# Measurement of the $\bar{B}_s^0\to D_s^-D_s^+$ and $\bar{B}_s^0\to D^-D_s^+$ effective lifetimes

[to restricted-access page]

## Abstract

The first measurement of the effective lifetime of the $\bar{B}_s^0$ meson in the decay $\bar{B}_s^0\to D_s^-D_s^+$ is reported using a proton-proton collision dataset, corresponding to an integrated luminosity of 3 fb$^{-1}$, collected by the LHCb experiment. The measured value of the $\bar{B}_s^0\to D_s^-D_s^+$ effective lifetime is $1.379\pm0.026\pm0.017$ ps, where the uncertainties are statistical and systematic, respectively. This lifetime translates into a measurement of the decay width of the light $\bar{B}_s^0$ mass eigenstate of \Gamma_L$=0.725\pm0.014\pm0.009$ ps$^{-1}$. The $\bar{B}_s^0$ lifetime is also measured using the flavor-specific $\bar{B}_s^0\to D^-D_s^+$ decay to be $1.52\pm0.15\pm0.01 {\rm ps}$.

## Figures and captions

 Ratio of selection efficiencies for $B ^- \rightarrow D ^0 D ^-_ s$ relative to $\overline{ B }{} ^0_ s \rightarrow D ^-_ s D ^+_ s$ decays as a function of decay time. The uncertainties shown are due to finite simulated sample sizes. EffRat[..].pdf [13 KiB] HiDef png [63 KiB] Thumbnail [59 KiB] *.C file Mass distributions and fits to the full data sample for (left) $\overline{ B }{} ^0_ s \rightarrow D ^-_ s D ^+_ s$ and (right) $B ^- \rightarrow D ^0 D ^-_ s$ candidates. The points are the data and the curves and shaded regions show the fit components. Bs2DsD[..].pdf [26 KiB] HiDef png [240 KiB] Thumbnail [179 KiB] *.C file B2D0Ds[..].pdf [25 KiB] HiDef png [202 KiB] Thumbnail [154 KiB] *.C file Efficiency corrected yield ratio of $\overline{ B }{} ^0_ s \rightarrow D ^-_ s D ^+_ s$ relative to $B ^- \rightarrow D ^0 D ^-_ s$ as a function of decay time, along with the exponential fit. The uncertainties are statistical only. CorrYi[..].pdf [14 KiB] HiDef png [100 KiB] Thumbnail [80 KiB] *.C file Mass distribution and fits to the full data sample for $\overline{ B }{} ^0_ s$ and $B ^0$ decays into the $D ^- D ^+_ s$ final state. The points are the data and the curves and shaded regions show the fit components. B2DsDF[..].pdf [30 KiB] HiDef png [320 KiB] Thumbnail [242 KiB] *.C file Animated gif made out of all figures. PAPER-2013-060.gif Thumbnail

## Supplementary Material [file]

 This ZIP file contains supplemetary material for the publication LHCb-PAPER-2013-060. The files are: DeltaGamma_Phis_Lifetimes.pdf : DeltaG[..].pdf [328 KiB] HiDef png [530 KiB] Thumbnail [263 KiB] *C file

Created on 16 August 2019.Citation count from INSPIRE on 23 August 2019.