Search for the semileptonic decays $D^+_s \to K_1(1270)^0 e^+\nu_e$ and $D^+_s \to b_1(1235)^0 e^+\nu_e$

TL;DR

This study searches for specific semileptonic decays of the $D_s^+$ meson using BESIII data but finds no significant signals, setting upper limits on their branching fractions for the first time.

Contribution

First search for the semileptonic decays $D_s^+ o K_1(1270)^0 e^+ u_e$ and $D_s^+ o b_1(1235)^0 e^+ u_e$, establishing upper limits on their branching fractions.

Findings

No significant signals observed for either decay mode.

Upper limits on branching fractions set at 90% confidence level.

Provides the first experimental constraints on these decay channels.

Abstract

By analyzing 7.33\,fb$^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we search for the semileptonic decays $D^+_s \to K_1(1270)^0 e^+\nu_e$ and $D^+_s \to b_1(1235)^0 e^+\nu_e$ for the first time. No significant signals are observed for either decay mode. The upper limits on the (product) branching fractions are determined to be ${\mathcal B}[D^+_s \to K_1(1270)^0 e^+\nu_e] < 4.1\times 10^{-4}$ and ${\mathcal B}[D^+_s \to b_1(1235)^0 e^+\nu_e]\cdot {\mathcal B}[b_1(1235)^0\to \omega\pi^0] < 6.4\times 10^{-4}$ at 90\% confidence level.