Transcript trd05 - Istituto Nazionale di Fisica Nucleare

• heavy flavors &
(di)leptons @ LHC
• detector performances
[email protected]
• selected physics channels
Heavy flavors:
what is different @ the LHC
central AA
• large primary production
• melting of (1S) by color screening
• none of the primary J/ survives the (PbPb)QGP
• a lot of charmonia from b hadron decay
• large secondary production of charmonia
statistical hadronization, kinetic recombination, DD annhililation
hard gluon induced
quarkonium breakup
hep-ph/0311048
LHC
[email protected]
RHIC
(di)leptons:
what is different @ the LHC
dimuons in ALICE, pt > 2 GeV/c
unlike-sign total
unlike-sign from bottom
unlike-sign from charm
like-sign from bottom
charm pure NLO
 in ALICE
Z. Conesa del Valle
(2005)
S. Grigoryan (2004)
• large & complex combinatorial background
pp @ 14TeV
• dileptons from b decay dominate the spectrum below  & J/
• large yield of secondary J/ from b decay
• dileptons from b decay have different origin at low & high mass
• sizeable yield of like-sign correlated dileptons from b decay
[email protected]
• W stick out from single lepton spectra with large statistics
J/ from b decay in central PbPb @ 5.5 TeV
• b  J/ (1S) anything : 1.16  0.10% (PDG)
• N(direct J/) in central (5%) PbPb @ 5.5 TeV : 0.49*
• N(bb pairs) in central (5%) PbPb @ 5.5 TeV : 4.56#
 N(b  J/) / N(direct J/) ~ 20% in 4 (22% in pp @ 14 TeV)
(with shadowing & feed-down, w/o nuclear absorption, suppression,
regeneration…)
• this is a lot!
• no obvious way to disentangle prompt & secondary J/ from pt dist.
(only 2nd vertexing or b measurement can help)
*from CERN-2004-009, hep-ph/0311048,
CEM, underpredicts CDF data by a factor 2
#from
ALICE PPR VII, CERN/LHCC 2005-030,
uncertainty: a factor 2-3 (mQ, F, R, PDF)
[email protected]
One physics case: on the relevance of
measuring  in heavy ion collisions at the LHC
using (2s) to unravel J/ suppression vs. regeneration
• J/ suppression & regeneration?
• c suppression (J/ TD > 1.5 Tc)?
enhanced
regeneration
• TLHC >> J/ TD ~ (2s) TD
C.-Y. Wong, PRC 72 034906
W.M. Alberico et al., PRD 72 114011
•  regeneration is small
L. Grandchamp et al., hep-ph/0507314
H. Satz, CERN Heavy Ion Forum, 09/06/05
enhanced
suppression
30
SPS
RHIC
LHC
[email protected]
Heavy ions
@ the LHC
CMS: strong heavy
ion program
D.d’Enterria
Tuesday parallel II
ATLAS: heavy ion
LOI (2004)
ALICE: the dedicated
heavy ion experiment
[email protected]
M.Rosati
Tuesday parallel II
ALICE (A Large Ion Collider Experiment)
ACORDE
HMPID
TRD
TOF
DIPOLE MAGNET
L3 MAGNET
PMD
FMD
ITS
MUON TRIGGER
CHAMBERS
TPC
PHOS
[email protected]
MUON FILTER
ABSORBER
MUON TRACKING CHAMBERS
How LHC detectors measure quarkonia
• nice complementarity between the 3 experiments
• ATLAS & CMS acceptance is large in  & limited to high pt
• ALICE acceptance covers low pt & high 
• ATLAS, CMS & ALICE-electron have inner tracking
[email protected]
LHC inner trackers expected performances
(d0) < 50 µm for pt > 1.5/2/3 GeV/c in
ALICE/CMS/ATLAS
• disentangle primary & secondary J/
• measure inclusive b cross-section
• probe b quark in-medium energy loss
[email protected]
ALICE: CERN/LHC 2005-030, CERN/LHCC 99-13,
ATLAS: EPJC 33 (2004) s1023, CMS: CMS NOTE 2006/031, 2001/008
acceptance
Transverse momentum acceptance
for quarkonia measurements
CMS J/
ALICE J/  e+e-
|| < 2.4
barrel
w/o trigger
with trigger
• ALICE can measure J/ down to 0 pt (unique @ LHC)
• ATLAS acceptance similar to CMS acceptance for J/
in central barrel
• ALICE, ATLAS & CMS can measure  down to 0 pt
note: ≠ trigger & reconstruction efficiencies
ALICE J/  µ+µ-
[email protected]
(expected statistics doesn’t scale with geo. acc.!)
ALICE: PPRVII, CERN/LHCC 2005-030, CMS: NOTE 2006/089
 mass resolution
(  100 MeV @ M ~ 10 GeV is needed to separate the  sub-states)
CMS
CMS
dN/d = 2500
|| < 2.4
no bkg
|| < 0.8
 ~ 90 MeV
 ~ 54 MeV
ALICE
electron
dN/d = 6000
warning:
ALICE muon
background level 1 = 2 HIJING evts
with dN/d = 6000 @  = 0 each
[email protected]
ATLAS
dN/d = 3000
|| < 2
 ~ 145 MeV
• ≠ simulation
frameworks & inputs
• ongoing analyses
ALICE: PPRVII, CERN/LHCC 2005-030,
ATLAS: CERN/LHCC/2004-009, CMS: NOTE 2006/089
Expected statistics in ALICE-muon
1 LHC year = 7 months pp (107s, 3·1030cm-2s-1) + 1 month AA (106s, 5·1026cm-2s-1)
PbPb MB
5.5 TeV
pp
14 TeV
J/
’

’
’’
S (103)
681.4
18.92
6.33
1.8
1.02
S/B
0.33
0.02
2.46
1.03
0.74
S/S+B
413
19.53
67.14
30.19
20.85
S (103)
4670
122
44.7
11.4
6.9
S/B
12.6
0.55
5.8
1.9
1.3
S/S+B
2081
209
195
86
62
full simulation including
from PbPb MB to pp, a factor ~ 10 more stat.
• realistic geometry
• J/: large stat., good significance
• trigger efficiency
• ’: small S/B
• reconstruction efficiency
• : good stat., S/B > 1, good significance
• tracking efficiency
• ’: good stat., S/B > 1, good significance
• resolutions
• ’’: low statistics
[email protected]
ALICE PPR VII, CERN/LHCC 2005-030, x-sections from CERN-2004-009, hep-ph/0311048,
with shadowing & feed-down, w/o nuclear absorption/suppression/regeneration…
From NA50’s (J/)/DY to ALICE’s /bbbar
NA50
PbPb @ 17GeV
ALICE
PbPb @ 5.5TeV
EPJC 39 (2005) 335
• statistics : one month PbPb
• (b) extracted à la UA1, CDF, D0
• statistics of the reference is in
5<M<20GeV ~5 times larger than
that of the probe
• systematic errors underway
[email protected]
ALICE PPRVII, CERN/LHCC 2005-030
dissociation temperatures: C.-Y. Wong, PRC 72 034906 & W.M. Alberico et al., PRD 72 114011
’/ ratio versus pt
J.P. Blaizot & J.Y. Ollitrault, Phys. Lett. B 199(1987)499; F. Karsch & H. Satz, Z. Phys. C 51(1991)209; J.F.
Gunion & R. Vogt, Nucl. Phys. B 492(1997)301
• melting depends on
• resonance formation time,
dissociation temp. & pt
• QGP temp., lifetime & size
• ratio is flat in ppbar (CDF)
• any deviation from the pp (pA)
value is a clear evidence for the
QGP (nuclear effects cancel-out)
• the pt dependence of the ratio is
sensitive to the characteristics of
the QGP
• full & realistic simulation
• error bars = 1 month of central PbPb (10%)
[email protected]
E. Dumonteil, PhD Thesis (2004), ALICE-INT-2005-002
Using b decays to probe the QGP
a measurement of (J/)/(b) = (2)1% or ’/(J/) = 0.0625
is an evidence for full J/ suppression (& no regeneration!)
no need to disentangle prompt & secondary J/!
[email protected]
ALICE PPRVII, CERN/LHCC 2005-030
Instead of a summary,
what will happen next year
2007
Aug.
Sept.
Oct.
2008
Nov.
10 weeks pp
Dec.
Jan.
Feb.
shut-down
Mar.
Apr.
Jun.
July
pp high L, 1st PbPb…
machine closure
set-up, injection
first physics run!
[email protected]
May
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BACKUP
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Heavy ion (ALICE) data taking scenario
one LHC year = 7 months pp (107s) + 1 month AA (106s), starts in 2007
• 5 first years:
• regular pp runs at 14 TeV: commissioning, reference, dedicated pp physics
• first PbPb run at low luminosity: global observables, large x-sections
• 2 PbPb runs at high luminosity (Lint = 0.5nb-1/year): small x-sections
• 1 pA run: structure functions, hadronic reference
• 1 light ion run: energy density dependence
• later (different options depending on the first results):
• pp (or pp-like) at 5.5 TeV
• other light or intermediate-mass systems
• other systems p-likeA & Ap-like
• PbPb at low energy
• PbPb at 5.5 TeV & high luminosity
[email protected]
ALICE collaboration, J. Phys. G 30 (2004) 1517
[email protected]
[email protected]
Combined momentum resolution
at low momentum dominated by
- ionization-loss fluctuations
- multiple scattering
at high momentum determined by
- point measurement precision
- alignment & calibration
(assumed ideal here)
F. Antinori, 06/20/05
resolution ~ 7% at 100 GeV/c
excellent performance in hard region!
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