# Presentation: 907020

## Bs and Λb Lifetimes and BRs at the Tevatron

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

- 25th September 2006                                            Beauty 2006, University of Oxford, UK

## Contents

- Introduction
**Lifetime Measurements**
- Motivation
- Λb lifetimes (Λb  J/Ψ Λ)
- Bs lifetimes
- Flavor specific
- (Bs  Ds l )
- (Bs  Ds , Ds   )
- ΔΓCP/ΓCP in L(Bs  K+ K-)
-  ΔΓCP/Γ in BR(Bs  Ds(*) Ds(*))
- Summary

**BR Measurements**
-  BR(Bs  Ds(*) Ds(*))
-  BR(Bs  Ds1(2536)   X)
- BR(Bs  Ds Ds) / BR(Ds D+)

-  BR(Bs   ) limits
**  **[ Talk by Cheng-Ju Lin ]
** **ΔΓ in Bs  J/Ψ 
-    [ Talk by Avdhesh Chandra ]

- Other talks:

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## The Tevatron

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## CDF and DØ Detectors in Run 2

-         _Both detectors_
** ****Silicon microvertex tracker**
** ****Solenoid**
** ****High rate trigger/DAQ**
** ****Calorimeters and muons**

**Good electron, muon ID and acceptance**
**Excellent tracking acceptance ****|********| < 2-3**

**L2 trigger on displaced vertices**
**Excellent tracking resolution**
**Good low momentum PID**

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## B Production at Tevatron

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

- Flavor Creation (annihilation)

**q**

**b**

- Flavor Creation
- (gluon fusion)

- Flavor Excitation

- Gluon Splitting

**b**

**g**

**g**

**g**

-  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

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Triggers for B Physics

**Single-/Di-lepton ****(****CDF****/****DØ****)**
- A high pT lepton or two leptons with lower pT
- J/Ψ modes, masses, lifetimes, x-section
-  Yields higher than Run I (low Pt threshold, increased acceptance)
**lepton + displaced track - semileptonic sample (****CDF****)**
- pT(e/) > 4 GeV/c, 120 m < d0(Trk) < 1mm, pT(Trk) > 2 GeV/c
- Semileptonic decays, lifetimes,  flavor tagging
- B Yields 3x Run I
**Two displaced vertex tracks - hadronic sample (****CDF****)**
-  pT(Trk) >2 GeV/c, 120 m < d0(Trk) < 1mm,   pT > 5.5 GeV/c
-  X-section, branching ratios, Bs mixing...

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Interests in B Hadron Lifetimes

- Test of non-spectator effects in decays of heavy hadrons which give rise to lifetime hierarchy:
-     (B+) ≥ (B0) ≈ (Bs0) > (Λb) » (Bc)
- Heavy Quark Expansion includes these effects (expansion in 1/mb) and predicts lifetime ratios:
- (B+)/(B0) = 1.00 ± 0.05 x (fB/200 MeV)2
- (Bs0)/(B0) = 1.00 ± 0.01
- (Λb)/(B0) ~ 0.9
- The B+,B0 lifetimes are precisely measured at B-factories. Λb and Bs0 ratios are unique to Tevatron.

- EXPERIMENT

- THEORY
- (NLO)

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

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Bs Lifetime Difference

- Bs has a large branching fraction to CP eigenstates
- Dominated by b  ccs transition: Bs  Ds(*)+Ds(*)-
*                            **(Bd: b ** ccd Cabibbo suppressed, 20x smaller)*

**Ways to measure:**
-  Compare (Bs  CP even) to (Bs  CP mixed or CP odd)
-   ***Angular analysis of B******s ****** J/************ ************ ***separates CP even and CP odd.
-    [ See the talk by Avdhesh Chandra ]
-  Indirect: Measure Br (Bs  Ds(*)+Ds(*)-) , L(Bs  K+ K-)

- SM prediction: s/s= L-H = (9.3 ± 4.6) % (***Beneke et al***)

- World average: s/s = 0.07+0.09

***(SLD, LEP, CDF I results + ************(B******s******)=************(B******d******) constraint)***

- -0.07 ( < 0.29 at 95% CL)

**hep-ph/0012222**

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Λb Lifetimes

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Λb Lifetime in Λb  J/Ψ Λ 

- 1 fb-1 data
- 174 ± 21 **Λ****b** events
- Extract lifetime by an unbinned maximum likelihood fit to mass and proper decay length.
- Major source of systematic is contamination from B0
- Using B0  J/Ψ Ks0 lifetime:

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Λb Lifetime in Λb  J/Ψ Λ 

- 1 fb-1 data
- 538 ± 38 **Λ****b** events
- Major sources of systematics are due to modeling of ct resolution and V0 pointing
- Using world average B0  J/Ψ Ks0 lifetime:

**World best measurement!**

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Λb Lifetime – Measurement vs Theory

- The world average on (Λb)/(B0) measurements used to show ~2σ lower value than the NLO prediction so far.
- The new result sits above the prediction!
- Need more experimental inputs to conclude the issue.
- Looking forward to (Λb) in fully hadronic decay modes, e.g. Λb  Λc 

******(****Λ****b****)/********(B****0****)**

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Bs Lifetime

**Differences**

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Bs Lifetime (Bs  Ds l X)

***B******s***** Lifetime ********(B****s**** ******** D****s**** l ********X)**

**World’s best result!**

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Bs Lifetime (Bs  Ds , 3)

- Fully reconstructed hadronic decays from displaced track trigger
- 360 pb-1 in CDF Run 2.
- Trigger bias is removed by a Monte Carlo approach.
- Mass and decay length fitted simultaneously to extract lifetime.
- Would be updated for 1 fb-1

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## ΔΓCP/ΓCP in L(Bs  K+ K-)

- Measure L (95% CP even state)
- 360 pb-1 data from displaced track trigger
- Four h+h- components are resolved by mass, kinematics and PID info.
- Bd lifetime is fixed to world average
- Dominant systematics from dE/dx based PID, MC pT input spectrum
- Extract ΔΓCP/ΓCP using flavor specific (Bs0) from other measurements.

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## ΔΓCP/ΓCP in BR(Bs  Ds(*) Ds(*))

- 1 fb-1 sample
- Ds  ,   Ds  
- Start with Ds sample (Ds  ), look for additional Ds sample
- Ratio of efficiencies estimated using simulated events.
- Directly fit Ds mass distribution to extract N(Ds). Unbinned likelihood  to extract N(Ds) (Lower statistics)
- Ds= 15225  310
- Ds= 19.3  7.9

-  **Dominant sources of systematics:**
** **BR(Bs  Ds(*))
-  MC pT reweighting

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Tevatron ΔΓCP/ΓCP Summary

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Bs Branching

**Fractions**

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Bs  Ds1()  X  

- Bs  Ds** 

- D* KS

-  D0 

-  

-  K 

-   c+s quark in L=1 state : Provide test HQET
-   A significant fraction of semileptonic decays :
-  Compare exclusive/inclusive decay rates
-  Extract CKM matrix elements
-  An additional channel for Bs mixing.
-  Need to develop more understanding in the light of discoveries which don’t agree with predictions : DsJ(2317), DsJ(2460), DsJ(2632) – SELEX and so on...

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Bs  Ds1()  X(Contd..)

-  ***N = 42.6 ************ 8.6******   ~ ******5 *********

-  **BR(B****s****->D****s1********X****) = 0.86********0.16 ********0.13 ********0.09 (%)**
**ISGW2  0.53%,      IQM 0.39%,     HQET&QCD Sum rules 0.20%**

-  ***Comparison with theory***

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## BR(Bs  Ds Ds) / BR(B0  Ds D-)

**fs/fd * BR(Bs → DsDs ) / BR(B0 → DsD+) = 0.43 ± 0.11(Stat) ± 0.03(Syst) ± 0.10(BR) ****BR(Bs → DsDs ) / BR(B0 → DsD+ ) = 1.67 ± 0.41(Stat) ± 0.12(Syst) ± 0.24 (fs/fd) ± 0.39(BR)**** **

**5.8σ Observation!**** **

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Summary

- With over 1 fb-1 accumulated data / experiment and much more to come, heavy flavor physics at Tevatron is entering a precision era.
- Using large Bs and Λb samples, unique to Tevatron, various theoretical predictions are put to stringent tests. Many world best measurements have been made.
- Lifetimes in fully hadronic Λb decays are underway. Other excited baryonic modes to follow.
- Check out more Tevatron B physics results:
**CDF: **http://www-cdf.fnal.gov/physics/new/bottom/bottom.html
**DØ:**   http://www-d0.fnal.gov/Run2Physics/WWW/results/b.htm

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006

## Backup-1 ΔΓCP/ΓCP in BR(Bs  Ds(*) Ds(*))

- Background processes:

- S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

- 25th Sep. 2006