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

_

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)

_

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

_

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)_

_

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

_

bb production

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

_

+ 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

_

_

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