B States at the Tevatron

February 28, 2008 Les Rencontres de Physique de la Vallee d'Aoste, 2008

1

B States at the Tevatron

Matthew Jones

Purdue University/CDF

http://www.physics.purdue.edu/

http://www-cdf.fnal.gov/

http://www-d0.fnal.gov/

February 28, 2008 La Thuile, 2008 2

The Goals of Heavy Flavor Physics

hep-ph/9612327

circa 1996

Is the CKM matrix unitary? Is it the

source of CP violation seen in the Kaon

system?

http://xxx.lanl.gov/abs/hep-ph/9612327


The Goals of Heavy Flavor Physics

New

New Physics:

• Expect many new phases in quark couplings

• Should be manifest at some level in heavy flavor decays

• Could be used to probe details of flavor structure in new physics scenarios

• Will require determining heavy flavor matrix elements with great precision

Lattice QCD HQET(and kin)


hep-lat/0510113

Lattice QCDPhysical light quark masses

Physical heavy quark masses

HQETChPT(small lattice spacing) (large lattice volume)

Symanzik-improved staggered quarks

NRQCD

Gold plated processes for Lattice QCD: Absolute mass

Heavy Quark Expansions: Mass splittings

How reliable are these methods? How can we check?

Talk by Vittorio Lubicz this afternoon!

http://xxx.lanl.gov/abs/hep-lat/0510113


• Orbitally excited B mesons

• New B-flavored baryons

• Λb lifetime

• Bc mass and lifetime

Talk by Heriberto Castilla this afternoon!


P-Wave B Mesons

45 MeV photon (unreconstructed)

eg, Godfrey & Isgur,

Phys. Rev. D32, 132

(1985). Also, Falk and

Mehen, Phys. Rev. D53,

231 (1996).


P-Wave B Mesons

Published PRL 99, 172001 (2007)

Using B+ J/ψK+, D0π, D03π: Using B+ J/ψK+:

overlaps with direct

http://www-cdf.fnal.gov/physics/new/bottom/070726.blessed-bss/Bds_PRplot.eps


P-Wave B0s Mesons

36±9

95±23

hep-ex/0710.4199, Accepted by PRL

Kaon ID: dE/dx + Time-of-Flight

hep-ex/0711.0319, Accepted by PRL

125±25 B*s2B+K-

decays(25±10)


P-Wave B MesonsProperties:

Production Rates from DØ:


B-flavored BaryonsS

tran

gene

ss

Isospin

Excited spin 3/2 state

Spin 1/2 ground state Using fully reconstructed Λb decays

Using clean J/ψ signal

???


• Analysis optimization

3180±60 ΛbΛ+

cπ-

decays in 1 fb-1

Observation of Σb at CDF

Background from Q sidebands, away from expected signal region.

Discriminating variables for

• pT(Σb)

• Pion impact parameter

• Angular information in decay

Signal from Monte Carlo


Observation of Σb at CDF • Signal region chosen

based on theoretical expectations (HQET):

• Dominant background from Λb with a random track.


Within 2 MeV of predicted splitting...

Observation of Σb at CDF

arXiv:hep-ph/0307243

arXiv:hep-ph/0611306

Published PRL 99, 202001 (2007)


CDF: dedicated tracking of Ξ- in silicon detector

Observation of Challenge: low pT, displaced track from

DØ: dedicated track reconstruction algorithm


• Prediction based on same technique as Σb-Λb prediction:

Ξb Observation

(arXiv:0706.2163)

Published: PRL 99, 052002 (2007)

Published: PRL 99, 052001 (2007)

CDF II,

• Clean enough to consider lifetime measurements?


B-baryon Lifetimes

Theory Experiment, ΛbΛc+ℓ-X

1.00

0.97

0.94

0.90

0.86

OPAL, 96

CDF, 96

ALEPH, 98

DELPHI, 99

DØ, 2007

Reaching agreement?


New Measurements

Theory Experiment, ΛbJ/ψΛ

1.00

0.97

0.94

0.90

0.86

Maybe... maybe not...

DØ, 2007

CDF, 2007

Most precise measurements to date


DØ Analysis of ΛbJ/ψΛ• 171±20 Λb decays

• 717±38 B0J/ψ K0s

Published: Phys. Rev. Lett. 99, 142001 (2007).

Consistent with PDG average.

(using world average B0 lifetime)


CDF Analysis of ΛbJ/ψΛ

• 3.2σ higher than world average

538±38

hep-ex/0609021 - Accepted by PRL

(using world average B0 lifetime)


CDF Analysis of ΛbJ/ψΛ• Lifetimes in other

decay modes consistent with world averages

• No evidence for bias from decay topology

• Some, but not all, systematic effects may be correlated with result from DØ.

• CDF and DØ lifetimes differ by only 1.7σ...

Precise, independent measurements are needed!


CDF: Exclusive decay

• Blind search, optimized using B+J/ψK+ as proxy for B-c decay.

• Precise mass measurement:• Lattice prediction:

hep-lat/0411027

CDF II 2.4 fb-1

hep-ex/0712.1506 – submitted to PRL

108±15 candidates

more than 8σ


DØ Observation ofDØ 1.3 fb-1

Now using 3D impact parameter significance:

Blind search using B+J/ψK+ as proxy for Bc

Corrected for observed mass biases, consistent with CDF result.

54 ±12 events

Preliminary: February 22, 2008


• Reconstruct J/ψμ+μ-, add a third track

• Apply muon ID, pT and vertexing requirements

• Evidence for semi-leptonic Bc decays

DØ: Bc Lifetime(includes )


DØ: Bc Lifetime• Backgrounds

constrained by M(J/ψμ)

• Prediction from QCD sum rules:

• Consistent with previous measurements.

• Most precise measurement to date.

hep-ph/0308214


Summary from CDF and DØ• New B states observed over the past year:

– No surprises: all were expected to exist– Demonstrates the power of a hadron collider

for heavy flavor physics

• B hadron lifetimes:– Continue to be quite interesting!– Lifetimes of newly observed baryons?

• Bc increasingly well characterized

• Useful constraints?



The Experiments

• 8x12 layer drift chamber, |η|<1• Muon coverage |η|<1• Triggers: 20 kHz Level 1 rate

– Di-muon, pT>1.5 GeV– Displaced tracks

• 8x2 layer fiber tracker, |η|<2• Muon coverage |η|<2• Triggers: 2 kHz Level 1 rate

– Single muon, pT> 3 GeV– Di-muon, pT > 2 GeV


Exclusive B Decays

51,500 B+ J/ K+ from 1.5 fb-1

(34,000 per fb-1)

23,300 B+ J/ K+ from 1.3 fb-1

(18,000 per fb-1)

σ~ 10 MeV/c2σ~ 40 MeV/c2

... but superb rapidity coverage!

http://www-d0.fnal.gov/

Documents

B States at the Tevatron