introduction to ultrarelativistic nucleus-nucleus collisions lecture 2

11

Introduction to Ultrarelativistic Introduction to Ultrarelativistic Nucleus-Nucleus Collisions Nucleus-Nucleus Collisions

Lecture 2Lecture 2

Federico AntinoriFederico Antinori(INFN Padova & CERN)(INFN Padova & CERN)

ContentsContents

YesterdayYesterday

Part 1: The QGP and A-A collisionsPart 1: The QGP and A-A collisions Two puzzles in QCDTwo puzzles in QCD Confinement and deconfinementConfinement and deconfinement

(an “intuitive” view)(an “intuitive” view) Nucleus-Nucleus collisionsNucleus-Nucleus collisions

Part 2: SPS and RHIC resultsPart 2: SPS and RHIC results Bulk particle productionBulk particle production Strangeness enhancementStrangeness enhancement High pHigh pTT suppression suppression

TodayToday

Part 2 cont’d: SPS and RHIC resultsPart 2 cont’d: SPS and RHIC results Recombination Recombination Elliptic flowElliptic flow Quarkonium suppressionQuarkonium suppression

Part 3: Hard Probes and the LHCPart 3: Hard Probes and the LHC Heavy Ions in the LHCHeavy Ions in the LHC LHC physics, with two examplesLHC physics, with two examples

QuarkoniaQuarkonia Heavy FlavoursHeavy Flavours

F Antinori, CERN-Fermilab HCP Summer School, 8-17 June 2009

22

RecombinationRecombination

33


44

Baryon puzzle @ RHICBaryon puzzle @ RHIC

Central Au-Au: as many Central Au-Au: as many -- (K(K--) as p () as p () at p) at pTT ~ 1.5 ~ 1.5 2.5 2.5 GeV GeV

ee++ee-- jet (SLD) jet (SLD) very few baryons very few baryons

from from fragmentation!fragmentation!

K

p

H.Huang @ SQM 2004F Antinori, CERN-Fermilab HCP Summer School, 8-17 June 2009

55

if loss is partonic, shouldn’t it if loss is partonic, shouldn’t it affect p and affect p and in the same way? in the same way?

RcpRcp

central AA,

periphAA,

periph AA,

central AA,cp Yield

Yield

Ncoll

NcollR

strange particles come to strange particles come to rescue!rescue!


66

Quark RecombinationQuark Recombination

if hadrons are formed by recombination, if hadrons are formed by recombination, features of the parton features of the parton spectrum are shifted to higher pspectrum are shifted to higher pTT in the hadron spectrum, in the hadron spectrum, in a different way for mesons and baryons in a different way for mesons and baryons

constituent quark countingconstituent quark counting

s

u

s

d

u d

u

u

u

u

uu

u

u

u

u

u

u

u

u dd

d

d

d

d

d

d

d d

d

dd

ds

s

s s

s

s

s

s

s

s

s ss

sd d

d

d

d

d

d

u

uu

u

u

uu

u

d

K+

u

+

+

-

p

-

S.Bass @ SQM`04


Elliptic flowElliptic flow

77


88

Elliptic FlowElliptic Flow Non-central collisions are azimuthally asymmetricNon-central collisions are azimuthally asymmetric

The transfer of this asymmetry to momentum space provides a The transfer of this asymmetry to momentum space provides a measure of the strength of collective phenomena measure of the strength of collective phenomena

Large mean free path Large mean free path particles stream out isotropically, no memory of the asymmetry particles stream out isotropically, no memory of the asymmetry extreme: ideal gas (infinite mean free path) extreme: ideal gas (infinite mean free path)

Small mean free pathSmall mean free path larger density gradient -> larger pressure gradient -> larger larger density gradient -> larger pressure gradient -> larger

momentum momentum extreme: ideal liquid (zero mean free path, hydrodynamic limit)extreme: ideal liquid (zero mean free path, hydrodynamic limit)

Reactionplane

In-planeOut

-of-

plan

e

Y

XFlow

Flow

Reactionplane

In-planeOut

-of-

plan

e

Y

XFlow

Flow

Reactionplane

In-planeOut

-of-

plan

e

Y

XFlow

Flow


99

Azimuthal AsymmetryAzimuthal Asymmetry

at low pat low pTT: azimuthal : azimuthal asymmetry as large as asymmetry as large as expected at hydro expected at hydro limit!limit! ““perfect liquid”?perfect liquid”?

very far from “ideal gas” very far from “ideal gas” picture of plasmapicture of plasma

...)2cos(2)cos(212

121

vv

dydpp

dN

dyddpp

dN

TTTT

flow" directed" cos1 v flow" elliptic" 2cos2 v


1010

elliptic flow velliptic flow v22

Recombination also offers an explanation for vRecombination also offers an explanation for v22 baryon puzzle... baryon puzzle...

STAR Preliminary

scaled with n(quarks)

...)2cos(2)cos(212

121

vv

dydpp

dN

dyddpp

dN

TTTT

flow"direct " cos1 v flow" elliptic" 2cos2 v


1111

Where should recombination Where should recombination work?work?

Proponents say @ pProponents say @ pTT between 1 and 4 GeV (6 GeV) for mesons between 1 and 4 GeV (6 GeV) for mesons (baryons)(baryons) hydrodynamics below, fragmentation above (at RHIC energy)hydrodynamics below, fragmentation above (at RHIC energy)

recombining partons:p1+p2=ph

fragmenting parton:ph = z p, z<1

R.Fries @ QM`04F Antinori, CERN-Fermilab HCP Summer School, 8-17 June 2009

1212

QuarkoniaQuarkonia

1313

QGP signature proposed by Matsui and Satz, 1986QGP signature proposed by Matsui and Satz, 1986

In the plasma phase the interaction potential is expected to be In the plasma phase the interaction potential is expected to be screened beyond the Debye length screened beyond the Debye length D D (analogous to e.m. Debye (analogous to e.m. Debye screening): screening):

Charmonium (cc) and bottonium (bb) states with r > Charmonium (cc) and bottonium (bb) states with r > D D will not will not bind; their production will be suppressedbind; their production will be suppressed

Charmonium suppressionCharmonium suppression

For T ~ 200 MeV:For T ~ 200 MeV:DD ~ 0.1 – 0.2 fm ~ 0.1 – 0.2 fm


1414

D , and therefore which onium states will be suppressed, depends on the temperature:

as long as the probability of later combining an uncorrelated QQ pair at as long as the probability of later combining an uncorrelated QQ pair at the hadronization stage is negligible, as it is at the SPS, the only chance the hadronization stage is negligible, as it is at the SPS, the only chance of producing a QQ bound state is shortly after the pair is produced, of producing a QQ bound state is shortly after the pair is produced, while the two quarks are still correlated in phase space. Debye while the two quarks are still correlated in phase space. Debye screening allows the two quarks to “forget” about each other’s screening allows the two quarks to “forget” about each other’s existence, and to loose the correlation.existence, and to loose the correlation.


1515

Nuclear absorptionNuclear absorption

There is a “normal” There is a “normal” suppression of the production suppression of the production of J/of J/, observed already in pA , observed already in pA and lighter ion collisions and and lighter ion collisions and attributed to nuclear attributed to nuclear absorpion absorpion

The Pb-Pb point falls below The Pb-Pb point falls below the nuclear absorption curve the nuclear absorption curve (“anomalous” suppression)(“anomalous” suppression)


1616

Anomalous J/Anomalous J/ suppression suppression

J/J/normalized to Drell-Yan as a normalized to Drell-Yan as a function of the transverse energy function of the transverse energy (i.e. centrality)(i.e. centrality)

The data points deviate from the The data points deviate from the solid curve, which indicates the solid curve, which indicates the prediction for nuclear absorptionprediction for nuclear absorption

The deviation increases with The deviation increases with increasing collision centralityincreasing collision centrality


1717

J/J/ suppression pattern suppression pattern

measured/expected measured/expected J/J/suppression vs estimated suppression vs estimated energy densityenergy density anomalous suppression sets anomalous suppression sets

in at in at ~ 2.3 GeV/fm ~ 2.3 GeV/fm33 ( (bb ~ 8 ~ 8 fm)fm)

effect seems to accelerate at effect seems to accelerate at ~ 3 GeV/fm ~ 3 GeV/fm33 ( (bb ~ 3.6 fm) ~ 3.6 fm)

this pattern has been this pattern has been interpreted as successive interpreted as successive melting of the melting of the c c and of the and of the J/J/


1818

J/J/ψψ suppression at RHIC suppression at RHIC

J/ψ ~ as suppressed as J/ψ ~ as suppressed as at SPS (NA50)at SPS (NA50)

[Hugo Pereira (PHENIX), QM05]


1919


all models reproducing all models reproducing magnitude of J/ψ magnitude of J/ψ suppression at SPS suppression at SPS predicted larger predicted larger suppression at RHICsuppression at RHIC



2020


Models including Models including recombination do recombination do better… better…



2121

J/J/ψψ: R: RAAAA at large rapidity at large rapidity

Larger suppression at Larger suppression at larger rapiditylarger rapidity

What controls suppression?What controls suppression? energy density?energy density? ……??

The LHC should tellThe LHC should tell see later…see later…

NA50 at SPS (0<y<1)PHENIX at RHIC (|y|<0.35)PHENIX at RHIC (1.2<|y|<2.2)


Plus…Plus…

enhanced dilepton productionenhanced dilepton production direct photon emissiondirect photon emission conical emission conical emission

at low pat low pT T opposite to high popposite to high pTT particle particle

““the ridge” the ridge” wide structure in rapidity on same side of high pwide structure in rapidity on same side of high pT T particle particle

““the horn”the horn” sharp peak in Ksharp peak in K++//ππ++ ratio as a function of ratio as a function of s s

evidence for parton saturation effectsevidence for parton saturation effects … … and many more…and many more…

(next time…)(next time…)


2222

Part 3: Hard Probes and the Part 3: Hard Probes and the LHCLHC

2323


Heavy Ions in the LHCHeavy Ions in the LHC

2424

LHC as a HI acceleratorLHC as a HI accelerator

Fully ionised Fully ionised 208208Pb nucleus accelerated in LHCPb nucleus accelerated in LHC

(configuration magnetically identical to that for pp)(configuration magnetically identical to that for pp)

the relevant figure is the relevant figure is s per nucleon-nucleon collision: s per nucleon-nucleon collision: ssNNNN

… … of course, real life is more complicated…of course, real life is more complicated… ion collimationion collimation sensitivity of LHC instrumentationsensitivity of LHC instrumentation injection chaininjection chain ……


2525

TeV 574TeV 782 pPb EZE

TeV 5.539.02

ppppPb

NN ssA

Z

A

Es

PeV 15.1PbPb s

Luminosity limitationsLuminosity limitations

Bound-Free Pair Production (BFPP):Bound-Free Pair Production (BFPP):

with subsequent loss of the with subsequent loss of the 208208PbPb81+81+

creates a small beam of creates a small beam of 208208PbPb81+81+, with an intensity , with an intensity Luminosity Luminosity impinging on a superconducting dipole (that you don’t want to quench…)impinging on a superconducting dipole (that you don’t want to quench…) cross section cross section Z Z77 (!) ~ 280 b for PbPb at LHC (hadronic cross section ~ 8 b…) (!) ~ 280 b for PbPb at LHC (hadronic cross section ~ 8 b…)

Collimation lossesCollimation losses collimation for ions (which can break up into fragments) is harder than for protonscollimation for ions (which can break up into fragments) is harder than for protons limitation on the total intensitylimitation on the total intensity

luminosity limited to ~ 10luminosity limited to ~ 102727 cm cm-2-2ss-1-1


2626

ePbPbPbPb 81208 82208 82208 82208

Pb nuclei in the LHCPb nuclei in the LHC

““Nominal” configuration:Nominal” configuration: 592 bunches 592 bunches (for protons: 2808)(for protons: 2808) 7 107 1077 ions/bunch ions/bunch (for protons: ~ 10(for protons: ~ 101111)) L ~ 10L ~ 102727 cm cm-2-2ss-1 -1 (for protons: 10(for protons: 103434 cm cm-2-2ss-1 -1 )) 8 kHz interaction rate8 kHz interaction rate

““Early scheme” configuration:Early scheme” configuration: for run expected at the end of first proton runfor run expected at the end of first proton run 62 bunches62 bunches 7 107 1077 ions/bunch ions/bunch L ~ 5 10L ~ 5 102525 cm cm-2-2ss-1-1

400 Hz interaction rate400 Hz interaction rate

a dedicated AA experiment: ALICEa dedicated AA experiment: ALICE

(+ AA capability in ATLAS and CMS)(+ AA capability in ATLAS and CMS)


2727

LHC physics, with two examplesLHC physics, with two examplesQuarkoniaQuarkonia

Heavy FlavoursHeavy Flavours

2828


Why high energy?Why high energy?

SPS RHIC LHC

sNN [GeV] 17.3 200 5500

dNch/dy 450 800 1500 – 3000 ?

ε [GeV/fm3] 3 5.5 10 – 20 ?


2929

large large εε deeper in deconfinement region deeper in deconfinement region closer to “ideal” behaviour?closer to “ideal” behaviour?

large cross section for “hard probes” !large cross section for “hard probes” ! a whole new set of tools to probe the mediuma whole new set of tools to probe the medium

access to low-x physicsaccess to low-x physics saturationsaturation Colour-Glass CondensateColour-Glass Condensate ……

Probing the medium at the LHCProbing the medium at the LHC

Soft observablesSoft observables multiplicity, strangeness, mmultiplicity, strangeness, mT T distrib., v2, interferometry, resonances, …distrib., v2, interferometry, resonances, …

global event characterisation global event characterisation energy density, temperatures, system size & lifetimes, viscosity, …energy density, temperatures, system size & lifetimes, viscosity, …

Hard observablesHard observables

probe the medium properties!probe the medium properties! e.g.:e.g.:


3030

Pb Pb

bb

b

b

31ALICE Set-upALICE Set-up

HMPID

Muon Arm

TRD

PHOS

PMD

ITS

TOF

TPC

Size: 16 x 16 x 26 m3

Weight: 10,000 tonnes

Quarkonia at the LHCQuarkonia at the LHC

3232


3333

present status:present status:

SPS RHIC LHC

very similar suppression at very similar suppression at RHIC and SPS...RHIC and SPS... J/J/ melting compensated by cc melting compensated by cc

recombination? recombination? or maybe only or maybe only ’and ’and cc melt? melt?

at LHC we should at LHC we should finally be able to finally be able to tell...tell...

larger larger J/ J/ finally melts? finally melts?

more cc more cc reco dominates? reco dominates?

ImportantImportant::

very large bb cross section very large bb cross section @ LHC; @ LHC;

expect 20-30% J/expect 20-30% J/ originating in B decaysoriginating in B decays

open b measurement!open b measurement!

F.Karsch et al.: PLB637 75 (2006)

J/J/ψψ@ LHC ?@ LHC ?


3434

Quarkonia to dimuons in ALICEQuarkonia to dimuons in ALICE 1 month Pb-Pb1 month Pb-Pb

Expected yields

StateState S[10S[1033]] B[10B[1033]] S/BS/B S/(S+B)S/(S+B)1/21/2

J/J/ 130130 680680 0.200.20 150150

’’ 3.73.7 300300 0.010.01 6.76.7

(1S)(1S) 1.31.3 0.80.8 1.71.7 2929

(2S)(2S) 0.350.35 0.540.54 0.650.65 1212

(3S)(3S) 0.200.20 0.420.42 0.480.48 8.18.1

PbPb cent, 0 fm<b<3 fm

J/ high statistics: 0-20 GeV/c ’ lower significance (1S) & (2S) : 0-8 GeV/c (3S) ok, but 2-3 runs needed


3535

Quarkonia Quarkonia Suppression Suppression

J/ψ, , ’: Excellent sensitivity to different suppression scenarios

’’: Needs 2-3 years of high luminosity

ψ’:Will be very difficult


Quarkonia in CMSQuarkonia in CMS

Very good performance Very good performance expected for the expected for the family family

expected in nominal Pb-Pb expected in nominal Pb-Pb run:run: ~ 25000 ~ 25000 ~~ 7000 7000 ’’ ~ 4000 ~ 4000 ’’’’


3636

3737

Probing the medium with c & Probing the medium with c & bb

3838

Charm and beauty: ideal probesCharm and beauty: ideal probes

study medium with probes of known colour charge study medium with probes of known colour charge and mass and mass e.g.: energy loss by gluon radiation expected to be:e.g.: energy loss by gluon radiation expected to be: parton-specific: stronger for gluons than quarks (colour parton-specific: stronger for gluons than quarks (colour

charge)charge) flavour-specific: stronger for lighter than for heavier quarks flavour-specific: stronger for lighter than for heavier quarks

(dead-cone effect)(dead-cone effect) study effect of medium on fragmentation (no extra study effect of medium on fragmentation (no extra

production of c, b at hadronization)production of c, b at hadronization) independent string fragmentation vs recombinationindependent string fragmentation vs recombination e.g.: De.g.: D++

ss/D/D++

+ measurement important for quarkonium physics+ measurement important for quarkonium physics open QQ production natural normalization for quarkonium open QQ production natural normalization for quarkonium

studiesstudies B meson decays non negligible source of non-prompt J/B meson decays non negligible source of non-prompt J/F Antinori, CERN-Fermilab HCP Summer School, 8-17 June

2009

3939

Heavy flavour production in AAHeavy flavour production in AA binary scaling: binary scaling:

can be broken by:can be broken by: initial state effects (modified PDFs)initial state effects (modified PDFs)

shadowingshadowing kkTT broadening broadening gluon saturation (colour glass)gluon saturation (colour glass)

(concentrated at lower p(concentrated at lower pTT))

final state effectsfinal state effects (modified fragmentation) (modified fragmentation) parton energy lossparton energy loss violations of independent fragmentation (e.g. quark violations of independent fragmentation (e.g. quark

recombination) recombination)

(at higher p(at higher pTT))

ppAA dcollNd


What do we know What do we know from lower energies?from lower energies?

4040


4141

Excess production at the SPS?Excess production at the SPS?

Intermediate mass dimuon Intermediate mass dimuon excess in central Pb-Pb at SPS excess in central Pb-Pb at SPS (NA50)(NA50)

Main known sources in that Main known sources in that region: Drell-Yan and charm region: Drell-Yan and charm pairspairs

M (GeV/c2)

centralcollisions


4242

Study of the I.M. excess in NA60Study of the I.M. excess in NA60

Fit weighted impact parameter distributionFit weighted impact parameter distribution prompt from J/prompt from J/ψψ dimuons, charm from PYTHIA dimuons, charm from PYTHIA requires > 2 x expected D-Y to fit datarequires > 2 x expected D-Y to fit data

6500 A, 2match < 3

sensitivity to assumption on cc psensitivity to assumption on cc pTT, , ΔφΔφ extracted value of cc cross section ~ 2 – 3 larger than extrap.extracted value of cc cross section ~ 2 – 3 larger than extrap.

but compatible with extrapolation from NA50 p-Abut compatible with extrapolation from NA50 p-A

NA60

H.Woehri and C.Lourenco, Phys.Rep. 433 (2006) 127-180


4343

Excess production at the SPS?Excess production at the SPS?

Intermediate mass dimuon Intermediate mass dimuon excess in central Pb-Pb at SPS excess in central Pb-Pb at SPS (NA50)(NA50)

Main known sources in that Main known sources in that region: Drell-Yan and charm region: Drell-Yan and charm pairspairs

M (GeV/c2)

centralcollisions


No!No!

4444

RHIC: “non-photonic” electronsRHIC: “non-photonic” electrons Identified electron spectraIdentified electron spectra

STAR: dE/dx in TPC + TOF at low pSTAR: dE/dx in TPC + TOF at low pTT, EMC at high p, EMC at high pTT

PHENIX: combined RICH and E/p (with E from EM cal)PHENIX: combined RICH and E/p (with E from EM cal)

Rejection of non-heavy-flavour electronsRejection of non-heavy-flavour electrons Main source of electrons: “photonic”Main source of electrons: “photonic”

ee++ee-- conversions conversions Dalitz decays Dalitz decays 00 e e++ee-- Dalitz decays Dalitz decays e e++ee--

STAR:STAR: rejected by full invariant mass analysis of erejected by full invariant mass analysis of e++ee-- combinations combinations

PHENIX:PHENIX: estimated by simulation and subtracted (“cocktail method”)estimated by simulation and subtracted (“cocktail method”) measured by “converter method” and subtractedmeasured by “converter method” and subtracted

Other sources of non-charm electrons:Other sources of non-charm electrons: ,,,,, K decays, K decays

estimated by sim. and subtracted (in both STAR and PHENIX)estimated by sim. and subtracted (in both STAR and PHENIX)

(“internal conversions”)(“internal conversions”)


4545

Non-Photonic Electrons’ RNon-Photonic Electrons’ RAAAA

seem to be ~ as suppressed as charged hadronsseem to be ~ as suppressed as charged hadrons


AApp

AAAA

1

Yield

Yield

NbinR

Words of caution…Words of caution…

non-photonic electrons: very indirect measurementnon-photonic electrons: very indirect measurement

PHENIX – STAR discrepancy on absolute values of cross sectionsPHENIX – STAR discrepancy on absolute values of cross sections

discrepancy ~ cancels out in Rdiscrepancy ~ cancels out in RAAAA!!

let’s forget about this for a moment, and take the results at face value let’s forget about this for a moment, and take the results at face value


4646

0,0 0,5 1,0 1,5 2,0 2,5 3,010-5

10-4

10-3

10-2

10-1

100

1/(2N

evp T

)d2 N

/dp T

d y [(G

eV/c

)-2]

pT [GeV/c]

STAR Combined fit MB , electrons and D-mesons

Phenix MB Au+Au data

in ppin pp … … and in and in AuAuAuAu

4747

Theoretically...Theoretically...

Energy loss for heavy flavours is expected to be reduced:Energy loss for heavy flavours is expected to be reduced:i)i) Casimir factorCasimir factor

light hadrons originate from a mixture of gluon and quark jets, light hadrons originate from a mixture of gluon and quark jets, heavy flavoured hadrons originate from quark jets heavy flavoured hadrons originate from quark jets

CCRR is 4/3 for quarks, 3 for gluons is 4/3 for quarks, 3 for gluons

ii)ii) dead-cone effectdead-cone effect gluon radiation expected to be suppressed for gluon radiation expected to be suppressed for < M < MQQ/E/EQQ

[Dokshitzer & Karzeev,[Dokshitzer & Karzeev, Phys. Lett. Phys. Lett. B519B519 (2001) 199] (2001) 199][Armesto et al., Phys. Rev. D69 (2004) 114003][Armesto et al., Phys. Rev. D69 (2004) 114003]

2 ˆ LqCE Rs

Casimir coupling factor

transport coefficient of the medium

average energy lossdistance travelled in the medium

R.Baier et al., Nucl. Phys. B483 (1997) 291 (“BDMPS”)


4848

Experimentally...Experimentally...

non ph. el. ~ as non ph. el. ~ as suppressed as light suppressed as light hadronshadrons

use of high density use of high density (qhat), introduction of (qhat), introduction of elastic (in addition to elastic (in addition to radiative) energy loss... radiative) energy loss... not enoughnot enough

high qhat and no beauty high qhat and no beauty electrons does betterelectrons does better

[B.I. Abelev et al (STAR): nucl-ex/0607012]


4949

How much beauty?How much beauty? high phigh pTT region expected region expected

to be beauty-dominated to be beauty-dominated but how “high”?but how “high”?

[M. Cacciari et al.: PRL 95 (2005) 122001]

not easy to disentangle c/b not easy to disentangle c/b contributions to RHIC non ph. contributions to RHIC non ph. el. samples (no heavy flavour el. samples (no heavy flavour vertex detectors in RHIC vertex detectors in RHIC experiments)experiments)

[A. Suaide QM06]


5050

Vertex Detectors!Vertex Detectors!

need less indirect measurementneed less indirect measurement

full reconstruction of charm decays!full reconstruction of charm decays! get rid of b/c ambiguitiesget rid of b/c ambiguities study relative abundances in charm sectorstudy relative abundances in charm sector

Silicon Pixels in ALICE (+ ATLAS, CMS)Silicon Pixels in ALICE (+ ATLAS, CMS)

Silicon Vertex upgrades in STAR, PHENIXSilicon Vertex upgrades in STAR, PHENIX


5151

Track Impact ParameterTrack Impact Parameter

track impact parameter (dtrack impact parameter (d00): separation of secondary tracks from HF ): separation of secondary tracks from HF decays from primary vertexdecays from primary vertex


expected dexpected d00 resolution in ALICE resolution in ALICE

5252

LHC is a Heavy Flavour Machine!LHC is a Heavy Flavour Machine! cccc and and bbbb rates rates

ALICE PPR (NTLO + shadowing)ALICE PPR (NTLO + shadowing)

115 115 // 4.64.60.65 0.65 // 0.850.856.6 6.6 // 0.20.2Pb-Pb 5.5 TeV (5% Pb-Pb 5.5 TeV (5% cent)cent)

0.160.16 // 0.0070.00711 // 1111.211.2 // 0.50.5 pp 14 TeVpp 14 TeV

shadowingshadowingsystemsystem NN x-sect (mb)NN x-sect (mb) total multiplicitytotal multiplicity

PbPbpp

PbPbpp

cc bbPbPb/pp PbPb/pp


5353

large cross-sectionslarge cross-sections low-x (a field on its own!)low-x (a field on its own!) bb

RHICbbLHC

ccRHIC

ccLHC

100

25

accessible x1, x2 regions in the ALICE experimentaccessible x1, x2 regions in the ALICE experiment

central detector

muonarm


5454

Heavy Flavour Quenching?Heavy Flavour Quenching?

some prediction ...some prediction ...T

BDpp

TBD

AA

collT

BDAA dpdN

dpdN

NpR

/

/1)(

,

,,

[Armesto et al.: Phys.Rev. D71 (2005) 054027]

charm beauty


5555

DD00 K K--++

expected ALICE expected ALICE performance performance S/B ≈ 10 %S/B ≈ 10 % S/S/(S+B) ≈ 40 (S+B) ≈ 40

(1 month Pb-Pb running)(1 month Pb-Pb running)

statistical.

systematic.

ppTT - differential - differential

similar performance in ppsimilar performance in pp (wider primary vertex (wider primary vertex

spread)spread)F Antinori, CERN-Fermilab HCP Summer School, 8-17 June 2009

5656

Beauty to electronsBeauty to electrons Expected ALICE performance (1 month Pb-Pb)Expected ALICE performance (1 month Pb-Pb)

ee±± identification from TRD and dE/dx in TPC identification from TRD and dE/dx in TPC impact parameter from ITSimpact parameter from ITS

pt > 2 GeV/c , 200 < |d0| < 600 m80% purity

8 104 e from Bpt > 2 GeV/c , 200 < |d0| < 600 m

80% purity

8 104 e from B

S/(S+B)S/(S+B) S per 10S per 1077 central Pb-Pb events central Pb-Pb events


5757

Electrons (from b) pElectrons (from b) ptt spectrum spectrum

Error compositionstat error

stat syst error

11% from overall normalization not included


5858

Beauty to single muonsBeauty to single muons

expected in the muon armexpected in the muon arm

very high statistics and heavy flavour purity expectedvery high statistics and heavy flavour purity expected


5959

tDpp

tDAA

collt

DAA dpdN

dpdN

NpR

/

/1)(

tepp

teAA

collt

eAA dpdN

dpdN

NpR

/

/1)(

Expected ALICE performance Expected ALICE performance on D, B R on D, B RAAAA

mb = 4.8 GeV

D0 K B e + X

1 year at nominal luminosity(107 central Pb-Pb events, 109 pp events)

mass dependencecolour charge dependence

)()()( D from eB from e/ tAAtAAtDB pRpRpR )()()(/ t

hAAt

DAAthD pRpRpR


Well visible event-by-event! e.g. 100 GeV jet + underlying event:Well visible event-by-event! e.g. 100 GeV jet + underlying event:

study fragmentation of jets in the medium!study fragmentation of jets in the medium!6060

At LHC: At LHC: realreal jets! jets!

2 GeV 20 GeV 100 GeV 200 GeV

Mini-Jets 100/event 1/event 100k/month


6161

good performance expectedgood performance expected e.g.: in ALICEe.g.: in ALICE

black line: example radiative black line: example radiative elosseloss

dashed line: flat (e.g. dashed line: flat (e.g. “opaque”)“opaque”)

Jet Fragmentation FunctionJet Fragmentation Function

sensitive to energy loss sensitive to energy loss mechanismmechanism

e.g.: radiativee.g.: radiative

z/1ln

N. Borghini, U. Wiedemann

Increase on # of particles with low z

Decrease on # of particles with high z

Ejet ~ 125 GeV

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b tagged jets in Pb-Pb?b tagged jets in Pb-Pb?

e.g.: ATLAS u rejection (Re.g.: ATLAS u rejection (Ruu) performance in Pb-Pb) performance in Pb-Pb

H H bb, uu with M bb, uu with MHH = 400 GeV = 400 GeV

study fragmentation function in tagged quark jets!study fragmentation function in tagged quark jets!F Antinori, CERN-Fermilab HCP Summer School, 8-17 June 2009

ConclusionsConclusions Based on lattice QCD, we expect a strongly interacting system to undergo Based on lattice QCD, we expect a strongly interacting system to undergo

a deconfinement phase transition for large values of T, a deconfinement phase transition for large values of T, εε we think that our Universe was in such a QGP state for the first few µs of its lifewe think that our Universe was in such a QGP state for the first few µs of its life

Conditions of heating/compression such that deconfinement is expected Conditions of heating/compression such that deconfinement is expected can be attained in the lab by collisions of ultrarelativistic heavy nucleican be attained in the lab by collisions of ultrarelativistic heavy nuclei

You saw some chosen “vistas” from 15 years of experiments at CERN and You saw some chosen “vistas” from 15 years of experiments at CERN and BNLBNL evidence that we are dealing with a partonic system evidence that we are dealing with a partonic system but what are its properties?but what are its properties?

At the LHC, we should be able to investigate the system properties with At the LHC, we should be able to investigate the system properties with hard, calibrated probes… we are at the dawn of a new erahard, calibrated probes… we are at the dawn of a new era

What to expect?What to expect? ““It’s hard to make predictions…It’s hard to make predictions…

……especially about the future” (Robert Storm Petersen)especially about the future” (Robert Storm Petersen) ……but if the past is anything to go by, every time we pushed through a new frontier in this but if the past is anything to go by, every time we pushed through a new frontier in this

field, spectacular things happened, so…field, spectacular things happened, so…


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… … stay tuned!stay tuned!

(Thank you for your attention!)(Thank you for your attention!)

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introduction to ultrarelativistic nucleus-nucleus collisions lecture 2

Documents

nquarksf antinori

quarkoniaf antinori

hydrodynamic limitf

higher pt

ideal liquid

asymmetry extreme

elliptic flow v2recombination

azimuthal asymmetryat