Search for the rare hadronic decay $B_s^0\to p \bar{p}$

TL;DR

This paper reports a search for the rare decay $B_s^0 o p ar{p}$ with no evidence found, setting the world's best upper limit, and confirms the observation of $B^0 o p ar{p}$ with precise measurement of its branching fraction.

Contribution

First search for the decay $B_s^0 o p ar{p}$ and precise measurement of $B^0 o p ar{p}$ branching fraction using LHCb data at 13 TeV.

Findings

No evidence for $B_s^0 o p ar{p}$ decay; upper limit set.

First observation of $B^0 o p ar{p}$ with a measured branching fraction.

Combined measurement yields ${ m BR}(B^0 o p ar{p}) = (1.27 imes 10^{-8})$ with improved precision.

Abstract

A search for the rare hadronic decay $B_s^0\to p \bar{p}$ is performed using proton-proton collision data recorded by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb$^{-1}$. No evidence of the decay is found and an upper limit on its branching fraction is set at ${\cal B}(B_s^0\to p \bar{p}) < 4.4~(5.1) \times 10^{-9}$ at 90% (95%) confidence level; this is currently the world's best upper limit. The decay mode $B^0\to p \bar{p}$ is measured with very large significance, confirming the first observation by the LHCb experiment in 2017. The branching fraction is determined to be ${\cal B}(B^0\to p \bar{p}) = \rm (1.27 \pm 0.15 \pm 0.05 \pm 0.04) \times 10^{-8}$, where the first uncertainty is statistical, the second is systematic and the third is due to the external branching fraction of the normalization channel $B^0\to K^+\pi^-$. The combination of the two LHCb measurements of the $B^0\to p \bar{p}$ branching fraction yields ${\cal B}(B^0\to p \bar{p}) = \rm (1.27 \pm 0.13 \pm 0.05 \pm 0.03) \times 10^{-8}$.