Measurement of the $B_s^0$ lifetime in the flavor-specific decay channel $B_s^0 \to D_s^- \mu^+\nu X$

TL;DR

This paper reports a precise measurement of the $B_s^0$ meson lifetime using semileptonic decay channels from the full Tevatron Run II dataset, providing results consistent with world averages and a detailed lifetime ratio.

Contribution

The study presents one of the most precise $B_s^0$ lifetime measurements using a novel technique that cancels systematic uncertainties, based on the full Tevatron Run II data.

Findings

Measured $B_s^0$ lifetime: 1.479 ps with uncertainties

Measured $B^0$ lifetime: 1.534 ps with uncertainties

Lifetime ratio $ au_{fs}(B_s^0)/ au(B^0) = 0.964$ with uncertainties

Abstract

We present an updated measurement of the $B_s^0$ lifetime from the D0 collaboration using the semileptonic decays $B_s^0\rightarrow D_s^-\mu^+\nu X$, with $D_s^- \to \phi \pi^-$ and $\phi \to K^+K^-$ (and the charge conjugate process). This measurement uses the full Tevatron Run II sample of proton-antiproton collisions at $\sqrt{s} = 1.96$~TeV, comprising an integrated luminosity of 10.4~fb$^{-1}$. We find a flavor-specific lifetime $\tau_{\mathrm{fs}}(B_s^0)=1.479\pm0.010\thinspace{\rm(stat)}\pm0.021\thinspace{\rm(syst)}\thinspace\rm{ps}$. This technique is also used to determine the $B^0$ lifetime using the analogous $B^0\to D^-\mu^+\nu X$ decay with $D^-\to\phi\pi^-$, yielding $\tau(B^0)=1.534\pm0.019\thinspace{\rm(stat)}\pm0.021\thinspace{\rm(syst)}\thinspace\rm{ps}$. Both measurements are consistent with the current world averages, and the $B_s^0$ lifetime measurement is one of the most precise to date. Taking advantage of the cancellation of systematic uncertainties, we determine the lifetime ratio $\tau_{\mathrm{fs}}(B_s^0)/\tau(B^0) = 0.964\pm0.013\thinspace{\rm(stat)}\pm0.007\thinspace{\rm(syst)}$.