B hadron masses and branching ratios at CDF

transcript

Saverio D’Auria CDF International Europhysics Conference on High Energy Physics, Aachen, July 17 2003

Saverio D’Auria, University of Glasgow

For the CDF collaboration

CDFContents

• Trigger types at CDF• Masses at CDF• Results on mass measurements:

- B,B0 - Bs

• 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)

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

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.

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

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

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

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

CDFBranching fractions at CDF

( )( )

( ) ( )d b

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

• Same mode for:

• D* peak also visible.

0S SB D

Branching FractionsNormalization decay mode: Bd D

First measurement: Bs Ds Branching Fractions

1.013 1.028K K

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

CDFBranching Fraction: s Ds

Results:

DBRKDBR

DBBRff

From MC: R = 1.08 0.02

From PDGRbr = 2.53 0.65

)(07.0)(11.0)(11.044.0)(

)(0 BRsysstat

DBBRff ss

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

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

CDFBranching Fraction: b c

Results:

pKBRKDBR

From MC: R = 1.20 0.02

From PDGRbr = 1.82 0.49

)(18.0)(09.0)(11.066.0)(

0BRsysstat

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 ) = (6.5 1.1(stat) 0.9(sys) 2.3(BR,f) ) 10-3

• required to be trigger tracks.

• Optimise offline Cuts on MC signal, data sideband:

Branching Fractions: B 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

•Defined in a cone about the B axis:

/B J K

CDFBranching Fractions B h+ h(’) -

• 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:

CDFBranching Fractions B h+h(’) -

• Choose 2 variables:

• Signal Likelihood:

0 /dB K K 0 /dB K K

/sB K K sB K K

/sB K K

1 2where: p p

Monte Carlo:

Kinematic separation:

G1,(ID1) G2,(ID2)

CDFBranching Fractions B h+h(’) -

( )0.26 0.11( ) 0.055( )

BR Bstat syst

BR B K

Yields:

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)(

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]

CDFBranching Fractions: forthcoming channels e.g.

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.

B hadron masses and branching ratios at CDF

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