Beauty production cross section measurements at E cm = 1.96 TeV

1. Beauty production cross section measurements at Ecm = 1.96 TeV Monica D’Onofrio University of Geneva On behalf of the D0 & CDF collaboration Rencontres de Moriond – QCD, 12-19 March 2005

2. The Tevatron, CDF and D0 experiments Theory of beauty production Run II results on beauty production: b-hadron cross section with J/ High pT b-jet cross section Bottomonium production Summary & Conclusions Outline Rencontres de Moriond-QCD

3. The Tevatron in RunII • Peak luminosity in 2005 above 1032 cm-2 s-1 • CDF and D0 collected > 500 pb-1 on tape • Analyses shown here use 40-300 pb-1 2002 2003 2004 2005 Rencontres de Moriond-QCD

4. CDF and D0 in RunII CDF • Both detectors • Silicon microvertex tracker • solenoid • High rate trigger/DAQ • Calorimeters and muons L2 trigger on displaced vertices Excellent tracking resolution D0 Excellent muon ID and acceptance Excellent tracking acceptance || < 2-3 Rencontres de Moriond-QCD

5. Beauty production • To understand and probe perturbative QCD • at Ecm=1.96 TeV s(bb) ~ 50 mb  few kHz event rate Leading Order Next to Leading Order Full calculations have been done up to NLO and beyond …. Flavor excitation Flavor creation Gluon splitting Many developments in the theoretical approach in the past years Rencontres de Moriond-QCD

6. Recent developments • Beyond NLO: resummation of • log(pT/m) terms  FONLL • Substantial change in fragmentation • function extraction (from LEP data) • new PDF functions now <1994 sbNLO(|y|<1) (mb) … the past CDF(1995) Release date of PDF • Good data/theory agreement • also due to improved treatment • of experimental inputs • (use b-jets and b-hadrons • rather than b-quark) … the present  Rencontres de Moriond-QCD

7. J/   B+ K+ B hadron production using J/y (CDF) Subm. to PRD, FERMILAB-PUB-04-440-E • Exclusive decays of B-Hadrons used to • measure the b production cross section • Find J/y inclusive cross section • Extract fraction of J/y from decay of long-lived b-hadrons • Find b-hadrons cross section for pT(B) down to 0 considering |y(J/y)|<0.6 Lum=39.7 pb-1 …Counting J/y (pT= 0 to 20 GeV/c) 1.25<pT(mm)<1.5 GeV/c 12.0<pT(mm)<14.0 GeV/c • muon trigger:e=0.9860.010 • for pmT>1.5 GeV/c (|y|<0.6) • use detector simulation • to model the shape as • expected for J/y signal • Mass resolution ~ 14-15 MeV Rencontres de Moriond-QCD

8. Tagging b … • J/y inclusive cross-section contribution from • Direct production of J/y • Decays of b-hadrons: B  J/y X • Decays from excited charmonium: (2S)J/y +-, …  J/yfrom B  J/y Xwill be displaced • In general b-tagging procedures take • advantage of the long life-time of • B hadrons ct ~ 450 mm • use Lxy, distance primary-secondary vertex in r-f space to define sec.vtx quality • If considering jets, selection also on Lxy direction with respect to jet axis Secondary vertex Jet axis Lxy Primary vertex Rencontres de Moriond-QCD

9. Extract b fraction To reduce dependence on J/y pT bin: x = Lxy(J/y) • M(J/y) / pT(J/y) = flight path of J/y in r-f plane Maximum likelihood fit to extract b fraction as function of pT(J/y) fb = 9.4% B  J/y X shape from MC templates fb = 33.7% Rencontres de Moriond-QCD

10. B hadron production cross section Total inclusive single b-hadron (Hb) cross section considering Br(HbJ/yX) = 1.160.10% and Br(J/ymm) = 5.880.10% comparison with RunI data |y(Hb)| < 1, s(RunII) multiplied by B+ fragmentation=0.4 (Ecm rescaled) RunI Very good agreement with theory prediction RunII Rencontres de Moriond-QCD

11. High PT b-jet cross section (CDF) b-jets include most of quark fragmentation remnants  small dependence on fragmentation • MidPoint algorithm for jet reconstruction • kinematics: jet PT and rapidity (y) • jet Rcone = 0.7, |yjet|<0.7 • PT range 30-360 GeV/c  38-400 GeV/c (Energy scale corrected for detector effects) Lum ~ 300 pb-1 • Use displaced tracks inside jet to reconstruct the secondary vertex (b-tagging) Rencontres de Moriond-QCD

12. b-jet cross section: b-fraction tagged jets 98 < pTjet < 106 GeV/c Extract fraction of b-tagged jets from data using shape of mass of secondary vertex as discriminating quantity  bin-by-bin as a function of jet pT non-b MonteCarlo templates b Rencontres de Moriond-QCD

13. b-jet cross section: results b-jet cross section as function of jet pT (Range 38-400 GeV/c) No comparison with NLO yet Data/Pythia Tune A ~ 1.4 in agreement with expectations Error bar: stat. error from data Rencontres de Moriond-QCD

14. High PT b-jet cross section (D0) • Measurement performed also in RunI for ET bjet of 30-100 GeV using muon jets • Preliminary results for m-tagged jets cross section shown here - Lum ~ 300 pb-1 - DR(m-jet) < 0.5 - |yjet|<0.5 - 50<pTjet<400 GeV/c extraction of the b-jet cross section expected soon Rencontres de Moriond-QCD

15. Upsilon production (D0) Subm. to PRD, FERMILAB-PUB-05/020-E Quarkonium production is a window on boundary region between perturbative and non-perturbative QCD. • Bottomonium states production • Prompt • b (1S) |y|<0.6 Fit components (1S),(2S),(3S) Here: production of (1S) state (1S)  m+m- Lum=159 pb-1 (dimuon trigger, e>99% if pTm>5 GeV/c) • Function of  pT • 3 rapidity range • - 0.<|y|<0.6 • - 0.6<|y|<1.2 • - 1.2<|y|<1.8 1.2<|y|<1.8 pT [4,6] GeV/c Rencontres de Moriond-QCD

16. Upsilon production: results (1S) cross section extracted MC pred. ds/dy*Br(mm)= 73219(stat)73(syst)48(lum) pb [CDF RunI: 68015(stat)18(syst)26(lum) Factor 1.11 between 1.96 and 1.8 TeV Ecm] E.L. Berger, J. Qiu, Y. Wang Phys Rev D 71 034007(2005) D0 RunII CDF Run I • Assume (1S) production unpolarized • small effect due to rapidity range • good agreement with theory prediction Rencontres de Moriond-QCD

17. Summary and Conclusion • Studies of beauty production are precision tests of NLO pQCD • New RunII measurements reported: • Central b-hadron cross section extracted from J/y production  very good agreement with recent theoretical prediction. • New b-jets analyses considerably extend range in pT of cross section: for CDF, NLO (and beyond) comparison expected soon, LO comparison as expected. • Improved measurement for Bottomonium production in a wider rapidity range: in agreement with earlier results and with theoretical expectation. • Many further improvements are expected…: • Extraction of b-jet cross section from m-tagged jets (D0) • bb cross section and correlations studies Rencontres de Moriond-QCD