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 Johanna Stachel Probing the Quark-Gluon Plasma with hard probes at the LHC J. Stachel – Physikalisches Institut der Universität Heidelberg ESQGP – 'Edward Shuryak Quark Gluon Plasma' Workshop Stony Brook   October2, 2008  
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Page 1: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

Probing the Quark­Gluon Plasma with hard probes at the LHC

J. Stachel – Physikalisches Institut der Universität HeidelbergESQGP – 'Edward Shuryak Quark Gluon Plasma' Workshop

Stony Brook   October2, 2008

 

Page 2: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Johanna Stachel

expected initial conditions in central nuclear collisions at LHC

hep­ph/0506049

initial conditions from pQCD+saturation of produced gluons

using pQCD cross sections find for central PbPb at LHC p0 = psat = 2 GeVand a formation time of0=1/psat=0.1 fm/cand with Bjorken formula:   w.  Jacobian ddz=1/

K. Eskola et al., hep­ph/0506049

as compared to RHIC: more than order of magnitude increase in intial energy density

initial temperature T0 1 TeV (factor 2­3 above RHIC)

 LHC

 RHIC

²0 = dEt=d´=(¿0¼R2)

depending on evolution of  saturation scaleget dN

ch/d = 1000 – 2500

Page 3: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

the challenge: identification and reconstruction of 5000 (up to 15000) tracks of charged particles

cut through the centralbarrel of ALICE:

tracks of charged particles  in a 1 degree segment

  (1% of tracks)

  ALICE is dedicated experiment to study all aspects of      heavy ion collisions at LHC   detector is starting operation after more than 10 years    

   of hard work and many novel developments

Page 4: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

1. high pt partons as probe of the medium, i.e. the QGP

prediction: in dense partonic matter a jet is losing energy rapidly                  order several GeV/fm

Page 5: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Johanna Stachel

RHIC result: jet quenching

high gluon densityof the plasma

induces energyloss of partons

most calculations based on radiation

RAA=yield(AuAu)/Ncoll yield(pp)

new run 4 data

Page 6: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

2000-350018-23190-400710-8500.2 LHC

800-12006-714-20380-4000.6 RHIC

200-3501.4-21.5-2.5210-2400.8 SPS0[ ]fmτ [ ]T MeV [ ]tot fmτ3[ / ]GeV fmε /gdN dy

•Consistent estimate with hydrodynamic analysis

 jet quenching indicative of high gluon rapidity density

I. Vitev, JPG 30 (2004)  S791 

several mechanisms describe jet quenching at RHIC ­> predictions for LHC span very wide range ­ RAA stays at 0.2 out to 100 GeV or so  ­ RAA rises slowly toward high pt ­ RAA much smaller than at RHIC  need to cover large pt rangego beyond leading particle analysis identified jets, frag.  function, ...

Page 7: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Johanna Stachel

Renk and Eskola, expanding QGP  BDMPS energy loss;    midrapidity at LHC

LHC: increase in gluon density and very high jet energy reach   to pin down energy loss mechanism 

Wicks and Gyulassy, sensitivity to gluon dens.and E­loss mechanism

Page 8: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Johanna Stachel

jet measurements in ALICE

  2 GeV        20 GeV  100 GeV                   200 GeV

Mini­Jets 100/event      1/event          1 Hz                   100k/month

 at p > 2 GeV/c :­ leading particle analysis­ correlation studies (similar to RHIC)

at high p: ­ reconstructed jets­ event­by­event well  distinguishable objects 

Example :100 GeV jet +underlying event

  for jet physics recently added EmCal  will play important role in conjunction  with existing charged particle tracking

Page 9: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Johanna Stachel

reconstructed jet energy spectrum

5 108 pp events, unfolded for detectors response and cuts

Ch. Klein­Boesing

Page 10: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

reconstruction of jets in PbPb collisions

Ch. Klein­Boesing

statistics corresponding to 1 month of PbPb runningcharged jets: reconstruct 33% of energycharged + EMCal: 68%

Page 11: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Johanna Stachel

measurement of jet fragmentation function

N. Borghini, U. Wiedemann

Increase on # of particles with low z

Decrease on # of particles with high z

z: energy fraction carried by leading hadron  ­  sensitive to energy loss mechanism

good reconstruction in ALICE

 = ln(1/z)

 = ln(1/z)

1%13 %

Page 12: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Johanna Stachel

even more sensitivity with identified hadrons from jet

Page 13: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

2. Charmonia as signature for deconfinement

 T. Matsui and H. Satz (PLB178 (1986) 416) predict J/ suppression in QGP due to                Debye screening

 significant suppression seen in central PbPb at top SPS energy (NA50)in line with QGP expectations

 

Page 14: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

 but prediction: at hadronization of QGP J/ can form again         from deconfined quarks,       in particular if number of       ccbar  pairs is large     NJ/N

cc2

  (P. Braun­Munzinger and J.Stachel, PLB490 (2000) 196)

PRL 98 (2007) 232301

J/  production  in AuAu collisions  at RHIC

at mid­rapidity suppression at RHIC very similar to SPSsuppression at forward/backward rapidity stronger!

RAA: J/ yield in AuAu / J/ yield in pp times Ncoll

Page 15: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Johanna Stachel

low energy: few c­quarks per collision  →  suppression of J/high energy: many     “              “           → enhancement     “                                                                  unambiguous signature for QGP!

what happens at higher beam energy when more and more charm­anticharm quark pairs are produced?

Page 16: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

but there is a more revealing normalization:

RAA: J/ yield in AuAu / J/ yield in pp times Ncoll

quantitative agreement!

data:  PHENIX nucl­ex/0611020         additional 14% syst error beyond shown

  remark: y­dep opposite in      'normal Debye screening'      picture; suppression               strongest at midrapidity         (largest density of color          charges)

model: A. Andronic, P. Braun­Munzinger, K. Redlich,               J. Stachel  Phys. Lett. B652 (2007) 259  

Page 17: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

energy dependence of quarkonium production in statistical hadronization model

centrality dependence and enhancement beyond pp value will be fingerprint of statistical hadronization at LHC­> direct signal for deconfinement

A. Andronic, P. Braun­Munzinger, K. Redlich, J. Stachel  Phys. Lett. B652 (2007) 259  

Page 18: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

predictions for charmonium rapidity and centrality distributions at LHC

centralbarrel muon

arm

ALICE

yellow band: uncertainty of pQCD prediction for ccbar prod.     line: central value

Page 19: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

measurement of charmonia in ALICE at mid­rapidity

electron identification with TPC and TRD

Good mass resolution and signal to backgroundexpect w full TRD and trigger2500 Upsilon per PbPb year

 Simulation: W. Sommer (Frankfurt)  2∙108 central PbPb coll.

J/ ee

Page 20: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

full simulation of central barrel performance

D. Krumbhorn, Heidelberg

Page 21: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

Charmonia in the di­muon channel at y=2.4­4.0

700 000 J/psi and 6800 Upsilon for 2 108 PbPb collisions (1 month)

resolution 74 MeV resolution 109 MeV

Page 22: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

flow of quarkonia at LHC?

there is evidence from RHIC that fireball is expanding hydrodynamicallydo heavy quarks follow?

pt spectra with flow are verydifferent for charmonia from those measured in pp_bar e.g. at Fermilabor expected for pp at LHC

should be easy to discriminate at LHC

Page 23: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

PRELIM.Run-4

Run-7

Rapp & van Hees, PRC 71, 034907 (2005)

minimum-bias

charm quarks at RHIC: spectra don't show initial state scattering effects     ­    follow elliptic flow

Page 24: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

bottomonium  at LHC

in terms of number of produced quarks, beauty at LHC like charm at RHICdo they thermalize and hadronize statistically??if yes,  population of 2s and 3s states completely negligible  (exp­m/T)hydrodynamic flow?  need to measure spectrum to 15 GeV

predictions with statistical hadronization model

Page 25: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

3. Open charm and beauty

normalization for quarkoniajet quenching for heavy flavorsthermalization and hydrodynamic expansion in QGP

Page 26: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

heavy quark distributions from inclusive electron spectra

surprize: suppression very similar to pions prediction (Dokshitzer, Kharzeev) less energy loss for heavy quarks (radiation suppr.)

STAR preliminary

Page 27: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

open/hidden heavy flavor measurements in ALICE

   id. hadrons, electrons: ­0.9 < y < 0.9          muons: y=2.5­4.0   in central barrel: vertex cut effective          for heavy quark identification

Hadronic decays:  D0→Kπ,  D+­→Kππ,  Ds→K K*, Ds→ φπ, …

Leptonic decays:

•  B→ l (e or µ) + anything

•  Invariant mass analysis of lepton pairs: BB, DD, BDsame, J/Ψ, Ψ’, ϒ family, B →J/Ψ + anything

•  BB →µ µ µ (J/Ψ µ)

•  e­µ correlations expected ITS resolution

Page 28: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

D0 → Kπ  channel

1<pT<2 GeV/c

107 central PbPb

109 pp 108 pPb 107 PbPb

high precision vertexing, better than 100 µm (ITS)

high precision tracking (ITS+TPC)

K and/or π identification (TOF)

ALICE PPR vol2 JPG 32 (2006) 1295

S/B = 10%S/√(S+B) = 40

Page 29: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

107 central PbPb

ALICE PPR vol2 JPG 32 (2006) 1295

open beauty from single electrons

B  efi ‚–  in ALICE ITS/TPC/TRDpt > 2 GeV/c & d0 = 200 ­600x� m:  

80 000 electrons with S/(S+B) = 80%

Page 30: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

N(B →  J/ψ) / N(direct J/ψ) ~ 20% in 4π  @ LHC

" (d0) < 50 µm for pt > 1.5 GeV/c in ALICE

"  disentangle primary & secondary J//y

"  measure inclusive b cross­section

"  probe b quark in­medium energy loss

J/  from B­decay

Page 31: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

high precision charm measurement

pp at 14 TeVsensitivity to PDF’s

Central PbPbshadowing + kT + energy loss

shadowing region

ALICE PPR vol2 JPG 32 (2006) 1295

Page 32: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

jet quenching for b­quarks relative to c­quarks

data of one full luminosityPbPb run (106 s) should

clarify heavy flavor quenching story 

Page 33: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

11/2006 PSI  J. Schukraft33

HMPID

Muon Arm

TRD

PHOS

PMD ITS

TOF

TPC

Size: 16 x 26 metersWeight: 10,000 tons

ALICE  

1000 scientistsfrom 90  institutes

in 27 countries

Page 34: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

the TPC (Time Projection Chamber) ­ 3D reconstruction  of up to 15 000 tracks of charged particles per event  

with 95 m3 the largest TPC ever

        560 million read­out pixels!  precision better than 500 m in all 3 dim.    180 space and charge points per track

Page 35: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

Laser

laser system

cosmic radiation

Krypton gain calibration

TPC calibration and alignment

Page 36: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

J.P. Wessels ­ Prospects for First Physics with ALICE

momentum resolution

M. Ivanov, A. Kalweit

particle identif.5•106 cosmics &Kr calibration

tracking cosmic rays in magnetic field

Page 37: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

the TRD (Transition Radiation Detector)identifies electrons at the trigger level 

 540 chambers (radiator + drift+  multiwire proportional chamber +     read­out with segmented cathode      pad plane,  operated with Xenon)  typical chamber size 1.7 m2

          over all detector area 750 m2

  in 18 supermodules (8m long)       1.16 million read­out channels       30 million pixels

from charge-clustern zu track segments 500 cpu Local Tracking Unit on each chamber:

origin

deflection

time

bins

read­out electronics: 2 custom ASICS on multichip modules developed at PI and KIP in Heidelberg

  275 000  CPU's  process raw data of   65 Mbyte to reconstruct tracks (of 6 seg­    ments) in 6.5 s for trigger decision:               high momentum electron pair 

Page 38: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

TRD Global Tracking Unit GTU Level­1 trigger (7 s) for cosmics  ­ first L1 contribution to CTP in ALICE  (planned for high energy electrons or jets)

Trigger on cosmics with TRD at Level 1

Page 39: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

cosmic ray induced shower, coincidene TRD and TPC

Page 40: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Cosmic ray event with magnetic field on

Page 41: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

TPC

SSD/SDD

SPD

ITS Russian Dolls ­  Sliding the SSD/SDD over the SPD

Page 42: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

ALICE Inner Tracking System alignment with cosmics

~50k cosmic µ for alignment collected since end of May, using Pixel trigger

Silicon Pixel Detector (SPD):• ~10M channels• 240 sensitive vol. (60 ladders)

Silicon Drift Detector (SDD):• ~133k channels• 260 sensitive vol. (36 ladders)

Silicon Strip Detector (SSD):• ~2.6M channels• 1698 sensitive vol. (72 ladders)

ITS total: 2.2k alignable sensitive volumes   13k degrees of freedomà

Typical event display Distribution of clusters in the 6 layers

Page 43: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Preliminary results for SPD (Pixels):

These results indicate a residual misalignment (after realignment with cosmics) of < 10 µm, to be compared to a detector position resolution of 12 µm in rφ  

ALICE Inner Tracking System alignment with cosmics

   Track­to­track (top vs bottom)    distance in transv. plane

(s� = 55  mm  (vs 40  mm in simul. without misalignment)

   Track­to­“extra clusters”    distance in transv. plane

σ = 21  mm  (vs 15  mm in simul. without misalignment)

after alignment

before alignment

after alignment

before alignment

Page 44: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

muon chambers

dipole magnet

ALICE (Di)­Muon Spectrometer

muon absorber

muon filter

Page 45: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

All cosmic tracks

Page 46: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Johanna Stachel

First interactions on Sept 12

Circulating beam 2stray particle causing an interaction in 

the ITS

Page 47: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

resolution ~ 3% at 100 GeV/c excellent performance in hard region!

ALICE physics performance report dNch/dy~5000

Combined Momentum Resolution in ALICE Central Barrel

Page 48: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

Particle Identification in ALICETPC

TRD

From test beam data: at 2 GeV and 90 % e eff   105    rejection

Page 49: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

Backup slides

Page 50: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Johanna Stachel

J.L.Albacete 0707.2545 [hep­ph] within k

t factorization framework

expected charged particle rapidity density at LHC

depending on evolution of  saturation scaleget dN

ch/d = 1000 – 2500

Page 51: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

Johanna Stachel

expected evolution of QGP fireball at LHC

hep­ph/0506049

K. Eskola et al.after fast thermalization hydrodynamic expansion of fireball and cooling hadronization starts at when Tc is reached (165 MeV)duration hadronization:    # degrees of freedom drops by factor 3.5     ­> volume has to grow accordingly ­> 3­4 fm/c   (this is independent of order of phase transition)

initial NAA determines final multiplicityestimate (Eskola) dNch/d = 2600overall several 10 k hadrons produced       'macroscopic state'

task of heavy ion program at LHC

T / ¿¡1=3  

Page 52: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

rapid hadrochemical equilibration at phase boundary

Lattice QCD calcs. F. Karsch et al.

 Known since years: two­body collisions are not sufficient to bring multi­strange baryons into equilibrium. The density of particles varies rapidly 

with T near the phase transition. Multi­particle collisions are strongly 

enhanced at high density and lead to chem. equilibrium very near to Tc.

P. Braun­Munzinger, J. Stachel, C. WetterichPhys. Lett. B596 (2004) 61nucl­th/0311005

Page 53: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

P. Braun­Munzinger, J. Stachel, C. WetterichPhys. Lett. B596 (2004) 61nucl­th/0311005

 rate of change of density due to multiparticle collisions n(T)nin   M     example: for small b,  reactions such as 

KKKNbar bring multi­strange baryons close to equilibrium. Equilibration time T­60 ! All particles freeze out within a very 

narrow temperature window close to Tc. 

chemical freeze­out takes place at Tc

Page 54: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

High pT Spectra in p­p Collisions (II)4/54

NLO

pQCD

withapropria

e FFdescribes well a w

de range o

Page 55: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

radiation fails, is scattering the solution for heavy quarks?

charm contribution indeedsuppressed as much as pionsbut adding beauty data are

not reproduced

 recently shown by Korinna Zapp (U. Heidelberg)  that scattering also important for parton energy loss; implementation in nonperturbative approach ­ SCI jet quenching model  (K. Zapp, G. Ingelman, J. Rathsman, J. Stachel, PLB637 (2006) 179

to match pion data

    need improved heavy quark data   – to come with RHIC upgrades   – or even earlier from ALICE

apply same approach to c and b   0­10% centr.   =5.2 mb

Page 56: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

comparison of model predictions to RHIC data: centrality dependence and rapidity distribution

good agreement, no freeparameters

nucl­ex/0611020

     but need for good open charm                  measurement obvious       (this is a lesson for LHC as well!)

pp open charm cross section FONLL  Cacciari et al., PRL 95 (2005) 122001     cc = 256+400

­146  b

P. Braun­Munzinger, K. Redlich, J. Stachel, Nucl. Phys. A789 (2007) 334 nucl­th/0611023 

Page 57: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

 Johanna Stachel

systematics of charm cross section compared to NLO pQCD

pQCD cross section consistent with data(modulo discrepancy between STAR and PHENIX)only in spectra at higher pt somedeviation

Page 58: Probing the QuarkGluon Plasma with hard probes at the LHCcs.physics.sunysb.edu/verbaarschot/html/conf/edward/talks/stachel_ESQGP.pdf · heavy quark distributions from inclusive electron

First hits and tracks in ALICE muon arm  June 2008

● Run 24908 (seg 010) event 79 

[email protected]


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