# Sensitivity limits on heavy-light mixing |UμN |2 from lepton number violating B meson decays

Gorazd Cvetič, C. S. Kim

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

## Abstract

We consider the lepton number violating decays B→μ±μ±π and B→D(∗)μ±μ±π which may be detected at the LHCb and Belle-II experiments and B→μ±μ±eν and B→D(∗)μ±μ±eν decays which may be detected at the Belle-II experiment. The projected total number of produced B mesons is 4.8×1012 at the LHCb upgrade and 5×1010 at Belle-II. For the case in which the above decays are not detected, we deduce the new upper bounds (sensitivity limits) for the mixing parameter |UμN|2 of heavy sterile neutrino with sub-eV light neutrino, as a function of the sterile neutrino mass in the interval 1.75 GeV<MN<5.0 GeV. We take into account the probability of decay of the sterile neutrino N within the detector, taking as the effective detector length L=2.3m at the LCHb upgrade and L=1m at Belle-II. In the interval 1.75 GeV<MN<3 GeV, the most stringent bounds can be obtained with the decays B→μ±μ±π at the LHCb upgrade. The sensitivity limits are expected to be, in general, more stringent at the LHCb upgrade than at Belle-II, principally because the number of produced B mesons in the LHCb upgrade is expected to be about 2 orders of magnitude larger than at Belle-II. We conclude that the LHCb upgrade and Belle-II experiments have the potential to either find a new heavy Majorana neutrino N or to improve significantly the sensitivity limits (upper bounds) on the heavy-light mixing parameter |UμN|2, particularly in the mass range 1.75 GeV<MN<3 GeV. This work is a continuation and refinement of our previous work [Phys. Rev. D 94, 053001 (2016); PRVDAQ2470-001010.1103/PhysRevD.94.053001Phys. Rev. D 95, 039901(E) (2017)PRVDAQ2470-0010] on the subject.

Original language English 035025 Physical Review D 96 3 https://doi.org/10.1103/PhysRevD.96.035025 Published - 2017 Aug 1

### Bibliographical note

Funding Information:
The work of C. S. K. was supported by the NRF grant funded by the Korean government of the MEST (No. 2016R1D1A1A02936965). We thank Y. J. Kwon and Sheldon L. Stone for providing us with valuable information on the Belle-II and LHCb upgrade experiments, respectively.