Measurement of the properties of the $\Xi_b^{*0}$ baryon

TL;DR

This paper reports a precise measurement of the mass, width, and production ratio of the $ ext{Xi}_b^{*0}$ baryon resonance, confirming previous findings and providing new detailed properties of this particle.

Contribution

It provides the most precise measurement of the $ ext{Xi}_b^{*0}$ mass and the first measurement of its natural width, confirming its quantum state as predicted by the quark model.

Findings

Mass difference measured as 15.727 MeV/c^2 with high precision.

Natural width of the $ ext{Xi}_b^{*0}$ is measured as 0.90 MeV.

Production ratio relative to $ ext{Xi}_b^-$ is 0.28.

Abstract

We perform a search for near-threshold $\Xi_b^0$ resonances decaying to $\Xi_b^- \pi^+$ in a sample of proton-proton collision data corresponding to an integrated luminosity of 3 fb$^{-1}$ collected by the LHCb experiment. We observe one resonant state, with the following properties: \begin{eqnarray*} m(\Xi_b^{*0}) - m(\Xi_b^-) - m(\pi^+) &=& 15.727 \pm 0.068 \, (\mathrm{stat}) \pm 0.023 \, (\mathrm{syst}) \, \mathrm{MeV}/c^2, \Gamma(\Xi_b^{*0}) &=& 0.90 \pm 0.16 \, (\mathrm{stat}) \pm 0.08 \, (\mathrm{syst}) \, \mathrm{MeV} . \end{eqnarray*} This confirms the previous observation by the CMS collaboration. The state is consistent with the $J^P=3/2^+$ $\Xi_b^{*0}$ resonance expected in the quark model. This is the most precise determination of the mass and the first measurement of the natural width of this state. We have also measured the ratio \begin{align*} \frac{\sigma(pp \to \Xi_b^{*0} X){\cal{B}}(\Xi_b^{*0} \to \Xi_b^- \pi^+)}{\sigma(pp \to \Xi_b^- X)} = 0.28 \pm 0.03 \, (\mathrm{stat}) \pm 0.01 \, (\mathrm{syst}) . \end{align*}