First observation of the rare purely baryonic decay $B^0 \to p \bar{p}$

TL;DR

This paper reports the first observation of the rare decay $B^0 o p ar{p}$, measuring its branching fraction using LHCb data, and sets an upper limit on the similar decay $B_s^0 o p ar{p}$.

Contribution

It provides the first experimental evidence of the purely baryonic decay $B^0 o p ar{p}$ and measures its branching fraction, advancing understanding of baryonic B meson decays.

Findings

First observation of $B^0 o p ar{p}$ decay.

Measured branching fraction: (1.25 ± 0.27 ± 0.18) × 10^{-8}.

Set an upper limit on $B_s^0 o p ar{p}$ branching fraction.

Abstract

The first observation of the decay of a $B^0$ meson to a purely baryonic final state, $B^0 \to p \bar{p}$, is reported. The proton-proton collision data sample used was collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponds to an integrated luminosity of 3.0 fb$^{-1}$. The branching fraction is determined to be $${\cal B}(B^0 \to p \bar{p}) = ( 1.25 \pm 0.27 \pm 0.18 ) \times 10^{-8} ,$$ where the first uncertainty is statistical and the second systematic. The decay mode $B^0 \to p \bar{p}$ is the rarest decay of the $B^0$ meson observed to date. The decay $B_s^0 \to p \bar{p}$ is also investigated. No signal is seen and the upper limit ${\cal B}(B_s^0 \to p \bar{p}) < 1.5 \times 10^{-8}$ at 90% confidence level is set on the branching fraction.