Measurement of the B hadron Lifetimes in the modes B+ → J/&psi K+, B0 → J/&psi K*0, B0 → J/&psi K0s, and /\b → J/&psi /\, and measurement of the B+/B0, and /\b/B0 lifetime ratios

Primary authors: Joe Boudreau, Juan Pablo Fernandez, Sneha Malde

This web page summarizes the results for the measurement of the above B hadron's lifetimes performed using the above fully reconstructed decay channels that include a J/&psi . The measurement uses 4.3 fb-1 of data.
The results were approved on December 17, 2009.
This result supersedes the previous measurement performed with 1fb-1.

We measure:

(Ratios Calculated using our lifetime measurements)
In terms of microns the results are

Analysis Motivation and strategy

The lifetime of ground state hadrons containing a b quark and lighter quarks is largely determined by the charged weak decay of the b quark. The spectator model which ignores the other quarks in the hadron, predicts equal lifetimes for all B hadrons. In reality, several effects change these lifetimes by up to about 10%. Fully reconstructed B hadron decays with a J/&psi decaying to muon pairs in the final states are reconstructed in 4.3 fb-1. We use data collected by the dimuon trigger, which has no biasing effects on the observed proper time distribution. Signal samples of 45 thousand B+, 29 thousand B0and 1.7 thousand /\b are collected. The analysis consists of a maximum likelihood fit that uses information from mass, proper decay time and proper decay time error to extract the lifetime of the hadrons. The use of similar final states and a unified analysis strategy allow partial cancellation of certain systematic uncertainties in the lifetime ratios. The measured lifetimes and are the most precise determination of the B+, B0 and /\b lifetime.

A more detailed summary of the results can be found here: pdf.

Below are the eps and gif versions of all figures meant for downloads.