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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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STAR heavy flavor results in view of LHC Jaroslav Bielčík FNSPE, Czech Technical University in Prague Workshop EJFČ , Bílý Potok, January 2013
Outline • Motivation for heavy flavor physics • Open heavy flavor • Charm mesons • Non-photonic electrons • Quarkonia • measurements • Summary • STAR upgrades firstname.lastname@example.org
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
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
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 email@example.com
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 firstname.lastname@example.org
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
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
Open heavy flavor email@example.com
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) firstname.lastname@example.org 10
ALICE charm measurements ALICE SQM2011 • Using secondary vertex detectors • Excellent capability to measure wide pT • spectrum on many charm mesons + Lc
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
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
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  STAR d+Au: J. Adams, et al., PRL 94 (2005) 62301  FONLL: M. Cacciari, PRL 95 (2005) 122001.  NLO: R. Vogt, Eur.Phys.J.ST 155 (2008) 213  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.
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
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
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
Charm x Beauty CMS Better 2011 statistics shows a first indication of RAAB>RAAD Warning: pT range not the same! Only in central collisions?
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
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
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
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
Nuclear modification factor in central Pb-Pb collisions Electrons from heavy-flavour hadron decays are suppressed at high pT
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
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 ?
QUARKONIA U -> e+e-
(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
Upsilon suppression Upsilon suppression (CMS): email@example.com
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 firstname.lastname@example.org
STAR Heavy flavor upgrades email@example.com
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
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
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
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 BJ/ 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
Measure charm correlation with MTD upgrade: ccbare+ 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
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
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
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
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
F.Videbæk / BNL Statistic projection of eD, eB RCP & v2 Curves: H. van Hees et al. Eur. Phys. J. C61, 799(2009). • (Be) 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
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
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
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.
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 firstname.lastname@example.org
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
STAR preliminary D0 and D* pT spectra in p+p 500 GeV D0 yield scaled by ND0/Ncc= 0.565 D* yield scaled by ND*/Ncc= 0.224  C. Amsler et al. (Particle Data Group), PLB 667 (2008) 1.  FONLL calculation: Ramona Vogt µF = µR = mc, |y| < 1 David Tlusty (NPI Prague) STAR analysis meeting, UCLA, November 2012 46
Future of Heavy Flavor Measurement at STAR MTD (MRPC)
PRD 82 (2010) 012004 Upsilon in p+p 200GeV PRD 82 (2010) 12004 pb
Upsilon in d+Au 200GeV NPA830(2009)235c NPA830(2009)235c nb • Consistent with Nbin scaling of cross-section p+p - d+Au 200GeV
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