Jaroslav Biel čí k FNSPE, Czech Technical University in Prague
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Jaroslav Bielčík FNSPE, Czech Technical University in Prague Workshop EJFČ , Bílý Potok, January 2013 STAR heavy flavor results in view of LHC
description
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 - PowerPoint PPT Presentation
Transcript of Jaroslav Biel čí k FNSPE, Czech Technical University in Prague
Jaroslav BielčíkFNSPE, Czech Technical University in Prague
Workshop EJFČ , Bílý Potok, January 2013
STAR heavy flavor results
in view of LHC
2
Outline
• Motivation for heavy flavor physics• Open heavy flavor • Charm mesons • Non-photonic electrons
• Quarkonia• measurements
• Summary• STAR upgrades
HEP 2007 Manchester, England
3
STAR
PHENIX
PHOBOSBRAHMS
RHIC has been
exploring nuclear matter
at extreme conditions
over the last years
STAR
Relativistic Heavy Ion ColliderRHIC site in BNL on Long Island - taking data from 2000
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
p+p 900 GeV, 7 TeV (14 TeV ) Pb+Pb 2.76 TeV (5.5 TeV)p+Pb 2013 now
Heavy ion experiments:ALICEATLAS + CMS hardprobes
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
)(Yield
)(Yield)(
ppAA
AAAA
T
TT pNbin
ppR
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 extract properties of the medium.
• Studying the quarkonia suppression
deconfinement
light
M.Djordjevic PRL 94 (2004)
ENERGY LOSS
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Quarkonia states in A+ACharmonia: J/, ’, c Bottomonia: (1S), (2S), (3S)
Key Idea: Quarkonia melt in 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
H. Satz, HP2006
When do states really melt?Tdiss(’) Tdiss(c)< Tdiss((3S)) < Tdiss(J/) Tdiss((2S)) < Tdiss((1S))
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Large acceptance
||<1, 0<<2
STAR detector and Particle ID
Time Projection Chamber
dE/dx, momentum
Time Of Flight detector particle velocity 1/lectroMagnetical Calorimeter
E/p, single tower/topological Trigger
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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 × pp
F = 4.7 ± 0.7 scale to full rapidity.
pp(NSD) = 30 mb
arXiv: 1204.4244 Phys. Rev. D 86 (2012)
• Consistent with FONLL upper limit• p+p 500 GeV similarly consistent with upper limit
ALICE charm measurements
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• Using secondary vertex detectors
• Excellent capability to measure wide pT
spectrum on many charm mesons + c
ALICE SQM2011
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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
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D0 spectra in Au+Au 200 GeV
Suppression at high pT in central and mid-central collisions.
Enhancement at intermediate pT, radial flow of light quarks coalescence with charm.
He,Fries,Rapp: PRC86,014903; arXiv:1204.4442; private comm.P. Gossiaux: arXiv: 1207.5445
Charm cross section versus Nbin at 200 GeV
Charm cross section follows number of binary collisions scaling =>Charm quarks are mostly produced via initial hard scatterings.
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:
[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.
STAR Preliminary
Low pT consistent with unity.High pT suppressed in most central collisions
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Prompt D meson RAA
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• 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
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• Little shadowing at high pT suppression is a hot matter effect• Similar suppression for D mesons and pions
– Hint of RAAD > RAA
π at low pT
– CMS measurement of displaced J/ (from B feeddown) indicate RAAB > RAA
D
Charm suppression at LHC
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D mesons (D0,D+,D*) extended atlow and high pT•Charm suppression up factor 5!•Strong suppression even at 30 GeV/cFirst Ds measurement Same suppression at high pT Low pT: suggestive of strangenessenhancement? HF-decay electrons up to 18 GeV/c Consistent with D mesons (consideringthat pT e~ 1/2 pT B) Doesn’t imply a difference D vs BHF-decay muons at forward rapidity Similar suppression as at central y
Charm x Beauty CMS
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Better 2011 statistics shows afirst indication of RAAB>RAAD Warning: pT range not the same! Only in central collisions?
Measurement of non-photonic electrons
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Background Dominated by Photonic Electrons from :
ee
ee
0
Same for All Experiments
ee )(0
•Mostly from •Conversion probability: 7/9* X0
Depend on Experiment
When X0 is large, gamma conversion dominate all the background.
These background has to be properly subtracted
Still mixture of B,D origin
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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:1207.6020T-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.
Extraction of the contribution from beauty hadron decays ALICE
Selection of tracks with a large radial distance to the primary vertex arXiv:1208.1902
c of •b: 500 m•c: 100 -300 m
Nuclear modification factor ALICE
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The nuclear modification factor is defined as
RAA 1
TAA
dNPbPb /dpT
dpp /dpT
• <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
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Electrons from heavy-flavour hadron decays are suppressed at high pT
Comparison to models
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BAMPS: arXiv:1205.4945 Rapp et al: arXiv:1208.0256 POWLANG: arXiv:1208.0705
• Rapp et al. and POWLANG describe the RAA but underpredict elliptic flow• BAMPS describes elliptic flow but slightly underpredicts the RAA
Charm flow
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Open charm hadrons exhibit a significantelliptic flow-> they may take part in collectiveexpansion of the QGP
Hint / NoHint for a finite J/ψ v2observed at LHC / RHIC-> consistent with re-generationscenario ?
QUARKONIA e+e-
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(2S+3S) vs. (1S) in PbPb
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PR
L 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
Summary• Heavy flavor is an important tool to understand medium properties.• Results are interesting and challenging. charm measurement
- FONLL QCD describes the data rather well.-Hint of diferent suppresion of heavy mesons and hadrons at LHC
charm flow•LHC significant flow of NPE, D•J/psi RHIC flow consistent with zero•J/psi LHC some flow
•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
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
11/17/2011 32
STAR-MTD physics motivation
The large area of muon telescope detector (MTD) at mid-rapidity allows for the detection of
• di-muon pairs from QGP thermal radiation, quarkonia, light vector mesons, resonances in QGP, and Drell-Yan production
• single muons from the semi-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 detector with long-MRPCs covers thewhole iron bars and leaves the gaps in-between uncovered. Acceptance: 45% at ||<0.5
118 modules, 1416 readout strips, 2832 readoutchannels
Long-MRPC detector technology, electronicssame as used in STAR-TOF
MTD
Quarkonium from MTD
1. J/: S/B=6 in d+Au and S/B=2 in central Au+Au collisions
2. Excellent mass resolution: separate different upsilon states
3. With HFT, study BJ/ X; J/ using displaced vertices
Heavy flavor collectivity and colorscreening, 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
15 -Nov-12
Heavy Flavor Tracker (HFT)
TPC Volume
Outer Field Cage
Inner Field Cage
FGT
SSDIST
PXL
HFT DetectorRadius
(cm)
Hit Resolution R/ - Z (m -
m)
Radiation length
SSD 22 20 / 740 1% X0
IST 14 170 / 1800 <1.5 %X0
PIXEL8 12/ 12 ~0.4 %X0
2.5 12 / 12 ~0.4% X0
SSD•existing single layer detector, double side strips
IST one layer of silicon strips along beam direction, guiding tracks from the SSD through PIXEL detector. - proven strip technology
PIXEL •two layers•18.4x18.4 m pixel pitch •10 sector, delivering ultimate pointing resolution that allows for direct topological identification of charm. •new monolithic active pixel sensors (MAPS) technology
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
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Physics – Run-14,15 projections
RCP=a*N10%/N(60-80)%
Assuming D0 v2 distribution from quark coalescence.
500M Au+Au m.b. events at 200 GeV.
- Charm v2 Medium thermalization degreeDrag coefficients!
Assuming D0 Rcp distribution as charged hadron.
500M Au+Au m.b. events at 200 GeV.
- Charm RAA Energy loss mechanism!Color charge effect!Interaction with QCD matter!
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Access bottom production via electronsAccess bottom production via electrons
particle
c (m)
Mass
qc,b →x
(F.R.)
x →e (B.R.)
D0 123 1.865
0.54 0.0671
D± 312 1.869
0.21 0.172
B0 459 5.279
0.40 0.104
B 491 5.279
0.40 0.109
Two approaches: Statistical fit with model assumptions
Large systematic uncertainties With known charm hadron spectrum to constrain or be used in subtraction
4015 -Nov-12 F.Videbæk / BNL
Statistic projection of eStatistic projection of eDD, e, eBB R RCPCP & v & v22
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?
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B tagged J/psiB tagged J/psi
Prompt
J/ from B
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
STAR Preliminary
Zebo Tang, NPA 00 (2010) 1.
HFT project statusHFT 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
15 -Nov-12
SummarySummary II 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
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STAR preliminary STAR preliminary
right sign : 1.83<M(K)<1.9 GeV/c2
wrong sign : K- + K+side band : 1.7<M(K)<1.8 +
1.92<M(K)<2 GeV/c2
STAR preliminary
D0 and D* signal in p+p 500 GeV
K2*(1430)
• Consistent results from two background methods.
K*0
D0
• Minimum bias 1.53 nb-1
STAR preliminary
45STAR analysis meeting, UCLA,
November 2012David Tlusty (NPI Prague)
D0 and D* pT spectra in p+p 500 GeV
[1] C. Amsler et al. (Particle Data Group), PLB 667 (2008) 1.
[2] FONLL calculation: Ramona Vogt µF = µR = mc, |y| < 1
STAR preliminary
D0 yield scaled by ND0/Ncc= 0.565[1]
D* yield scaled by ND*/Ncc= 0.224[1]
46STAR analysis meeting, UCLA,
November 2012
David Tlusty (NPI Prague)
47
Future of Heavy Flavor Measurement at STAR
MTD (MRPC)
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Upsilon in p+p 200GeV
)()(38114 2324
0
sysstatdy
dB
y
ee
pb
PRD 82 (2010) 12004
PRD 82 (2010) 012004
49
Upsilon in d+Au 200GeV
)(5)(4350
sysstatdy
dB
y
ee
nb
)(2.0)(3.08.0 sysstatRdAu
NPA830(2009)235c
NPA830(2009)235c
• 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
Rosi Reed - Quarkmatter 201150
CentralMid-CentralPeripheral
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STAR with HFT
Yifei Zhang LBNL5252
D* reconstruction
Background combinations:Wrong sign:D0 and -, D0bar and +
Side band:1.72< M(K) < 1.80 or1.92 < M(K) < 2.0 GeV/c2
All triggers included.More than 4 signal at low pT and very significant at high pT - mostly from EMC-based high neutral energy triggers.
• Production mechanism is not clear• Observed J/ is a mixture of direct production + feeddown
– All J/ ~ 0.6 J/ (Direct) + ~0.3 c + ~0.1’
• Suppression and enhancement in the “cold” nuclear medium– Nuclear Absorption, Gluon shadowing, initial state energy loss,
Cronin effect and gluon saturation
• Hot/dense medium effect – J/, dissociation, i.e. suppression– Recombination from uncorrelated charm pairs
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Charmonia in nuclear matter
H. Satz, Nucl. Phys. A (783):249-260(2007)
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0D
D0
K+
l
K-
e-/-
e-/-
e+/+
Heavy quarkonia
Open heavy flavor
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• Higher c and b cross sections: – More abundant heavy
flavour production– Better precision (reduced
errors)
• High precision vertex detectors– Background removal– Separate c and b
What can we learn at the LHC
bbRHIC
bbLHC
ccRHIC
ccLHC
100
10
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High T: the potential between the quarks is modified.
• Charmonium suppression: longstanding QGP signature– Original idea: High T leads
to Debye screening– Screening prevents heavy
quark bound states from forming!
– J/suppression: • Matsui and Satz, Phys. Lett. B
178 (1986) 416
– lattice calculations confirm screening effects
• Nucl.Phys.Proc.Suppl.129:560-562,2004
O. Kaczmarek, et al.,Nucl.Phys.Proc.Suppl.129:560-562,2004
J/ in Pb+Pb at 2.76 TeV
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First time that the prompt and non-prompt J/′sare separated in heavy-ion collisions90±13 [B → J/] events for pT
J/ > 6.5 GeV/c
Excellent mass resolution of ~1%,comparable to pp
= 34 MeV
396±24 J/(6.5 < pT < 30 GeV/c)
HIN-10-006
The proton-proton reference
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Large uncertainties Use FONLL-scaled spectrum at 7 TeV
Electrons from heavy-flavour hadron decays studied in pp collisions at 2.76 TeV
60Beauty production described very well by central value ofcalculation
MB
7.8fm
7.8fm
MB
20-40%
20-60%7.8fm
J/ elliptic flow v2
STAR Preliminary
• Consistent with zero, first hadron that does not flow• Disfavor coalescence from thermalized charm quarks at high pT.
[1] V. Greco, C.M. Ko, R. Rapp, PLB 595, 202.[2] L. Ravagli, R. Rapp, PLB 655, 126.[3] L. Yan, P. Zhuang, N. Xu, PRL 97, 232301.[4] X. Zhao, R. Rapp, 24th WWND, 2008.[5] Y. Liu, N. Xu, P. Zhuang, Nucl. Phy. A, 834, 317.[6] U. Heinz, C. Shen, priviate communication.
STAR QM2011
