Measurement of $\mathcal{B}(\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c1})$ and search for $\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c2}$

Measurement of $B (ψ (3770) \to γ χ_{c 1})$ and search for $ψ (3770) \to γ χ_{c 2}$

M. Ablikim et al. (BESIII Collaboration)

Phys. Rev. D 91, 092009 – Published 26 May 2015

Abstract

We report a measurement of the branching fraction for $ψ (3770) \to γ χ_{c 1}$ and search for the transition $ψ (3770) \to γ χ_{c 2}$ based on $2.92 {fb}^{- 1}$ of $e^{+} e^{-}$ data accumulated at $\sqrt{s} = 3.773 GeV$ with the BESIII detector at the BEPCII collider. We measure $B (ψ (3770) \to γ χ_{c 1}) = (2.48 \pm 0.15 \pm 0.23) \times 1 0^{- 3}$ , which is the most precise measurement to date. The upper limit on the branching fraction of $ψ (3770) \to γ χ_{c 2}$ at a 90% confidence level is $B (ψ (3770) \to γ χ_{c 2}) < 0.64 \times 1 0^{- 3}$ . The corresponding partial widths are $Γ (ψ (3770) \to γ χ_{c 1}) = (67.5 \pm 4.1 \pm 6.7) keV$ and $Γ (ψ (3770) \to γ χ_{c 2}) < 17.4 keV$ .