heavy flavours in alice

Outline Charm and Beauty at the LHC Heavy-flavour program in ALICE

Measurements in preparation Examples of expected performance

Conclusions

Heavy Flavours in ALICE

Giuseppe E BrunoUniversità di Bari and INFN – Italy

for the ALICE collaboration

SQM08@Beijing Giuseppe E. Bruno 2

LHC

Running conditions:

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

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

Collision system

√sNN(TeV) L0 (cm-2s-1) Run time (s/year)

geom (b)

pp 14.0 1034 * 107 0.07

PbPb 5.5 1027 106 ** 7.7

pPb 8.8 1029 106 1.9

ArAr 6.3 1029 106 2.7


Heavy Flavour @ LHC cc and bb rates

NLO predictions (ALICE baseline)

* M.Mangano

beautycharm

115 / 4.60.65 / 0.856.6 / 0.2Pb-Pb 5.5 TeV (5% cent)

0.16 / 0.0071 / 111.2 / 0.5 pp 14 TeV

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

factor ~2uncertainty


Probe unexplored small-x region with HQs at low pt and/or forward y

Charm measurements at low-pt or forward y

Window on high-density PDFs phenomenology: gluon saturation / recombination effects / CGC

The charm of small-x gluons

Cartoon

char

mbea

uty

D mesons pt0, y=0 J/ pt0, y4

x~10-4x~10-6

s=14 TeV

s=14 TeV


Charm & beauty as probes calculable in pQCD; calibration measurement from

pp rather solid ground

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

pA reference fundamental!

produced essentially in initial impact probes of high density phase

no extra production at hadronization probes of fragmentation

e.g.: independent string fragmentation vs recombination


Probing the medium quenching vs colour charge

heavy flavour from quark (CR = 4/3) jets light flavour from (pT-dep) mix of quark and gluon (CR

= 3) jets

quenching vs mass heavy flavour predicted to suffer less energy loss

gluonstrahlung collisional loss

beauty vs charm


Quarkonia at LHC: (cc) & (bb) J/ suppression & regeneration? c, ’ suppression (J/ TD ~ 1.5-2 Tc)?

SPSRHICLHC

30

enhanced suppression

enhanced regeneration

TLHC >> J/ TD

melts only at LHC ’ TD ~ J/ TD Small regeneration

’ can unravel J/ suppression VS regeneration

SQM08@Beijing Giuseppe E. Bruno 8Physics at LHC - Philippe Pillot

MUON Spectrometer

Acceptance: η<|0.9|• (di)electrons: J/, ’, , ’, ’’ open charm & beauty• hadrons: D±, D0, …

Acceptance: -4<η<-2.5• (di)muons: J/, ’, , ’, ’’ open charm & beauty

• electron-muon coincidences: open charm & beauty

8

TOFPIDTOFPID

TRDElectron IDTRDElectron ID

ITSVertexing,Low pt tracking

ITSVertexing,Low pt tracking

TPCTracking, dE/dxTPCTracking, dE/dx

The ALICE detector

99

ALICE StatusComplete: ITS, TPC, TOF, HMPID,FMD, T0, V0, ZDC, Muon arm, Acorde

Partial installation:1/5 PHOS 4/18 TRD 9/48 PMD0/6 EMCAL

~ 40% DAQ/HLT

ALICE Detector Installation mid 2008

Installation targets met by mid 2008


Hadronic charm

TPC (tracking)

TOF (K/ id)

ITS (vertexing)

K

D0 K D+ K Ds KK D* D0 D0 K c Kp

understudy

D0


Impact parameter resolution

d0 = distance of closest approach between track and primary vertex

d0 resolution mainly provided by the two innermost layers of the ITS (pixels) R=4 and 7 cm, ~107 channels

pixel size

50425 m

BEAM (Z)PIXEL CELL

z: 425 m

r: 50 m

Two layers:r = 4 cmr = 7 cm

Silicon Pixel Detector

Impact parameter

< 50 m for pt > 1.5 GeV

d0 resolution


pair of opposite-charge tracks with large impact parameters

good pointing of reconstructed D momentum to the primary vertex

D0

Charm reconstruction: D0 K-+

Invariant mass analysis

Two vertexing algorithms with full error-matrix treatment Large combinatorial background (dNch/dy=6000 in Pb-Pb simul.) Main selection: displaced-vertex selection

system pp pPb PbPb

s (TeV) 14 8.8 5.5

trig MB MB CC

Nevt 109 108 107

time (months) 8 1 1

pt min (GeV/c) 0.5 0.5 1

Estat (%) 3 2 7

Esyst (%) 14 16 17


Beauty from single electrons

ITS (vertexing)TPC (tracking + e/ id)TRD (e/ id)

e

PrimaryVertex B

e

Xd0

rec. track

Be+X


Expected ALICE performance (1 month Pb-Pb) e± identification from TRD and dE/dx in TPC impact 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

Beauty in the barrel:displaced e’s

Error compositionstat error

stat syst error

11% from overall normalization not included


Beauty from displaced J/

TPC (tracking + e/ id)

TRD (e/ id)

ITS (vertexing)

e+ e

y

x

B

e+

e-

J X

BJ/+X

e-e+


Beauty in the barrel:

Even

ts/1

0 M

eV

109 pp events

350

300

250

200

150

100

50

2.8 2.9 3.0 3.1 3.2

m(e+,e-) [GeV]

Even

ts/1

0 M

eV

totJ/bkg

34BS

S

displaced J/e-e+

Analysis based on a simultaneous fit of

1. the invariant mass spectrum


Beauty in the barrel:

)/()/( /

Jp

MJLx

T

Jxy

displaced J/e-e+

Analysis based on a simultaneous fit of

1. the invariant mass spectrum2. an “impact parameter” to

separate prompt from detached J/e.g. pseudo- proper decay time (à la CDF) D.Acosta et al Phys. Rev. D 71 (2005) 032001

This measurements can allow a determination of the dbb/dpt cross-section down to pt≈0

)/(

)/()/(

Jp

JpLJL

T

Txy

prim

vtxsec

vtx rrL

pT>0

-2000 -1000 0 1000 2000 3000x [m]

102

10

1Entr

ies/

10

0m

103 2<pT<3 Gev

-2000 -1000 0 1000 2000 3000x [m]

102

10

1Entr

ies/

10

0m

pT>5 Gev

x [m]-2000 -1000 0 1000 2000 3000

102

10

1Entr

ies/

10

0m

CDF

tot J/J/ from B

bkg

sum

ALICE

109 pp events


tDpp

tDAA

collt

DAA dpdN

dpdN

NpR

/

/1)(

tepp

teAA

collt

eAA dpdN

dpdN

NpR

/

/1)(

Expected performance on D, B RAA

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 mechanism

mass dependencecolour charge dependence

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

hAAt

DAAthD pRpRpR


ITS (vertexing)TPC (tracking)TRD (e/ id)

MUON (tracking,id)

e e

Quarkonia

Measured both in the di-electron (midrapidity, TRD) and di-muon (forward rapidity, MUON) channel

20

Particle Charmonia +- Charmonia e+e- Bottonia +- Bottonia e+e-

Bkg-subtracted

mass plot

acc. -4 < < -2.5 || < 0.9 -4 < < -2.5 || < 0.9

M res. 65 MeV 35 MeV 90 MeV 90 MeV

J/ 150, ’ 7 J/ 245 30, ’ 12,

’’ 8 21, ’ 8

perf. , ?’ , ??’ , ’, ?’’ , ?’, no ’’

pt J/ 0-20 GeV J/ 0-10 GeV 0-8 GeV --

Quarkonia PerformanceBkg input: dNch/dy=4000 in central Pb-Pb. for 1 month

BS

S

BSS /


Many other channels

charm: exclusive hadronic channels

• D0 K (tested in pp & PbPb)

• D+ K (tested in pp & PbPb)

• D±s KK (under study)

• D* D0 (under study)

• D0 K (under study)

• c pK (under study)

charm & bottom: semi-inclusive leptonic channels

• c l + X (à la CDF & D0)

• b l + X (à la CDF & D0)

• b J/ + X (à la CDF & D0)

• bbbar J/ + l (under study)

• bbbar 3 (should work in pp)

• bbbar l+l-,l-l+ (Bchain & BBdiff)

• bbbar l-l-,l+l+ (Bchain & B osc.)


Summary

LHC: heavy quarks and quarkonia factory Heavy quarks as probes of QCD in extreme conditions

low pt: probe small-x structure of p and nucleus intermediate pt: probe medium thermalisation (reco/flow) high pt: probe medium density via energy loss

Charmonia & bottomonia as probes of QCD phase transition

ALICE in excellent position: dedicated detectors promising performance for all key measurements


Thank you

First interaction in ALICE: 11.9.2008(beam – pixel collisions)

heavy flavours in alice

Documents

alice measurements

alice statuscomplete

lmax alice

lint alice

expected alice performance

y suppression j td

dedxthe alice detectorgiuseppe

lhc td