# Study of the decays ${D}_{s}^{+}\to {K}_{S}^{0}{K}^{+}$ and ${K}_{L}^{0}{K}^{+}$

12 June 2019

Abstract: Using an ${e}^{+}{e}^{-}$ annihilation data sample corresponding to an integrated luminosity of $3.19\text{}\text{}{\mathrm{fb}}^{-1}$ and collected at a center-of-mass energy $\sqrt{s}=4.178\text{}\text{}\mathrm{GeV}$ with the BESIII detector, we measure the absolute branching fractions $B\left({D}_{s}^{+}\to {K}_{S}^{0}{K}^{+}\right)=\left(1.425±0.03{8}_{\mathrm{stat}.}±0.03{1}_{\mathrm{syst}.}\right)%$ and $B\left({D}_{s}^{+}\to {K}_{L}^{0}{K}^{+}\right)=\phantom{\rule{0ex}{0ex}}\left(1.485±0.03{9}_{\mathrm{stat}.}±0.04{6}_{\mathrm{syst}.}\right)%$. The branching fraction of ${D}_{s}^{+}\to {K}_{S}^{0}{K}^{+}$ is compatible with the world average and that of ${D}_{s}^{+}\to {K}_{L}^{0}{K}^{+}$ is measured for the first time. We present the first measurement of the ${K}_{S}^{0}\text{−}{K}_{L}^{0}$ asymmetry in the decays ${D}_{s}^{+}\to {K}_{S,L}^{0}{K}^{+}$, and $R\left({D}_{s}^{+}\to {K}_{S,L}^{0}{K}^{+}\right)=\frac{B\left({D}_{s}^{+}\to {K}_{S}^{0}{K}^{+}\right)-B\left({D}_{s}^{+}\to {K}_{L}^{0}{K}^{+}\right)}{B\left({D}_{s}^{+}\to {K}_{S}^{0}{K}^{+}\right)+B\left({D}_{s}^{+}\to {K}_{L}^{0}{K}^{+}\right)}=\phantom{\rule{0ex}{0ex}}\left(-2.1±1.{9}_{\mathrm{stat}.}±1.{6}_{\mathrm{syst}.}\right)%$. In addition, we measure the direct $CP$ asymmetries ${A}_{CP}\left({D}_{s}^{±}\to {K}_{S}^{0}{K}^{±}\right)=\left(0.6±2.{8}_{\mathrm{stat}.}±0.{6}_{\mathrm{syst}.}\right)%$ and ${A}_{\mathrm{CP}}\left({D}_{s}^{±}\to {K}_{L}^{0}{K}^{±}\right)=\left(-1.1±2.{6}_{\mathrm{stat}.}±0.{6}_{\mathrm{syst}.}\right)%$.

Published in: Physical Review D 99 (2019)