Four-body baryonic $B\to{\bf B_1\bar B'_1 B_2 \bar B'_2}$ decays

TL;DR

This paper explores the phenomenology of four-body baryonic B decays, predicts invariant mass spectrum features, and estimates branching fractions for various decay modes, providing guidance for future experimental verification.

Contribution

It is the first to analyze the phenomenology of other tree and penguin dominated four-body baryonic B decays and predicts specific spectral features and branching fractions.

Findings

Double threshold effect with two peaks in invariant mass spectra.

Predicted branching fractions for specific decay modes.

Branching fractions are within experimental reach.

Abstract

LHCb has recently reported the first observation of a four-body baryonic $B\to{\bf B_1\bar B'_1 B_2\bar B'_2}$ decay, where ${\bf B_1\bar B'_1}$ and ${\bf B_2\bar B'_2}$ represent the two pairs of octet baryon states. In our classification, the measured $\bar B^0\to p\bar p p\bar p$ decay is a tree dominated process via internal $W$-boson emission, whose branching fraction is explained as small as $2.2\times 10^{-8}$. We investigate for the first time the phenomenology of other tree and penguin dominated $B\to{\bf B_1\bar B'_1 B_2\bar B'_2}$ decays, and predict the presence of a double threshold effect, manifested as two peaks around $m_{\bf B_1\bar B'_1}\sim m_{\bf B_1}+m_{\bf\bar B'_1}$ and $m_{\bf B_2\bar B'_2}\sim m_{\bf B_2}+m_{\bf\bar B'_2}$ in the invariant mass spectra of ${\bf B_1\bar B'_1}$ and ${\bf B_2\bar B'_2}$, respectively. Moreover, we predict the following branching fractions: ${\cal B}(B^-\to n\bar p p\bar p)=(1.7^{+0.4}_{-0.2}\pm 0.1^{+0.7}_{-0.4})\times 10^{-7}$, ${\cal B}(B^-\to \Lambda\bar p p\bar p)=(7.4^{+0.6}_{-0.2}\pm 0.03^{+3.6}_{-2.6})\times 10^{-7}$, and ${\cal B}(\bar B^0_s\to \Lambda\bar \Lambda p\bar p)=(1.9^{+0.3}_{-0.1}\pm 0.01^{+1.1}_{-0.6})\times 10^{-7}$, which are accessible to experimental facilities.