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Determine the absolute branching fraction of Xi_b^- → J/psi Xi^-

Determine the absolute branching fraction of the decay Xi_b^- → J/psi Xi^- to enable absolute normalization of Xi_b^- decay rates measured via ratios and to facilitate direct comparisons with theoretical predictions for weak decays of bottom baryons.

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Background

The analysis measures the relative branching ratio R = B(Xi_b- → psi(2S) Xi-)/B(Xi_b- → J/psi Xi-). The choice of Xi_b- → J/psi Xi- as the normalization channel reduces systematic uncertainties due to similar topology and kinematics between the signal and normalization channels.

However, the absolute branching fraction B(Xi_b- → J/psi Xi-) has not been measured, which prevents converting the reported relative measurement into an absolute branching fraction for Xi_b- → psi(2S) Xi- and limits absolute rate comparisons across experiments and with theoretical models of heavy-baryon weak decays.

References

Even though the value of $\br(\XbJX)$ is not known, the choice of this normalization channel is quite natural since it has the same topology and similar kinematic properties as the signal channel, reducing the systematic uncertainty in the ratio related to the reconstruction of the muons and the other charged particle tracks from the \Xb decays.

— Observation of the $Ξ^-_\mathrm{b}$ $\to$ $ψ$(2S)$Ξ^-$ decay and studies of the $Ξ_\mathrm{b}$(5945)$^{0}$ baryon in proton-proton collisions at $\sqrt{s}$ = 13 TeV (2402.17738 - Collaboration, 27 Feb 2024) in Section 1 (Introduction), following Eq. (1)