February 28, 2008 La Thuile, 2008 1
B States at the Tevatron
Matthew Jones
Purdue University/CDF
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?
February 28, 2008 La Thuile, 2008 3
The Goals of Heavy Flavor PhysicsNew
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)
February 28, 2008 La Thuile, 2008 4
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: At most one hadron in initial and final state.Particularly well suited for heavy hadron masses.
February 28, 2008 La Thuile, 2008 5
• Orbitally excited B mesons• New B-flavored baryons• Λb lifetime• Bc mass and lifetime
February 28, 2008 La Thuile, 2008 6
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).
February 28, 2008 La Thuile, 2008 7
P-Wave B Mesons
Published PRL 99, 172001 (2007)
Using B+ J/ψK+, D0π, D03π: Using B+ J/ψK+:
overlaps with direct
February 28, 2008 La Thuile, 2008 8
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)
February 28, 2008 La Thuile, 2008 9
P-Wave B MesonsProperties:
Production Rates from DØ:
February 28, 2008 La Thuile, 2008 10
B-flavored BaryonsS
trang
enes
sIsospin
Excited spin 3/2 state
Spin 1/2 ground state Using fully reconstructed Λb decays
Using clean J/ψ signal
???
February 28, 2008 La Thuile, 2008 11
• 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
February 28, 2008 La Thuile, 2008 12
Observation of Σb at CDF • Signal region chosen
based on theoretical expectations (HQET):
• Dominant background from Λb with a random track.
February 28, 2008 La Thuile, 2008 13
Within 2 MeV of predicted splitting...
Observation of Σb at CDF
arXiv:hep-ph/0307243
arXiv:hep-ph/0611306
Published PRL 99, 202001 (2007)
February 28, 2008 La Thuile, 2008 14
CDF: dedicated tracking of Ξ- in silicon detector
Observation of Challenge: low pT, displaced track from
DØ: dedicated track reconstruction algorithm
February 28, 2008 La Thuile, 2008 15
• Prediction based on same technique as Σb-Λb prediction:
• Clean enough to consider lifetime measurements?
Ξb Observation
(arXiv:0706.2163)
Published: PRL 99, 052002 (2007)
Published: PRL 99, 052001 (2007)
February 28, 2008 La Thuile, 2008 16
B-baryon Lifetimes
Theory Experiment, ΛbΛc+ℓ-X
1.000.970.940.900.86
OPAL, 96CDF, 96ALEPH, 98DELPHI, 99DØ, 2007
Reaching agreement?
February 28, 2008 La Thuile, 2008 17
New Measurements
Theory Experiment, ΛbJ/ψΛ 1.00
0.970.940.900.86
Maybe... maybe not...
DØ, 2007
CDF, 2007
Most precise measurements to date
February 28, 2008 La Thuile, 2008 18
DØ Analysis of ΛbJ/ψΛ• 171±20 Λb decays • 717±38 B0J/ψ K0
s
Published: Phys. Rev. Lett. 99, 142001 (2007).
Consistent with PDG average.
February 28, 2008 La Thuile, 2008 19
CDF Analysis of ΛbJ/ψΛ
• 3.2σ higher than world average
538±38
February 28, 2008 La Thuile, 2008 20
CDF Analysis of ΛbJ/ψΛ• Lifetimes in many
other decay modes consistent with world averages
• No evidence for bias due to decay topology
• Some, but not all, systematic effects may be correlated with result from DØ.
• CDF and DØ results differ by only 2.3σ...• Precise, independent measurements would benefit both theory and experiment.
February 28, 2008 La Thuile, 2008 21
CDF: Exclusive decay
• Blind search, optimized using B+J/ψK+ as proxy for B-c decay.
• Precise mass measurement:• Lattice prediction:
hep-lat/0411027
February 28, 2008 La Thuile, 2008 22
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
February 28, 2008 La Thuile, 2008 23
• Reconstruct J/ψμ+μ-, add a third track• Apply muon ID, pT and vertexing requirements
• Significant evidence for semileptonic Bc decays
DØ: Bc Lifetime(includes )
February 28, 2008 La Thuile, 2008 24
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
February 28, 2008 La Thuile, 2008 25
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 possible,
but challenging
• Bc increasingly well characterized
February 28, 2008 La Thuile, 2008 26
February 28, 2008 La Thuile, 2008 27
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
February 28, 2008 La Thuile, 2008 28
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!