# Presentation: 791861

## Bs Lifetime Difference Measurements from Tevatron

**B****s**** Lifetime Difference Measurements from Tevatron**

**Kin Yip**

**BEACH 2006, Lancaster, July 2-8, 2006**

**B****s**** lifetime difference from various channels**
** ****B****s**** ******** J/******** + ******** **
** ****B****s**** ******** K****+ ****K**
** ****B****s**** ******** **

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Neutral Meson Mixing

**Quark mixing ******** non-diagonal Hamiltonian for**
**Diagonalizing the Hamiltonian results in**
**two mass eigenstates               and**
**two masses *****m******H***** and *****m******L*****, with ***********m ********** m******H****** – m******L***
**two decay widths ***********H***** and ***********L*****, with ***************************L ************ *****************(> 0 in Standard Model)**

****

****

**dominated by top quark contribution**

- April 9, 2006

## Bs  System and CP violation

**B****s  ****System and CP violation**

**c**

**CP violating weak phase**

** ****In Standard Model, ******** ******** ********λ********η************ ********(0.03), very small.**
** ****Much larger measurement of ******** ******** a striking signal of new physics in B****s ****– ********B****s ****mixing.**

** ****New physics tends to increase ******** ******** smaller**** ******
** ****Any dependence on ********m****s**** cancels in untagged samples.**** **

******s ******** ********SM)**

**B****s**** ******** J/******** + ******** **

**B****s**** ******** K****+**** K**- & ** **

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Untagged Bs  J/ +  Decay

**B****s**** ******** ****J/******** :**
**Pseudoscalar ******** Vector Vector****   decay**** **
**Three waves: ****S, P, D****, or****  ************************┴**
**Both CP-even and CP-odd present, but  separated in angular distributions**
**measure two lifetimes**
**S, D**** (Parity, CP even) :**
**linear combination of**** ******************** **
**P**** (Parity, CP odd) :****       ********┴**
**R****┴********┴****(t=0)|**************

****

**Untagged B****s**** ******** J/******** + ******** Decay**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Untagged Bs Decay Rate in Time & Angles 

** ****************Arg[A****||****(0****************┴********and****************Arg[A****0****(0)********A****┴****(0)] are CP-conserving strong phases**
** ****No dependence on ********m****s**

**correction for acceptances, kinematic cuts**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Maximum Likelihood Fit

**Simultaneous fit to mass, proper decay length and 3 angles  using an unbinned maximum log-likelihood method**

**30 parameters**:       **1        f****sig**** = signal fraction**
**                                 ****2        signal mass, width**
**                                 ****3        A******** , |A****0****|****2****-|A****||****|****2****,  1 strong phase**
**                                 ****1        c******** = c /******** ****, ****        ******** ****= (********L****+ ********H****) /2**
**                                 ****1        ******** = ******** ****L**** -**** ********H**
**                                 ****3        bkg  mass (1 prompt, 2 long-lived)**
**                                 ****1        ********(ct ) scale**
**                                 ****6        bkg ct shape**
**                                 ****4        bkg transversity (2 prmpt + 2 long-lived)**
**                                 ****4        bkg angle ****φ**** (2 prompt + 2 long-lived)**
**                                 ****2        bkg angle ****ψ**** (1 prompt + 1 long-lived)**
**                                 ****2        bkg “interference” (1 prompt + 1 bkg)****    **

**set ******

** ****CDF should have similar no. of parameters**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Bs  J/ +  and 

**B****s ******** J/******** + ******** and ******

**D0    (PRL 2005) used 1 angle,  ****θ****,                  513 events**

**3 angle ******** analysis : ****	****N****signals**** = 978 ******** 45**** **

**All events**

**Preliminary****	****    ~0.8 fb********1**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Data:Fit projections in signal regions

**Data:****Fit projections ****in signal regions**

****

****

******transversity)**

- Daria Zieminska, IU

- FNAL, March 18, 2005

##   ~260 pb-1  data

**Earlier,  PRL 94, 101803, 2005, CDF has used a similar 3 angle ( ********fit/analysis with 260 pb****-1 ****of**** ****data**

- Daria Zieminska, IU

- FNAL, March 18, 2005

**  **

**NNewew results based on X2 **

** ****With**** ************ free**** ****and**** ************ = 0****, ****we obtain**** ******** ****= -0.9 ± 0.7****;**
** ****CP-violating angle ******** ~consistent with 0 (no CP violation) within statistical uncertainty of ± 0.7.**
** ****Working on to constrain all these ************************and************better.**

- Daria Zieminska, IU

- FNAL, March 18, 2005

##  Combined:

- R. Van Kooten: _[hep-ex/0606005](http://arxiv.org/abs/hep-ex/0606005)_

** ****Combined:**
******ps********1**
****** **
-       **1.520 ******** 0.068 ps**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Bs  K+K-  lifetime analysis 

**Add lifetime information to the fit of composition ****(of various hadronic states)****:**

**Trigger bias for signal is extracted from detailed simulation.**
**Procedure validated in unbiased  *****B***** → *****J/******ψ******X***** decays from dimuon trigger.**
**Check that lifetime fits of samples **_**with/without**_**  applying track-trigger cuts yield consistent results. **
**Lifetime p.d.f for background is extracted from higher mass data sideband.**

**CP-even ******** lifetime of the CP-even state  **

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Bs K+K-  lifetime results (360 pb1)

***B*****s**** ******** *****K*****+*****K*****-  ****is CP-even (~ 5% uncertainty): has the lifetime of “light *****B*****s****” :**
** **
**Combine with HFAG average (*****τ******L******2****** *****+ *****τ******H******2****** *****)/(*****τ******L *****+ *****τ******H *****):**

-  **detector  alignment;**
** ****input *****p*****T****(*****B*****) in simulation;**
** ****lifetime model of background;**

- Dominant systematics :

-  **dE/dx model;**
** ****trigger-bias.**

**                              **

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Precise measurement of flavor-specific decays further constrain s  and s .

- R. Van Kooten: _[hep-ex/0606005](http://arxiv.org/abs/hep-ex/0606005)_

**Precise measurement of flavor-specific decays further constrain ********s****  and ********s** .

**See E. de la Cruz-Burello’s talk !**

- Daria Zieminska, IU

- FNAL, March 18, 2005

##                       and S

***                      ******and *********S**

**CP**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## :

**:**

**:**

**,**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Bs DS+ DS- (exclusive hadronic mode)

***B******s************ D******S******+****** D******S******-****** (exclusive hadronic mode)***

** ****1****st**** observation of this fully reconstructed decay**
** ****Working on to extract ********S**
** ****good prospect with 1 fb****-1**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## new physics tends to reduce the measured s

**2.3 ******** from zero,**
**new physics tends to reduce the measured**** ********s**

**R. Van Kooten:**** **_[hep-ex/0606005](http://arxiv.org/abs/hep-ex/0606005)_

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Updating from Phys. Lett. B 459, 631 (1999) by U. Nierste:
 SM prediction:

Expt. meas. from s and latest ms:

                                                                        Disappointingly in agreement 
                                                      with Standard Model prediction !

**Updating from Phys. Lett. B 459, 631 (1999) by U. Nierste:**
****** ****SM prediction:**
**Expt. meas. from ********s**** and latest ********m****s****:**
-                                                                         **Disappointingly in agreement **
**                                                      ****with Standard Model prediction !**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Summary

**CP eigenstate mixures and branching fraction measurements now give a “world average” of ********s ****~2.3 ******** away from zero;**
**Results are consistent with SM so far;**
**More results from Tevatron (and elsewhere) will pin ********s**** down to greater accuracy.**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## BACKUP

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Lifetime Difference & CP violation

***B******s****** ************ J/************ ***********   :**** ****Pseudoscalar ******** Vector – Vector **
**Decay amplitude decomposed into 3 linear polarization states**
**A****0**** = S + D wave ******** P even**
**A****||**** = S + D wave ******** P even**
**A******** = P wave ******** P odd**
**If CP violation neglected ******** interpreted as lifetimes of 2 mass eigenstates:**
***B******s*****,Light**** ******** CP even**
***B******s*****,Heavy**** ******** CP odd**
**angular distributions are different**
**Angular analysis separates CP eigenstates ******** measure two lifetimes**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## CKM Matrix and Unitarity triangle

**                 ****‘****bd’**** **
**    ****(THE unitary triangle)**
**  ****Large effort in B physics**
**    ****Mainly at B factories**

**                         ****’****bs’**
**     ****(A ‘squashed’ unitary triangle)**

****** ******** ********s, ****small  in SM**

**Interesting to check how small/big ********s ****really is.**
**Currently: Tevatron domain**

**Relates quark**
**mass  ****and ****weak eigenstates**** **

**  **

**SM: CP-violating processes solely related to one phase in CKM.**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Fit projection (lifetime)

**Fit projection (lifetime)**

**All events**

**Background mass region**

**Signal mass region****	******

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Detector Acceptance (MC & data)

**G(cos ********) = 1 + Bcos****2******** + Ccos****4******

**F(********) = 1 + J cos(2********) + K cos****2****(2********)**

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Systematics

** ****One “outlyer” ******** treat its effect as systematic uncertainty**
**         ****Event  Run #: 210344  Event #:23385781**
**          ****unlikely signal or background**
**          ****Signal:  mass 2.3 ******** from peak, lifetime 8.5 x mean**
**          ****Bkg:     10.2 x mean for “right slope long”**
**                  **

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Some selection cuts

| Bs candidate mass
J/ candidate mass
Non-J/ meson mass
Bs pT
J/ pT
 pT
J/,  2
K± pT
SMT hits each track (incl. fdisk)
SMT+CFT hits on track
B candidate decay length error |  5.0 < M(J/,) < 5.8 GeV
   2.9 < M(+,-) < 3.3 GeV
1.01 < M(K+,K-) < 1.03 GeV
> 6.0 GeV
> 4.0 GeV if || < 1.0
> 1.5 GeV
< 10.0
> 0.7 GeV
>1
>7
< 0.006 cm |
| --- | --- |

**Total number of B****s******** ****J******** ****candidates: 21380    ****(PRL 2005: 9699)**

**data before last Tevatron shutdown**** **

- Daria Zieminska, IU

- FNAL, March 18, 2005

## Data 

- Daria Zieminska, IU

- FNAL, March 18, 2005