B hadron masses and branching ratios at CDF

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


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)


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

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.


CDF

• Same mode for:

• D* peak also visible.

0S SB D

0b c

Branching FractionsNormalization decay mode: Bd D


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


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


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


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


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


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:


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


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]


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.

Documents

B hadron masses and branching ratios at CDF