Beauty at the Tevatron

Brendan CaseySEL11, TIFR,

1/11/11

Tevatron

• Only machine currently at both the Energy and Luminosity Frontiers

• Complementary to other machines at each frontier

– Large Bs data set compared to B factories

– Different channels compared to LHC

• qqbar WH lnbb vrs gg H gg

• Weak sector (charginos, neutralinos) vrs strong sector (squarks, gluinos)

• Interference effects (top Afb) vrs resonance search (GA )

• Will be superseded by LHC and super B factories but expect to be relevant for a few more years– Still have a lot to analyze with the 2011

data.2/281/11/11B. Casey, SEL11

pbar complex

Now producing 2.6 ng of antimatter per

year

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Some familiar faces (plus many more)

B. Casey, SEL11

Overlapping beauty

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BVV polarization

CPV in charm mixing

BDADSK

B. Casey, SEL11

Complementary Beauty

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Very Rare Processes

charged currents

neutral currents

B

fact

ori

es Te

vatro

nAnomalous CP Violation

Db = Ds = 1 Db = Ds = 2

b

u n

b

s

l-

l+

l-

b

s

s

bb s

q

q

6/25

Leptonic B decays

• Standard Model rate well understood

• Standard Model rate is small

• New physics enhancements can be large

SM BF:

B(Bs→mm) = (3.6±0.3) x 10-9

Buras, arXiv:0904.4917

B. Casey, SEL11 1/11/11 6/28

Kp

bc

KBs

m

m

Signal and Background

c

p

p

b

b

m

m

p

p

Bs

m

m

b p

p

m

mbc

Signal sequential

double

B→KK

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Background reduction

SV

PV

Flight length significance

sidebands

Signal MC + J/y K data and MC

Minimum DCA

Signal MC + J/y K data and MC

sidebands

sidebands

Signal MC + J/y K data and MC

Angle between

momentum and directionVertex c2

sidebands

Signal MC + J/y K data and MC

pT

(mm)

sidebands

Signal MC + J/y K

data and MCsidebands

Minimum pT (m)

Signal MC + J/y K

data and MC

mm

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Background reduction

Multivariate discriminants

Expect ~3 signal events in D0 data with these cuts

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Expect ~1 signal event in CDF data with these cuts

Almost 2x rapidity coverage at D0 + higher purity

Results

preliminary 2009:43 x 10-9 observed

(12xSM) 33 x 10-9 expected (9xSM)

B. Casey, SEL11 1/11/11

2010:51 x 10-9 observed

(14xSM) 38 x 10-9 expected

(11xSM)

B. Casey, SEL11

Why?

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Tracker radius1.3 m

vrs 0.5 m

B. Casey, SEL11

What’s next?

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~20k B+ @ 3.7 fb-1, 2 TeVvrs

~10k B+ @ 34 pb-1, 7 TeV

A. Schopper, CERN Council Report, Dec. 17 2010

B. Casey, SEL11

CPV in Bs mixing

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(WS Hou)

B. Casey, SEL11

Dimuon charge asymmetry

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tW Wb

s b

s

tW Wb

s b

s

t

t

)()(

)()(

XbbNXbbN

XbbNXbbNASL

Bs mixing in the mirror

B. Casey, SEL11

Measurement history at Dzero• 1992: first internal note outlining measurement

• 1994: 7.3 pb-1: A = (81-96)/(81+96)

• 1996: significant asymmetries observed due to asymmetries in range-out.

– From then on, Dzero switches polarity every few weeks to enable this measurement

• 2003: analysis of ~100 pb-1 RunII data indicates we are competitive. Begin planning for a 1 fb-1

result.

– Dimuon result. Single muon result ruled out because completely dominated by Kaon asymmetry1/11/11 15/28

Iron toroid+ -

B. Casey, SEL11

Measurement history at Dzero

• 1 fb-1 result:

– ASL = -(0.92 ± 0.44 ± 0.32)%

– World leading measurement

– Dominant error is now Kaon asymmetry determined using D*Dp, DKp, KmX

• Raw asymmetry A = -(0.05± 0.13)%

• Kaon asymmetry AK = -(0.23 ± 0.08)%

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B. Casey, SEL11

2010 Update

• Need a way to constrain the Kaon asymmetry

• Two samples:

– Like-sign dimuon system = physics + Kaon

– Single muon system: asymmetry is almost entirely from the Kaons

• Use the single muon system to make a high statistics measurement of the kaon asymmetry and subtract it from the dimuon asymmetry

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B. Casey, SEL11

Dimuon results

• ASL = (0.957±0.251±0.146)%

• Systematic error dominated by Kaon asymmetry

– In dimuon analysis:

• 2.1%

– In combined single and dimuon analysis:

• 0.15%

• Verified the B content by measuring the mixing probability in the first fb-1 data set

– X = 0.136±0.001±0.024

– PDG: 0.1281± 0.00761/11/11 18/28

19/25

Bs →J/y f: Kaon type CPV

Pseudo scalar →Vector + Vector. Both even and odd states contribute.

Angular analysis tells if its even or odd.

Lifetime measurement tells if its long or short Look for even states decaying

with a longer lifetime⇛ CPV

/Dt t ≈ 10%

(t Short)(t Long)

Bs(even)

Bs(odd)

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Bs →J/y f: Bd type CPV

Need to analyze Bs and Bs initial states separately

Bs

Bs

J/ y f

Mirror image of a double slit experiment

mm

KK

Fragmentation: s or s?

recoil: b or b?

m

K

Validate tagging performance using B± samples

Act

ual p

erfo

rman

ce

expected performance

Bs

Bs

J/ y f

p

p

21/25

J/y f resultsResults taken from a multi-parameter fit including flavor, lifetime, polarization, backgrounds, CP conserving, and CP violating interference

Latest comb not available but expect less than 2s effect

B. Casey, SEL11

Future

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A. Schopper, CERN Council Report, Dec. 17 2010

23/25

Future• The large anomalous CPV in Bs

mixing reported at the Tevatron + minimal flavor violation predicts EDMs are “around the corner!”– Gino Isidori, ICHEP 2010 plenary talk

• Need lepton and quark EDM searches to distinguish new weak interaction from a small QQCD

• Need different leptons to determine if the new phase is universal

• New g-2 experiment: muon EDM below 10-21 e-cm

• Nuclear EDMs can be probed at Project X wit copious production of high-Z nuclei to perform EDM measurements far beyond limits from Hg

Large Bs CPV shrinks available parameter space

Titaniumneutron

Mercury

10-25

10-30

Buras, Isidori, Paradisi arXiv:1007.5291

Bs CPV

B. Casey, SEL11

Conclusions

• Beauty at the Tevatron has been beautiful (even in a somewhat ugly environment.)

• Next round of updates should still be interesting and competitive. Then its LHCb’s turn.

• In any case, the Tevatron has clearly demonstrated the advantages of having a luminosity frontier program at an energy frontier machine.

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