Sergey Burdin Fermilab - PowerPoint PPT Presentation

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Sergey Burdin Fermilab

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Collider Run II Peak Luminosity. Tevatron and Detectors Performance. Delivered ~800pb-1 ... From 483 32 Bs J/y( m m-) ( K K-) candidates ... – PowerPoint PPT presentation

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Title: Sergey Burdin Fermilab


1
Bs Mixing, Lifetime Difference and Rare Decays at
Tevatron
  • Sergey Burdin (Fermilab)
  • XXXXth Moriond QCD 3/13/05

2
Tevatron Detectors
  • CDF
  • Excellent Tracking
  • Good impact parameter and mass resolution
  • Hadronic Triggers
  • Particle ID by dE/dx and TOF
  • Excellent Coverage
  • Muon System ?lt2
  • Tracking System ?lt3
  • Good Muon Triggers
  • High Yields for Events with Muons
  • Large B samples

3
Tevatron and Detectors Performance
  • Delivered 800pb-1
  • Recorded 600pb-1 per experiment
  • 10x increase in statistics before 2009
  • High Data Taking Efficiency

90
4
B / B mixing
  • Flavour of Bd and Bs mesons can change
    phenomenon called mixing
  • 1987 ARGUS (DESY) large mixing for Bd
  • First indication that top quark was very heavy
  • In SM B-mixing is explained by box diagrams
  • Constrains Vtd and Vts elements of CKM matrix
  • New physics ? new particles in the box
  • Mixing frequency ?md has been measured with high
    precision at B factories (0.502 ? 0.006 ps-1)
  • Dms/Dmd is free from many theoretical
    uncertainties
  • Oscillations in Bs system havent been observed
    yet

5
Bs Mixing Measurement _at_ DØ
  • Complex measurement with many components
  • Goal was to develop necessary tools and have a
    baseline result to build on in the future
  • Use semileptonic data sample µDs
  • One decay mode Ds?Fp, F ?KK-
  • 13,300 candidates in 460pb-1
  • Charge of the muon provides Final State Tag
  • Initial State Tagging using the Opposite-Side B
    hadron
  • Always require muon
  • Improve tagging using additional information
    (PT, PTrel, Secondary Vertices)
  • Combine tagging variables into probability
    discriminator
  • Binned Asymmetry
  • Asymmetry(Nnomix-Nmix)/(NnomixNmix)
  • Visible Proper Decay Length
  • Use first 0.06cm of VPDL where resolution is not
    strongly affected by neutrino

6
µDs sample and resolution _at_ DØ
  • 37631 tagged µDs candidates in VPDL range
    -0.01 0.06 cm
  • Understanding of resolution is crucial for ?ms
    measurement
  • Measured and tuned tracking errors in data and
    MC
  • Track momentum and angles
  • Silicon detector hit configuration and cluster
    width
  • one configuration is shown below

D
Ds
DØ Run II Preliminary
DØ Run II Preliminary
ln(s2IP)
Data before tuning
ln(s2IP)
-ln(p2sin3?)
7
Asymmetry Fit Input Parameters _at_ DØ
  • Assume that Mistag Rate is the same for Bu, Bd
    and Bs mesons
  • Use asymmetries in µD0 (dominated by Bu) and µD
    (dominated by Bd) samples to determine and
    cross-check the Mistag Rate
  • Mistag Rate for Bu
  • Wrong Tag Fraction 26.61.5
  • Dilution 46.83.0
  • Mistag Rate for Bd
  • Wrong Tag Fraction 27.62.1
  • Dilution 44.84.2
  • Sample composition
  • Bs?Ds()µ?X ? Signal
  • contamination
  • c?µX, c?DsX
  • Suppressed by requirement of muon

    from other side
  • Bs?Ds()Ds()X
  • Bu,d?DDsX

8
Bs Mixing Result from DØ
  • Asymmetry in µDs sample shows no evident
    oscillations
  • Use Amplitude method to set limit
  • 95 CL limit ?mslt5.0ps-1
  • Sensitivity 4.6ps-1
  • Contributions to systematic error from
    uncertainties in
  • Mistag Rate
  • Sample Composition
  • Resolution
  • Lifetime
  • Efficiency
  • Mass Fitting Procedure
  • Momentum
  • Non-zero ?Gs

µDs
9
?Gs/Gs Angular Analysis
  • Bs?J/? F is mixture of
    CP 1 CP -1 states
  • Three-angle distribution for Bs decay
  • are muon and kaon angles in J/? and
    F rest frames
  • Integration over leads to one-angle
    distribution
  • In Standard Model
  • ?GS/GS0.120.06
  • ?GS/?mS 3.70.8-1.5x10-3

10
Result on ?Gs/Gs from CDF
  • Three-angle analysis
  • 20315 Bs?J/? F candidates
  • Unconstrained Fit
  • tL1.050.16-0.130.02ps
  • tH2.070.58-0.460.03ps
  • ?Gs0.470.19-0.240.01ps-1
  • ?Gs/Gs 0.650.25-0.330.01
  • Constrained Fit ltGsgt Gd
  • tL1.130.13-0.090.02ps
  • tH2.380.56-0.430.03ps
  • ?Gs0.460.180.01ps-1
  • ?Gs/Gs 0.710.24-0.280.01

11
Result on ?Gs/Gs from DØ
  • From 48332 Bs? J/y(? m m-) ? (?K K-)
    candidates
  • With constraint from the world average c?s from
    Bs semileptonic decays
  • Allowing for a free CP violating angle
    ?Gs/Gs(?Gs/Gs)SMcos2(df)
    using SM constraint
    (?Gs/Gs)SM0.12 0.06

DØ Run II Preliminary
12
Bs ?µDs1(2536)X _at_ DØ
  • Ds spectroscopy expects two narrow states with
    orbital momentum L1 above DK threshold
    Ds1 and Ds2
  • Ds1?DKs (50)
  • Use large µD sample (53k candidates in
    483pb-1)
  • Combine with KS
  • See 18.55.5 Bs?XµDs1(?DKS) candidates
  • First observation of this Bs decay mode

13
Bs??? _at_ CDF
  • b?sss decays in Bs mesons
  • Standard model
  • BR(Bs???) (2.5-5.0)x10-5
  • First observation of Bs ???
  • 12 events in signal region with 2
    background events expected
  • Normalized to Bd?J/? K0
  • BR(Bs???) (1.40.6stat.0.2syst. 0.5BR)x10-5

14
Search for Bs?µµF _at_ DØ
  • Rare decay induced by electroweak penguin and
    box diagrams
  • Use Bs?J/? F for normalization (7411 ev.)
  • Expected sensitivity _at_95CL ltBR(Bs?µµF)gt1.210
    -5
  • Limit is BR(Bs?µµF) lt 6.710-5 (CDF Run I )

Bs?J/? F
15
Search for Bs?µµ _at_ CDF DØ
  • Standard Model BR 4x10-9
  • BR could be 100x larger in some SUSY models
  • Tevatron results
  • CDF BR(Bs?µµ)lt7.5x10-7 (95CL) PRL 93 032001
    (2004) (171pb-1)
  • DØ BR(Bs?µµ)lt5.0x10-7 (95CL) PRL 94 071802
    (2005) (240pb-1)
  • DØ Update
  • BR(Bs?µµ)lt3.7x10-7 (95CL) (300pb-1)

16
FCNC Charm Decays
  • Large cross section for beauty AND charm
  • BR(D0?µµ)2.4x10-6 _at_90CL (CDF Run II,
    69pb-1)
  • Search for D?pµµ _at_ DØ, 530pb-1
  • First search for resonances f ?mm
  • gt7s observation of Ds
  • D lt 3.1 x 10-6 _at_90CL

f ?mm
?,? ?mm
17
Summary
  • Large B samples _at_ work
  • CDF DØ presented for the first time key
    measurements of the B physics program at
    Tevatron
  • Bs mixing
  • ?Gs
  • Exploring unknown territory in rare beauty and
    charm decays
  • More data is coming
  • Double statistics every year next few years
  • 10x increase statistics by 2009
  • Stay tuned!
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