Search for D⁰ → γγ and Improved Measurement of the Branching Fraction for D⁰ → π⁰π⁰


Using 2.92 fb⁻¹ of electron-positron annihilation data collected at √s̅ = 3.773 GeV with the BESIII detector, we report the results of a search for the flavor-changing neutral current process D⁰ → γγ using a double-tag technique. We find no signal and set an upper limit at 90% confidence level for the branching fraction of ℬ(D⁰ → γγ) < 38 x 10⁻⁶. W also investigate D⁰ meson decay into two neutral pions, obtaining a branching fraction of ℬ{D⁰ → π⁰π⁰ = (8.24 ± 0.21(stat) ± 0.30(syst)) x 10⁻⁴, the most precise measurement to date and consistent with the current world average.



Quantum flavor dynamics, Branching fractions (Nuclear physics), Causality (Physics), Quantum flavor dynamics, Radioactive decay, Mesons, Photons

This work is supported in part by National Key Basic Research Program of China under Contract No. 2015CB856700; National Natural Science Foundation of China (NSFC) under Contracts Nos. 11125525, 11235011, 11322544, 11335008, 11425524; Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contracts Nos. 11179007, 11179014, U1232201, U1332201; CAS under Contracts Nos. KJCX2-YW-N29, KJCX2-YW-N45; German Research Foundation DFG under Contract No. Collaborative Research Center CRC-1044; Ministry of Development of Turkey under Contract No. DPT2006K-120470; Russian Foundation for Basic Research under Contract No. 14-07-91152; U.S. Department of Energy under Contracts Nos. DE-FG02-04ER41291, DE-FG02-05ER41374, DE-FG02-94ER40823, DESC0010118; WCU Program of National Research Foundation of Korea under Contract No. R32-2008-000-10155-0.


©2015 American Physical Society