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STAR heavy flavor results in view of LHC. Jaroslav Biel čí k FNSPE, Czech Technical University in Prague. Workshop EJFČ , Bílý Potok , January 201 3. Outline. Motivation for heavy flavor physics Open heavy flavor Charm mesons Non-photonic electrons Quarkonia

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Jaroslav Biel čí k FNSPE, Czech Technical University in Prague


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    1. STAR heavy flavor results in view of LHC Jaroslav Bielčík FNSPE, Czech Technical University in Prague Workshop EJFČ , Bílý Potok, January 2013

    2. Outline • Motivation for heavy flavor physics • Open heavy flavor • Charm mesons • Non-photonic electrons • Quarkonia •  measurements • Summary • STAR upgrades jaroslav.bielcik@fjfi.cvut.cz

    3. BRAHMS PHOBOS PHENIX STAR Relativistic Heavy Ion Collider RHIC site in BNL on Long Island - taking data from 2000 RHIC has been exploring nuclear matter at extreme conditions over the last years Lattice QCD predicts a phase transition from hadronic matter to a deconfined state, the Quark-Gluon Plasma Colliding systems: p+p, d+Au, Cu+Cu, Au+Au Cu+Au, U+U Energies √sNN = 20, 62, 130, 200 GeV (500 GeV) + 7.7, 11.5, 27, 39 GeV STAR HEP 2007 Manchester, England

    4. Heavy ion experiments: ALICE ATLAS + CMS hardprobes p+p 900 GeV, 7 TeV (14 TeV ) Pb+Pb 2.76 TeV (5.5 TeV) p+Pb 2013 now

    5. Nuclear modification factor • Hard probes - produced in hard scatterings in initial phase of collision • Nuclear matter influences the final particle production • e.g. production of particles at given pT • supresion of particle production of particular type • Nuclear modification factor - quantification of nuclear effects RAA jaroslav.bielcik@fjfi.cvut.cz

    6. light ENERGY LOSS M.Djordjevic PRL 94 (2004) Heavy quarks as a probe of QGP • p+p data:  baseline of heavy ion measurements.  test of pQCD calculations. • Due to their large mass heavy quarks are primarily produced by gluon fusion in early stage of collision.  production rates calculable by pQCD.M. Gyulassy and Z. Lin, PRC 51, 2177 (1995) • heavy ion data: • Studying energy loss of heavy quarks.  independent way to extractproperties of the medium. • Studying the quarkonia suppression •  deconfinement jaroslav.bielcik@fjfi.cvut.cz

    7. Quarkonia states in A+A Charmonia: J/y, Y’, ccBottomonia: (1S), (2S), (3S) Key Idea: Quarkonia meltin the QG plasma due to color screening of potential between heavy quarks • Suppression of states is determined by TC and their binding energy • Lattice QCD: Evaluation of spectral functions  Tmelting • Sequential disappearance of states: •  Color screening  Deconfinement •  QCD thermometer  Properties of QGP When do states really melt? Tdiss(y’)  Tdiss(cc)< Tdiss((3S)) < Tdiss(J/y)  Tdiss((2S)) < Tdiss((1S)) H. Satz, HP2006

    8. STAR detector and Particle ID Large acceptance |h|<1, 0<f<2p • Time Projection Chamber • dE/dx, momentum • Time Of Flight detector • particle velocity 1/b • ElectroMagneticalCalorimeter • E/p, single tower/topological Trigger 8

    9. Open heavy flavor jaroslav.bielcik@fjfi.cvut.cz

    10. D0 and D* pT spectra in p+p 200 GeV D0 scaled by Ncc /ND0 = 1 / 0.56 D* scaled by Ncc /ND* = 1 / 0.22 Xsec = dN/dy|ccy=0 × F × spp F = 4.7 ± 0.7 scale to full rapidity. spp(NSD) = 30 mb • Consistent with FONLL upper limit • p+p 500 GeV similarly consistent • with upper limit arXiv: 1204.4244 Phys. Rev. D 86 (2012) jaroslav.bielcik@fjfi.cvut.cz 10

    11. ALICE charm measurements ALICE SQM2011 • Using secondary vertex detectors • Excellent capability to measure wide pT • spectrum on many charm mesons + Lc

    12. Comparison to pQCD • Data compatible with pQCD prediction within uncertainties • As observed at lower energies, data are on the upper edge of FONLL uncertainty band

    13. D0 spectra in Au+Au 200 GeV He,Fries,Rapp: PRC86,014903; arXiv:1204.4442; private comm. P. Gossiaux: arXiv: 1207.5445 • Suppression at high pT in central and mid-central collisions. • Enhancement at intermediate pT, radial flow of light quarks coalescence with charm. 13

    14. Charm cross section versus Nbin at 200 GeV Year 2003 d+Au 16M : D0 + e Year 2009 p+p 105M : D0 + D* Year 2010 + 2011 Au+Au 800M : D0 Assuming ND0 /Ncc = 0.56 does not change for total cross section. The charm cross section at mid-rapidity: The total charm cross section: STAR Preliminary Low pT consistent with unity. High pT suppressed in most central collisions [1] STAR d+Au: J. Adams, et al., PRL 94 (2005) 62301 [2] FONLL: M. Cacciari, PRL 95 (2005) 122001. [3] NLO:  R. Vogt, Eur.Phys.J.ST 155 (2008) 213    [4] PHENIX e: A. Adare, et al., PRL 97 (2006) 252002. Charm cross section follows number of binary collisions scaling => Charm quarks are mostly produced via initial hard scatterings.

    15. Prompt D meson RAA • Suppression of prompt D mesons in central (0-20%) Pb+Pb collisions by a factor 3-4 for pT>5 GeV/c • Smaller suppression for peripheral events

    16. Prompt D meson RAA • Little shadowing at high pT suppression is a hot matter effect • Similar suppression for D mesons and pions • Hint of RAAD > RAAπ at low pT • CMS measurement of displaced J/y (from B feeddown) indicate RAAB> RAAD

    17. Charm suppression at LHC • D mesons (D0,D+,D*) extended at • low and high pT • Charm suppression up factor 5! • Strong suppression even at 30 GeV/c • First Ds measurement • Same suppression at high pT • Low pT: suggestive of strangeness • enhancement? • HF-decay electrons up to 18 GeV/c • Consistent with D mesons (considering • that pT e~ 1/2 pT B) • Doesn’t imply a difference D vs B • HF-decay muons at forward rapidity • Similar suppression as at central y

    18. Charm x Beauty CMS Better 2011 statistics shows a first indication of RAAB>RAAD Warning: pT range not the same! Only in central collisions?

    19. Measurement of non-photonic electrons Background Dominated by Photonic Electrons from : Same for All Experiments Depend on Experiment • Mostly from • Conversion probability: 7/9* X0 When X0 islarge, gamma conversion dominate all the background. These background has to be properly subtracted Still mixture of B,D origin

    20. Non-photonic electron RAA in Au+Au 200 GeV • Strong suppression at high pT in central collisions • D0, NPE results seems to be consistent  kinematics smearing & charm/bottom mixing • Models with radiative energy loss underestimate the suppression • Uncertainty dominated by p+p result. • Compare with Au+Au spectra directly, if possible. • High quality p+p data from Run09 and Run12 are on disk. DGLV: Djordjevic, PLB632, 81 (2006) CUJET: Buzzatti, arXiv:1207.6020 T-Matrix: Van Hees et al., PRL100,192301(2008). Coll. Dissoc. R. Sharma et al., PRC 80, 054902(2009). Ads/CFT: W. Horowitz Ph.D thesis. 20

    21. Extraction of the contribution from beauty hadron decays ALICE • c of • b:  500 m • c:  100 -300 m Selection of tracks with a large radial distance to the primary vertex arXiv:1208.1902

    22. Nuclear modification factor ALICE The nuclear modification factor is defined as • <TAA>: Nuclear overlap • dNPbPb/dpT: Measurement in PbPb • dσpp/dpT: Reference from pp collisions at the same energy

    23. Nuclear modification factor in central Pb-Pb collisions Electrons from heavy-flavour hadron decays are suppressed at high pT

    24. Comparison to models • Rapp et al. and POWLANG describe the RAA but underpredict elliptic flow • BAMPS describes elliptic flow but slightly underpredicts the RAA BAMPS: arXiv:1205.4945 Rapp et al: arXiv:1208.0256 POWLANG: arXiv:1208.0705

    25. Charm flow Open charm hadrons exhibit a significant elliptic flow -> they may take part in collective expansion of the QGP Hint / NoHint for a finite J/ψ v2 observed at LHC / RHIC -> consistent with re-generation scenario ?

    26. QUARKONIA U -> e+e-

    27. (2S+3S) vs. (1S) in PbPb PRL 107, 052302 (2011) • Fraction of excited states (2S+3S) relative to (1S) • Core Gaussian with power-law tail of EM final state radiation • Resolutions and efficiencies fixed by MC • Peak separation fixed to the PDG values • Background as a second-order polynomial

    28. Upsilon suppression Upsilon suppression (CMS): jaroslav.bielcik@fjfi.cvut.cz

    29. Summary • Heavy flavor is an important tool to understand medium properties. • Results are interesting and challenging. charm measurement - FONLL QCD describesthe data ratherwell. • Hintofdiferentsuppresionofheavymesons and hadronsatLHC charm flow • LHC significant flow of NPE, D • J/psi RHIC flow consistent with zero • J/psi LHC some flow U • Suppression of Y(1S+2S+3S) in central Au+Au observed. • Suppression of Y(1S) in CMS Pb+Pb observed • LHC recent results are inspiration x STAR will cover them with HFT+ MTD jaroslav.bielcik@fjfi.cvut.cz

    30. STAR Heavy flavor upgrades jaroslav.bielcik@fjfi.cvut.cz

    31. STAR near term upgrades • Muon Telescope Detector (MTD) • Accessing muons at mid-rapidity • R&D since 2007, construction since 2010 • Significant contributions from China & India • Heavy Flavor Tracker (HFT) • Precision vertex detector • Ongoing DOE MIE since 2010 • Significant sensor development by IPHC, Strasbourg

    32. STAR-MTD physics motivation • The large area of muon telescope detector (MTD) at mid-rapidity allows forthe detection of • di-muon pairs from QGP thermal radiation,quarkonia, light vector mesons, resonances in QGP, and Drell-Yan production • single muons from thesemi-leptonic decays of heavy flavor • hadrons • advantages over electrons: no  conversion, much less Dalitz decay contribution, less affected by radiative losses in the detector materials, trigger capability in Au+Au collisions • trigger capability for low to high pT J/ in central Au+Au collisions and • excellent mass resolution allow separation of different upsilon states • e-muon correlation can distinguish heavy flavor production from initial lepton pair production

    33. Concept of design of the STAR-MTD Multi-gap Resistive Plate Chamber (MRPC): gas detector, avalanche mode A detectorwith long-MRPCs covers the whole iron bars and leavesthe gaps in- between uncovered. Acceptance: 45% at ||<0.5 118 modules, 1416 readout strips, 2832 readout channels Long-MRPC detector technology, electronics same as used in STAR-TOF MTD

    34. Quarkonium from MTD • J/: S/B=6 in d+Au and S/B=2 in central Au+Au collisions • Excellent mass resolution: separate different upsilon states • With HFT, study BJ/ X; J/ using displaced vertices • Heavy flavor collectivity and color • screening, quarkonia production • mechanisms: • J/ RAA and v2; upsilon RAA … Z. Xu, BNL LDRD 07-007; L. Ruan et al., Journal of Physics G: Nucl. Part. Phys. 36 (2009) 095001

    35. Measure charm correlation with MTD upgrade: ccbare+ An unknown contribution to di-electron mass spectrum is from ccbar, which can be disentangled by measurements of e correlation. Simulation with Muon Telescope Detector (MTD) at STAR from ccbar: S/B=2 (Meu>3 GeV/c2 and pT(e)<2 GeV/c) S/B=8 with electron pairing and tof association

    36. Heavy Flavor Tracker (HFT) HFT SSD IST PXL Inner Field Cage • PIXEL • two layers • 18.4x18.4 m pixel pitch • 10 sector, delivering ultimate pointing resolutionthat allows for direct topological identification of charm. • new monolithic active pixel sensors (MAPS) technology Magnet Return Iron FGT Outer Field Cage • SSD • existing single layer detector, double side strips • ISTone layer of silicon strips along beam direction, guiding tracks from the SSD through PIXEL detector. - proven strip technology TPC Volume Solenoid EAST WEST

    37. Physics of the Heavy Flavor Tracker at STAR 1) Direct HF hadron measurements (p+p and Au+Au) (1) Heavy-quark cross sections: D0±*, DS, ΛC , B… (2) Both spectra (RAA, RCP) and v2 in a wide pT region: 0.5 - 10 GeV/c (3) Charm hadron correlation functions, heavy flavor jets (4) Full spectrum of the heavy quark hadron decay electrons 2) Physics (1) Measure heavy-quark hadron v2, heavy-quark collectivity, to study the medium properties e.g. light-quark thermalization (2) Measure heavy-quark energy loss to study pQCD in hot/dense medium e.g. energy loss mechanism (3) Measure di-leptons to study the direct radiation from the hot/dense medium (4) Analyze hadro-chemistry including heavy flavors

    38. Physics – Run-14,15 projections RCP=a*N10%/N(60-80)% • Assuming D0 Rcp distribution as charged hadron. • 500M Au+Aum.b. events at 200 GeV. • Charm RAA • Energy loss mechanism! • Color charge effect! • Interaction with QCD matter! Assuming D0 v2 distribution from quark coalescence. 500M Au+Aum.b. events at 200 GeV. - Charm v2  Medium thermalization degree Drag coefficients! 38

    39. Access bottom production via electrons • Two approaches: • Statistical fit with model assumptions • Large systematic uncertainties • With known charm hadron spectrum to constrain or be used in subtraction 39

    40. F.Videbæk / BNL Statistic projection of eD, eB RCP & v2 Curves:  H. van Hees et al. Eur. Phys. J. C61, 799(2009). • (Be) spectra obtained via the subtraction of charm decay electrons from inclusive NPEs: • - no model dependence, reduced systematic errors. • Unique opportunity for bottom e-loss and flow. • - Charm may not be heavy enough at RHIC, but how is bottom? 40

    41. B tagged J/psi Zebo Tang, NPA 00 (2010) 1. STAR Preliminary Prompt • Current measurement via J/-hadron correlation with large uncertainties. • Combine HFT+MTD in di-muon channel • Separate secondary J/psi from promptJ/psi • Constrain the bottom production at RHIC J/ from B 41

    42. HFT project status • HFT upgrade was approved CD2/3 October 2011 and is well into fabrication phase. • All detector components have passed the prototype phase successfully. • A PXL prototype with 3+ sectors instrumented is planned for an engineering run and data taking in STAR in early 2013. • The full assembly including PXL, IST and SSD should be available for RHIC Run-14, which is planned to be a long Au-Au run

    43. Summary II • Initial heavy flavor measurements have been performed by STAR. • Further high precision measurements are needed. • HFT upgrades will provide direct topological reconstruction for charm. • MTD will provide precision Heavy Flavor measurements in muon channels.

    44. Politováníhodný je člověk, který s nejušlechtilejšími ze všech nástrojů, vědou a uměním, neusiluje o nic vyššího a k vyššímu nesměřuje než námezdná síla s nástrojem nejnižším! Protože v říši naprosté svobody v sobě nosí duši otroka! Friedrich Schiller 1789 jaroslav.bielcik@fjfi.cvut.cz

    45. STAR preliminary STAR preliminary STAR preliminary STAR preliminary right sign :1.83<M(Kp)<1.9 GeV/c2 wrong sign : K-p+p-+ K+p-p+ side band : 1.7<M(Kp)<1.8 + 1.92<M(Kp)<2 GeV/c2 D0 and D* signal in p+p 500 GeV K2*(1430) K*0 D0 • Minimum bias 1.53 nb-1 • Consistent results from two background methods. 45 David Tlusty (NPI Prague) STAR analysis meeting, UCLA, November 2012

    46. STAR preliminary D0 and D* pT spectra in p+p 500 GeV D0 yield scaled by ND0/Ncc= 0.565[1] D* yield scaled by ND*/Ncc= 0.224[1] [1] C. Amsler et al. (Particle Data Group), PLB 667 (2008) 1. [2] FONLL calculation: Ramona Vogt µF = µR = mc, |y| < 1 David Tlusty (NPI Prague) STAR analysis meeting, UCLA, November 2012 46

    47. Future of Heavy Flavor Measurement at STAR MTD (MRPC)

    48. PRD 82 (2010) 012004 Upsilon in p+p 200GeV PRD 82 (2010) 12004 pb

    49. Upsilon in d+Au 200GeV NPA830(2009)235c NPA830(2009)235c nb • Consistent with Nbin scaling of cross-section p+p - d+Au 200GeV

    50.  Yield by centrality • System uncertainties • p+p luminosity and bbc trigger efficiency •  Line-shape • Drell-Yan and bb background Peripheral Mid-Central Central Rosi Reed - Quarkmatter 2011