Heavy Flavour photoproduction at HERA - Zeus
Heavy Flavour photoproduction at HERA - Zeus
Heavy Flavour photoproduction at HERA - Zeus
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<strong>Heavy</strong> <strong>Flavour</strong> <strong>photoproduction</strong> <strong>at</strong> <strong>HERA</strong>Verena SchönbergPhysikalisches Institut der Universität BonnThe 2009 Europhysics Conferenceon High Energy PhysicsCracow, Poland, 17 th July 2009IntroductionCharm ProductionBeauty ProductionV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 1 / 26
Motiv<strong>at</strong>ion<strong>Heavy</strong> <strong>Flavour</strong> production provides multiple hard scales:large mass m b /m chigh momenta p T→ Should ensure reliable predictions?→ Test of perturb<strong>at</strong>ive QCDMonte Carlo programs (leading order + parton shower)PythiaNLO Calcul<strong>at</strong>ionsGeneral Mass Variable <strong>Flavour</strong> Number Scheme (GMVFNS)Fixed <strong>Flavour</strong> Number scheme (FFNS → FMNR)V. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 2 / 26
<strong>Heavy</strong> <strong>Flavour</strong> Production MechanismDominant process: Boson-gluon fusion”direct””resolved”(including flavour excit<strong>at</strong>ion)e +qqe +qpqpqpqpV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 3 / 26
<strong>Heavy</strong> <strong>Flavour</strong> TaggingJet 1e + /µ +Different experimental techniques to use(combine) for heavy flavour tagging:Meson identific<strong>at</strong>ionD ∗± tagging (”Golden Decay”)Decay spectraof lepton to jet axisp relTLifetime inform<strong>at</strong>ionMeasure impact parameter withrespect to primary vertex (beam spot)γ¯bbgdD ∗−¯cJet 2¯bB 0e + /µ +ν e/µW +V. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 4 / 26
Part ICharm ProductionV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 5 / 26
D ∗ production in PhotoproductionH1Charm quark tagged by a D ∗ meson decaying in the golden channelD ∗± → D 0 π ± slow → K ∓ π ± π ± slowD<strong>at</strong>a: L = 93 pb −1Kinem<strong>at</strong>ic rangeQ 2 < 2 GeV 2100 < W < 285 GeVp t (D ∗ ) > 1.8 GeV|η(D ∗ )| < 1.5Entries / 0.5 MeV3000200010000H1 Preliminary<strong>HERA</strong> II Fast Track Trigger+K-π - + K π +2< 2 GeV0.14 0.15 0.16 0.17M(K π π) - M(K π)[GeV]2Q100 < W γP< 285 GeVp (D*) > 1.8 GeVt|η(D*)| < 1.5∆M distribution for determin<strong>at</strong>ion ofnumber of D ∗ mesonsV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 6 / 26
Differential cross-sections in p t (D ∗ ) and η(D ∗ )tH1[nb/GeV]dσ(ep → eD*X)/dp210101H1 Preliminary<strong>HERA</strong> IID* in PhotoproductionH1 d<strong>at</strong>a (prel.)FFNS (CTEQ5F3)1.3 < m c < 1.7 GeV20.5 < µ / m 2c +p < 2r,ftGMVFNS (CTEQ6.5)dσ(ep → eD*X)/dη[nb]403020H1 Preliminary<strong>HERA</strong> IID* in PhotoproductionH1 d<strong>at</strong>a (prel.)FFNS (CTEQ5F3)1.3 < m c < 1.7 GeV20.5 < µ / m 2c +p < 2r,ftGMVFNS (CTEQ6.5)-1102Q2< 2 GeV100 < W γ P < 285 GeVp (D*) > 1.8 GeVt|η(D*)| < 1.510-2102 4 6 8 10 12p(D*)[GeV]t-1.5 -1 -0.5 0 0.5 1 1.5η(D*)D<strong>at</strong>a compared to NLO predictions:◮ FFNS: Fixed <strong>Flavour</strong> Number Scheme (FMNR)◮ GMVFS: General Mass Variable <strong>Flavour</strong> Number Scheme→ D<strong>at</strong>a in reasonable agreement with both preditions→ GMVFNS too steep in p t , slightly different shape in ηV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 7 / 26
Double-diff. cross-sections in p t (D ∗ ) and η(D ∗ )tttH1dη (D*)[nb/GeV]d 2 σ/dp302010H1 Preliminary<strong>HERA</strong> IID* in Photoproduction1.8 < p (D*) < 2.5 GeVtdη (D*)[nb/GeV]d 2 σ/dp108642H1 Preliminary<strong>HERA</strong> IID* in Photoproduction2.5 < p (D*) < 4.5 GeVtdη (D*)[nb/GeV]d 2 σ/dp0-1.5 -1 -0.5 0 0.5 1 1.5η(D*)0.50.40.30.20.1H1 Preliminary<strong>HERA</strong> IID* in Photoproduction4.5 < p (D*) < 12.5 GeVt0-1.5 -1 -0.5 0 0.5 1 1.5η(D*)0-1.5 -1 -0.5 0 0.5 1 1.5η(D*)H1 d<strong>at</strong>a (prel.)FFNS (CTEQ5F3)1.3 < m c < 1.7 GeV20.5 < µ / m 2c +p < 2r,ftGMVFNS (CTEQ6.5)Good agreement between D<strong>at</strong>a and NLO predictionsexcept for high p t / high η regionV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 8 / 26
Part IIBeauty ProductionV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 9 / 26
Beauty in Dijet PhP using electronsZEUSD<strong>at</strong>a: L = 120 pb −1Dijet events with E T > 7(6)GeVSemileptonic decays to electronsCombine severaldiscrimin<strong>at</strong>ing variablesin likelihood test function:◮ Electron identific<strong>at</strong>ion:dE/dx, EMC fraction, E/p◮ Decay identific<strong>at</strong>ion:∆φ and p reltN Cand51041031021010-1ZEUS 120 pbPYTHIA (scaled)b → e Xc → e XBkgZEUS-110 1 10-2 ln TV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 10 / 26
Beauty in Dijet PhP using electronsZEUS(pb/GeV)dσ b /dpe(pb/GeV)jet 1dσ b /dE T210T101011 2 3 4 5 6 7 8ep(GeV)T(pb)/dη edσ b(pb)jet 1dσ b /dη12010080604020ZEUS 120 pb -1b → e XNLO QCDPYTHIA x 1.750-1.5 -1 -0.5 0 0.5 1 1.5η e10050-1ZEUS 120 pbb → e XNLO QCDPYTHIA x 1.75Differentialcross-sections inp e T , ηe , E jet1T, ηjet1NLO prediction(FMNR)consistent withD<strong>at</strong>aScaled MCdistributionsdescribe theshape well10 15 20 25 30jet 1E T(GeV)0-1 0 1 2jet 1ηarXiv:0805.4390v3V. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 11 / 26
Beauty in Dijet Photoproduction using muonsZEUSD<strong>at</strong>a: L = 124pb −1Dijet PhP events withp jetT > 7(6)GeVSemileptonic decaysto muons◮ −1.6 < η µ < 2.3◮ pµt > 2.5(1.5)GeVSimultaneous fit ofimpact parameterand p reltmuons31021010e +Jet axis(a)p reltµp−1ZEUS 126pbbb+cc+LF MCZEUSmuonsδ < 0Beam−spot31021010δ > 0LF MCccMCbb MC(b)µ helixJet axisarXiv:0901.2226v210 1 2 3 4 5relp (GeV)T1−0.08 −0.04 0 0.04 0.08δ (cm)V. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 12 / 26
Beauty in Dijet Photoproduction using muonsZEUSTotal cross-sectionσ vis= 38.6pb±3.5(st<strong>at</strong>.) pb+4.6−4.9(syst.) pbσ NLO = 37.0 +11.9−7.5 pb(pb/GeV)dσ / dpµ10T1(a)-1ZEUS 126pbNLO QCD ⊗ hadPYTHIA MC x 1.32 3 4 5 6 7 µp8 (GeV)9 10TZEUS(pb)dσ / dηµ30252015105ZEUS 96-00 110pb(b)0-1.5 -1 -0.5 0 0.5 1µ-1ηPrevious analysis(ZEUS 96-00 110 pb −1 )with external constrainton charm!ZEUS 126 pb −1without constraint(pb/GeV)dσ /dp10110 -1µ-jT(c)10 15 20 25 30µ-jp(GeV)T(pb)µ-jdσ /dη30252015105(d)0-1.5 -1 -0.5 0 0.5 1µ-jηV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 13 / 26
Beauty in Dijet Photoproduction using muonsH1D<strong>at</strong>a: L = 170pb −1Entries610510H1 Preliminary<strong>HERA</strong> IIH1 d<strong>at</strong>a (prel.)sumbcudsDijet PhP events withp jetT > 7(6)GeVSemileptonic decays to muons◮ −0.55 < η µ < 1.1◮ pµt > 2.5 GeVSimultaneous fit ofimpact parameter and p reltEntries410-0.05 0 0.05 0.1Impact Parameter δ [cm]8000600040002000H1 Preliminary<strong>HERA</strong> IIH1 d<strong>at</strong>a (prel.)sumbcuds00 0.5 1 1.5 2 2.5 3 3.5relp [GeV]TV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 14 / 26
Beauty in Dijet Photoproduction using muonsH1[pb/GeV]dσ/dpep → ebbX → ejjµX10H1 <strong>HERA</strong> IH1 <strong>HERA</strong> II 06/07 prelim.PythiaNLO QCD × HadµTH1 Preliminary[pb]dσ/dη µ50H1 PreliminaryH1 <strong>HERA</strong> I40H1 <strong>HERA</strong> II 06/07 prelim.PythiaNLO QCD × Had3020110ep → ebbX → ejjµX4 6 8 10 12µp[GeV]T0-0.5 0 0.5 1ηµ[pb/GeV]jet1dσ/dpT101H1 Preliminaryep → ebbX → ejjµXH1 <strong>HERA</strong> IH1 <strong>HERA</strong> II 06/07 prelim.PythiaNLO QCD × Had[pb/°]jetsdσ/dδφ1H1 <strong>HERA</strong> II 06/07 prelim.PythiaH1 Preliminaryep → ebbX → ejjµXNLO QCD ×Had-11010 15 20 25jet1p[GeV]T100 120 140 160 180δφ[°]jetsGood agreement between D<strong>at</strong>a and NLO predictionsShapes well-described by Pythia MCNew measurement closer to NLO prediction than previous <strong>HERA</strong> I resultV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 15 / 26
Beauty in PhP using incl. secondary vertexingZEUSD<strong>at</strong>a: L = 128pb −1Jet axisDijet PhP events withp jetT > 7(6)GeVNo specific B decay channel→ Inclusive measurementSecondary vertexing:◮ Associ<strong>at</strong>e tracks to jets andfit secondary vertices◮ Calcul<strong>at</strong>e 2D decay length asdistance between beam spotand secondary vertex in x-y(projected onto jet axis)Projectionontojet axisDecaylengthBeam spotSecondaryvertexV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 16 / 26
Beauty in PhP using incl. secondary vertexingZEUSZEUS510m vtx < 1.4 GeV 1.4 ≤ mvtx < 2 GeV 2 ≤ mvtx < 7.5 GeV31010−110−1ZEUS (prel.) 128 pbPYTHIA (b+c+lf)PYTHIA (b)PYTHIA (c)PYTHIA (lf)0 5 10 15 0 5 10 15 0 5 10 15 20+ −S −SFit mirrored and subtracted decay length significance (S + -S − )in bins of the secondary vertex mass m vtxV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 18 / 26
Beauty in PhP using incl. secondary vertexingZEUS(pb/GeV)Jet/dP Tdσ b21010ZEUS-1ZEUS (prel.) 128 pbPYTHIA x 1.12NLO QCD ⊗ had(pb)dσ b /dη Jet400300ZEUS1200-1ZEUS (prel.) 128 pb-110100PYTHIA x 1.12NLO QCD ⊗ had10 15 20 25 30 35JetP T(GeV)0-1.5 -1 -0.5 0 0.5 1η JetDifferential cross-sections in P JetTGood agreement between D<strong>at</strong>a andPythia / NLO predictions (FMNR)and ηJetV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 19 / 26
Beauty in PhP using incl. secondary vertexingZEUSZEUS(pb)dσ b /dη Jet400300200100-1ZEUS (prel.) 128 pbZEUS 96-00PYTHIA x 1.12NLO QCD ⊗ had0-1.5 -1 -0.5 0 0.5 1η JetNew measurement in good agreement with previous <strong>HERA</strong> I resultSt<strong>at</strong>istical error substantially reducedV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 20 / 26
Beauty productionH1+ZEUS<strong>HERA</strong>dσ/dp Tb(pb/GeV)10 210110 -1H1 99-00 b jetH1 99-00 b→µ jetZEUS 96-00 b→µ jetZEUS 05 b→µ jetH1 (prel) 06/07 b→µ jetZEUS 96-97 b→eZEUS 120 pb -1 b→eH1 97-00 b→D*µZEUS 96-00 b→D*µZEUS 114 pb -1 bb→µµZEUS (prel) 128 pb -1 b jetdσ/dp bT(ep→ebX)Q 2
SummaryL<strong>at</strong>est results of heavy flavour <strong>photoproduction</strong> <strong>at</strong> <strong>HERA</strong> presented<strong>HERA</strong> II d<strong>at</strong>a provide large increase in st<strong>at</strong>isticsNew methods used and improved (lifetime tagging)First ZEUS analysis with inclusive secondary vertexing presentedVarious H1 and ZEUS measurements using different experimentaltechniques in very good agreementGeneral agreement with NLO QCD predictionsV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 22 / 26
BACKUPV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 23 / 26
Beauty in PhP - double tagZEUSD<strong>at</strong>a: Hera I (L = 114pb −1 )LO: Pythia + RapgapNLO: FMNRPhP and DISTwo identified muons in thefinal st<strong>at</strong>eExtract b fraction fromdifference between unlike-signand like-sign distributionsAdvantages:No jet requirementsLow p µ t thresholdsMeasure bb correl<strong>at</strong>ionsV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 24 / 26
Beauty in PhP - double tagZEUSMethodSample split into different charge combin<strong>at</strong>ions2 muons from same b quark→ Unlike-sign muon pair2 muons from different b quarks→ Like-sign or unlike-sign muon pairUse difference between unlike-sign and like-sign distributions toextract beauty contribution→ Almost free from false-muon background→ Other background sources: Charm, heavy vector mesons,Bethe-HeitlerV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 25 / 26
Beauty in PhP - double tagZEUSEvents250200150ZEUSZEUS 114 pb -1bb MC ψ’J/ψ, ψ’, BH MCcc MC ψ’false µ bg1005000 0.5 1 1.5 2 2.5 3µµ∆φ∆φ µµ = angle between muons from different quarksCorrel<strong>at</strong>ions expected to show higher order effects→ Good description, but large uncertaintiesV. Schönberg (Uni Bonn) <strong>Heavy</strong> <strong>Flavour</strong> PhP <strong>at</strong> <strong>HERA</strong> 17/07/2009 26 / 26
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