Heavy Flavours in ALICE
Yvonne Pachmayer, University of Heidelbergfor the ALICE Collaboration
Motivation
Cold nuclear matter effects
Results from p-Pb collisions
Open heavy flavour
J/ψ, ψ(2S), ϒ(1S)
Comparison with models and Pb-Pb results
Conclusion
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 2
Physics MotivationHeavy Flavour in Pb-Pb Collisions
Cold nuclear matter effects+ hot nuclear matter effects (related to the Quark-Gluon Plasma)
D meson RPbPb
RPbPb(pT )=1
⟨T PbPb ⟩×
dN PbPb /dpT
d σ pp /dpT
Heavy-flavour quarks (c, b)
Originate from initial scattering processes
Sensitive to the full history of the collision
Excellent probes to study the de-confined medium produced in Pb-Pb collisions
Elementary collisionNo nuclear matter effects
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 3
Physics MotivationHeavy Flavour in Pb-Pb Collisions
Cold nuclear matter effects+ hot nuclear matter effects (related to the Quark-Gluon Plasma)
ALICE: arXiv:1202.1383PHENIX: Phys. Rev. Lett. 98 (2007) 232301; Phys.Rev. C 84 (2011) 054912; Phys. Rev. C (2005) 049901
J/ψ RPbPb
J/ψ Meson (cc)
Original idea (1986): J/ψ suppression via colour screening discussed as probe of de-confinement
Quark-Gluon Plasma screens all charmonia, but charmonium production takes place at the phase boundary
Elementary collisionNo nuclear matter effects
C o l o r S c r e e n i n g
cc
Matsui, Satz PLB 178 (1986)Braun-Munzinger, Stachel PLB 490 (2000)Thews et al. PRC 62 (2000)
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 4
Control experiment for Pb-Pb measurements
Cold nuclear matter effects
Gluon shadowing or saturation
Initial state energy loss
Energy loss of incoming parton
Coherent energy loss
kT broadening of initial partons
Physics MotivationHeavy Flavour in p-Pb Collisions
Cold nuclear matter effects+ hot nuclear matter effects (related to the Quark-Gluon Plasma)
Elementary collisionNo nuclear matter effects
Cold nuclear matter effects -without Quark-Gluon Plasma
Eskola et al., JHEP 0904 (2009) 65Kharzeev et al., arXiv:1205.1554Dominguez et al. ArXiv:1109.1250Vogt PRC 81 (2010) 044903 Arleo arXiv:1204.4609Lourenco et al., JHEP 0902 (2009) 14
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 5
A Large Ion Collider ExperimentMuon Spectrometer
Forward Muon Arm Acceptance in p-Pb/Pb-p:Forward: 2.03 < y
cms < 3.53
Backward: -4.46 < ycms
< -2.96
pT > 0 GeV/c
Semi-muonic decays:Semi-muonic decays:D, B, Λ
c, … → μ + anything
Charmonium and Bottomonium:Charmonium and Bottomonium:J/ψ, ψ(2S), Y(1S) → μ+ + μ-
p/Pb
Pb/p
μ
μ
Iron Wall 7 λi
Front Absorber 10 λi
Trigger Chambers
Tracking Chambers
μ-ID via tracksmatched withtrigger system
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 6
Central Barrel:-0.9 ≤ η ≤ 0.9p
T > 0 GeV/c
A Large Ion Collider ExperimentCentral Barrel
ITS
TPC
TRD
TOF
Semi-electronic decays:Semi-electronic decays:D, B, Λ
c, … → e + anything
Hadronic decays:Hadronic decays:D0 → K-π+ D+
s → K+K-π+
D+ → K-π+π+ D*+ → D0π+ Charmonium:Charmonium:J/ψ → e+ + e-
K π
e e
Track impact parameter and PID
D*+J/ψ
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 7
Electrons from Semi-electronic c/b Decays
Analysis strategy
Electron Identification with TOF+TPC (more suited for low pT) or
EMCal+TPC (more suited for high pT)
Subtraction of the background sources via data-tuned MC cocktail or invariant mass analysis
→ RpPb
consistent with unity
within uncertainties
RpPb( pT )=1
⟨T pPb⟩×
dN pPb /dpT
d σ pp /dpT
RpPb
= 1 → no nuclear effects
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 8
Electrons from Semi-electronic c/b Decays
Analysis strategy
Electron Identification with TOF+TPC (more suited for low pT) or
EMCal+TPC (more suited for high pT)
Subtraction of the background sources via data-tuned MC cocktail or invariant mass analysis
RpPb( pT )=1
⟨T pPb⟩×
dN pPb /dpT
d σ pp /dpT
RpPb
= 1 → no nuclear effects
→ Prediction including initial state effects agrees with data within uncertainties
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 9
D Meson RpPb
→ Compatible results for D0, D+, D*+ and D+
S
→ All results consistent with unity
→ Models including initial state effects describe data
Comparison with models
pQCD calculation for heavy-flavour production with EPS09 parametrizations of nuclear PDF (Mangano et al., Nucl. Phys. B 373 (1992) 295. Eskola et al., JHEP 0904 (2009) 065)
CGC predictions (Fujii-Watanabe, arXiv:1308.1258)
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 10
D meson: Comparison R
pPb(p
T) and R
PbPb(p
T)
RPbPb
: suppression up to a factor of 5
at pT ~10 GeV/c for 0-7.5% most central
collisions
RpPb
: results consistent with unity
→ Suppression observed in Pb-Pb is a final state effect – charm quark in-medium energy loss
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 11
Quarkonia
Mocsy, Eur. Phys. J.C61, 2009
Matsui, Satz PLB 178 (1986)Karsch, Satz Z. Phys. C 51 (1991) 209Braun-Munzinger, Stachel PLB 490 (2000)Thews et al. PRC 62 (2000)
C o l o r S c r e e n i n g
cc
Kluberg and Satz, arXiv:0901.3831
Start of Collision Development ofQGP
Hadronisation
Braun-Munzinger and Stachel, arXiv:0901.2500
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 12
J/ψ RpPb
vs rapidity
Significant suppression at mid- and forward rapidity
Backward rapidity result consistent with no suppression
Pbp
pPb
Systematic uncertainties:coloured boxes: uncorrelatedshaded areas: (partially) correlatedgrey box at unity: fully correlated
Forward and backward: ALICE: arXiv:1308.6726
small x-rangelarge x-range
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 13
J/ψ RpPb
vs rapidity
Pbp
pPb
Systematic uncertainties:coloured boxes: uncorrelatedshaded areas: (partially) correlatedgrey box at unity: fully correlated
Forward and backward: ALICE, arXiv:1308.6726 Significant suppression at mid- and forward rapidity
Backward rapidity result consistent with no suppression
Models of CNM effects
Shadowing model CEM + EPS09 NLO (Vogt, arXiv:1301.3395)
Coherent energy loss (Arleo et al., arXiv:1212.0434) with pp data parametrization
Gluon saturation (Fuji et al., arXiv:1304.2221): Color Glass Condensate framework with CEM LO with saturation scaleQ2
s,A(x=0.01) = 0.7-1.2 GeV/c2
→ Shadowing: backward rapidity data well reproduced, strong shadowing favoured at forward rapidity
→ Coherent energy loss: y-dependence well reproduced
→ CGC calculations: underestimate the data
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 14
J/ψ RpPb
vs pT
Backward rapidity: RpPb
shows small pT dependence close to unity
Mid-rapidity: RpPb
tends to increase with pT, more precision needed
Forward rapidity: RpPb
increases with pT, consistent with unity for p
T > 5 GeV/c
Backward rapidity Mid-rapidity Forward rapidity
→ At forward rapidity data tends to favour strong shadowing→ CGC calculations underestimate data→ Coherent energy loss model overestimates suppression at forward rapidity for p
T < 2 GeV/c
p Pbp PbPb p
Vogt, arXiv:1301.3395, Arleo et al., arXiv:1212.0434, Fuji et al., arXiv:1304.2221
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 15
J/ψ: Comparison RpPb
(pT) and R
PbPb(p
T)
Backward rapidity & Forward rapidity Mid-rapidity
→ Different pT dependencies in Pb-Pb and p-Pb/Pb-p
→ Small CNM effect for pT > 4 GeV/c
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 16
One among several possible implications of RpPb
on RPbPb
interpretation
→ Small effects from extrapolated shadowing at pT > 7 (4) GeV/c
at mid (forward) rapidity→ At low p
T in Pb-Pb collisions the J/ψ yield is enhanced (or equal to)
compared with the expectation from CNM effects
Assuming 2 → 1 kinematics + factorization of nuclear effect (only nPDF as nucl. effects in pA)
Backward rapidity & Forward rapidity Mid-rapidity
J/ψ: Comparison RpPb
(pT) and R
PbPb(p
T)
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 17
ψ(2S) RpPb
vs rapidity
RpPbψ(2S)
=RpPbJ / ψ σpPb
ψ(2S)
σpPbJ /ψ
σppJ / ψ
σ ppψ(2S)
→ Strong decrease of ψ(2S)/J/ψ from pp to p-Pb→ Not described by initial state CNM effect and coherent energy loss→ Similar result as PHENIX experiment at √s
NN = 0.2 TeV (arXiv:1305.5516)
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 18
ϒ(1S) RpPb
vs rapidity
→ Similar RpPb
of J/ψ and ϒ
→ EPS09 shadowing in fair agreement within uncertainties
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 19
Conclusion
Open heavy-flavour results
Good agreement with pQCD calculations including shadowing predictions
p-Pb results confirm that the suppression in central Pb-Pb collisions is a final state effect – charm quark in-medium energy loss
J/ψ measurements
Support strong shadowing at forward rapidity and/or the coherent energy loss model
J/ψ suppression observed in Pb-Pb collisions cannot be ascribed to cold nuclear matter effects alone
ψ(2S) suppressed relatively to J/ψ by up to 45% at backward rapidity
Final state effect?
(1S) measurements show a similar suppression as the ones from ϒ J/ψ but large uncertainties (pp interpolation, limited statistics)
More measurements to come, stay tuned!More measurements to come, stay tuned!
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 20
Back-Up
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 21
Electrons from Semi-electronic c/b Decays
→ Similar result as PHENIX experiment (√s
NN = 0.2 TeV)
PHENIX: Phys. Rev. Lett. 109 (2012) 242301
Analysis strategy
Electron Identification with TOF+TPC (more suited for low pT) or
EMCal+TPC (more suited for high pT)
Subtraction of the background sources via data-tuned MC cocktail or invariant mass analysis
RpPb( pT )=1
⟨T pPb⟩×
dN pPb /dpT
d σ pp /dpT
RpPb
= 1 → no nuclear effects
Moriond 2014 Yvonne Pachmayer (University of Heidelberg) 22
D Meson RpPb
: Comparison with Models
→ Compatible results for D0, D+, D*+ and D+
S
→ All results consistent with unity
→ No rapidity dependence observed (within narrow y range)
Comparison with models
pQCD calculation for heavy-flavour production with EPS09 parametrizations of nuclear PDF (Mangano et al., Nucl. Phys. B 373 (1992) 295. Eskola et al., JHEP 0904 (2009) 065)
CGC predictions (Fujii-Watanabe, arXiv:1308.1258)
→ Models including initial state effects describe data