Study of Two-Body $e^+e^- \to B_s^{(*)}\bar{B}_s^{(*)}$ Production in the Energy Range from 10.77 to 11.02 GeV

TL;DR

This study investigates the production of $B_s^{(*)}ar{B}_s^{(*)}$ pairs in electron-positron collisions near 10.77 to 11.02 GeV, confirming the $
$ resonance's role and measuring production ratios and angular distributions.

Contribution

First measurement of $B_s^{(*)}ar{B}_s^{(*)}$ production cross sections and ratios near the $
$ resonance energy, including angular analysis at Belle.

Findings

Clear $
$ resonance signal observed for $B_s^{(*)}ar{B}_s^{(*)}$ production.

No significant signal observed for $$ resonance in the same process.

Measured production ratio of $B_s^*ar{B}_s^*$ to other final states at 10.866 GeV.

Abstract

We report results on the studies of the $e^+e^-\to B_s^{(*)}\bar{B}_s^{(*)}$ processes. The results are based on a $121.4$ fb$^{-1}$ data sample collected with the Belle detector at the center-of-mass energy near the $\Upsilon(10860)$ peak and $16.4$ fb$^{-1}$ of data collected at 19 energy points in the range from 10.77 to 11.02 GeV. We observe a clear $e^+e^-\to\Upsilon(10860)\to B_s^{(*)}\bar{B}_s^{(*)}$ signal, with no statistically significant signal of $e^+e^-\to \Upsilon(11020)\to B_s^{(*)}\bar{B}_s^{(*)}$. The relative production ratio of $B_s^*\bar{B}_s^*$, $B_s\bar{B}_s^{*}$, and $B_s\bar{B}_s$ final states at $\sqrt{s}=10.866$ GeV is measured to be $7:$ $0.856\pm0.106(stat.)\pm0.053(syst.):$ $0.645\pm0.094(stat.)^{+0.030}_{-0.033}(syst.)$. An angular analysis of the $B_s^*\bar{B}_s^*$ final state produced at the $\Upsilon(10860)$ peak is also performed.