1 fa - him, seoul - 18 april 2007 heavy flavours and heavy-ion collisions: status and alice...

11

FA - HIM, Seoul - 18 April 2007FA - HIM, Seoul - 18 April 2007

Heavy Flavours Heavy Flavours andand Heavy-Ion Collisions: Heavy-Ion Collisions: Status and ALICE Status and ALICE

PerspectivesPerspectivesFederico AntinoriFederico Antinori

INFN Padova & CERNINFN Padova & CERN

FA - HIM, Seoul - 18 April 2007FA - HIM, Seoul - 18 April 2007 22

ContentsContents

Heavy Flavours Heavy Flavours as medium probes in AA collisionsas medium probes in AA collisions

decaysdecays

production in QCDproduction in QCD

in p/in p/-A-A

fragmentationfragmentation

at Tevatronat Tevatron

in AAin AA

in ALICEin ALICE

33


Intro: Heavy Flavours Intro: Heavy Flavours as as medium probesmedium probes in AA in AA

collisionscollisions


Charm & beauty: ideal probesCharm & beauty: ideal probes

calculable in pQCD; calibration measurement from ppcalculable in pQCD; calibration measurement from pp rather solid groundrather solid ground

caveat: modification of initial state effects from pp to AAcaveat: modification of initial state effects from pp to AA shadowing ~ 30 %shadowing ~ 30 % saturation?saturation?

pA reference fundamentalpA reference fundamental!!

produced essentially in initial impactproduced essentially in initial impact probes of high density phaseprobes of high density phase

no extra production at hadronizationno extra production at hadronization probes of fragmentation probes of fragmentation

e.g.: independent string fragmentation vs recombinatione.g.: independent string fragmentation vs recombination


Heavy Flavour QuenchingHeavy Flavour Quenching

quenching vs colour chargequenching vs colour charge heavy flavour from quark (Cheavy flavour from quark (CRR = 4/3) jets = 4/3) jets light flavour from (plight flavour from (pTT-dep) mix of quark and gluon (C-dep) mix of quark and gluon (CRR = 3) jets = 3) jets

quenching vs massquenching vs mass heavy flavour predicted to suffer less energy lossheavy flavour predicted to suffer less energy loss

gluonstrahlung: dead-cone effectgluonstrahlung: dead-cone effect beauty vs charmbeauty vs charm

heavy flavour should provide a fundamental tool to heavy flavour should provide a fundamental tool to investigate the properties of the medium formed in investigate the properties of the medium formed in heavy-ion collisionsheavy-ion collisions

at LHC: high stats and fully developed jetsat LHC: high stats and fully developed jets

66


Heavy Flavour Heavy Flavour DecaysDecays


Some zoology...Some zoology...

Lower mass heavy flavour hadrons decay weakly Lower mass heavy flavour hadrons decay weakly ~ ps~ ps cc ~ 100’s µm ~ 100’s µm

weakly decaying states from PDG 2006 summary tables:weakly decaying states from PDG 2006 summary tables:

µm 21c MeV 2698m )(

µm 34c MeV 2472m )(

µm 132c MeV 2466m )(

µm 60c MeV 2285m )(

µm 147c MeV 1968m )(

µm 123c MeV 1865m )(

µm 312c MeV 1869m )(

0

0

0

ssc

dsc

usc

udc

scD

ucD

dcD

c

c

c

c

s

µm 368c MeV 5624m )(

µm 200001c GeV 6.4 m )(

µm 438c MeV 5370m )(

µm 460c MeV 5279m )(

µm 501c MeV 5279m )(

0

0

0

udb

bcB

bsB

bdB

buB

b

c

s


Impact parameter ~ cImpact parameter ~ c

In UR limit In UR limit bb ~ Lorentz invariant: ~ Lorentz invariant:

... so b ~ independent of ... so b ~ independent of

if cos if cos CMCM distribution is flat: distribution is flat:

so, in space,so, in space,

in projection:in projection:

so:so:

primary vertexprimary vertex

decay vertexdecay vertex

decay length = Ldecay length = L

impact parameter =

impact parameter = bb

,

1

e)proper tim(

CMCM

LAB

CMLAB

ctctLb

tctL

2)sin(

2

1

)sin(2

1)(

0

CMCMCMCM

CMCMCMCM

d

ddf bdbd

df

bd

2cos

1

;1

)(

cos

2/

2/

cc CM 2b

yy

xx

dd

bb

cd


Weak decays of charmWeak decays of charm typically:typically:

large branching ratio to kaonslarge branching ratio to kaons:: DD++: :

DD++ K K--+X BR ~ 28 %+X BR ~ 28 % ““golden” channel: Dgolden” channel: D++ K K--++++ BR ~ 9% BR ~ 9%

DD00:: DD00 K K--+X BR ~ 50%+X BR ~ 50% ““golden” channels: Dgolden” channels: D00 K K--++ BR ~ 4% ; D BR ~ 4% ; D00 K K--++++-- BR ~ 7% BR ~ 7%

WW±± branchings: branchings:

large semileptonic branching ratio, varies with heavy flavour large semileptonic branching ratio, varies with heavy flavour particle, typical ~ 10%particle, typical ~ 10%~ 10% heavy flavour hadrons give in final state an e~ 10% heavy flavour hadrons give in final state an e±± (and ~ 10% a µ (and ~ 10% a µ±±))

(and with a respectable p(and with a respectable pTT...)...)

cc s’s’

WW++

dsdss CC 22.097.0sincos'

cc s’s’

WW++uu

d’d’

ee++

ee

µµ++

µµ

bb cc

WW--

(similarly: )(similarly: )

CC = “Cabibbo angle” = “Cabibbo angle”


Experimental toolsExperimental tools

Silicon vertex detectors:Silicon vertex detectors: so: tracks from heavy flavour weak decays typically “miss” so: tracks from heavy flavour weak decays typically “miss”

primary vertex by ct ~ 100’s µmprimary vertex by ct ~ 100’s µm impact parameter res. of typical heavy flavour apparatus ~ impact parameter res. of typical heavy flavour apparatus ~

10’s µm10’s µm

ee±± and/or µ and/or µ ±± identification identification

charged kaon identificationcharged kaon identification

primary vertexprimary vertex

decay vertexdecay vertex

decay length = Ldecay length = L

impact parameter =

impact parameter = bb

WA92:WA92:Si µstripsSi µstrips

[Adamovich et al.: NIM A 379 (1996) 252][Adamovich et al.: NIM A 379 (1996) 252]

1111


Heavy Flavour Heavy Flavour Production in Production in QCDQCD


Heavy Flavour hadro-production in Heavy Flavour hadro-production in pQCDpQCD

Factorization:Factorization:

)()( // bBbaAa xGxG )ˆ(ˆ sxxs baccab )(/ zD cD DXAB

XDBA hadronhadron hadronhadron charmedcharmed

hadronhadron

cross-section at parton level

e.g.:parton distribution functions

xa = momentum fraction of

parton a in hadron A

fragmentation

z = fraction of c momentum to hadron D

cross-section at hadron level

a=q

b=q Q

Q

(at sufficiently large Q(at sufficiently large Q22))


factorization implies:factorization implies: PDFs can be measured with one reaction... PDFs can be measured with one reaction...

say: Drell-Yan: A+B say: Drell-Yan: A+B e e++ee- - + X + X

... and used to calculate a different one ... and used to calculate a different one say: heavy-flavour productionsay: heavy-flavour production

fragmentation independent of the reaction (e.g.: same in pp, fragmentation independent of the reaction (e.g.: same in pp, ee++ee--) )

)()( // bBbaAa xGxG )ˆ(ˆ sxxs baccab )(/ zD cD DXAB


Leading-order (LO)Leading-order (LO)

Relevant diagrams: pair creationRelevant diagrams: pair creation qq qq QQ QQ (quark-antiquark annihilation)(quark-antiquark annihilation)

gggg QQ QQ (gluon-gluon fusion)(gluon-gluon fusion)

q

q Q

Q

Q

Qg

g Q

Qg

gQ

Qg

g


A few resultsA few results the partonic cross-section decreases with energythe partonic cross-section decreases with energy

faster for qq than for gg (which therefore is expected to dominate, faster for qq than for gg (which therefore is expected to dominate, except near threshold)except near threshold)

the parton luminosities near threshold increase with energy, the parton luminosities near threshold increase with energy,

the cross section increases with the energy of the hadron-hadron the cross section increases with the energy of the hadron-hadron collisioncollision

the pair cross section is proportional to:the pair cross section is proportional to:

y (y): rapidity of Q (Q)y (y): rapidity of Q (Q)

Q and Q therefore expected to be close in yQ and Q therefore expected to be close in y

Experimentally: EHS, 360 GeV Experimentally: EHS, 360 GeV --p p DDX DDX

2)]cosh(1[

1

yy

z

z

pE

pEy log2

1

[EHS: PLB 123 (1983) 98]


Next-To-Leading-Order (NTLO)Next-To-Leading-Order (NTLO) in absolute value, LO cross sections are typically underestimated in absolute value, LO cross sections are typically underestimated

by factor 2.5 - 3 (“K factor”)by factor 2.5 - 3 (“K factor”)

at NTLO: additional diagrams, such as:at NTLO: additional diagrams, such as:

Q

Q

Q

Q

Q

Q

higher order corrections to pair creationhigher order corrections to pair creation

flavour excitationflavour excitation

gluon splittinggluon splitting


the agreement with experiment for the total cross-the agreement with experiment for the total cross-section is good (within large bands...)section is good (within large bands...) e.g.: charm cross section at fixed target:e.g.: charm cross section at fixed target:

[Mangano: hep-ph/9711337]


results depend on the values of:results depend on the values of: mmcc, µ, µRR (renormalization scale), µ (renormalization scale), µFF (factorization scale) (factorization scale)

the result of an exact calculation would be the result of an exact calculation would be independent of the choice of the scale parameters µindependent of the choice of the scale parameters µRR, , µµFF

the residual scale dependence is a measure of the accuracy of the residual scale dependence is a measure of the accuracy of the calculationthe calculation

e.g.: for b production at Tevatron (µe.g.: for b production at Tevatron (µRR=µ=µFF=µ):=µ):

[Mangano: hep-ph/9711337]


it is important to match the PDFs with the order of the it is important to match the PDFs with the order of the calculation.calculation.

e.g. one must avoid double counting:e.g. one must avoid double counting: at LO:at LO:

at NTLO:at NTLO:

“intrinsic flavour”

“flavour excitation”Q

Q

QQ

2020


Heavy Flavour in Heavy Flavour in p/p/-A-A


Nuclear shadowingNuclear shadowing PDFs in the nucleus different from PDFs in free protonPDFs in the nucleus different from PDFs in free proton

R = ratio of nuclear to nucleon PDFs R = ratio of nuclear to nucleon PDFs from Deep Inelastic Scattering (efrom Deep Inelastic Scattering (e--+p; e+p; e--+A), Drell-Yan (p+p, p+A -> +A), Drell-Yan (p+p, p+A -> l l ++l l --

+X)+X)

e.g.: e.g.: R for gluons vs R for gluons vs gluon momentum gluon momentum fraction fraction xxfrom EKS parametrization from EKS parametrization [Eskola et al.: EPJ C9 (1999) 61][Eskola et al.: EPJ C9 (1999) 61]

typical typical xx for cc production ( for cc production (yy 0)0) xx 10 10-1-1 @ SPS @ SPS xx 10 10-2-2 @ RHIC @ RHIC xx a few 10 a few 10-4-4 @ LHC @ LHC

shadowing

antishadowing

SPSSPS

RHICRHIC

LHCLHC


Nuclear dependenceNuclear dependence

From pQCD one expects the cross section for production off From pQCD one expects the cross section for production off nuclei to increase like number of nucleon-nucleon collisions nuclei to increase like number of nucleon-nucleon collisions

(“binary collision scaling”) (“binary collision scaling”) proportional to number of nucleons (for min. bias collisions):proportional to number of nucleons (for min. bias collisions):

modulo shadowing effects, expected to be smallmodulo shadowing effects, expected to be small

Experimentally: not far... e.g. WA82: Experimentally: not far... e.g. WA82: D production in D production in --+W/Si at SPS (340 GeV beam momentum)+W/Si at SPS (340 GeV beam momentum) (relatively) central production(relatively) central production

AQQQQ

A

)()(

0 with =1

06.092.0 s

pppx z

zzF

2/ max 24.0 @ Fx

“Feynman’s x”


Caveats...Caveats...

i) i) = 1 does not work down to pp! = 1 does not work down to pp!

e.g.: MacDermott & Reucroft e.g.: MacDermott & Reucroft [PLB 184 (1987) 108] compare pA results compare pA results with earlier hydrogen data from NA27, good agreement using:with earlier hydrogen data from NA27, good agreement using:

note: similar situation for light flavours! note: similar situation for light flavours!

systematic study by Barton et al. systematic study by Barton et al. [PRD 27 (1983) 2580],[PRD 27 (1983) 2580], for various for various reactions at 100 GeV FT reactions at 100 GeV FT

e.g.: central for production of e.g.: central for production of , K, p from p on nuclear targets:, K, p from p on nuclear targets:

ccpp

cc 0

AK ccpp

ccpA 0 5.1 ,1 0 K

6.0 25.10 Kwith


ii) lower ii) lower at large x at large xFF?? early beam dump experiments, sensitive at large xearly beam dump experiments, sensitive at large xFF (max acceptance for x (max acceptance for xFF

0.5)0.5)

(in tracking experiments, typically max. acceptance for x(in tracking experiments, typically max. acceptance for xFF 0.2) 0.2)

e.g. WA78 [Cobbaert et al.: PLB 191 (1987) 456]e.g. WA78 [Cobbaert et al.: PLB 191 (1987) 456]

for muons escaping dump (for muons escaping dump (--A at 320 GeV FT ):A at 320 GeV FT ):

note: note: is known to decrease is known to decrease

with xwith xFF for light hadrons for light hadrons

06.083.0)(

08.076.0)(

4.0Fx

[Barton et al.: PRD 27 (1983) 2580][Barton et al.: PRD 27 (1983) 2580]

2525


Heavy Flavour Heavy Flavour FragmentationFragmentation


Fragmentation functionFragmentation function

c c D, D takes fraction D, D takes fraction zz of c momentum of c momentum fragmentation function: Dfragmentation function: DD/cD/c((zz)) depends only on fraction zdepends only on fraction z e.g.:e.g.:

2/ )]1/(/11[

1)(

zzzzD cD

Peterson

zzzD cD )1()(/ Colangelo-Nason

Peterson ( = 0.015)

Colangelo-Nason ( = 0.9, =6.4)

e.g.: (parameters from fits to charm production at LEP)


How to measure the fragmentation function?How to measure the fragmentation function? we don’t measure the original we don’t measure the original QQ momentum ... momentum ... but in ebut in e++ee-- we do know the we do know the QQ energy (by energy energy (by energy

conservation!)conservation!) e.g.:e.g.:

fragmentation functions are usually extracted from efragmentation functions are usually extracted from e++ee-- measurements and then used for other collisionsmeasurements and then used for other collisions

e-

Q

Q

e+

Z0


e.g.: fits to charm x = 2E/e.g.: fits to charm x = 2E/s distributions in es distributions in e++ee--::[Cacciari & Greco: PRD55 (1997) 7134][Cacciari & Greco: PRD55 (1997) 7134]

very similar parameters at the two very similar parameters at the two energies (as expected)energies (as expected)

s = 10.6 GeV (ARGUS) s = 91.2 GeV (OPAL)

Peterson fragmentation

= 0.015 (OPAL)

= 0.019 (ARGUS)


like for the PDFs, the fragmentation function has to be matched like for the PDFs, the fragmentation function has to be matched to order of pQCD calculationto order of pQCD calculation e.g. at NTLO the e.g. at NTLO the QQ can radiate: can radiate:

so final energy before so final energy before

non-perturbative part of non-perturbative part of

fragmentation lower than at LO fragmentation lower than at LO harder fragmentation at NTLOharder fragmentation at NTLO

at NTLO: at NTLO: 0.015 0.015 at LO: at LO: 0.06 0.06

(e.g.: (e.g.: [Cacciari & Greco: PRD55 (1997) 7134][Cacciari & Greco: PRD55 (1997) 7134]))

Peterson fragmentation

= 0.015 (NTLO)

= 0.06 (LO)

Q

Q

3030


Heavy Flavour at Heavy Flavour at TevatronTevatron


Beauty at TevatronBeauty at Tevatron Discrepancy between pQCD and data seems to have disappeared...Discrepancy between pQCD and data seems to have disappeared...

from...from...

a factor 5.5 (but only 1.6 a factor 5.5 (but only 1.6 ...) ...) to...to...

[CDF: PRL 68 (1992) 3403][CDF: PRL 68 (1992) 3403]

Run 0Run 0

Run IIRun II

[Cacciari et al: JHEP 0407 (2004)][Cacciari et al: JHEP 0407 (2004)]

Spectrum of J/Spectrum of J/ from secondary B decays from secondary B decays


From run I on, important improvements in accuracy:From run I on, important improvements in accuracy: experiment (vertex detectors, high statistics)experiment (vertex detectors, high statistics) prediction (post-HERA PDF sets)prediction (post-HERA PDF sets)

Levels of stability over time:Levels of stability over time:

no large room for new physics any more...no large room for new physics any more... for more see, e.g.: for more see, e.g.:

[Cacciari et al: JHEP 0407 (2004) 033, Cacciari: hep-ph/0407187, Mangano: hep-ph/0411020][Cacciari et al: JHEP 0407 (2004) 033, Cacciari: hep-ph/0407187, Mangano: hep-ph/0411020]

DataData PredictionsPredictions

from [Cacciari et al: JHEP 0407 (2004) 033]from [Cacciari et al: JHEP 0407 (2004) 033]


What about charm?What about charm?

Nice data from CDF run IINice data from CDF run II

[CDF: Phys.Rev.Lett. 91 (2003) 241804][CDF: Phys.Rev.Lett. 91 (2003) 241804]

roughly in agreement with full roughly in agreement with full pQCD calculationpQCD calculation

(though prediction somewhat low)(though prediction somewhat low)

A curiosity (?):A curiosity (?):

good agreement between data good agreement between data and prediction for bare quarkand prediction for bare quark

[Vogt: talk at SQM 2004][Vogt: talk at SQM 2004]

3434


Heavy Flavour in Heavy Flavour in AAAA


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


PHENIX ppPHENIX pp

Excess wrt FONLL:Excess wrt FONLL:

Similar situation also in CDF:Similar situation also in CDF:

[A. Adare et al. (PHENIX) Phys.Rev.Lett. 97 (2006) 252002]

Ratio: 1.72 0.02 (stat) 0.19 (sys)(0.3 < pT < 9.0 GeV/c)

D0

[D. Acosta et al. (CDF) PRL 91 (2003) 241804]


STAR v PHENIX ppSTAR v PHENIX pp

~ a factor 2 discrepancy~ a factor 2 discrepancy

hep-ex/0609010

[J. Lajoie (PHENIX) QM06]


STAR dAu, AuAuSTAR dAu, AuAu

Internal consistencyInternal consistency

[M. Calderon (STAR) QM06]


STAR v PHENIX dAu, AuAuSTAR v PHENIX dAu, AuAu Discrepancy pretty “stable” v system, pDiscrepancy pretty “stable” v system, pTT

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

looks like something very basic...looks like something very basic... of course then Rof course then RAAAA not too different... not too different...

[A. Suaide QM06]


STAR v PHENIX: RSTAR v PHENIX: RAAAA

RRAAAA of non-photonic electrons of non-photonic electrons

[A. Suaide QM06]

similar picture from STAR and PHENIXsimilar picture from STAR and PHENIX


Heavy flavour energy loss?Heavy flavour energy loss?

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 predominantly from gluon jets, light hadrons originate predominantly from gluon jets, heavy flavoured hadrons originate from heavy quark jets heavy flavoured hadrons originate from heavy 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”)


Large suppression at RHIC!Large suppression at RHIC!

yet, region above 3-4 GeV yet, region above 3-4 GeV expected to be dominated expected to be dominated by beauty...by beauty...

[Xin Dong@QM05]

n.p. electrons ~ as suppressed as n.p. electrons ~ as suppressed as expected for c only (no b)expected for c only (no b)

scaled to

M. Cacciari et al., hep-ph/0502203

[J.Bielcik @QM05] disentangling c/b is a mustdisentangling c/b is a must!!

e.g. full reconstruction of D verticese.g. full reconstruction of D vertices

4343


Heavy Flavour in Heavy Flavour in AliceAlice


LHCLHC

Running conditions: Running conditions:

+ other ions (Sn, Kr, O) & energies (e.g.: pp @ 5.5 TeV)+ other ions (Sn, Kr, O) & energies (e.g.: pp @ 5.5 TeV)

*Lmax (ALICE) = 1031 ** Lint (ALICE) ~ 0.5 nb-1/year

Collision systemCollision system √√ssNNNN(TeV)(TeV) LL0 0 (cm(cm-2-2ss-1-1)) Run time Run time (s/year)(s/year)

geomgeom (b) (b)

pppp 14.014.0 101034 34 ** 101077 0.070.07

PbPbPbPb 5.55.5 10102727 101066 ** ** 7.77.7

pPbpPb 8.88.8 10102929 101066 1.91.9

ArArArAr 6.36.3 10102929 101066 2.72.7

4545

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% cent)Pb-Pb 5.5 TeV (5% 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


ALICE Set-ALICE Set-upup

HMPID

Muon Arm

TRD

PHOS

PMD

ITS

TOF

TPC

Size: 16 x 26 meters

Weight: 10,000 tons


|η| < 0.9:B = 0.4 TTRDTPCITS with: - Si pixel- Si drift- Si strip

TrackingTracking


PIXEL CELL

z: 425 m

r: 50 m

Two layers:r = 4 cmr = 7 cm

9.8 M

Full reconstruction of D decaysFull reconstruction of D decays

expected dexpected d00 resolution resolution (() )

ALICE Silicon PixelsALICE Silicon Pixels


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 spread)(wider primary vertex spread)


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


tDpp

tDAA

collt

DAA dpdN

dpdN

NpR

/

/1)(

tepp

teAA

collt

eAA dpdN

dpdN

NpR

/

/1)(

Expected performance on D, B Expected performance on D, B RRAAAA

mb = 4.8 GeV

D0 K B e + X

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

should clarify the heavy flavour quenching storyshould clarify the heavy flavour quenching story

mass dependencecolour charge dependence

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

hAAt

DAAthD pRpRpR


Heavy Flavour vHeavy Flavour v22

vv22 = azimuthal anisotropy = azimuthal anisotropy elliptic flow elliptic flow

can get charm vcan get charm v22 from from direct charm elliptic flowdirect charm elliptic flow non-flowing c recombining with flowing matternon-flowing c recombining with flowing matter azimuthally dependent energy lossazimuthally dependent energy loss ...?...?

in general, vin general, v22 0 if charm “strongly coupled” with azimuthally 0 if charm “strongly coupled” with azimuthally asymmetric medium...asymmetric medium...


puzzle: at QM`05 different results from PHENIX and STAR...puzzle: at QM`05 different results from PHENIX and STAR...

[F.Laue@QM`05]

PHENIX:PHENIX: subtraction of conversions by subtraction of conversions by

converter method and cocktail converter method and cocktail

STAR:STAR: rejection of conversions by inv. mass rejection of conversions by inv. mass

combinationscombinations @ RIKEN-BNL heavy flavour workshop @ RIKEN-BNL heavy flavour workshop

in december STAR said measurement in december STAR said measurement affected by “too much photonic affected by “too much photonic background”background”

electron v2 at RHICelectron v2 at RHIC


question:question:to what extent can one accommodate small vto what extent can one accommodate small v22 with large with large suppression?suppression?

[S.Butsyk@QM`05]

[Xin Dong@QM05]


Charm vCharm v22 at LHC? at LHC?

Full reconstruction of D decays at LHC Full reconstruction of D decays at LHC qualitatively different measurement from non-photonic electrons!qualitatively different measurement from non-photonic electrons! better correlation with original heavy-quark momentum better correlation with original heavy-quark momentum b vs cb vs c

First indications from preliminary studies in ALICE: First indications from preliminary studies in ALICE: expected error ~ few % (D vexpected error ~ few % (D v22))


DDss++

DDss++

as probe of hadronization?as probe of hadronization? from string fragmentation: cs / cd ~ 1/3from string fragmentation: cs / cd ~ 1/3

after decays: Dafter decays: Dss++ (cs) / D (cs) / D++ (cd) ~ 0.6 (cd) ~ 0.6

from recombination: cs / cd ~ N(s) / N(d)from recombination: cs / cd ~ N(s) / N(d) how large at LHC?how large at LHC?

experimentally accessible?experimentally accessible? DD++ (c (c ~ 310 µm) ~ 310 µm) K K--++++ with BR ~ 9.2 % with BR ~ 9.2 %

in Alice: probably similar performance as for Din Alice: probably similar performance as for D00 K K--++

DDss++ (c (c ~ 150 µm) ~ 150 µm) K K--KK++++ with BR ~ 4.4 % with BR ~ 4.4 %

but mostly resonant decays: but mostly resonant decays: ++ or K or K00**KK++ (non resonant only 20 %) (non resonant only 20 %)

favours bkgnd rejection (for Dfavours bkgnd rejection (for D++ K K--++++, non-resonant ~ 96 %), non-resonant ~ 96 %) may be well visible (expecially if Dmay be well visible (expecially if Dss

++/D/D++ is large!) is large!)

DDss v v22 would be particularly interesting! would be particularly interesting!


Heavy flavour jets?Heavy flavour jets? 2 GeV 20 GeV 100 GeV 200 GeV

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

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

For high energy jets: For high energy jets: Nb ~ Nu,dNb ~ Nu,d

heavy flavour rich!heavy flavour rich!

b-tagged jets?b-tagged jets? study quenching of b study quenching of b

jets!jets!


Away side cone?Away side cone?

Collective behaviour Collective behaviour opposite to jet?opposite to jet? eg: Mach cone eg: Mach cone

[Casalderrey-Solana, et al.: hep-ph/0411315][Casalderrey-Solana, et al.: hep-ph/0411315]

[Stocker: Nucl.Phys. A750 (2005) 121])[Stocker: Nucl.Phys. A750 (2005) 121])

What happens with big-fat-heavy quark jets?What happens with big-fat-heavy quark jets?

PHENIX Preliminary

*=

*=

John Lajoie @ QM2006


Modified Mach cone?Modified Mach cone?

Heavy quarks at moderate pHeavy quarks at moderate pTT move with substantially lower move with substantially lower speedspeed

e.g.: for beauty, taking:e.g.: for beauty, taking: ccSS

22 = 0.2 = 0.2 m(b) = 4.5 GeVm(b) = 4.5 GeV

b quark is “subsonic” b quark is “subsonic”

for pfor p < 2.25 GeV< 2.25 GeV for p ~ 3-4 GeV, for p ~ 3-4 GeV,

shock wave angle ~ 40shock wave angle ~ 40OO

[FA, E Shuryak: J.Phys. G31 (2005) 19][FA, E Shuryak: J.Phys. G31 (2005) 19]

p(b) [GeV]

shoc

k w

ave

angl

e [d

egre

es]

Now: Now:

observing THAT observing THAT

would be something!would be something!


ConclusionConclusion

Heavy flavours kindly provide us with a very Heavy flavours kindly provide us with a very promising tool to study the properties of the strongly promising tool to study the properties of the strongly interacting medium produced in ultra-relativistic interacting medium produced in ultra-relativistic nucleus-nucleus collisionsnucleus-nucleus collisions

LHC is the place to be LHC is the place to be very high ratesvery high rates ppTT reach reach recombination?recombination? jets?jets?

ALICE is well equipped for heavy flavour physicsALICE is well equipped for heavy flavour physics

1 fa - him, seoul - 18 april 2007 heavy flavours and heavy-ion collisions: status and alice...

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