/\b Lifetime in /\b → /\c π Decays

/\_b Lifetime in /\_b → /\_c π Decays

This web page summarizes the results for the measurement of the /\_b Lifetime in /\_b → /\_c π, based on a 1070 ± 60 pb^-1 sample of data, collected using the CDF two displaced track trigger. It was approved by the CDF B group on 07/3/2008.

On April 16, 2009 the analysis was reblessed with the following changes:

The SVT modelling systematic uncertainty was updated using larger data samples which include all the run periods used in the /\_b lifetime analysis. The resulting systematic uncertainty changed from 8.8 μm to 10.6 μm.
A small coding bug in the lifetime fit PDF was corrected which shifted the lifetime value from 422.8 μm to 420.1 μm.

The analysis employs a 2-step fit, first a binned fit of the /\_b mass and second an unbinned maximum likelihood 2D fit of the decay length and its error distributions to extract the /\_b lifetime. We measure

cτ(/\_b) = 420.1 ± 13.7(stat.) ± 10.6 (syst.) μm

Using our measurement of the /\_b lifetime and the PDG 2007 world average B⁰ lifetime, we obtain

&tau(/\_b)/&tau(B⁰) = 0.916 ± 0.038

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

[/\_b Decay Length Projection]

[Comparison with Other Experiments]

EPS and GIF Figures for Download:

Figure 1: /\_b selection cuts (.eps)(.gif)
Figure 2: /\_b mass (.eps)(.gif)
Figure 3: /\_b signal and background yields table (.eps)(.gif)
Figure 4: SVT efficiency distribution (.eps)(.gif)
Figure 5: /\_b lifetime fit: Decay length (ct) projection (.eps)(.gif)
Figure 6: Systematics table (.eps)(.gif)
Figure 7: /\_b lifetime comparison with other experiments (.eps)(.gif)
Figure 8: /\_b lifetime comparison: The 2006 status (.eps)(.gif)
Figure 9: ct error distributions in data(.eps)(.gif)
Figure 10: Lifetime fit stability in Monte Carlo over possible /\_b lifetime values(.eps)(.gif)
Figure 11: Systematic Error: SVT efficiency ratio as a function of L_xy(.eps)(.gif)
Figure 12: Data vs. Monte Carlo comparison: track pairs satisfying the Two Track Trigger(.eps)(.gif)
Figure 13: Data vs. Monte Carlo comparison: /\_c decay length distribution(.eps)(.gif)