charm and beauty production at the tevatron tara shears university of liverpool on behalf of the cdf...

Charm and beauty production at the Tevatron

Tara Shears

University of Liverpool

On behalf of the CDF and D0 collaborations

248, 725, 730

Tevatron

p p collisions at √s = 1.96 TeV

CDF

D0

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Historical context:

Run 1Nason, Cacciari

UPRF-2002-4

CDF Preliminary:(D*)

Cacciari: hep-ph/9702389

(B+): Phys Rev D65 052005

B

C

Discrepancy from Run 1:

B: (data)/(improved theory) ~ 1.7

C: similar effects seen

Aim: test predictions at Run 2

Tests of b and c production in Run 2

Inclusive b and c production:– Charm Phys. Rev. Lett. 91 241804 (2003)

– Beauty Phys. Rev. D71 032001 (2005)

– Combined

c/b + X:– b + b – c,b + – b + Z Phys. Rev. Lett. 94 161801 (2005)

– b +W Phys. Rev. Lett. 94 091802 (2005)

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4 analyses presented:1. Muon tagged jet

production

2. Inclusive b production

3. bb production

4. Photon + heavy flavour production

Tests of b and c production at Run 2

charm

beauty

Direct and combined measurements

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tagged jet production

Require events with at least 1 jet, ||<0.5, containing a muon (pt>5 GeV)

Jet Et 90 – 400 GeV considered294 pb-1 data analysed

Extract heavy flavour component

from simulation

Measurement sensitive to b + c production

Pythia MC

tagged jet production

Results consistent with LO (Pythia CTEQ 6L) and NLO (NLOJET++ CTEQ6M)

NLOJET++: Z. Nagy, Phys. Rev. Lett. 88 122003 (2002); Phys. Rev. D68 094002 (2003)

Inclusive b production

Require 1 jet, ||<0.7, with separated secondary vertex

Jet Et 38 – 400 GeV

300 pb-1 data analysed

Determine b fraction by fit to secondary vertex mass

Results compared to LO (no NLO yet) : ratio ~1.4 as expected

bb production

Require 2 jets, ||<1.2, both with separated secondary vertex

Et 1 > 30 GeV, Et 2 > 20 GeV

64.5 pb-1 data analysed

Determine b fraction by fit to secondary vertex mass

Calculate cross-section as fn. of :

Jet Et, m(bb), (b jets)_

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bb production

Results consistent with LO (Pythia CTEQ5L) and NLO (MC@NLO + JIMMY U.E. simulation)

Note: selection enhances flavour creation (LO)

bb)(||<1.2, Et1>30GeV, Et2>20GeV) = 34.5 ± 1.8 ± 10.5 nb

LO: 38.7 ± 0.6 nb

NLO: 35.7 ± 2.0 nb

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bb production

Results consistent with LO (Pythia CTEQ5L) and NLO (MC@NLO + JIMMY U.E. simulation)

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+ b / + c production

Sec. Vertex mass (GeV)

Et > 25 GeV (||<1.0) + jet with secondary vertex

Determine b, c, uds contributions (fit secondary vertex mass)

Subtract bkg, find cross-section as fn. Et

25–29 GeV 29–34 GeV

34–42 GeV 42–60 GeV

+ b / + c production

Results consistent with LO

(+b) (+c)

( + c) / ( + b)

Ratio consistent with LO

Charm, beauty production well understood theoretically at Tevatron in Run 2– Many analyses published (inclusive b, inclusive c,

W+bb, Z+b)Shown here:– Inclusive analysis in agreement with LO, NLO– Inclusive b ratio to LO as expected (NLO

comparisons forthcoming)– bb production in agreement with LO, NLO + b, + c in agreement with LO (4x stats.

forthcoming)

Conclusions

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Backup slides

b,c production @ Tevatron

Gluon splitting

Flavour excitation

Flavour creation

How to isolate b,c experimentally

• Large cross-section

• Isolate by triggering on:– Decays to J/– Semileptonic

decays– Displaced tracks

(SVT)

√s (TeV)0.001 0.01 0.1 1.0 10 102

1mb

1b

1nb

1pb

SppSTevatron

LHC(pp→X)(-)

(bb)

Inclusive systematics

Quantity Uncertainty (%)

Efficiency ± 13.0

Luminosity ± 6.5

Heavy flavour fraction ± 20.0

Jet Correction ± 20.0 (Pt=100) +80.0 -50.0 (Pt=400)

Unfolding ansatz ± 5.0

Total ± 32.2 (100) +83.9 -56.0 (400)

Inclusive b systematics

Inclusive (bb) systematics

Quantity Uncertainty /nb

Luminosity ± 2.1

B tagging efficiency ± 5.5

B fraction ± 1.0

Acceptance (trigger efficency, jet corrections, pdfs)

± 7.0

Total ± 10.5

+ b / + c production

Dominates for c

Diagrams equal for b

LO

+

(estimates from Madgraph)

Systematic errors: (b)

Systematic error (pb)

25 – 29 GeV

29 – 34 GeV

34 – 42 GeV

42 – 60 GeV

Tag efficiency +1.7 –1.3 +2.6 –2.0 +0.9 –0.7 +1.1 –0.9

Photon id ± 0.2 ± 0.1 < 0.1 ± 0.1

Jet correction ± 0.5 ± 0.5 ± 0.1 ± 0.1

Jet energy scale +3.3 –1.4 +2.2 –2.1 +0.5 –0.3 +0.5 –0.4

B jet correction ± 0.2 ± 0.3 ± 0.1 ± 0.1

CPR fake estimate - 0.1 < 0.1 < 0.1 < 0.1

trigger +2.5 –1.7 < 0.1 < 0.1 < 0.1

PDF ± 0.3 ± 0.5 ± 0.2 ± 0.2

luminosity +0.7 –0.6 +1.1 –1.0 +0.4 – 0.3 +0.5 –0.4

Final value 11.2 +16.4

-8.2

17.2 +12.3

–10.1

6.2 +6.4

–4.4

7.9 +5.0

-4.1

Systematic errors: (c)

Systematic error (pb)

25 – 29 GeV

29 – 34 GeV

34 – 42 GeV

42 – 60 GeV

Tag efficiency +26.5 –19.8 +13.1 –9.9 +7.4 – 5.6 +8.7 –6.4

Photon id ± 2.2 ± 0.4 ± 0.3 ± 0.4

Jet correction +7.9 –7.2 +2.5 –2.4 0.8 0.4

Jet energy scale +48.0 –21.0 +10.4 –9.6 +3.5 –2.4 +2.9 –2.3

CPR fake estimate - 0.6 - 0.1 - 0.2 + 0.2

trigger +37.3 –25.3 < 0.1 < 0.1 < 0.1

PDF ± 2.2 ± 0.7 ± 0.3 ± 0.2

luminosity +9.6 – 8.6 +5.0 –4.4 +2.8 –2.5 +3.0 –2.7

Final value 164.7+163.2 -106.5

81.1 +71.0

–53.0

45.4 +46.8

–31.3

50.0 +37.3

–30.9

Systematic errors: (c)/(b)

Systematic error (pb)

25 – 29 GeV

29 – 34 GeV

34 – 42 GeV

42 – 60 GeV

B tag efficiency - 1.2 - 0.6 - 1.0 - 0.8

C tag efficiency +2.4 –1.8 +0.8 –0.6 +1.3 –0.9 +1.1 –0.8

B jet correction ± 0.2 ± 0.1 ± 0.1 ± 0.1

CPR fake estimate + 0.1 < 0.1 - 0.1 < 0.1

Final value 14.1 +41.5

-9.8

4.8 +8.7

–3.3

7.4 +19.3

–5.4

6.4 +9.7

–4.1