# Presentation: 536284

## Measurement of the B0s Oscillation Frequency:Matter-Antimatter Transformations at 3 THz

**Measurement of the B****0****s**** Oscillation Frequency:****Matter-Antimatter Transformations at 3 THz**

**Prof. Joseph Kroll**
**University of Pennsylvania**

**SLAC**
**23 May 2006**

**Notes:**
find photos to superimpose

## Presenting results on ms and |Vtd/Vts|

**Presenting results on ********m****s**** and |V****td****/V****ts****|**

**Data are from the CDF Collaboration at Fermilab**

**CDF = 60 Institutions, > 700 Physicists**

**All results are preliminary unless indicated otherwise**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Tevatron Performance

**Tevatron Performance**

**Typical L = 10****32**** cm****-2**** s****-1**

**∫****Ldt = 1.5 fb****-1**

**This analysis uses 1 fb****-1**

**Collected**
**1.2 fb****-1**

**Data up to March 2006**

**Presently in 14 week shutdown**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Neutral Meson Flavor Oscillations (Mixing)

**Due to phase space suppression:**
**K****0****L**** very long-lived****: 5.2****£**** 10****-8**** s**
**(K****0****S****: 0.0090****£**** 10****-8**** s)**

**1954: over 50 years ago**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Long-Lived Neutral Kaon

**Long-Lived Neutral Kaon**

**Led to discovery of **
**CP Violation in 1964 **
**(Nobel Prize in 1980)**
**BF(K****0****L**** ****!**** ********+********-****) = 0.2%**

**Discovered in 1956**

- Phys. Rev. **103**, 1901 (1956)

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Neutral Meson Mixing (Continued)

- Joseph Kroll - SLAC Seminar

- 23 May 2006

**Notes:**
time integrated amount of K0

## Neutral B Meson Flavor Oscillations

******= 1/******** = 1.6 psec**

**Units: We use ****~****=1 and quote ********m in ps****-1**
**To convert to eV multiply by 6.582****£**** 10****-4**** **

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Until Two Months Ago... 

**Until Two Months Ago... **

**at least 3.5 cycles per lifetime**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

**Notes:**
Not exactly correct that the Bs follows a simple exponential

## 1st Evidence: Time Integrated Mixing:  

******is the time integrated mixing probability**

**In principle, a measurement of ******** determines ********m**
** ****- 1****st**** B****d**** mixing measurements were ******** measurements**
** ****- ********d**** = 0.187 ****§**** 0.003 (PDG 2005)**
** ****- ****this does not work for B****s****: ********s**** = 0.5 (the limit as x****!1****)**

**Inclusive measurements at hadron colliders, LEP, SLC yield **

**1987**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Discovery of Neutral B Flavor Oscillations

**Implications: m****top****>50 GeV/c****2**
**Top quark is heavier than expected**
**Ellis, Hagelin, Rudaz, **
**Phys. Lett. B 192, 201 (1987)**

**UA1 1987: Evidence for B****0**** & B****0****s**** mixing**

**Followed up by observation**
**of B****0**** mixing by ARGUS:**
**H. Albrecht et al., (25 June 87) **
**Phys. Lett. B 192, 245 (1987)**

**See also:**
- M. Artuso *et al*., (CLEO) PRL** 69**, 2233 (1987)
- H. R. Band et al., (MAC) PL B **200**, 221 (1988)
- A. J. Weir et al. (Mark II) PL B **240**, 289 (1990)

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Basic Measurement Principle

**Measure asymmetry *****A *****as a function of proper decay time t**

**“****unmixed”:**** ****particle**** decays as ****particle      **

**For a ****fixed value of ********m****s****, data should yield**
**Amplitude ****“A” is 1****, at the ****true value of ********m****s**
**Amplitude ****“A” is 0, otherwise**

**    “****mixed”:**** ****particle**** decays as ****antiparticle**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Status of Published Results on ms

**Status of Published Results on ********m****s**

**Results from LEP, SLD, CDF I**

******m****s**** > 14.4 ps****-1**** 95% CL**

**see http://www.slac.stanford.edu/xorg/hfag/osc/PDG_2006/index.html**

**Amplitude method:**
- H-G. Moser, A. Roussarie,
- NIM **A384** p. 491 (1997)

**expected limit**
**(sensitivity)**

**1**

**0**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

**Notes:**
at the end of the talk show CDF result on A for fixed Dms

## Recent Result from DØ Collaboration

**17 < ********m****s**** < 21 ps****-1**** @ 90% CL**

**1****st**** reported direct experimental upper bound**

**Probability**
**“****Signal” is**
**random **
**fluctuation**
**is 5%**

**V. M. Abazov et al. hep-ex/0603029**
**accepted by Phys. Rev. Lett.**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Recent Result from the CDF Collaboration

**Recent Result from the CDF Collaboration**

**Probability**
**“****Signal” is**
**random **
**fluctuation**
**is 0.5%**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## The Flavor Parameters (CKM Matrix)

- mass eigenstates ≠ weak eigen.

- weak

- mass

- related by Cabibbo-Kobayashi-Maskawa Matrix

- V is unitary: VyV = 1

- Measurements + Unitarity assuming 3 generations

- PDG: S. Eidelman *et al*. Phys. Lett. B **592**, 1 (2004)

- Ranges are 90% CL

**These fundamental parameters must be measured**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

**Notes:**
get updated numbers from pdg 2004

## Wolfenstein Parametrization Illustrates Hierarchy

- Original reference: L. Wolfenstein, PRL, **51**, p. 1945 (1983)
- See also: J. Charles *et al.*, Eur. Phys. J. **C41**, p. 1 (2005); *ibid*, hep-ph/0406184

- from hep-ph/0406184

**Expand matrix in small parameter:******** = V****us**** = sin********Cabibbo****»**** 0.2**

**3 ****£**** 3 complex unitary matrix: 3 real & 1 imag. parameters ****≡ 3 angles, 1 phase**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Small Vcb Means Long B Lifetime

**Small V****cb**** Means Long B Lifetime**

**Bill Ford, John Jaros, Nigel Lockyer**

**2006 APS Panofsky Prize**

- also E. Fernandez, **W. T. Ford** *et al.,* PRL **51** 1022 (1983)

**Long B lifetime ******** possible to see B****0****s,d**** particle-antiparticle transitions**

**•**

**}**

**{**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Standard Model Expectations for m

**Flavor oscillations occur through**
**2****nd**** order weak interactions**

*e.g.*

**Same diagrams and formula for ********m****s**** for B****s**** except replace “d” with “s”**

**All factors known well *****except***** “bag factor” ****£**** “decay constant”**

******m****d**** = 0.505 ****§**** 0.005 ps****-1**** **
**           ****(1%) (PDG 2005)**

**from Lattice QCD calculations – see Okamoto, hep-lat/0510113**

**From measurement of ********m****d**** derive |V*********tb****V****td****|****2**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## B Meson Flavor Oscillations (cont)

**If we measure ********m****s**** then we would know the ratio ********m****s****/********m****d**

**Many theoretical quantities cancel in this ratio, we are left with**

**Ratio measures |V****td****/V****ts****|**
**This is why ********m****s**** is**
**high priority in Run II**

**Using measured ********m****d**** & B masses, expected |V****ts****/V****td****|**

**Predict ********m****s**** ****»**** 18 ps****-1**

**We know what to expect**

- M. Okamoto Lattice 2005
- hep-lat/0510113
- PoS LAT2005 (2005) 013

- Joseph Kroll - SLAC Seminar

- 23 May 2006

**Notes:**
Here is where we predict Dms from Dmd and the above formulas

## Why is this Interesting? Probe of New Physics

**Additional virtual particles**
**change ********m****s**** from SM expected value**
**Measured value can be used**
**to restrict parameters in models**

- Lunghi, Perod, Vives, hep-ph/0605177

**Example**

******+**

******-**

**CDF limit @ 95% CL**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Why is this Interesting? Probe of New Physics

**Supersymmetric particles**

**4****th**** Generation**

**Additional virtual particles**
**change ********m****s**** from SM expected value**
**Measured value can be used**
**to restrict parameters in models**

*e.g.,* Harnik *et al.* Phys. Rev. D **69** 094024 (2004)

*e.g.,* W. Huo Eur. Phys. J. C **24** 275 (2002)

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Experimental Steps for Measuring Bs Mixing

**1. Extract B****0****s**** signal – decay mode must identify b-flavor at decay (TTT)**

- Examples:

**2. Measure decay time (*****t*****) in B rest frame (*****L***** = distance travelled) (L00)**

**3. Determine b-flavor at production “flavor tagging” (TOF)**

**“****unmixed” means production and decay flavor are the same**

**“****mixed” means flavor at production opposite flavor at decay**

**Flavor tag quantified by dilution *****D = 1 – 2w, w***** = mistag probability **

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Measuring Bs Mixing (cont.)

**4. Measure asymmetry**

**these formulas assume perfect resolution for t**

**Asymmetry is conceptual: actually perform likelihood fit to expected**
**“****unmixed” and “mixed” distributions**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Measurement ... In a Perfect World

- what about detector effects?

- “Right Sign”

- “Wrong Sign”

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Realistic Effects

- flavor tagging power,
- background

- displacement
- resolution

- momentum
- resolution

- mis-tag rate 40%

- L) ~ 50 m

- p)/p = 5%

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## All Effects Together

**All Effects Together**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## B Physics at Hadron Machines

- Example of lowest order (LO) s2

- Example of  next leading order (NLO) s3

**NLO contribution comparable to LO contribution**

- see P. Nason, S. Dawson, R. K. Ellis
- Nucl. Phys. **B273**, p. 49 (1988)

- called “flavor creation”

- “gluon splitting”

- “flavor excitation”

**b pairs produced close in *****y***

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## B Physics at Hadron Machines (cont.)

**b quarks then fragment to B hadrons**

**B factories running on Y(4S) only produce lightest B mesons**

**Hadron colliders (and e****+****e****-**** colliders running above Y(4S)) produce other B’s**

**fragmentation is hard: B hadron gets large fraction of b quark E**

**Many unique B measurements at hadron colliders**

***e.g.,***** ********m****s****, B****s**** rare decays, observation B****c****, ********b**** lifetime**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Measured Production Fractions at CDF II

| Signature | Yield |
| --- | --- |
| lD | 46,848 ± 275 |
| lD* | 8,490 ± 95 |
| lD+ | 31,015 ± 262 |
| lDs+ | 3,081 ± 95    |
| lΛc+ | 4,739 ± 168 |

- Thesis: K. Gibson (CMU)

**Recent preliminary result from 360 pb****-1**

**High statistics samples**
**semileptonic decays of**
**B****+****, B****0****, B****0****s****, ********0****b**

**comparison to previous results**

**Results**

**Signals**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## B Production at Tevatron

**The inclusive b cross-section is enormous: on the order of 100********b**

**For *****L *****= 10****31**** cm****-2****s****-1**** (10****32****)  ******** ********£**** *****L***** = 1kHz (10kHz)**

**Much of this not useful (trigger, acceptance, analysis selection criteria)**
**The useful cross-section is order 10********b**

**This is still well above production cross-section at B Factories, Z pole**

- The CDF Collaboration, D. Acosta *et al.*, Phys. Rev. **D65, **052005 (2002)

**B factory rate: *****L***** = 10****34**** cm****-2****s****-1**** ******** ******** ****£**** *****L***** = 10 Hz**

******£**** *****L***** ****»**** 100 Hz**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Trigger Strategy for B Physics

**Exploit the characteristics of B production and decay**

**1. B mass relatively large ******** decay products have relatively high p****T**

**require p****T**** > 1.5 – 2.0 GeV/*****c *****or larger**

**2. B decay produces high p****T**** leptons (electron and muon)**

**B****!******** X, e X  & B****!**** J/******** X, J/********!********+********-**

**3. B’s have long decay distance**
**    ****trigger on displaced tracks**

**4. Combine lepton & displaced track**

******b**** large, *****but***
********inelastic**** ****» ****10****3**** larger**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## CDF II

**CDF II**

**Front-end elec. & DAQ: 7.6 MHz clock (132 ns)**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Key Features of CDF for B Physics

**“****Deadtime-less” trigger system**
**3 level system with great flexibility**
**First two levels have pipelines to reduce deadtime**
**Silicon Vertex Tracker:**** trigger on displaced tracks at 2****nd**** level**
**Charged particle reconstruction – Drift Chamber and Silicon**
**excellent momentum resolution: R = 1.4m, B = 1.4T**
**lots of redundancy for pattern recognition in busy environment**
**excellent impact parameter resolution (L00 at 1.5cm, 25********m ****£**** 25********m beam)**
**Particle identification**
**specific ionization in central drift chamber (dE/dx)**
**Time of Flight measurement**** at R = 1.4 m**
**electron & muon identification**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Silicon Vertex Tracker (SVT)

**Silicon Vertex Tracker (SVT)**

**d****0**

**Luciano Ristori, INFN-Pisa**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Example of Specific Trigger for B Physics

- Hadronic Path – designed for B0s! D-s+

**Level 1**
-  - 2 XFT tracks with pT > 1.5 GeV
-  - opposite charge
-  -  < 135o
-  - |pT1| + |pT2| > 5.5 GeV

**Level 2**
-  - confirm L1 requirements
-  - both XFT tracks
-     - SVT 2<15
-     - 120 m< |d0| <1mm
-  - 2o <  < 90o
-  - Decay length Lxy > 200m

**Level 3**
-  - confirm L2 with COT & SVX
-    “offline” quality track reco.

**At Level 3 using**
**trigger criteria**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## B0s Decay Modes

**B****0****s**** Decay Modes**

**Fully reconstructed**
**  ****better decay time resolution**
**Lower statistics**
**Signal 3,700**

**Not fully reconstructed**
**  ****poorer decay time resolution**
**Higher statistics**
**Signal 36,000**

**Majority of signal collected with displaced track trigger**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Example: Fully Reconstructed Signal

**Cleanest decay sequence**

**Four charged particles in**
**final state: K****+**** K****-**** ********+**** ********-**

**Also use 6 body modes:**

**Used for ********m****s**** analysis**

**Signal: 1600**
**This mode only**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## 1992: First Direct Evidence of Bs

**Signal: 16.0 ****§**** 4.3 (********)**
**             ****17.0 ****§**** 4.5 (K*****0****K)**

- D. Buskulic *et al.* (Aleph) Phys. Lett. B **294**, 145 (1992)

- also:
- P. Abreu *et al.* (Delphi) Phys. Lett. B **289**, 199 (1992)
- P. D. Acton *et al.* (Opal) Phys. Lett. B **295**, 357 (1992)

**Sample: 450K hadronic Z**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

**Notes:**
write down which diagrams are signal and background, write down decay mode and signal size

## The Same Signal at CDF Today

**48,000**

**s**

**Purity: 75% from direct semileptonic B****0****s**** decay**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Lifetime Measurement

******B****0****s****) = 1.538 ****§**** 0.040 ps**
**(statistical error only)**
**PDG 2006: 1.466 ****§**** 0.059 ps**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Aside: Recent b Lifetime from CDF

**Uses fully reconstructed ********b ****!**** J/******** ******** instead of semileptonic: ********c****+**** l****-********l**

******= 1.59 ****§**** 0.08 (stat.) ****§**** 0.03 (syst.)**

**Signal**
**542 ****§**** 38**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Unexpected result: Lifetime much larger than previously measured

**Precision of this measurement**
**comparable to World average**

**Problem with semileptonics?**
** ****- sample composition**
** ****- boost correction**

**Measured lifetimes with control modes**
**(B****0****, B****+****) agree well with other exps.**

**Next step for CDF:**
**use ********b****!********c******

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Decay Time Resolution: Hadronic Decays

**Maximize sensitivity:**
**use candidate specific**
**decay time resolution**

**Superior decay time**
**resolution gives CDF**
**sensitivity at much**
**larger values of ********m****s**
**than previous experiments**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Measuring Resolution in Data

**Use large prompt D meson sample**

- CDF II, D. Acosta *et al.*, PRL **91**, 241804 (2003)

**Real prompt D****+**** **
**from interaction point**

**pair with random track**
**from interaction point**

**Compare reconstructed decay point to interaction point**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Semileptonics: Correction for Missing Momentum

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## B Flavor Tagging

- We quantify performance with efficiency* *** and dilution *D*

**= fraction of signal with flavor tag

*D = 1-2w,  w* = probability that tag is incorrect (mistag)

- Statistical error ***A* on asymmetry *A* (*N* is number of signal)

- statistical error scales with ***D**2*

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Two Types of Flavor Tags

**Opposite side**

**Same side**

- Based on fragmentation tracks or B**

-  **+** Applicable to both B0 and B0s

**−**** **other b not always in the acceptance

**−**** **Results for B+ and B0  _*not*_ applicable to B0s

**+** better acceptance for frag. tracks than opp. side b

**Reminder: for limit on ********m****s**** must *****know***** D**

**Calibrate on B****+****, B****0**** data**

**Must rely on**
**MC for D**

**Requires**
**Extensive**
**comparison**
**data and MC**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Types of Opposite Side Flavor Tags

**Lepton tags**

**Jet charge tag**

**Kaon tag**

**mistags from**

**low ******
**high D**

**high ******
**low D**

**Largest ********D****2**** @ B factories**

**Not used in present **
**analysis**

**TOF**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Calibrate with Large Statistics Samples of B+ & B0

**Calibrate with Large Statistics Samples of B****+**** & B****0**

**Example: semileptonic signals**

**Results:**
******D****2**** = 1.54 ****§**** 0.05**
**[******** m****d**** = 0.509 ****§**** 0.010 (stat) ****§**** 0.016 (syst)]**

**Hadronic signals:**
**B****+**** (D****0********+****) = 26,000**
**B****0**** (D****-********+****) = 22,000**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Increase Tagging Power with “Binning”

**Example: lepton tags**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Performance of OST’s is Poor – Why?

**Part of the problem is acceptance of opposite side b**

- Generator Level study from K. Lannon, Ph. D. Dissertation, Illinois, 2003

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Same Side Flavor Tags

**Based on correlation between**
**charge of fragmentation particle**
**and flavor of b in B meson**

**TOF Critical**
**(dE/dx too)**

**Decay of P-wave mesons**
**B********** also contributes to B****0****, B****+**
**(not B****0****s****)**

**Expected correlations**
***different***** for B****+****, B****0****, B****0****s**

- Ali & Barriero, Z. Phys. C **30**, 365 (1986)
- Gronau, Nippe, Rosner PRD **47**, 1988 (1993)
- Gronau & Rosner, PRD **49**, 254 (1994)

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Time of Flight Detector (TOF)

-  216 Scintillator bars, 2.8 m long, 4 £ 4 cm2
-  located @ R=140 cm
-  read out both ends with fine mesh PMT
-   (operates in 1.4 T B field – gain down ~ 400)
-  measured resolution TOF=100 - 130 ps
-  (limited by photostatistics)

**Kaon ID for B physics**

_**Measured quantities:**_
**s = distance travelled**
**t = time of flight**
**p = momentum**
_**Derived quantities:**_
***v***** = s/t**
**m = p/*********v***

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Kaons Produced in Vicinity of B’s

**Larger fraction of Kaons near B****0****s**** compared to B****0****, B****+****, as expected**

- Ph. D. Thesis, Denys Usynin

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Compare PerformanceData and Simulation

**Check prediction for kaon tag on B****+****, B****0**

**Good agreement between data & MC**
**Systematic based on comparisons**

**K**

**K**

****

****

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Flavor Tagging Summary

**Same-side kaon tag increases effective statistics ****£**** 3 – 4**

|  | D2 Hadronic (%) | D2 Semileptonic (%) |
| --- | --- | --- |
| Muon | 0.48 § 0.06 (stat) | 0.62§ 0.03 (stat) |
| Electron | 0.09 § 0.03 (stat) | 0.10 § 0.01 (stat) |
| JQ/Vertex | 0.30 § 0.04 (stat) | 0.27 § 0.02 (stat) |
| JQ/Prob. | 0.46 § 0.05 (stat) | 0.34 § 0.02 (stat) |
| JQ/High pT | 0.14 § 0.03 (stat) | 0.11 § 0.01 (stat) |
| Total OST | 1.47 § 0.10 (stat) | 1.44 § 0.04 (stat) |
| SSKT | 3.42 § 0.98 (syst) | 4.00 § 1.02 (syst) |

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Unbinned Maximum Likelihood Fit

-  **Fix ********m****s**
** ****Integrate: t & k**
** ****Fit for ****A**

**Check procedure: fit for ********m****d**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Amplitude Scan: Hadronic Decays

**Amplitude Scan: Hadronic Decays**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Amplitude Scan: Semileptonic Decays

**Amplitude Scan: Semileptonic Decays**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Combined Amplitude Scan

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Results: Amplitude Scan

**A/********A**** = 3.5**

**Sensitivity**
**25.3 ps****-1**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

**Notes:**
give A/sigma A and sensitivity

## Measured Value of ms

- - log(Likelihood)

**Hypothesis of A=1 compared to A= 0**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

**Notes:**
quote Dms and p-value

## Significance: Probability of Fluctuation

**Probability of**
**random fluctuation**
**determined from data**

**Probability = 0.5%**
**(2.8********)**

**Below threshold to**
**claim “observation”**
**Continue improving**
**analysis to increase**
**potential significance**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Determination of |Vtd/Vts|

**Previous best result:**

**D. Mohapatra *****et al.***
**(Belle Collaboration)**
**hep-ex/0506079**

**CDF**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Summary of CDF Results on B0s Mixing

**First direct measurement of ********m****s**

**Precision: 2.4%    Probability of random fluctuation: 0.5%**

**Most precise measurement of |V****td****/V****ts****|**

**All results are preliminary**

**( 2.76 THz, 0.011 eV) **

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Perspective and Outlook

**Mixing in Neutral Kaons**** **
**led to discovery of CP violation**
**necessary condition for matter antimatter asymmetry in Universe.**
**Mixing in B****0**** mesons**
**made possible by surprisingly long b hadron lifetime**
**led to possibility of observing CP Violation in another system **
**validated that SM mechanism for CP Violation is dominant mechanism**
**Discovery of B****0**** mixing pointed to a much heavier top quark:**** **
**Results on B****0****s**** mixing could point to heavier new particles or exclude them**
**Establishing B****0****s**** mixing sets the stage for the next step:**** **
**measuring CP asymmetries in B****0****s**** decays**
**could produce unambiguous signals of new physics.**
**We are coming to the end of a long story:**** **
**a 20 year quest to measure ********m****s**
**a tremendous technical achievement**
**allows precise measurement of fundamental parameters**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Additional Slides for Reference

**Additional Slides for Reference**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Systematic Uncertainties

**Systematic Uncertainties**

**related to absolute value of amplitude, relevant only when setting limits **
**cancel in A/********A****, folded in in confidence calculation for observation**
**systematic uncertainties are very small compared to statistical **

- Hadronic

- Semileptonic

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Systematic Uncertainties on ms

**systematic uncertainties from fit model evaluated on toy Monte Carlo**
**have negligible impact**
**relevant systematic unc. from lifetime scale**

|  | Syst. Unc  |
| --- | --- |
| SVX Alignment | 0.04 ps-1 |
| Track Fit Bias | 0.05 ps-1 |
| PV bias from tagging | 0.02 ps-1 |
| All Other Sys | < 0.01ps-1 |
| Total | 0.07 ps-1 |

- All relevant systematic uncertainties are common
- between hadronic and semileptonic samples

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Amplitude Scan: Hadronic Period 1

- Bs ! Ds / Ds

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Amplitude Scan: Hadronic Period 2

- Bs ! Ds / Ds

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Amplitude Scan: Hadronic Period 3

- Bs ! Ds / Ds

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Semileptonic Scan: Period 1

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Semileptonic Scan: Period 2

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Semileptonic Scan: Period 3

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## The Unitarity Triangles

**V is unitarity ******** **

- geometric representation:
- triangle in complex plane

**There are 6 triangles**

**Kaon UT**

**Beauty UT**

- flat

*n.b.* these triangles are
***rescaled*** by one of the sides

*i* = 1 is previous page

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## The Beauty Unitary Triangle

**The Beauty Unitary Triangle**

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Results from CKM/UT with Recent CDF ms Result

- http://www.slac.stanford.edu/xorg/ckmfitter/ckm_intro.html
- J. Charles *et al.*, Eur. Phys. J. **C41**, p. 1 (2005); *ibid*, hep-ph/0406184

- _[http://utfit.roma1.infn.it/](http://utfit.roma1.infn.it/)__ M. Bona _*et al*.,
- _[JHEP ](http://arxiv.org/abs/hep-ph/0509219)__[0603](http://arxiv.org/abs/hep-ph/0509219)__[ (2006) 080 [hep-ph/0509219]](http://arxiv.org/abs/hep-ph/0509219)_
- _[JHEP ](http://arxiv.org/abs/hep-ph/0501199)__[0507](http://arxiv.org/abs/hep-ph/0501199)__[ (2005) 028 [arXiv:hep-ph/0501199]](http://arxiv.org/abs/hep-ph/0501199)__ _

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Results from CKM/UT without Recent ms Results

- http://www.slac.stanford.edu/xorg/ckmfitter/ckm_intro.html
- J. Charles *et al.*, Eur. Phys. J. **C41**, p. 1 (2005); *ibid*, hep-ph/0406184

- _[http://utfit.roma1.infn.it/](http://utfit.roma1.infn.it/)__ M. Bona _*et al*.,
- _[JHEP ](http://arxiv.org/abs/hep-ph/0509219)__[0603](http://arxiv.org/abs/hep-ph/0509219)__[ (2006) 080 [hep-ph/0509219]](http://arxiv.org/abs/hep-ph/0509219)_
- _[JHEP ](http://arxiv.org/abs/hep-ph/0501199)__[0507](http://arxiv.org/abs/hep-ph/0501199)__[ (2005) 028 [arXiv:hep-ph/0501199]](http://arxiv.org/abs/hep-ph/0501199)__ _

- Joseph Kroll - SLAC Seminar

- 23 May 2006

## Projected Tevatron Performance

**Final critical improvement: antiproton stacking rate: current best ~ 20mA/hr**

**Achieved:**
**~ 20mA/hr**

- Joseph Kroll - SLAC Seminar

- 23 May 2006