Measurement of the form factors in the decay $D^{+}\to \ddot{I}‰e^{+}\hat{I}{½}_e$ and search for the decay $D^{+}\to \ddot{I}•e^{+}\hat{I}{½}_e$

Abstract

Using 2.92 fb${}^{-1}$ of electron-positron annihilation data collected at a center-of-mass energy of $\sqrt{s}=3.773$ GeV with the BESIII detector, we present an improved measurement of the branching fraction $\mathcal{B}(D^{+}\to \ddot{I}‰e^{+}\hat{I}{½}_e)=(1.63\pm 0.11\pm 0.08)\times 10^{-3}$. The parameters defining the corresponding hadronic form factor ratios at zero momentum transfer are determined for the first time, we measure them to be $r_V=1.24\pm 0.09\pm 0.06$ and $r_2=1.06\pm 0.15\pm 0.05$. The first and second uncertainties are statistical and systematic, respectively. We also search for the decay $D^{+}\to \ddot{I}•e^{+}\hat{I}{½}_e$. An improved upper limit $\mathcal{B}(D^{+}\to \ddot{I}•e^{+}\hat{I}{½}_e)<1.3\times 10^{-5}$ is set at 90\% confidence level.

9pages,6figures