# Presentation: 923489

## Measurements of B  Hadron Lifetimes at CDF

**Satyajit Behari** (For the CDF Collab.)
- Johns Hopkins Univ., Baltimore,USA

- 1st August 2008                                                                 ICHEP 2008, Philadelphia

## Contents

- Introduction
**Measurements of...**
-   Bc lifetime                                **(semi-leptonic)**
-   Flavor-specific Bs lifetime        **(fully hadronic)**
-   Λb lifetime                               **(fully hadronic)**
-   Bu lifetime                                **(fully hadronic)**
-    - using a Monte Carlo free technique
- Summary

**B hadron properties (plenary) by ****Paulini**

- Watch out for ...

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Tevatron and CDF Detector

**Muon Detectors**

**Central Tracker**

**ToF**

**Tevatron and CDF Detector**

** ****SVXII + L00**
** ****Vertex resolution: 25 ****μ****m**
** ****Central Tracker**
** ****σ****p****T****/p****T****2**** ****< 0.1%, dE/dx**
** ****Time-of-Flight**
** ****Hadron ID**
** ****Muon detectors**
** ****Lepton triggers, Lepton ID**

**Silicon Vertex Detector**

** ****Tevatron performing well!**
** ****> 3 fb****-1**** on tape**
** ****In this talk ****1-2 fb****-1**** results!**

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## B Production at Tevatron

**Since ********(bb) << ********(pp)****    ********  ****Events have to be selected with specific ****triggers**
**Trigger requirements:**        large bandwidth, background suppression, deadtimeless

-  Tevatron is a source of all B-hadron
-    species, B**d**, B**u**, B**c**, B**s** and Λ**b**
**  ********b** = 29.4 **±** 0.6 **±** 6.2 ****b (|η| < 1) (**CDF**)
-  Huge cross-sections compared to the
-    the B-factories but proportionally
-    large backgrounds as well

**b production talk by ****Seidel**

- Watch out for ...

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Triggers for B Lifetime Measurements

**Di-Muon Triggers**
- One muon with pT > 1.5 GeV and |η| < 0.6,
-         other muon with the same condition or
-       with pT > 2.0 GeV and 0.6 < |η| < 1.0.
- J/Ψ modes, masses, lifetimes, x-section ...
**Today B****c**** lifetime in J/****Ψ**** l X, l=e,****μ**
**Two displaced track triggers**
-  pT(Trk) >2 GeV/c, 120 m < d0(Trk) < 1mm,
- pT > 5.5 GeV/c
-  X-section, branching ratios, Bs mixing...
**Today B****s****, ****Λ****b**** lifetimes with MC correction**
**                      ****and**
**      ****B****u**** lifetime with MC-free method**

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Interests in B Hadron Lifetimes

- (B+) ≥ (B0) ≈ (Bs0) > (Λb) » (Bc)

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Interests in B Hadron Lifetimes Continued...

- Long standing discrepancy between world average of (Λb)/(B0) and its HQE prediction up to O(1/mb3).
- Including **O(1/m****b****4****)** effects:
- (B+)/(B0) = 1.06 ± 0.02
- (Bs0)/(B0) = 1.00 ± 0.01
- (Λb)/(B0) = 0.88 ± 0.05
- The B+,B0 lifetimes are precisely measured at B-factories.
- Experimental error on (Bs0)/(B0) far higher than theory error!

- EXPERIMENT

- THEORY
- (NLO)

**C. Tarantino, hep-ph/0310241**

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Bc : A Special Case...

- Doubly heavy        bound state
- Decays via weak decays of b- or c-quark or via weak annihilation
- Shorter lifetime than light B mesons

**Theory prediction:**
******(B****c****) = 0.47 – 0.59 ps**

- arXiv:hep-ph/0308214v1
- Phy Rev. D 64, 14003 (2001)
- Phy Lett. B 452, 129 (1999)
- hep-ph/0002127

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Lifetime in BcJ/ψ e,μ 

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Lifetime in BcJ/ψ e,μ 

**World best measurement!**

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Bs Lifetime in Bs→ Ds+() - X

- Data sample:
-  **1.3 fb-1**, collected with displaced vertex trigger
- ~ 1100 fully reconstructed events
- ~ 2000 partially reconstructed events
- Lifetime bias is modeled with a trigger efficiency curve from MC
- Partially reconstructed channels:    Bs→ Ds*Ds(+ ) add double statistics!

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Bs Lifetime in Bs→ Ds+() - X

- For partially reconstructed modes a k-factor accounts for missing momentum and mass
- Extensive test on B0, B+ control samples
**Two-step fit**
- mass fit: relative fraction of various modes and background
- lifetime fit: shapes from MC/data, fractions from mass fit.
**Extract lifetime only**

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Bs Lifetime in Bs→ Ds+() - X

- Lifetime for control samples:
- B0→ D-(K+--) +                                        B0→ D*-(D0(K+-)-) +                                 B+ →D0(K+-) +
- Agrees well with PDG

- D0 had Bs semileptonic lifetime in 2006 from Bs→Ds-+X
- =1.398±0.044(stat)+0.0280.025(syst) ps
- PRL 97, 241801 (2006)

**World best measurement!**

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Λb Lifetime in Λb  Λc  

- 1 fb-1 data, 2900 events
- Trigger efficiency curve from MC simulation

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Λb Lifetime in Λb  Λc  

- Two step fit: mass fit followed by lifetime fit
- Using world average B0 lifetime:

**World best measurement!**

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Λb Lifetime in Λb  Λc 

- Λb** Lifetime in ****Λ****b**** ******** ****Λ****c**** ******

- Good agreement with world average and theory.
- Long standing discrepancy resolved!

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Bu Lifetime Using MC-free Method

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Bu Lifetime Using MC-free Method

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Bu Lifetime Using MC-free Method

- 24200 +- 200 events
- t(B+) = 1.662 +- 0.023
-                          +- 0.013 ps

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Summary

- With over 3 fb-1 accumulated data and much more to come, heavy flavor physics at CDF has entered a precision era.
- Using world’s largest Bs, Bc and Λb samples, unique to Tevatron, various theoretical predictions are being put to stringent tests.
- World’s best B hadron lifetime measurements from CDF in agreement with the HQET view of nature.
-  Stay tuned for more!!
-       http://www-cdf.fnal.gov/physics/new/bottom/bottom.html

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008

## Backup-1

- S.Behari, Measurements of B Hadron Lifetimes at CDF, ICHEP 2008

- 1st August 2008