$D_s^{\ast }\to \varphi$ helicity form factors and the exclusive weak decays

Abstract

The decay width of the $D_s^{\ast }$ meson is dominated by the electromagnetic mode $D_s^{\ast }\to D_s\gamma$, and it is thus the longest-lived charged vector meson. In light of this point, we perform the first QCD LCSRs calculation of $D_s^{\ast }\to \varphi$ helicity form factors and discuss the experiment potential of discovering exclusive $D_s^{\ast }$ weak decays. The main result is the partial decay widths, which read as ${\Gamma }_{D_s^{\ast }\to l\nu }=2.44\times 10^{-12}\mathrm{GeV}$, ${\Gamma }_{D_s^{\ast }\to \varphi l\nu }=(3.28_{-0.71}^{+0.82})\times 10^{-14}\mathrm{GeV}$, ${\Gamma }_{D_s^{\ast }\to \varphi \pi }=(3.81_{-1.33}^{+1.52})\times 10^{-14}\mathrm{GeV}$ and ${\Gamma }_{D_s^{\ast }\to \varphi \rho }=(1.16_{-0.39}^{+0.42})\times 10^{-13}\mathrm{GeV}$. We show that these channels are promising in the near future, serving as the first experimental observation of weak decays of a vector meson, and would open up a new playground for precision test of the standard model.

Comments: 14 pages, 3 figure, 4 tables, matches version accepted for publication in EPJC