Measurement of the form factors in the decay D+ ??e+?e and search for the decay D+ ??e+?e

Abstract

Using 2.92 fb-1 of electron-positron annihilation data collected at a center-of-mass energy of s=3.773 GeV with the BESIII detector, we present an improved measurement of the branching fraction B(D+??e+?e)=(1.63±0.11±0.08)×10-3. The parameters defining the corresponding hadronic form factor ratios at zero momentum transfer are determined for the first time; we measure them to be rV=1.24±0.09±0.06 and r2=1.06±0.15±0.05. The first and second uncertainties are statistical and systematic, respectively. We also search for the decay D+??e+?e. An improved upper limit B(D+??e+?e)<1.3×10-5 is set at 90% confidence level. © 2015 American Physical Society.