ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2015, vol. 91, 11, p. -
Search for D<sup>0</sup> →γγ and improved measurement of the branching fraction for D<sup>0</sup> →π<sup>0</sup>π<sup>0</sup>
© 2015 American Physical Society. Using 2.92 fb<sup>-1</sup> of electron-positron annihilation data collected at √s = 3.773 GeV with the BESIII detector, we report the results of a search for the flavor-changing neutral current process D<sup>0</sup> →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(D<sup>0</sup> →γγ)< 3.8 × 10-6. We also investigate D<sup>0</sup>-meson decay into two neutral pions, obtaining a branching fraction of B(D<sup>0</sup> →π<sup>0</sup>π<sup>0</sup>)= (8.24 ± 0.21(stat) ± 0.30(syst)) × 10-4, the most precise measurement to date and consistent with the current world average.