Measurement of the Lambda^0_b lifetime in the decay Lambda^0_b -> J/psi Lambda^0 with the D0 Detector

TL;DR

This paper reports the first measurement of the Lambda^0_b baryon lifetime using a fully reconstructed decay channel, based on data from the D0 detector, and compares it to the B^0 meson lifetime.

Contribution

It provides a new, fully reconstructed decay channel measurement of the Lambda^0_b lifetime, improving precision over previous semileptonic decay-based measurements.

Findings

Lambda^0_b lifetime measured as 1.22 ps with uncertainties.

B^0 lifetime measured as 1.40 ps with uncertainties.

Lifetime ratio of Lambda^0_b to B^0 is approximately 0.87.

Abstract

We present measurements of the Lambda^0_b lifetime in the exclusive decay channel Lambda^0_{b}->J/psi Lambda^0, with J/psi to mu+ mu- and Lambda^0 to p pi-, the B^0 lifetime in the decay B^0 -> J/psi K^0_S with J/psi to mu+ mu- and K^0_S to pi+ pi-, and the ratio of these lifetimes. The analysis is based on approximately 250 pb^{-1} of data recorded with the D0 detector in pp(bar) collisions at sqrt{s}=1.96 TeV. The Lambda^0_b lifetime is determined to be tau(Lambda^0_b) = 1.22 +0.22/-0.18 (stat) +/- 0.04 (syst) ps, the B^0 lifetime tau(B^0) = 1.40 +0.11/-0.10 (stat) +/- 0.03 (syst) ps, and the ratio tau(Lambda^0_b)/tau(B^0) = 0.87 +0.17/-0.14 (stat) +/- 0.03 (syst). In contrast with previous measurements using semileptonic decays, this is the first determination of the Lambda^0_b lifetime based on a fully reconstructed decay channel.