutrinos
• Distinguishing Dirac from Majorana Heavy Neutrino at Future Lepton Colliders