Measurement of B(psi(3770) -> gamma chi(c1)) and search for psi(3770) -> gamma chi(c2)

Abstract

We report a measurement of the branching fraction for ?(3770)???c1 and search for the transition ?(3770)???c2 based on 2.92 fb-1 of e+e- data accumulated at s=3.773 GeV with the BESIII detector at the BEPCII collider. We measure B(?(3770)???c1)=(2.48±0.15±0.23)×10-3, which is the most precise measurement to date. The upper limit on the branching fraction of ?(3770)???c2 at a 90% confidence level is B(?(3770)???c2)<0.64×10-3. The corresponding partial widths are ?(?(3770)???c1)=(67.5±4.1±6.7) keV and ?(?(3770)???c2)<17.4 keV. © 2015 American Physical Society.