heavy flavor productionUlrich HeintzBoston University

U. Heintz - PiC 2005

disclaimers/acknowledgementsnot a comprehensive review but selected results with concentration on b-production at the Tevatronnot covered at allc-productionresults from e+e- collisionsmaterial from talks at Moriond, La Thuile, Beauty 2005thanks to D.Bauer, I.Belyaev, I.Bloch, M.DOnofrio, M.Hildreth, V.Papadimitriou

U. Heintz - PiC 2005

why?check our understanding of QCDheavy flavor production at high energies checks perturbative QCDextracting fundamental parameters of the standard model at hadron colliders requires deep understanding of QCD

U. Heintz - PiC 2005

b production at high energiesHERA (H1/ZEUS) 30/920 GeVphotoproduction Q21 GeV2hard scales: mb, pT, Q2Tevatron (D0/CDF) s=1.96 TeVhard scales: mb, pT at least one hard scale pQCD should work

concentrate on Tevatron

U. Heintz - PiC 2005

b production at high energiesDO Run I (PRL 84 (2000) 5478)CDF Run I (PRL 85 (2002) 5068)

U. Heintz - PiC 2005

Dexcellent muon acceptance ||

CDFexcellent mass resolutionparticle id: tof and dE/dximpact parameter trigger @L2

U. Heintz - PiC 2005

Tevatron performancesince June 2003 3-fold increase in peak luminosityintegrated luminosity per weektotal integrated luminosity instantaneous luminosities above 1032cm-2s-1 total integrated luminosity just reached 1 fb-1

analyses shown use 40-300 pb-1

U. Heintz - PiC 2005

b production at Tevatronb production cross section at s=1.96 TeV 50brate few kHz at current luminosities

many developments in theory in recent yearsfull calculations to NLO resummation of log(pT/mb) terms (fixed order NLO +NLL FONLL)substantial changes in fragmentation functionsnew pdfsleading ordernext to leading order

U. Heintz - PiC 2005

b cross section measurementsJ/ and b-hadron production cross sections (CDF)

Inclusive b-jet cross section (CDF)

High pT cross section for -tagged jets (D)

U. Heintz - PiC 2005

b cross section using J/ (CDF)use exclusive decays of b-hadrons to measure the b-production cross sectioninclusive J/ cross sectionfraction of J/ from decay of b-hadronsb-hadron cross section for all pT

U. Heintz - PiC 2005

b cross section using J/ (CDF)J/s can originate fromdirect productiondecay of excited cc-statesdecay of b-hadrons

dimuon trigger 300k J/ eventsmass resolution 15-20 MeV

U. Heintz - PiC 2005

b cross section using J/ (CDF)inclusive J/ cross section

U. Heintz - PiC 2005

b cross section using J/ (CDF)long life time of b-hadrons c 450 mJ/ decay vertex displaced

plot pseudo proper decay time x=Lxy m/pT in bins of pT of J/max likelihood fit for b-fractionfb = 9.4%fb = 33.7%

U. Heintz - PiC 2005

b cross section using J/ (CDF)systematic error on b-fraction 3-13%

U. Heintz - PiC 2005

b cross section using J/ (CDF)total inclusive b-hadron cross sectioncomparison with Run I B+ cross sectionRun II scaled for B+ fragmentation, |y|

high-pT b-jet cross section (CDF)reconstruct b-decay vertex using displaced tracks in jetRjet=0.7, |yjet|

high-pT b-jet cross section (CDF)determine b-fraction of tagged jets in bins of jet pT using mass of particles that point to secondary vertex

U. Heintz - PiC 2005

high-pT b-jet cross section (CDF)b-jet cross section for 38

high pT -tagged jet cross section (D)first step to b-production cross sectionjet with in coneLdt = 300 pb-1Rjet=0.5, |yjet|

high pT -tagged jet cross section (D)unsmear detector resolutionNLO: Z. Nagy, Phys. Rev. D 68, 094002

U. Heintz - PiC 2005

what changed?long-standing discrepancies between predicted and measured cross sections seem resolvedbetter theory: sum terms with log(pT/mb) (FONLL) e.g. Cacciari, Frixione,Mangano, Nason, Ridolfi, JHEP 0407 (2004) 033better understanding of fragmentation functionsbetter estimate of theory errors (upward!)better parton distributions: add more gluonsbetter experimental observables:not b-quarks but b-hadrons

U. Heintz - PiC 2005

quarkonia productionslightly different theoretical contextnon-relativistic QCD (NRQCD) Lepage et al., PRD 46 4052 (1992)production described by short distance cross sections and nonperturbative matrix elements for evolution to quarkonium state.color octet modes required on top of color singlet to describe production (demonstrated by CDF in Run I)results: D: (1s) production, final stateCDF: prompt J/ polarization

U. Heintz - PiC 2005

Y(1S) production (D)test boundary between perturbative and non-perturbative QCDperturbative color singlet production suppressed by scolor evaporation (soft gluons carry away color/spin non-perturbative)perturbative color octet production can reproduce high pT regionV.A. Khoze , A.D. Martin, M.G. Ryskin, W.J. Stirling, hep-ph/0410020resum logs to address low pT regionE.L. Berger, J.Qiu, Y.Wang, Phys Rev D 71 034007 (2005)

color singlet processcolor octet process

U. Heintz - PiC 2005

Y(1S) production (D)unlike charmonium, all bb-states are produced directly50% of Y(1S) from decay of other bb-states

U. Heintz - PiC 2005

Y(1S) production (D)fix mass splittings and relative widths in fit5 free parameters: m(1S), (1S), n(1S), n(2S), n(3S)|y(Y)|

Y(1S) production (D)little variation in the shape of the cross section as a function of rapidityreasonable agreement with calculations by Berger et al, hep-ph/0411026Ldt = 159 pb-1 hep-ex/0502030, PRL 94 232001 (2005)

U. Heintz - PiC 2005

prompt J/ polarization (CDF)large prompt J/ cross section (Run I)color octet mechanism Braaten/Fleming PRL 74 3327 (1995)transversely polarized J/ at large pTtransverse alignment (symmetric decays)longitudinal alignment (asymmetric decays)

U. Heintz - PiC 2005

HERAcontributing processes:

g fusionresolved contributes to photoproductionsuppressed at high Q2

1999-2000 H1e p (72 pb-1) ZEUSe+ p (50 pb-1)920 GeV28 GeV

U. Heintz - PiC 2005

HERA + dijetphotoproductionQ2

HERA + jetdeep inelastic scattering2 GeV2 < Q2 < 100 GeV2

vis(epebbXejX)=16.32.0(stat)2.3(syst) pbprediction: 9.0-1.6+2.6 GeV

U. Heintz - PiC 2005

HERAsee discrepancy at low pT and high

U. Heintz - PiC 2005

HERAdiscrepancy at high also seen in ZEUS data

ZEUSvis(epebbXejX)=40.95.7(stat)-4.4+6.0(syst) pbprediction: 20.6-2.2+3.1 GeVhep-ex/0405069hep-ex/0502010

U. Heintz - PiC 2005

conclusionsb production at the Tevatron finally NLO QCD and data agreebetter theory calculation: FONLL + fragmentation functions + pdfswell-defined observables quarkonium productionY(1S) production agrees with pQCD + resummation predictions J/ is not transversely polarized as expected by color octet productionb production at HERApQCD predictions are 2 lowdiscrepancies at low pT and high

U. Heintz - PiC 2005

U. Heintz - PiC 2005