Heavy-flavour measurements atLHC-ALICE
Shingo Sakai

Heavy Flavour (HF) in pp, p-Pb & Pb-Pb} Heavy-flavour (charm & beauty) production}

Initial hard scatterings (MHF >> ΛQCD)} pp collisions

Test for perturbative QCD (pQCD)} Reference for heavy ion collisions (both experiment & theory)}} Heavy ion collisions

Created in initial parton-parton scatterings} Traverse and interact with the hot & dense QCD matter}

A good probe to study properties of the QCD matter} Energy loss (RAA), collectivity (v2), hadronization}} pA collisions}Control measurement for heavy ion collisions to disentangle initialfrom final state effects}

2Cold nuclear matter effect on heavy-flavour production

Energy Loss of heavy flavours§ In-medium parton energy loss
§ Radiative energy loss (PLB 632, 81)§ gluon bremsstrahlung§ smaller energy loss for heavy than for light quarks
due to “dead cone” effect (PLB 519 (2001) 199.)§ energy loss depends on the colour charge and islarger for gluons than for quarks§ Collisional energy loss (PLB 649, 139)
§ energy loss via elastic scattering§ Theoretical predictions:§ mass & colour charge dependence of energy loss
§ Eloss(g) > Eloss(u,d,s) > Eloss(c) > Eloss(b)Nuclear modification factor?
3

Azimuthal anisotropy of Heavyflavours
ｙn Elliptic flowdN/d(φ-ψRP) = …+ N0(1+2v2cos(2(φ-ψRP))) +…

ｘ§ Transfer initial spatial anisotropy
to momentum anisotropy
p macroscopic: hydro model=> pressure gradientp microscopic=> scattering in the medium§ Low pT
§ coupling of heavy quarks withthe medium and their thermalization§ Intermediate pT§Hadronization mechanism (recombination)§ High pT§ Path-length dependence of energy loss
4

Initial spatial anisotropy

pｙpｘ
Momentum space anisotropyof particle emission

Heavy-flavour measurements in ALICE
TPC + EMCal (dE/dx+E/p)§ D meson reconstruction (|y|<0.5)§ displaced-vertex topology§ π/K ID: TPC+TOF§ HFE (|y|<0.5 or 0.6)
§ background subtraction: cocktail & invariant
mass method§ HFM (2.5<y<4)§ background subtraction: used MC normalized
to data at low pT (pp), inputs from centralbarrel & extrapolation with MC (Pb-Pb)
5

TPC +TOF (dE/dx+TOF)

HF production (c,b->l) in pp collisions
Phys. Rev. D 86, 112007

c->e + b->e (eHF)

Phys. Lett. B 708(2012) 265

c->μ + b->μ (μHF)§ Productions of leptons (e,μ) from charm+ beauty decays in different rapidity ranges
are described by pQCD calculations
6

HF production (D mesons) in pp collisionsl D meson productions in pp collisions at 7 TeV are consistent with pQCD calculations
7

Initial state effects: p-A collisions} Heavy-flavour in p-A collisions}

control measurement for heavy-ion collisions to disentangle
initial (cold nuclear matter effects) from final state effects} Cold nuclear matter effects}

nuclear modification of Parton
distribution Functions (PDF):
shadowing or gluon saturation
K.J. Eskola et al., JHEP 0904(2009)65
H. Fuji & K. Watanabe, NPA 915 (2013) 1

energy loss I.Vitev et al., PRC 75(2007) 064906} kT broadening (Cronin enhancement)} multiple collisions}

A.M. Glenn et al., PLB 644(2007)1198

Initial state effects on heavy-flavour
productionsl No Significant cold nuclear matter effects on heavy-flavour productionl A small suppression at low pT is consistent with models included PDF
9HF productions (c,b->e) in PbPb collisions at
2.76 TeVl A strong suppression of heavy-flavour production in most-central collisions
l Energy loss of heavy quarks in the dense QCD matterl Less suppression in peripheral collisions
10

HF productions (c,b->l) in PbPb collisions at
2.76 TeVl Similar suppression between mid (electrons) and forward (muon) rapidityl No significant y dependence of heavy flavour productions
11

D mesons in central Pb-Pb collisionsl Strong suppression of D meson production in most central (0-20%) collissions
l Less suppress from central to peripheral
l Similar suppression of light hadronsl Larger suppression than non-prompt J/ps (B decays)
12

Azimuthal anisotropy of eHF and µHF
v2

eHF :arXiv: 1606.00321, μHF: PLB 753 (2016) 41-56
0.5

0-10% Pb-Pb, s NN = 2.76 TeV

0.50.40.4

10-20% Pb-Pb, sNN = 2.76 TeV
e± ← HF, v 2{EP, |∆η| > 0.9}, |y | < 0.70.50.40.3µ± ← HF, v 2{2, |∆η| > 1.7}, 2.5 < y < 40.3

0.2

0.2

0.2

0.1

0.1

0.1

000−0.1

0.1

0.1

0.3

−0.2

ALICE024ALI−PUB−106769

680.2
10 12 0p (GeV/c )T24680.2
10 120p (GeV/c )20-40% Pb-Pb, s NN = 2.76 TeV

24T§ Non-zero v2 of eHF at |y|<0.7 and μHF at 2.5<y<4§ the magnitude is compatible in mid- and forward-rapidities§ v2 of eHF measured from pT > 0.5 GeV/c§ similar pT dependence to other light hadron v2
136810 12
p T (GeV/c )Azimuthal anisotropy of D mesonsv2

PRC 90 (2014) 034904
0.6

Pb-Pb,

0Prompt D |y |<0.8, v 2{EP}

0.6

ALICE

0.6

Syst. from datasNN = 2.76 TeV

Syst. from B feed-down

0.4

0.4

0.2

0.2

0.2

000-0.2

-0.2

-0.2

4

68

0.4

Centrality 10-30%

Centrality 0-10%
2Charged particles, v 2{EP,|∆ η|>2}

10 12 14 16 18

p (GeV/c )T2468

Centrality 30-50%

10 12 14 16 18p (GeV/c )T2468

10 12 14 16 18p (GeV/c )T

ALI−PUB−70100§ Non zero D v2 at low pT§ Tends to get large from central (0-10%) to mid-central (30-50%)§ Hydrodinamical behavior§ Consistent with charged particle v2§ Heavy quarks participate collective expansion in the QCD matter
14RAA

Comparison with models (1)
1.2
0+*+

ALICE D , D , D average, |y|<0.5

1Pb-Pb, sNN = 2.76 TeV
Centrality 0-20%

0.8

WHDG rad+coll
POWLANG
Cao, Qin, Bass
Aichelin et al, Coll+LPM radBAMPSTAMU elastic
UrQMD

0.6
0.4
0.200
ALI−DER−486622468101214 16p (GeV/c)
T§ Theoretical calculations§ initial: with/without cold nuclear matter from PDF§ medium modeling: Hydro, Glauber, parton transportation§ interaction: radiative, collisional, resonant interaction§ hadronization: fragmentation, coalesenc
15

BAMPS: J. Phys. G 38 (2011) 124152,
POWLANG: Eur. Phys. J C 71(2011)1666,
UrQMD: arXiv:1211.6912,J. Phys. Conf.
Ser. 426,012032(2013),
TAMU: Phys. Rev. C 86 (2012) 014903,
WHDG: J. Phys. G38(2011)124114,
Aichelin: Phys. Rev. C79(2009)044906, J.
Phys. G37(2010)094019
Cao,Qin, Bass: arXiv:1308.0617

Comparison with models (2)0+1Pb-Pb, sNN = 2.76 TeV
Centrality 0-20%

0.8

WHDG rad+coll
POWLANG
Cao, Qin, Bass
Aichelin et al, Coll+LPM radBAMPSTAMU elastic
UrQMD

0.6
0.4

0.4

468

10

121416p (GeV/c)
T*+Pb-Pb, sNN = 2.76 TeV
Centrality 30-50%

0.2
0.1-0.1
2+ALICE D ,D , D average
Syst. from data
Syst. from B feed-down0.300.2

ALI−DER−48662

0*+

ALICE D , D , D average, |y|<0.500

PRC 90 (2014) 034904
v2RAA

JHEP09(2012)1121.20
ALI−DER−48710

WHDG rad+coll
POWLANG
Cao, Qin, Bass
Aichelin et al, Coll+LPM rad
BAMPS

2468

TAMU elastic
UrQMD

10121416p (GeV/c)
T§ Theoretical calculations§ initial: with/without cold nuclear matter from PDF§ medium modeling: Hydro, Glauber, parton transportation§ interaction: radiative, collisional, resonant interaction§ hadronization: fragmentation, coalesence§ Large suppression and non-zero v2 (at low pT) are represented by models, but
simultaneous reproduction of the RAA and v2 is challenging
16Summary}

Heavy-flavour measurements at LHC-ALICE} Studies by measuring leptons from charm and beauty decays and D

The productions are well described by pQCD calculations in pp collisions} Cold nuclear matter effects is very small on heavy-flavour productions}}Pb-Pb collisions} Strong suppression of heavy-flavour productions} Clear indication for substantial energy loss of charm and beauty in the hot¨ No rapidity and energy dependence}

Non-zero & centrality dependence of v2} Suggest strong re-interaction in the medium}

Heavy flavours observed to be significantly affected by hot and dense QCDmedium}

Outlook at Run2: beauty (e, non-prompy J/psi), heavy-flavour jet,heavy-flavour correlations