Observation of $B_s^0\to J/\psi f_0(980)$ and Evidence for $B_s^0\to J/\psi f_0(1370)$

TL;DR

This paper reports the first observation of the decay $B_s^0 o J/ar{ ext{psi}} f_0(980)$ and evidence for $B_s^0 o J/ar{ ext{psi}} f_0(1370)$, providing new insights into CP eigenstate decay modes of $B_s^0$ mesons.

Contribution

The study presents the first measurement of these decay modes and their branching fractions using data from the Belle detector at KEKB.

Findings

First observation of $B_s^0 o J/ar{ ext{psi}} f_0(980)$ with 8.4σ significance.

Evidence for $B_s^0 o J/ar{ ext{psi}} f_0(1370)$ with 4.2σ significance.

Measured branching fractions for both decay modes.

Abstract

We report the first observation of $B_s^0\to J/\psi f_0(980)$ and first evidence for $B_s^0\to J/\psi f_0(1370)$, which are CP eigenstate decay modes. These results are obtained from $121.4\;\mathrm{fb}^{-1}$ of data collected at the $\Upsilon(5S)$ resonance with the Belle detector at the KEKB $e^+e^-$ collider. We measure the branching fractions $\mathcal{B}(B_s^0\to J/\psi f_0(980);f_0(980)\to\pi^+\pi^-)=(1.16^{+0.31}_{-0.19}(\mathrm{stat.})^{+0.15}_{-0.17}(\mathrm{syst.})^{+0.26}_{-0.18}(N_{B_s^{(*)}\bar B_s^{(*)}})) \times 10^{-4}$ with a significance of $8.4\sigma$, and $\mathcal{B}(B_s^0\to J/\psi f_0(1370);f_0(1370)\to\pi^+\pi^-)=(0.34^{+0.11}_{-0.14}(\mathrm{stat.})^{+0.03}_{-0.02}(\mathrm{syst.})^{+0.08}_{-0.05}(N_{B_s^{(*)}\bar B_s^{(*)}})) \times 10^{-4}$ with a significance of $4.2\sigma$. The last error listed is due to uncertainty in the number of produced $B_s^{(*)}\bar B_s^{(*)}$ pairs.