Precision Measurement of the Decay ${\Sigma }^{+}\to p\gamma$ in the Process $J/\psi \to {\Sigma }^{+}{\bar{\Sigma }}^{-}$

Abstract

Using $(10087\pm 44)\times 10^6$ $J/\psi$ events collected with the BESIII detector, the radiative hyperon decay $\Sigma \to p\gamma$ is studied at an electron-positron collider experiment for the first time. The absolute branching fraction is measured to be $\left(0.996\pm 0.021_{stat.}\pm 0.018_{syst.}\right)\times 10^{-3}$, which is lower than its world average value by $4.2$ standard deviations. Its decay asymmetry parameter is determined to be $-0.652\pm 0.056_{stat.}\pm 0.020_{syst.}$. The branching fraction and decay asymmetry parameter are the most precise to date, and the accuracies are improved by $78\%$ and $34\%$, respectively.

9 pages, 4 figures, 1 table

References in corpus (9)

• Secluded U(1) below the weak scale
• Method for detector description transformation to Unity and application in BESIII
• TopoAna: A generic tool for the event type analysis of inclusive Monte-Carlo samples in high energy physics experiments
• Number of $J/\psi$ events at BESIII
• ${\Sigma }^{+}$ and ${\bar{\Sigma }}^{-}$ polarization in the $J/\psi$ and $\psi (3686)$ decays
• Joint description of weak radiative and nonleptonic hyperon decays in broken SU(3)
• New physics in $s\to d$ semileptonic transitions: rare hyperon vs. kaon decays
• Hyperon Weak Radiative Decay
• Revisiting Weak Radiative Decays of Hyperons

Cited by in corpus (4)

• Measurement of the Decay ${\Xi }^0\to \Lambda \gamma$ with Entangled ${\Xi }^0{\bar{\Xi }}^0$ Pairs
• ${\Sigma }^{+}\to p{\ell }^{+}{\ell }^{-}$ decays within the standard model and beyond
• Observation of the very rare ${\Sigma }^{+}\to p{\mu }^{+}{\mu }^{-}$ decay
• Observation of the electromagnetic radiative decays of the \boldmath{$\Lambda (1520)$} and \boldmath{$\Lambda (1670)$} to \boldmath{$\gamma {\Sigma }^0$}