Beauty photoproduction at Hera S. MiglioranziS. Miglioranzi UCL / Argonne National Lab. 10th International Conference on B-Physics at Hadron Machines Assisi (Perugia), Italy. June 20-24, 2005 Outline: Introduction to beauty production at HERA B measurements using different tagging techniques Comparison of data to MC(LO) and NLO predictions On behalf of the H1 and ZEUS Collaborations HERA collider The world's only ep collider H1 and ZEUS integrated luminosity: √s ~ 320 GeV e (27.6 GeV) 96-00 /03-0596-00 /03-05 e+ L ~ 100 /40 pb-1 e- L ~ 15 /100 pb-1 2007 ~600pb-1 ? p (920 GeV) b production in ep collision Dominant production process in ep collision:Dominant production process in ep collision: BBoson oson GGluon luon FFusionusion Multiple scales involved: M b ~ 5 GeV Q2 ≤ 1 GeV2 (photoproduction – p)γ Q2 ≥ 1 GeV2 (deep inelastic scattering – DIS) P t b ~few GeV (event selection:p t jet >6,7 GeV) powerful tool for testing p structure powerful tool for testing p structure and pQCDand pQCD resolved photon: flavour excitation b production in ep collision MASSIVEMASSIVE scheme FFNS (heavy quarks dynamically generated in the hard process) MONTE CARLOMONTE CARLO: leading order + parton shower models available, including flavour excitation, DGLAP evolution (PYTHIA , HERWIG) CCFM evolution with k t factorisation (CASCADE) THEORETICAL CALCULATIONTHEORETICAL CALCULATION: full NLO calculation (FMNR) available PARTON SHOWER B tagging techniques 2jets + 2jets + µ beauty eventsµ beauty events Large B-mass pp tt relrel: Pt of mu relative to jet axis: Pt of mu relative to jet axis Long B-lifetime : δ μ: δ μ impact parameter impact parameter μ + jets and δ (H1) simultaneous 2-dimensional Ptrel and fitδ data 99-00 (50 pb-1) data tend to rise more steeply then NLO QCD at low p t μ Q2<1GeV2 0.22.5GeV -0.55<η μ <1.1 p t jet>7(6) GeV |η lab jet|<2.5 enhanced statistics and reduced systematic uncertainties μ + jets and δ : comparison H1 - ZEUS Agreement within errors of H1 and ZEUS agreement within errors with massive NLO QCDNLO QCD (FMNR) H1: ptrel + delta , (hep-ex/0502010) ZEUS: Ptrel , (hep-ex/0312057) lifetime tagging (H1) H1 preliminary S1S1 (1 track associated to jet) significance of the track S2S2 (≥2 tracks associated to the jet) second highest significance enhanced sensitivity to b advantageadvantage: higher statistics w.r.t. D* or lepton analysis Inclusive sample (all tracks p t >500MeV) extract b and c fraction from fit to subtracted significance distributions Significance = DCA/σ(DCA) lifetime tagging (H1) Main difference between beauty data and NLO QCD NLO QCD in region +ve rapidity large contribution from resolved photon events to the xsections PYTHIAPYTHIA and CASCADECASCADE (LO+PS): good shape description but generally data higher in normalisation (factors ~1.8,1.6) H1 preliminary x γ (H1 & ZEUS) xx γγ jetjet = Σ = Σ j1,j2 j1,j2 (E(E-p-p zz ) / Σ) / Σ hh (E-p(E-p zz )) lifetime tagging +μ jets gg bb b-excitation:bg gb → → at LO QCD xx γγ is the fraction of photon's energy entering the hard interaction xx γγ ≤0.75≤0.75 H1 beauty from di-μ events b double tag ep bbX X'→ →μμ →D* X'μ Full phase space for beauty production low P t threshold for muon identification large rapidity coverage of ZEUS muon system Low background di-mu selection separation of the sample in high-low mass, isolated and non-isolated,like and unlike-sign muon pair Direct measure total bb cross section without any cutsDirect measure total bb cross section without any cuts - charm pair productioncharm pair production contributes to the unlike-sign muon sample only and was estimated from D*+muon analysisestimated from D*+muon analysis - fake muon bkg fake muon bkg was removed by taking the difference between like sign and unlike sign samples (lfl contribution cancels) beauty from di-μ events (ZEUS) what is left is only beauty contribution...what is left is only beauty contribution... low+high mass unlike sign beauty from di-μ events (ZEUS) ZEUS preliminary beauty from di-μ events (ZEUS) ZEUS preliminary agreement in shape with MC (LO+PS) P t μ>1.5 GeV -2.2<η<2.5 for ΔΦ additional request: true level: μ coming from different bs rec level: m μμ >3.25GeV D* + μ events (H1) This measure extends to significantly lower centre-of-mass energies of bb system than previous HERA xsections. Simultaneously detection of D* and test high order QCD effectsμ D* sensitive to a possible transverse momentum kμ t of the gluons entering the quark pair production process deviations from LO -> high order effects, good agreement with NLO D* + μ events (H1 & ZEUS) σ b vis(ep eD* X)=206±57(stat.)±40(syst.)pb→ μH1: ZEUS: σb vis(ep eD* X)=159±41(stat.)→ μ +68 -62 (syst.)pb μμ PHP (ZEUS) D* μ PHP (ZEUS) D* μ DIS (ZEUS) D* μ PHP (H1) Hera II : μ + jets and δ (ZEUS) ZEUS vertex detector since 2001 upgrade First ZEUS result using impact parameter technique summary p t rel, and significance measurements have been performed in php:δ - H1 and ZEUS measurements agreeH1 and ZEUS measurements agree - general agreementgeneral agreement at large P at large P t t of beauty data with of beauty data with NLO QCDNLO QCD - H1 data slightly higher at low P t μ,P t jet1 (observed also in DIS) HERA II is running smoothly in e- mode Improved analysis and detector performances (e.g. ZEUS MVD) high precision results are coming... analysis with jets: double tag analysis: D* and di- measurements (μ μ sensitive at low PP tt ) have been presented ) have been presented - - beauty data larger than NLO QCDbeauty data larger than NLO QCD outlook inclusive b-quark cross section extrapolation to ep-> ebX good agrement with NLO QCD backup slides Data/theory backup slides simultaneous 2-dimensional Ptrel and fitδ enhanced statistics and reduced systematic uncertainties data 99-00 (50 pb-1) data tend to rise more steeply then NLO QCD at low p t μ,p t jet1 Q2<1GeV2 0.22.5GeV -0.55<η μ <1.1 p t jet>7(6) GeV |η lab jet|<2.5 backup slides