Measurement of the Lambda_b Lifetime in Lambda_b -> Lambda_c+ pi- Decays in p-pbar Collisions at sqrt(s) = 1.96 TeV

TL;DR

This paper reports a precise measurement of the Lambda_b baryon lifetime in proton-antiproton collisions, using a large dataset and fully reconstructed decay events, providing results consistent with theoretical expectations.

Contribution

The study presents the first measurement of Lambda_b lifetime in Lambda_c+ pi- decays at Tevatron, with improved precision and comparison to B^0 lifetime ratios.

Findings

Lambda_b lifetime measured as 1.401 ps with uncertainties

Lifetime ratio Lambda_b to B^0 is 0.918

Results agree with recent theoretical predictions

Abstract

We report a measurement of the lifetime of the Lambda_b baryon in decays to the Lambda_C+ pi- final state in a sample corresponding to 1.1 fb^-1 collected in p-pbar collisions at sqrt(s) = 1.96 TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 fully reconstructed Lambda_b events we measure tau(Lambda_b) = 1.401 +- 0.046 (stat) +- 0.035 (syst) ps (corresponding to c.tau(Lambda_b) = 420.1 +- 13.7 (stat) +- 10.6 (syst) um, where c is the speed of light). The ratio of this result and the world average B^0 lifetime yields tau(Lambda_b)/tau(B^0) = 0.918 +- 0.038 (stat and syst), in good agreement with recent theoretical predictions.