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Outline Charm and Beauty at the LHC Heavy-flavour program in ALICE
Measurements in preparation Examples of expected performance
Conclusions
Heavy Flavours in ALICEGiuseppe E Bruno
Università di Bari and INFN – Italyfor 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 0.07PbPb 5.5 1027 106 ** 7.7pPb 8.8 1029 106 1.9ArAr 6.3 1029 106 2.7
SQM08@Beijing Giuseppe E. Bruno 3
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
SQM08@Beijing Giuseppe E. Bruno 4
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 charm
beauty
D mesons pt0, y=0 J/ pt0, y4
x~10-4 x~10-6
s=14 TeV
s=14 TeV
SQM08@Beijing Giuseppe E. Bruno 5
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
SQM08@Beijing Giuseppe E. Bruno 6
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
SQM08@Beijing Giuseppe E. Bruno 7
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
TOFPID
TRDElectron ID
ITSVertexing,Low pt tracking
TPCTracking, 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
SQM08@Beijing Giuseppe E. Bruno 10
Hadronic charm
TPC (tracking)
TOF (K/ id)
ITS (vertexing)K
D0 K D+ K Ds KK D* D0 D0 K c Kp
understudy
D0
SQM08@Beijing Giuseppe E. Bruno 11
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
SQM08@Beijing Giuseppe E. Bruno 12
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
SQM08@Beijing Giuseppe E. Bruno 13
Beauty from single electrons
ITS (vertexing)TPC (tracking + e/ id)TRD (e/ id)
e
PrimaryVertex B
e
Xd0
rec. track
Be+X
SQM08@Beijing Giuseppe E. Bruno 14
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 m 80% purity8 104 e from B
pt > 2 GeV/c , 200 < |d0| < 600 m 80% purity8 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
SQM08@Beijing Giuseppe E. Bruno 15
Beauty from displaced J/
TPC (tracking + e/ id)
TRD (e/ id)
ITS (vertexing)e+ e
y
xB
e+
e-
J X
BJ/+X
e-e+
SQM08@Beijing Giuseppe E. Bruno 16
Beauty in the barrel:
Even
ts/1
0 M
eV
109 pp events350300250200150100
50
2.8 2.9 3.0 3.1 3.2m(e+,e-) [GeV]
Even
ts/1
0 M
eV
totJ/bkg
34 BSS
displaced J/e-e+
Analysis based on a simultaneous fit of
1. the invariant mass spectrum
SQM08@Beijing Giuseppe E. Bruno 17
Beauty in the barrel:
)/()/( /
JpM
JLxT
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
)/()/()/(
JpJpLJL
T
Txy
prim
vtxsec
vtx rrL
pT>0
-2000 -1000 0 1000 2000 3000x [m]
102
10
1Entri
es/1
00m
103 2<pT<3 Gev
-2000 -1000 0 1000 2000 3000x [m]
102
10
1Entri
es/1
00m
pT>5 Gev
x [m]-2000 -1000 0 1000 2000 3000
102
10
1Entri
es/1
00m
CDF
tot J/J/ from B
bkgsum
ALICE
109 pp events
SQM08@Beijing Giuseppe E. Bruno 18
tDpp
tDAA
collt
DAA dpdN
dpdNN
pR//1)(
tepp
teAA
collt
eAA dpdN
dpdNN
pR//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
SQM08@Beijing Giuseppe E. Bruno 19
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 || < 0.9M 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
BSS
BSS /
SQM08@Beijing Giuseppe E. Bruno 21
Many other channelscharm:
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.)
SQM08@Beijing Giuseppe E. Bruno 22
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
SQM08@Beijing Giuseppe E. Bruno 23
Thank you
First interaction in ALICE: 11.9.2008(beam – pixel collisions)