sqm 2007 - levoca, 28.06.07 andrea dainese 1 alice potential for heavy-flavour physics sqm 2007...
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SQM 2007 - Levoca, 28.06.07 Andrea Dainese 1
ALICE potential for ALICE potential for heavy-flavour physicsheavy-flavour physics
SQM 2007SQM 2007LevoLevočča, Slovakia, June 24-29, 2007a, Slovakia, June 24-29, 2007
Andrea DaineseINFN – Legnaro
for the ALICE Collaboration
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Contents
Charm and beauty at the LHC
Physics motivation for open flavour and quarkonia measurements
Heavy-flavour program in ALICE
Measurements in preparation
Examples of expected performance (charm & quarkonia)
more on beauty J.Faivre’s talk
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LHC: hard cross sectionslots of heavy quarks!
NLO predictions (ALICE baseline for charm & beauty)
* M.Mangano
system, s pp, 14 TeV Pb-Pb (0-5%), 5.5 TeV
11.2 / 0.5 4.3 / 0.2
0.16 / 0.007 115 / 4.6
[mb] QQNNQQ
totN
MNR code (NLO): Mangano, Nason, Ridolfi, NPB373 (1992) 295.
beautycharm
factor ~2uncertainty
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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
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Heavy quarks as medium probes:Energy Loss
Parton Energy Loss by medium-induced gluon radiation collisions with medium gluons
q: colour triplet
QCD medium
u,d,s: m~0, CR=4/3(difficult to tag at LHC)
g: m=0, CR=3> E loss, dominant at LHC
c: m~1.5 GeV, CR=4/3small m, tagged by D’sb: m~5 GeV, CR=4/3large mass, < E loss
Parton Energy Loss by medium-induced gluon radiation collisions with medium gluons
pred:
),,;( LmCE RQGPbqcg EEE
BAA
DAAAA RRR
Q: colour triplet
g: colour octet
Dokshitzer and Kharzeev, PLB 519 (2001) 199. Armesto, Salgado, Wiedemann, PRD 69 (2004) 114003.
Djordjevic, Gyulassy, Wicks, nucl-th/0512076
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HQ Energy loss at LHC
Armesto, Cacciari, Dainese, Salgado, Wiedemann, “Last Call for LHC Predictions” workshop
)()()(/ tDAAt
BAAtDB pRpRpR
massive
heavy-to-light ratio
Wicks, Gyulassy, “Last Call for LHC Predictions” workshop
see also talk by W.Horowitz
)( . )( tDAAt
BAA pRvspR
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Heavy quarks as medium probes:Azimuthal asymmetry (v2)
v2 of D and B mesons in non-central collisions tests:
at low/moderate pt: recombination scenario, flow of c/b quarks (?), hence degree of thermalization of medium
van Hees, Rapp, Greco, “Last Call for LHC Predictions” workshop
Armesto, Cacciari, Dainese, Salgado, Wiedemann, “Last Call for LHC Predictions” workshop
at higher pt: path-length dependence of E loss in almond-shaped medium
flow+reco E loss only
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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
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The ALICE DetectorThe ALICE Detector
||| < 0.9, B = 0.5 T| < 0.9, B = 0.5 TTPC + silicon trackerTPC + silicon tracker,,ee, , , K, p identification, K, p identification
-4 < -4 < < -2.5 < -2.5muonsmuons
ALICE Collaboration: >1000 people, 30 countries, ~ 90 Institutes
Size: 16 x 26 meters
Weight: 10,000 tons
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Getting Ready for Beam!
Ready to move
TPC (largest ever) installed, ITS moving in
MUON arm: largest dipole ever
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Open charm and beautyOpen charm and beauty
TPC (tracking)
TOF (K/ id)
ITS (vertexing)
K
D0 K D+ K Ds KK D* D0 D0 K c Kp
understudy
D0 K D+ K Ds KK D* D0 D0 K c Kp
understudy
B e+X B 5 pr. B J/ee
understudy
ITS (vertexing)TPC (tracking e/ id)TRD (e/ id)
e
TPC (tracking)ITS (vertexing)MUON (tracking,id)
B +X
D0 K D+ K Ds KK D* D0 D0 K c Kp
understudy
B e+X B 5 pr. B J/ee
understudy
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PrimaryVertex B
e
Xd0
rec. track
Vertexing: track d0 resolution
< 60 m (r)for pT > 1 GeV/c
Resolution mainly provided by the 2 layers of silicon pixels
PIXEL CELL
z: 425 m
r: 50 m
Two layers:r = 4 cmr = 7 cm
9.8 M
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pair of opposite-charge tracks with large impact parameters
good pointing of reconstructed D momentum to the primary vertexD0
Charm reconstruction: D0 K-+ & D+ K-++
Two vertexing algos with full error-matrix treatment
Large combinatorial background (dNch/dy=6000 in Pb-Pb simul.)
Main selection: displaced-vertex selection
Invariant mass analysis
large distance (dPS) between primary and secondary vertex
good pointing of reconstructed D momentum to the primary vertexD+
1 year at nominal luminosity(109 pp events, 107 central Pb-Pb events)
10
20
30
40
50
D+D0
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Beauty in the barrel: displaced e’s, displaced J/ee
Excellent electron identification capabilities (TPC and TRD)
Displaced electrons (& di-electrons from J/ from B decays) tagged by an impact parameter cut (ITS)
see talk by J.Faivre
J/ e+e-
)/()/( /
Jp
MJL
T
Jxy
primarysecondary
J/ pseudoproper decay time (pt>5GeV)
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Charm and Beauty E Loss : RAA
mb = 4.8 GeV
D0 K
B e + X
1 year at nominal luminosity(107 central Pb-Pb events, 109 pp events)
D+ K
mC = 1.2 GeV
mC = 0
B eE loss calc.:Armesto, Dainese, Salgado, Wiedemann
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Heavy-to-light ratios
1 year at nominal luminosity(107 central Pb-Pb events, 109 pp events)
)()()(/ thAAt
DAAthD pRpRpR probes colour-charge dep.
of QCD energy loss
)()()( D from eB from e/ tAAtAAtDB pRpRpR
probes mass dep.of QCD energy loss
E loss calc.:Armesto, Dainese, Salgado, Wiedemann
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Charm v2: D+ example
First estimate of statistical errors on D+ v2:
best sensitivity at intermediate pt: 3 – 7 GeV/c charm recombination
Under study: performance with D0 + D+
2107 min.bias evts 2107 6<b<9 fm evts
v2 calc. from Ko et al.
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Beauty via (forward) muons
inner bars: stat. errorsouter bars: syst. errors
Muons “identified” in the spectrometer (-4 << -2.5)
Pb-Pb 0-5%(1 month)
W (medium-blind reference) dominates for pt > 30 GeV/c!!
ALICE muon spectrometer acc.:-4 < < -2.5, pt > 1 GeV, p > 4 GeV
single muons in the spectrometer: b dominates for pt > 2-3 GeV/c
thin: no mass effectthick: mass effect
RCP
b quarkE loss
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ITS (vertexing)TPC (tracking)TRD (e/ id)
MUON (tracking,id)
e e
QuarkoniaMeasured both in the di-electron (midrapidity, TRD) and di-muon (forward rapidity, MUON) channel
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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 /
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Medium effect on Quarkonia:Quarkonia/BB , Quarkonia RAA
Normalization of quarkonia yields: BB yield (from intermediate-mass di-leptons), but b E loss?
Possible alternative: RAA (à la PHENIX),
but different c.m.s. energy,
need p-Pb for initial-state effects
Plots for channel
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SummaryLHC: 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 (ITS, TRD, MUON)
promising performance for all key measurementsThanks to:
F.Antinori, C.Blume, C.Bombonati, E.Bruna, G.E.Bruno, Z.Conesa, P.Crochet, H.Ding, J.Faivre, R.Guernane, M.Lunardon, G.Martinez,
M.Masera, F.Prino, R.Turrisiand ALICE “HF & Quarkonia” working group
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EXTRA SLIDES
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LHC running conditions
Ldt = 5.1026 cm-2 s-1 x 106 s
5.1032 cm-2 PbPb run, 5.5 TeV
NPbPb collisions = 2 .109 collisions
Ldt dt = 3.1030 cm-2 s-1 x 107 s
5.1037 cm-2 for pp run, 14 TeV
Npp collisions = 2 .1012 collisions
Muon triggers: ~ 100% efficiency, ~ 1kHz Electron triggers: Bandwidth limitation NPbPb central = 2 .108 collisions
Muon triggers: ~ 100% efficiency, < 1kHz
Pb-PB nominal run pp nominal run
Electron triggers: ~ 50% efficiency of TRD L1 20 physics events per event
Hadron triggers: NPbPb central = 2 .107 collisions
Hadron triggers: Npp minb = 2 .109 collisions
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pp: perspectives for the 1st month
Detector configuration:ITS + TPC + TOF
When? Latest statement from the machine (June 7): “Machine Closure: 31.8.07 Set up of machine, injection, followed by up to 10 weeks of pp collisions: Sept. to Dec. 2007”
Expected statistical errors for a low-stats sample:Scaling of statistical errors according to Nevts
No dedicated cuts study yet
D0 K
Detector configuration:ITS + TPC + TRD
B e + X
~1 month at end 2007
1 year at nominal luminosity
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Quarkonia: mass spectraMeasured both in the di-electron (midrapidity, TRD) and di-muon (forward rapidity, MUON) channel
J/ family family
Mμμ (GeV/c)Mμμ (GeV/c)
di-electron ||<0.9
di-muon -4<<-2.5
1 month at nominal luminosity(107 central Pb-Pb events)
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Suppression Scenarii
• Suppression-1 Tc =270 MeV D/Tc=1.7 for J/ D/Tc= 4.0 for .
• Suppression-2 Tc=190 MeV D/Tc=1.21 for J/ D/Tc= 2.9 for .PRC72 034906(2005)
Hep-ph/0507084(2005)
Good sensitivity J/, (1S) & (2S)
Ph. CROCHET, F, GUERIN, R. GUERNANE, S. GRIGORYAN et al.
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Energy loss, from RHIC to LHC (I)
Armesto, Cacciari, Dainese, Salgado, Wiedemann, “Last Call for LHC Predictions” workshop
Radiative energy loss (BDMPS): charm ~ m=0 quark probe colour charge dependence; beauty probe mass dependence
Au-Au 200 GeV Pb-Pb 5.5 TeV
)()()(/ tDAAt
BAAtDB pRpRpR
massive
heavy-to-light ratio
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Energy loss, from RHIC to LHC (II)
Wicks, Gyulassy, “Last Call for LHC Predictions” workshop
Heavy quarks (esp. beauty) may help to disentangle relative importance of radiative and collisions losses
see also talk by W.Horowitz
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Energy loss, from RHIC to LHC (III)
I.Vitev, A.Adil, “Last Call for LHC Predictions” workshop
Conceptually different approach: Fragmentation & dissociation of heavy-flv hadrons inside QGP
D
B
D+B
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Heavy quarks as medium probes:Azimuthal asymmetry (v2)
v2 of D and B mesons in non-central collisions tests:
at low/moderate pt: recombination scenario, flow of c/b quarks (?), hence degree of thermalization of medium
van Hees, Rapp, Greco, “Last Call for LHC Predictions” workshop
Armesto, Cacciari, Dainese, Salgado, Wiedemann, “Last Call for LHC Predictions” workshop
at higher pt: path-length dependence of E loss in almond-shaped medium
RHIC LHC
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