1Chunhui Chen, University of Pennsylvania

Heavy Flavor Production and Heavy Flavor Production and Cross Sections at the TevatronCross Sections at the Tevatron

(Run II results only)

Chunhui ChenUniversity of Pennsylvania

For CDF and D0 Collaboration

Beauty 2003 October 14-18, 2003 Pittsburg, USA

2Chunhui Chen, University of Pennsylvania

Outline

• Tevatron and CDF/D0 upgrade• Prompt charm meson production cross section • Inclusive J/ cross section • b cross section• b-jet cross section • Conclusion

3Chunhui Chen, University of Pennsylvania

Tevatron Run IIThe Tevatron is a proton-antiproton collider with 980 GeV/beam

1.80TeV in Run I

36 bunches p 36 bunches p_

396 ns bunch crossing time

66 in Run I

Tevatron Performance: L~5.0 x 1031 cm-2s-1 9 pb-1/weekLint~300 pb-1 delivered by Tevatron

Goal: L~1032 cm-2s-1

3.5s in Run I

4Chunhui Chen, University of Pennsylvania

The upgraded detectors

•New tracking: silicon and fibers in magnetic field•Upgraded muon system•Upgraded DAQ/trigger (displaced track soon)

•New silicon detector new drift chamber•Upgraded calorimeter, •Upgraded DAQ/trigger, esp. displaced-track trigger•New TOF PID system

5Chunhui Chen, University of Pennsylvania

Heavy Flavor Production X-Section

B cross section measured from Run Iat Tevatron is consistently higher than NLO QCD

Theoretical development still ongoing.Ex: fragmentation effect …….

Experimental Approaches:Experimental Approaches:More cross section measurement -- energy at 1.96TeV -- lower pT(B)

Study bb correlation

Measure charm production cross section

6Chunhui Chen, University of Pennsylvania

CDF Silicon Vertex Trigger (SVT)

Read out Silicon information and reconstruct tracks online at ~10’s KHz

Collect large amount and fully reconstructed B,D Hadrons:

Tracks from B, D displaced from primary vertex

Using track impact parameterInformation to make trigger decision

Primary Vertex

Secondary Vertex

BDecay LengthLxy

Lxy 450mPT(B) 5 GeV

d = impact parameter

OnlineTrackImpactParam.

35m33m resolbeam 48m

7Chunhui Chen, University of Pennsylvania

Prompt Charm Meson X-Section5.85.80.3pb0.3pb-1-1

Measure prompt charm meson production cross section

Data collected by SVT triggerfrom 2/2002-3/2002

Large and clean signalMeasurement not limited by statistics

8Chunhui Chen, University of Pennsylvania

Separate Prompt/Secondary Charm

Direct Charm Meson Fraction:Direct Charm Meson Fraction:DD00: f: fDD=86.5±0.4±3.5=86.5±0.4±3.5%%D*D*++: : ffDD=88.1±1.1±3.9%=88.1±1.1±3.9%DD++: f: fDD=89.1±0.4±2.8%=89.1±0.4±2.8%DD++

ss: f: fDD=77.3±4.0±3.4%=77.3±4.0±3.4%

Tail due to BD

Detector I.P. resolution Measured from data

Need to separate direct D and BD decay• Direct D point back to collision point I.P.=0• Secondary D not point back to PV I.P.0

Most reconstructed charm mesons are direct

Separate prompt and secondarySeparate prompt and secondarycharm based on theircharm based on their impact parameter distributionimpact parameter distribution..

9Chunhui Chen, University of Pennsylvania

Prompt Charm Meson X-Sections

Integral cross section: (|Y|Integral cross section: (|Y|1)1)

bpDbpDbpDbpD

Ts

T

T

T

22.005.075.0)1|Y|GeV,8,(7.01.03.4)1|Y|GeV,6,(8.01.02.5)1|Y|GeV,6,*(

5.12.03.13)1|Y|5.5GeV,,( 0

bpB T 6.06.3)1|Y|6GeV,,(

Determine trigger and reconstruction efficiency from data and MCMeasure charm meson pT spectrum

CDF I

Prompt charm cross section result submitted to PRL hep-ex/0307080

10Chunhui Chen, University of Pennsylvania

Differential Charm Meson X-Section

Calculation from M. Cacciari and P. Nason: Resummed perturbative QCD (FONLL)JHEP 0309,006 (2003)

CTEQ6M PDFMc=1.5GeV,

Fragmentation: ALEPH measurementRenorm. and fact. Scale: mT=(mc

2+pT2)1/2

Theory uncertainty: scale factor 0.5-2.0

D*+ also include calculation from B.A. Kniehl(private communication)

11Chunhui Chen, University of Pennsylvania

Comparison with Theory Ratio of the measured to the predicted cross section

Measured cross section higher : similar to B

I CDF XBpp

PRL89:122003,2002

Not incompatible with uncertaintiespT shape consistent for D mesons

12Chunhui Chen, University of Pennsylvania

Inclusive J/ Cross SectionCDF: Lower pT trigger

threshold for : pT()≥1.5GeV

J/ acceptance down to pT=039.739.7±2.3±2.3 pb pb-1-1

00ppTT(J/(J/))0.25GeV0.25GeV

D0: Larger y acceptance for

114 pb114 pb-1-1

13Chunhui Chen, University of Pennsylvania

Inclusive J/ Cross Section

bsyststatJyXJpp )()(02.008.4)6.0|)/(|,/( 60.048.0

D0: 4.74 pbD0: 4.74 pb-1-1CDF: 39.7CDF: 39.7±2.3±2.3 pb pb-1-1

14Chunhui Chen, University of Pennsylvania

Extract Contribution from b J/X

The J/ inclusive cross section includes contribution from•Direct production of J/•Decays from excited charmonium: (2S)J/+-, ……•Decays of b-hadrons: B J/X, ……

b hadrons have long lifetime, J/ decayed from b hadronsWill be displaced from primaryvertex

15Chunhui Chen, University of Pennsylvania

Extract Contribution from b J/X

012.0010.0010.0097.0

GeV5.125.1

b

T

f

p006.0006.0005.0143.0

GeV5.50.5

b

T

fp

008.0007.0012.0279.0

GeV1210

b

T

fp

A unbinned maximum likelihood fit to the flight path of theJ/ in the r plane to extract the b fraction

16Chunhui Chen, University of Pennsylvania

b Hadron Differential Cross Section

)/(/)/()/,( JdpJBrXJHXHppd Tbb

But:We can not extract b fraction when bhadron is at restWe want total b hadron cross sectionWe want b cross section as a function of b hadron transverse momentum

Hb denote both b hadron and anti b hadron

|Y(Hb)|<0.6

17Chunhui Chen, University of Pennsylvania

b Hadron Differential X-Section

Bottom decays transfer about 1.7GeV pT to the J/

We can probe b near pT=0 if we can measure b fraction

of J/ with pT below this value.

Unfold pT(Hb) from pT(J/) using MC

Iterate to obtain the correct pT spectrum

b-hadron X-section d/dpT(Hb)

Assume a b-hadron pT spectrum

b-hadron differential and total X-section

New b-hadron pT spectrum

18Chunhui Chen, University of Pennsylvania

b Hadron Differential X-Section

)(/)/()/,( bTbb HdpJBrXJHXHppd

19Chunhui Chen, University of Pennsylvania

Total b Quark Production X-Section

nb)(7.4)(5.05.24)/()/()6.0||,(

syststatJBrXJHBryXHppd bb

b)(8.3)(4.00.18)6.0||,( syststatyXbppd

b)(2.6)(6.04.29)0.1||,( syststatyXbppd

MC extract to high Y region

20Chunhui Chen, University of Pennsylvania

b-jet X-Section

+ jet sample Using pT spectrum to fit the b and

non b content as a function of jet ET

D0: 4.8 pbD0: 4.8 pb-1-1

21Chunhui Chen, University of Pennsylvania

Conclusion

• Large amount data collected by both CDF and D0 already surpass the run I statistics• New Charm, Bottom cross section results• Lots of analysis in progress:

J/, (2S) cross section and polarizationUpsilon cross section and polarizationUpdated b cross section ……

• Tevatron will contribute the knowledge of heavy flavor production• Stay tuned