Download - Physics Reach
Physics Reach
Christoph Blume
University of Frankfurt/Main
for the ALICE Collaboration
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Physics Reach
Outline
ALICE physics
Strongly interacting matter
Observables
p+p physics
The ALICE experiment
Running conditions for Pb+Pb
and p+p running
Acceptance
Tracking performance
Particle identification
Low pt physics examples
Heavy quarks
Open charm
Open beauty
Quarkonia family
Parton energy loss
High pt particle spectra
Jets via correlations
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
ALICE Physics
Phases of Strongly Interacting Matter
Exploring the phase diagram of
strongly interacting matter
LHC provides access to the high
T, vanishing B QGP phase
Lattice QCD, B = 0Lattice QCD, B = 0
LHCLHC
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
ALICE Physics
Properties of QGP Phase @ LHC
Initial conditions
Hard processes
Probe of early state of reaction
Pertubative QCD
Significant part of cross section
High density parton distributions
Bulk of partons at x 10-3
Saturated gluon densities
Classical QCD: Qs A1/3/ x
Evolution of system will be
dominated by partons
Longer lifetime of QGP phase
Collective effects will be strongly
influenced by parton dynamics
partonic flow
Energydensity 1000 GeV/fm3
Temperature T 1 GeV
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
ALICE Physics
Observables
Jets
Open charm, beauty
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
ALICE Physics
Observables
Soft Regime
pt = 0–2 GeV/c
non-perturbative
Particle yields
chem. freeze-out
HBT interferometry
thermal freeze-out
Flow
expansion
Soft Regime
pt = 0–2 GeV/c
non-perturbative
Particle yields
chem. freeze-out
HBT interferometry
thermal freeze-out
Flow
expansion
Semi-hard Regime pt
= 2–5/10 GeV/c
Thermal photons
temp. evolution
Open charm, J/
plasma screening
pt-Spectra
mini-jets
Semi-hard Regime pt
= 2–5/10 GeV/c
Thermal photons
temp. evolution
Open charm, J/
plasma screening
pt-Spectra
mini-jets
Hard Regime pt
> 10 GeV/c
perturbative
Hard photons
Open beauty,
Jets
initial collisions
Hard Regime pt
> 10 GeV/c
perturbative
Hard photons
Open beauty,
Jets
initial collisions
ALICE will cover the transition from the soft (hadronic) to the hard (partonic) regime
Correlations between soft and hard probes only possible within ALICE
ALICE will cover the transition from the soft (hadronic) to the hard (partonic) regime
Correlations between soft and hard probes only possible within ALICE
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
ALICE Physics
p+p Physics
Benchmark for Pb+Pb: Multiplicities (strangeness)
J/ and Parton energy loss (jets)
Thermal photons
High energy densities @ LHC: 1.2 GeV/fm3
Comparable to N+N @ SPS/RHIC
Bulk of cross section at low pt
Investigation in a new energy regime
p+A program Nuclear structure functions
Benchmark for Pb+Pb
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
The ALICE Experiment
ITSLow pt trackingVertexing
ITSLow pt trackingVertexing
TPCTracking, dEdxTPCTracking, dEdx
TRDElectron IDTRDElectron ID
TOFPID, talk by C. WilliamsTOFPID, talk by C. Williams
HMPIDPID (RICH) @ high pt
HMPIDPID (RICH) @ high pt
PHOS,0 PHOS,0
MUON -pairs talk by A. Morsch
MUON -pairs talk by A. Morsch
PMD multiplicityPMD multiplicity
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
The ALICE Experiment
Running conditions for Pb+Pb
Large charged multiplicity
Estimates quite uncertain
Design for dNch/dy|max = 8000
Luminosity:
Lmax = 11027 cm-2s-1
Event rate:
8000 minimum bias coll./ s
~109 events/year
1% collected
Trigger for low cross section
observables
MUON, PIXEL, PHOS, TRD
High-Level Trigger (HLT)
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
The ALICE Experiment
Event Display Pb+Pb
TRDTRD
HMPIDHMPID
TOFTOF
TPCTPC
PHOSPHOS 60 << 6260 << 62
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
The ALICE Experiment
p+p Running Conditions
“Low“ luminosity: Lmax =
2-5 1030 cm-2 s-1
Event pile-up
TPC drift 88 s
On average 25 events
(for Lmax = 2 1030 cm-2 s-1)
Pile-up can be removed with
High-Level Trigger
Reduction in data volume:
factor 5
Short run periods with ‘‘ultra-low‘‘
luminosity no pile-up
Lmax 1029 cm-2 s-1
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
The ALICE Experiment
Acceptance Central Barrel
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
The ALICE Experiment
Tracking Performance
Reconstruction efficiency
dNch/dy = 8000, B = 0.4T
98% in TPC
Acceptance at high pt: ~90%
Momentum resolution:
dNch/dy = 8000, B = 0.4T
Combined tracking
ITS+TPC+TRD
9% (pt = 100 GeV/c)
9%
TPCprimary tracksTPCprimary tracks
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
The ALICE Experiment
Main Vertex Determination
For heavy-ion collisions
Large track statistics
Resolution in bending projection:
10–15 m (beam spot
15 m)
Resolution in non-bending
projection:
better than 10 m
For p+p collisions
Low track statistics
Effect on charm measurement
p+pp+p
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Momentum
ITSITS
dE
/dx
HMPIDPrototype in STARHMPIDPrototype in STAR
TPC dE/dx resolution:6.8% for dN/dy = 80005.3% for dN/dy = 800
TPC dE/dx resolution:6.8% for dN/dy = 80005.3% for dN/dy = 800
Momentum (GeV/c)
dE/d
x (a
.u.)
The ALICE Experiment
Particle Identification
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
The ALICE Experiment
PID Summary
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Low pt Physics Examples
Event-by-Event ++ HBT
Single event
Raw correlation function
Uncorrected for Coulomb
R = 8 fm, = 0.5
Tracking with ITS+TPC, B = 0.2T
Qinv (GeV)C
(Qin
v)
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Low pt Physics Examples
Resonances: K*
Decay channel K* K+-
Invariant mass distribution
for 550 events
M(K+-) (GeV/c2)
En
trie
s
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Heavy Quarks
Heavy quarks probe dynamics of whole QGP phase Perturbative in intial collisions
Thermal production in QGP
Direct measurement of heavy flavour in p+p and A+A mandatory
Quarkonia (J/ and states) Binding energy in the order of
mean energy in QGP
Sensitive to screening effects
Aim: correlation of heavy quark and quarkonia production as
function of pt
Uncertainty of factor 4 in predictions for pp @ LHCUncertainty of factor 4 in predictions for pp @ LHC
Quarkonia +-: MUON
Quarkonia e+e-: TPC+TRD
D K, ITS+TPC+TOF
Semileptonic decays of D + B:
ITS+TPC+TRD and MUON
DD (BB) via e coincidences: TRD+MUON
Quarkonia +-: MUON
Quarkonia e+e-: TPC+TRD
D K, ITS+TPC+TOF
Semileptonic decays of D + B:
ITS+TPC+TRD and MUON
DD (BB) via e coincidences: TRD+MUON
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Heavy Quarks
Open Charm via Hadronic Decays
Affected by main vertexresolution in p+p caseAffected by main vertexresolution in p+p case
D0 K-
c= 123.7 0.8mBR: (3.83 0.09) %
D0 K-
c= 123.7 0.8mBR: (3.83 0.09) %
cuts depend on D0 ptcuts depend on D0 pt
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Heavy Quarks
Open Charm via Hadronic Decays
Input to simulation cc: PYTHIA, tuned to NLO
calculations, with CTEQ4L and nuclear shadowing EKS98
Background: HIJING
Reconstruction effects included
PID with TOF
System (s) Pb-Pb (5.5 TeV) pp (14 TeV)
Signal
for 107 (109) evts13000 20000
S/B 11 % 50 %
Significance
for 107 (109) evts37 84
Pb+PbPb+Pb
minv = 12 MeV (B = 0.4T)minv = 12 MeV (B = 0.4T)
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Heavy Quarks
Open Charm via Hadronic Decays
Pb+Pb:Pb+Pb:
dN/dpt Significance
pt > 1 GeV/cpt > 1 GeV/c
p+p:p+p:
pt > 0 GeV/c !pt > 0 GeV/c !
dN/dpt SignificanceSignificance =
BSS /
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Heavy Quarks
Open Beauty via Semileptonic Decays
B e- + X
Electron ID in TPC + TRD
Cuts:
Impact parameter d0
Electron pt
pt > 2 GeV/c + d0 > 150 m:
5-10·104 e with S/(S+B) = 90 %
pt > 2 GeV/c + d0 > 150 m:
5-10·104 e with S/(S+B) = 90 %
d0 (m)
En
trie
s (a
.u.)
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Heavy Quarks
J/ and via Dielectrons
Mass resolution for 100 MeV (B = 0.4T)Mass resolution for 100 MeV (B = 0.4T)
::
J/:J/:
Acceptance down to pt = 0!Acceptance down to pt = 0!
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Heavy Quarks
Secondary J/from B Meson Decays
B J/ e+e- (BR: 1%)
Large contribution to observable J/ signal
Possibility to disentangle primary and secondary J/s
J/from B decays
Impactparameter
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Parton Energy Loss
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Parton Energy Loss
Medium induced gluon radiation
Depends on traversed distance
L2
Stronger in deconfined matter
Effects:
Reduction of single inclusive high
pt particles
• Parton specific (stronger for
gluons than quarks)
• Flavour specific (stronger for
light quarks)
• Measure identified hadrons (, K,
p, , etc.) + partons (charm,
beauty) at high pt
Suppression of mini-jets
• same-side / away-side
correlations
Change of fragmentation function
for hard jets (pt >> 10 GeV/c)
• Transverse and longitudinal
fragmentation function of jets
• Jet broadening reduction of jet
energy, dijets, -jet pairs
p+p and p+A measurements
crucial
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
High pt
RHIC Results
RAA clearly different between
mesons and baryons
Importance of PID at high pt
p+p baseline measurement!
tdpppdtdpAAd
collNtpAAR
)()(1)(
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
High pt
Minimum Bias Pb+Pb and p+p
Estimates for the pt limit in one
year ALICE running
107 Pb+Pb events
109 p+p events
p+p simulation PYTHIA 6.210 +
CTEQ5L (default tuning)
Scaled to 107 Pb+Pbmin. bias events Scaled to 107 Pb+Pbmin. bias events
104 rec.p+p evts.104 rec.p+p evts.
~2103 tracks pt > 50 GeV/c~2103 tracks pt > 50 GeV/c
109 p+p events: 103 tracks with pt 40 GeV/c
109 p+p events: 103 tracks with pt 40 GeV/c
pt (GeV/c)
pt (GeV/c)
dN/d
p tN
( p
t)
High pt trigger (TRD, HLT) will extend pt range to > 100 GeV/c
High pt trigger (TRD, HLT) will extend pt range to > 100 GeV/c
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
High pt
Identified Particles:
One year of ALICE running (107 events)
s up to pt = 12 GeV/c
Can be improved using PID for daughters
S/B 15.5 /event
S/B 15.5 /event
% of rec. s vs pt% of rec. s vs pt
Reconstructedpt spectrumReconstructedpt spectrum
M(p) (GeV/c2)
Ent
ries
%
pt (GeV/c)
pt (GeV/c)
Y
ield
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
High pt
Identified Particles: +
Direct Direct
Inclusive : Direct + 0Inclusive : Direct + 0Inclusive : Direct + 0Inclusive : Direct + 0
Direct Direct
with high-pt triggerwithout high-pt trigger for 107 events
Separationof/0 and detection up to 100 GeV/c Statistically for low pt (< 30-40 GeV/c) E-by-E at higher pt (> 30-40 GeV/c)
pt (GeV/c)
dN/d
p t
pt (GeV/c)
dN/d
p t
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Jets in Pb+Pb
Correlations with Leading Particle
Transformation d2N/dd1/R dN/dR with: R2
= 2 + 2
1000 HIJING events (default)
pt(seed) = 5 GeV/cpt > 3 GeV/c
pt(seed) = 5 GeV/cpt > 3 GeV/c
R
1/R
dN
/dR
pt (GeV/c)
1 < R < 2 1 < R < 2
R < 0.3R < 0.3
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Jets in Pb+Pb
Two Particle Correlations
Correlation
increases with pt
Effect of gluon
radiation
System size
dependence
p+p
21
21acospp
pp
)mixed(/)real(/)(
ddNddNc
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Summary
ALICE physics reach extends
from:
Low pt > 0.1 GeV/c
• Identified particles
• Correlations, HBT
• Event-by-event observables
• Flow
to:
High pt ~ 100 GeV/c
• Heavy quarks
• Quarkonia
• Photons
• Jets
p+p and p+A physics
Baseline for A+A
Important physics on its own
Integral part of ALICE physics
program
Physics Performance Report
Full simulations for all projected
physics observables