b hadron masses and branching ratios at cdf
DESCRIPTION
B hadron masses and branching ratios at CDF. Saverio D’Auria, University of Glasgow For the CDF collaboration. Contents. Trigger types at CDF Masses at CDF Results on mass measurements: B ,B 0 B s L b Branching fractions at CDF Results on branching fractions: B s D s p - PowerPoint PPT PresentationTRANSCRIPT
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDF
B hadron masses and branching ratios at CDF
Saverio D’Auria, University of Glasgow
For the CDF collaboration
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFContents
• Trigger types at CDF• Masses at CDF• Results on mass measurements:
- B,B0 - Bs
- b
• Branching fractions at CDF• Results on branching fractions:
- Bs Ds - b - B h+h-
• Conclusions and prospective analyses
Related talks:S. Farrington: B lifetime and Flavour tagging at CDF (HF)S. Giagu: Results on CP violation from CDF (CP)J. Thom: Rare Charm decays from CDF (RareDecays)T. Shears: Bottom and Charm quark production in CDF (QCD)C. Ginsburg: CDF run-II muon detector system (DDH) G. Bolla: Commissioning, operations and first results of the CDF run-II-a Silicon (DDH)
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFIntroduction
Used in this analysis:COT tracking chamber, XFTrigger
(1/pT) ~ 0.1% GeV –1; (hit)~150m
dE/dx K- separation is 1.3 at pt > 2GeV/cSilicon detector, SVTrigger: 5 Layers, i.p. resolution 30 m, SVT
Integrated Luminosity
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFTrigger types
B-Physics at CDF is based on 3 trigger types:• di-lepton trigger (“J/”) • two tracks with d0 > 120m (“2-Track Trigger”)• lepton + track with impact parameter > 120m (“lepton+SVT”)
}Used here
SVT: 33m beam 35m res.
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFMasses at CDF
The di-lepton trigger has a large statistics of fully reconstructed B decaysMass scale calibrated on J/, check performed on ’ and Y(1S)
dE/dx: use GEANT descriptionMaterial adjustmentMagnetic field: +0.165%
CDF mass PDG mass
’ 3685.80 0.12
3685.96 0.09
Y(1S) 9461.1 1.5 9460.30 0.26
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFMass measurements: results
Analysis cuts:J/ mass window: ±80 MeV mass window: ±80 MeVDecay length (B): >100 mPt (B) > 6.5 GeV
Analysis cuts:J/ mass window: ±80 MeVPt±) : > 2 GeVDecay length (B): >100 mPt (B) > 6.5 GeV
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFMass measurements: results
Analysis cuts:J/ mass window: ±80 MeV mass window: ±15 MeVDecay length (b): >100 mPointing cut: cos B> 0.95
Analysis cuts:J/ mass window: ±80 MeV mass window: ±10 MeVDecay length (Bs): >100 mPt (Bs) > 6.5 GeV
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFMass measurements: summary
Prospects: what can we do with more statistics- Systematic error will decrease: correct for smaller effects- Statistical error will scale with integrated Luminosity: mass differences- Mass of other Meson, Baryons will be measured.
Mass (MeV/c) Best single meas. PDG
PDG value
B+ 5279.32 0.68 0.94
5279.1 0.4 0.4 5279.0 0.5
B0 5280.30 0.92 0.96
5279.1 0.7 0.3 5279.4 0.5
Bs 5365.50 1.29 0.94
5369.9 2.3 1.3 5369.6 2.4
b 5620.4 1.6 1.2 5621 4 3 5624 9Mass constrained fit 0.8
B-field corrections 0.2
dE/dx corrections 0.2
Alignment/tracking 0.4
Main sources of systematic errors MeV
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFBranching fractions at CDF
0 0
0 0
0
0
( )( )
( ) ( )d b
b d
Bb baryon b c
b d d cB
N BR D Kf BR
f BR B D N BR pK
Ratios of Branching Fractions
- Uncertainties on b cross section (+ 9% c.m. Energy)
- Systematic effects on trigger efficiency
- Rely on other measurements for Production fractions fx allow for measurement in future Branching ratio of control mode Branching fractions to daughter’s daughters
Fully reconstructed decays from the “Two-Track Trigger” stream
e.g.
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDF
• Same mode for:
• D* peak also visible.
0S SB D
0b c
Branching FractionsNormalization decay mode: Bd D
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDF
First measurement: Bs Ds Branching Fractions
1.013 1.028K K
m GeV
sD
4t sp D GeV
2D-Dist Prim 400sD m
2D-Flight-Dist 100sB m
Impact-Par 100sB m
4t sp B GeV
Analysis Cuts:
2 Tracks required to be Trigger Tracks.
mass constrained to
PDG value
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFBranching Fraction: s Ds
Results:
)()(
)()(
)(
)(
0
0
0
sB
sB
s
ss
d
s
DBRKDBR
N
N
BB
DBBR
DBBRff
From MC: R = 1.08 0.02
From PDGRbr = 2.53 0.65
)(07.0)(11.0)(11.044.0)(
)(0 BRsysstat
DBBR
DBBRff ss
d
s
From data fit:
Ns = 44 11 (stat) 7 (sys)NB0 = 505 44 (stat) 20 (sys)
New measurement !Previous limit set by OPAL: BR (Bs Ds ) < 13%
BR(Bs Ds ) = ( 4.8 1.2 1.8 0.8 0.6) 10-3 (Stat) (BR) (sys) (fs/fd)
From PDG: 0.273 0.034 :s
d
f
f
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDF
First measurement: b c p K
Branching Fractions
“Reflections”: take a for a p and
the control channel B0(K has a reflection peak right under the signal. • Use MC to parametrise the shape.• Use data to normalize the amplitude• Take into account into fitting function
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFBranching Fraction: b c
Results:
)()(
)()(
)(
)(
0
0
0
pKBRKDBR
N
NB
DBBR
BRff
cB
b
b
cb
d
b
From MC: R = 1.20 0.02
From PDGRbr = 1.82 0.49
)(18.0)(09.0)(11.066.0)(
)(
0BRsysstat
DBBR
cbBR
dfb
f
From data fit:
Nb = 96 13 (stat) +6 –7 (sys)NB0 = 321 22 (stat) 20 (sys)
New Result ! Previous observations:Delphi 3 evtsAleph 4 evts
BR(b c ) = (6.0 1.0(stat) 0.8(sys) 2.1(BR) ) 10-4
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDF
• required to be trigger tracks.
• Optimise offline Cuts on MC signal, data sideband:
Branching Fractions: B h+ h(’) -
h h
1 2 5.5t tp p GeV
1 2, 150IP IP m
2D-Flight-Dist 300B m
80BIP m
• Isolation:
•Efficiency from data
tB daughters
tAll Tracks
p
Ip
•Defined in a cone about the B axis:
/B J K
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFBranching Fractions B h+ h(’) -
dE
dx
• Total width due to several different contributions.
• on top of each other
• Disentangle using:
• Invariant Mass
• Relative momentum
• PID
,d sB B K K PID essential
← Most Important
{Kinematic Separation
Monte Carlo:
Different signal contributions:
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFBranching Fractions B h+h(’) -
• Choose 2 variables:
• Signal Likelihood:
dB
0 /dB K K 0 /dB K K
/sB K K sB K K
/sB K K
M
11
2
1p
qp
1 2where: p p
Monte Carlo:
Kinematic separation:
G1,(ID1) G2,(ID2)
)()(
2
1exp
2
12
PMM
F
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFBranching Fractions B h+h(’) -
0
0
( )0.26 0.11( ) 0.055( )
( )d
d
BR Bstat syst
BR B K
Yields:
0dB K
0dB
0sB K
0sB KK
3 11(stat)
90 17(stat)
148 17(stat)
39 14(stat)
Ratio of B-factories average:
Present Results:
)(017.0)(15.002.0)( sysstatKAdirCP
03.026.0)(
)( 0
BBR
BBR d
Consistent with no CPV
Using B-factories average for BR(Bd) = (18.5 0.1) 10-6
We obtain:BR(Bd) = (4.81 2.05 1.02) 10-6
[Heavy Flavor Averaging Group]
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFBranching Fractions: forthcoming channels e.g.
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Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003
CDFConclusions:• Mass and Branching ratio techniques in CDF are well established:
new channels are now available thanks to improved trigger (SVT)
• Most precise measurement of b and Bs mass
• New branching ratios have been measured: Bs Ds and bc
• BR sensitivity: O(5 10-6) with present data.
• We have just opened the lid: a large number of new measurements will be performed in the near future.