# Presentation: 563680

## Precision B Lifetimesand B Mixing in CDF

- Precision *B* Lifetimes
- B+  J/ K+
- Bd  J/ K*0
- Bs  J/ 
- B  J/ 
- Measurement of Polarization Amplitudes
- Bd  J/ K*0
- Bs  J/ 
*B* Mixing
*B* Flavor Tagging using Opposite Side *SMT* and *JQT*
- md using *SST* in Fully Reconstructed *B* Decays
- md using *SST* in Semileptonic *B* Decays
- ms Measurement Prospects

- Jónatan Piedra, June 28 2004
**6th International Conference on Hyperons, Charm and Beauty Hadrons**

- J. Piedra

- BEACH 04

## Tevatron & CDF

- Improved Silicon coverage
- || < 2
- Central Drift Chamber (COT)
- 96 layers
- Time of Flight
- Expanded muon coverage
- Trigger on displaced tracks at L2

***EXCELLENT TRACKING***

***EXCELLENT TRACKING***

## Tevatron & CDF Luminosity

- Acquired luminosity in 2004 already surpassed 2003 total
- But with high luminosity
- Less trigger bandwidth for *B* Physics
- Overlapping events degrade performance

- Record peak luminosity
- 	9.23 x 1031 sec-1 cm-2
- 	*June 22, 2004*

- BEACH 04

## B Physics & B Triggers

- Huge production rates
- (pp  bX, |y| < 0.6) = 17.6  0.4 (stat.)  2.5 (syst.) b
- 3 orders of magnitude higher than at e+e-  (4S)
- Heavy states produced
- B0, B+, Bs, Bc, b, b
- Backgrounds are also 3 orders of magnitude higher
- Inelastic cross section 100 mb
- Challenge is to pick one *B* decay from ~103 QCD events
- Di-muon trigger
- pT() > 1.5 GeV/c
*B* yields 2x Run I (lowered pT threshold, increased acceptance)
- Lepton + displaced-track trigger
- pT(,e) > 4 GeV/c, 120 m < d0 < 1 mm, pT > 2 GeV/c
*B* yields 3x Run I
- Two displaced-tracks trigger
- pT > 2 GeV/c, 120 m < d0 < 1 mm,  pT > 5.5 GeV/c

***IT’S ALL ABOUT THE TRIGGER***

***HADRONIC MODE SENSITIVITY INCREASED ~4 ORDERS OF MAGNITUDE WRT RUN I***

**CDF Run II Preliminary**

## Precision B Lifetimes

## Precision B Lifetimes Motivation

- Test HQET measuring
- Extract          with *Polarization Amplitudes*

- indirect ms measurement

**FERMILAB-Pub-01, 197**

## Precision B Lifetimes Selection and Fit Method

- Fraction of signal events in the sample *1 parameter*
- Mass *3 parameters*
- Proper decay length *8 parameters*
- _Unbinned maximum likelihood_ *1+3+8 = 12 parameters*

| Decay | pT(B) GeV/c2 | pT(K/) GeV/c2 | Pr(2) | K/ mass MeV/c2 | B mass MeV/c2 |
| --- | --- | --- | --- | --- | --- |
| B+  J/ K+ | > 5.5 | > 1.6 | > 10-3 | –   | 5170 – 5390 |
| Bd  J/ K*0 | > 6.0 | > 2.6 | > 10-4 | MPDG(K*0)  50.0 | 5170 – 5390 |
| Bs  J/  | > 5.0 | > 1.5 | > 10-5 | MPDG()  6.5 | 5220 – 5520 |

## Precision B Lifetimes Bs Projections

***long lived***
**  ****Displaced J/******** **(**~15%**)** paired with **(**random**)** track**
***  ******b***** ******** *****c***** ******** *****s***
**  ****Remaining reflections and partially reconstructed *****B***
***short lived***
**  ****Combinations with mis-measured tracks **(*** lived***)
**  ****Prompt J/******** **(**~85%**)** paired with **(**slightly**)** displaced    track **(*+* ***lived***)

**L~240 pb****-1**

**L~240 pb****-1**

**arbitrary scale**

## Precision B Lifetimes B+ and B0 Projections

**L~240 pb****-1**

**L~240 pb****-1**

**L~240 pb****-1**

**L~240 pb****-1**

**K*****0**** ******** K****+********-**
**m(true K) ******** m******
**m(true ********) ******** m****K**

## Precision B Lifetimes Results

- J. Piedra

- BEACH 04

## Precision B Lifetimes B  J/  J/  + -,   p+ -

- First measurement of (B) in a fully reconstructed mode
- 	B  cl (c  pK) = 1.33  0.15  0.07 ps

- World average2002 for (B)/(B0) is 0.798  0.052
- Theory predicts 0.9 – 1.0
- Nowadays **only Tevatron produces ********B**

**CDF Run I**

## Polarization Amplitudes

## Polarization Amplitudes Motivation

- Bd(s)  J/ K*0() Pseudoscalar  Vector – Vector
- Decay amplitude decomposed into 3 linear polarization states
- |A0|2 + |A|||2 + |A|2 = 1
- A0 = S + D wave  P even
- A|| = S + D wave  P even
- A = P wave  P odd
- The mass eigenstates Bs,H and Bs,L have
- If CP violation neglected
- Bs,Light  CP even
- Bs,Heavy  CP odd
- Angular distributions are different
- Together with lifetime measurement, angular analysis can separate both states and determine s

**WORLD AVERAGE WITH**** ********(B****s****)**** ******** ********(B****d****)**** ****CONSTRAINT**

## Polarization Amplitudes Event Reconstruction

- |MJ/ - 3096.87(PDG)| < 80 MeV
- |M - 1019.46(PDG)| < 15 MeV
- |MK*0 - 896(PDG)| < 80 MeV
- c(*B*) > 0

- Bd  J/ K*0

- 1000 candidates
*** **= 13.2 **** 1.0 MeV/c**2*

## Polarization Amplitudes Transversity Basis

*Polarization Amplitudes* Transversity Basis

-  = +1  particle
-  = -1  antiparticle
-  = 0  untagged Bs

**Notes:**
BaBar (hep-ex 0107049)
CDF‘s phi_T = pi - BaBar's phi_T
CDF‘s theta_T = pi - BaBar's thetaT

## Polarization Amplitudes Angular Projections

**B****d**** ******** J/******** K*****0**

**B****d**** ******** J/******** K*****0**

**B****d**** ******** J/******** K*****0**

- cos T

- T

- cos K

***sideband subtracted distributions***

- J. Piedra

- BEACH 04

## Polarization Amplitudes Results

- A|| = (0.436  0.057  0.045) e(3.07  0.40  0.07)i
- A = (0.428  0.059  0.063) e(0.11  0.23  0.06)i

- A0 = 0.767  0.045  0.017
- A|| = (0.424  0.118  0.013) e(2.11  0.55  0.29)i
- |A| = 0.482  0.104  0.014

*Polarization Amplitudes* Results

- 1 s contour

- Bs  J/ 

## B Mixing

## B Mixing Motivation

*B Mixing* Motivation

*B**d* oscillations are sensitive to *|V**td**|*
- Compromised by hadronic uncertainties
- Most cancel in *B**d **/B**s* oscillation ratio

- New Physics may     affect ms/md
- ms prerequisite for       time-dependent *B**s* CP    violation measurement

- J. Piedra

- BEACH 04

## B Mixing Bs Mixing Current Status

- Heavy Flavor Averaging Group
*	**LEP, SLD and CDF I combined*
- Most analyses used partially reconstructed decays
- 	*Poor sensitivity at high ****m**s*

- ms > 14.5 ps-1 95% CL (more than 3 full oscillations per lifetime)
- From CKM fit ms < 30 ps-1 95% CL

- BEACH 04

## B Mixing Ingredients

- Efficiency   fraction of tagged events
- Dilution D  2P - 1 with P the correct answer probability
- Tagging effectiveness D2  shows statistical power of the tagger
- Flavor taggers can be topologically separated
- Same-Side is sample dependent
- Opposite-Side is based on properties of the non-reconstructed *b*

- BEACH 04

## B Mixing Soft Muon & Jet Charge

- Find events with Opposite Side B  X
- Opposite Side  charge gives Soft Muon Tagger **SMT** decision
- Qualities
- High purity (OS  almost always from B  X)
- Low efficiency, BR(B  X) ~ 10%
- OS *B* mixing reduces performance
- Combined D2 for all subsamples
*	**based on muon subdetectors and p**T**rel** bins*

- Find jet of the Opposite Side *b*
- Calculate weighted average Q of jet tracks
- Qjet sign gives Jet Charge Tagger **JQT** decision
- Qualities
- Moderate purity (Qjet not 100% correlated with *b* flavor)
- High efficiency (*b* in acceptance almost always gives a jet)
- Non-*b* jets in the event complicate *b*-jet finding
- Combined D2 for all subsamples
*	**with or without secondary vertex and Q**jet** bins*

******D****2**** = 0.660 ******** 0.193 (stat.) %**

******D****2**** = 0.415 ******** 0.017 (stat.) %**

** ****Run I JQT algorithm**
** ****Not optimized**

## B Mixing Same Side Tagger Algorithm

*B Mixing* Same Side Tagger Algorithm

- Look for the fragmentation track that is charge correlated with the produced *B*
- Divide data into 3 subsamples depending on tagger decision
- Right-Sign events (unmixed), Wrong-Sign events (mixed) and Not-Tagged events

- Consider tracks close to the *B* meson
- Originating from primary vertex
- If multiple track candidates,               select the one with minimum pTrel

## B Mixing Fully Reconstructed Decays

- J/
- |M(J/) - MPDG| < 80 MeV/c2
- K*0
- |m(K*0) – mPDG| < 50 MeV/c2
- Reject events with >1 K*0 candidate
- B
- Vertex probability > 0.1%
- Lxy > 100 m

- D
-  < 14
- R(D,B) < 1.5
- B
- pT > 1.6 GeV/c
- B
- r < 15
- Lxy > 300 m

## md using SST in Bd  J/ K*0 (D-+)

******m****d**** = 0.55 ******** 0.10 (stat.) ******** 0.01 (syst.) ps****-1**
**D = 12.4 ******** 3.3 (stat.) ******** 1.2 (syst.) %**
******D****2**** = 1.0 ******** 0.5 (stat.) ******** 0.2 (syst.) %**

*combined ****2** fit*

** ****More decays soon**
** ****Increased statistics**
** ****SST not optimized**

## md using SST in Bd  lD(*) Decays

******m****d**** = 0.443 ******** 0.052 (stat.) ******** 0.030 (s.c.) ******** 0.012 (syst.) ps****–1**
**D****0**** = 12.8 ******** 1.6 (stat.) ******** 1.0 (s.c.) ******** 0.6 (syst.) %**
**D****+**** = 28.3 ******** 1.3 (stat.) ******** 1.1 (s.c.) ******** 1.0 (syst.) %**
******D****2****(B****0****) = 1.1 ******** 0.3 (stat.) ******** 0.2 (s.c.) ******** 0.1 (syst.) %**

*69500 candidates*

*36000 candidates*

*9700 candidates*

## B Mixing ms Measurement Prospects

- Requirements
- Clean signals (S/B)
- Vertexing resolution
- Tagging effectiveness
- Modest improvements
- Adding *D**s** **** K*** **K*,  *D**s** **** K**s **K* and *B**s** **** D**s **3***
- L00 innermost silicon layer                                                                  ***t** = 67 fs **** ****t** = 50 fs*
- Short term 500 pb-1  *no improvement up to 2005*
- 2(for ms = 15 ps-1)
- Reach the current limit
- Cover the Standard Model favored range
- Beyond the SM favored range  *conservative improvements up to 2008*
- 5 if ms = 18 ps-1 with 1.8 fb-1
- 5 if ms = 24 ps-1 with 3.2 fb-1

- J. Piedra

- BEACH 04

## Conclusions

*B**d* amplitudes consistent with *B* factories
- Best *B**s* amplitude measurement
- Bs  J/   mostly CP-even  *********s****** measurement imminent***

- J. Piedra

- BEACH 04

## Slide 29

## Back Up Slides

## B Mixing Semileptonic Sample

- Test arena for Soft Muon and Jet Charge
- Based on lepton + displaced-track trigger
- High statistics ~1 million semileptonic *b* events
-  lepton charge  signal *B* flavor at decay
- Background suppression  pure *bb* sample
- QCD background  *pp*  *uu*, *dd*, *ss*
- Remove with signed impact parameter
- Charm background  *pp*  *cc*
- Remove by 2 < Mlepton-track < 4 GeV/c2

- J. Piedra

- BEACH 04