What We’ve Learned & Have Yet to Learn John Harris (Yale) AIM Session, ALICE Physics Week, April...
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Transcript of What We’ve Learned & Have Yet to Learn John Harris (Yale) AIM Session, ALICE Physics Week, April...
What We’ve Learned
& Have Yet to Learn
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
My disclaimer – My charge from the ALICE “Brass”:“Summary of differences compared to RHIC, what we have not done to compare to RHIC results, where should we focus effort to gain knowledge?”
My view today – what we have done, still need to do….on the “standard menu” of measurements
for better precisiondetermination of properties of the QGP!
People in ALICE are working on all of this….tremendous progress!
Emphasis on gaining physics knowledge from ALICE!Apologies to those whose work I have not noted here…..
Why this Talk?
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
“LHC & RHIC provide consistent picture” of dynamics & evolution of collisions
multiplicities, system size & lifetimes from RHIC to LHC
properties of medium (e, h/s, vs, ….?)
What Have We Learned? – Spacetime Evolution
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Muller, Schukraft & Wylsouch, arXiv:1202.3233
Small differences due to initial conditions (PDF shadowing vs geometry, hard
processes ~ # binary collisions at LHC vs RHIC)?
ALICE, Phys. Rev. Lett. 105, 252301 (2010)
Must establish initial conditions – p-Pb and Pb-p this year!
“LHC & RHIC provide consistent picture” of dynamics & evolution of collisions
multiplicities, system size & lifetimes from RHIC to LHC
properties of medium (e, h/s, vs, ….?)
More on Spacetime Evolution – Constraints
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Size Volume ~ dN/dh
tf (LHC) ~ 1.4 x tf (RHIC) !
VLHC ~ 2 x VRHIC !
ALICE, Phys.Lett. B696 (2011) 328
tf ~ dNch/dh 1/3 tf (central PbPb) ~ 10 – 11 fm/c
Lifetime hydrodynamic expansion
More on Spacetime Evolution
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Blast Wave Fits
RHIC
LHC
Slope changes at LHC vs RHIC
Smooth extrapolation?
Somewhat stronger radial flow, b ≈ 0.66, at LHC
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Blast Wave Fits
RHIC
LHC
Slope changes at LHC vs RHIC
Smooth extrapolation?
Somewhat stronger radial flow, b ≈ 0.66, at LHC
x3
PID Spectra – more particles & higher statistics to higher pT
Enhanced baryon/meson ratio
at LHC like RHIC
Increases with centrality
Central B/m peak ratio 3x pp
More on Spacetime Evolution
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
x3Enhanced baryon/meson ratio
at LHC like RHIC
Increases with centrality
Peak central B/m ratio 3x pp value
PID Spectra – more particles & higher statistics to higher pT
P. Kalinak APW
Enhanced baryon/meson ratio
at LHC like RHIC
Increases with centrality
Central B/m peak ratio 3x pp
More on Spacetime Evolution
More on Spacetime Evolution
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Blast Wave Fits
RHIC
LHC
x3Enhanced baryon/meson ratio
at LHC like RHIC
Increases with centrality
Peak central B/m ratio 3x pp value
PID Spectra – more particles & higher statistics to higher pT
P. Kalinak APW
P. Christiansen APWEnhanced baryon/meson ratio
at LHC like RHIC
Increases with centrality
Central B/m peak ratio 3x pp
Mounting Evidence from Thermal Fits!
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Same at LHC, but more work needed:
(also to understand proton yields)
Calculation - A. Andronic et al., Phys. Lett. B 673:142,2009
Particles yields at RHIC
equilibrium abundances
universal hadronization Tcritical
Need to complete the ratio studies!
extrapolations, feed-down, …
protons?
Elliptic Flow vs Collision Energy
v2 vs transverse momentum (pT)same for 2.76 TeV down to 39 GeV!
ALICE, Phys. Rev. Lett .105, 252302 (2010)STAR: PRC 77 (2008) 054901; PRC 75 (2007) 054906
v 2 {E
P}
pT (GeV/c)
Change in v2 vs pT
below 39 GeV (at 7.7 & 11.5 GeV)!
pT (GeV/c)
v 2 {4
}
STARpreliminary
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Elliptic Flow – Identified ParticlesALICE, M. Krzewicki, R. Snellings, QM 2011
PHENIX bands: Phys. Rev. Lett. 91, 182301 (2003) STAR bands: Phys. Rev C 77, 054901 (2008)
Larger mass splitting at LHC than at RHIC
Hydro: CGC initial conditions, h/s = 0.2
ALICE (p, K, p) data points
Hydro curves: Shen, Heinz, Huovinen & Song, arXiv:1105.3226
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Identified Particle Elliptic Flow
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Hydro: Shen, Heinz, Huovinen, Song, Phys. Rev. C84 (2011) 044903.
Clear mass ordering! nq scaling? Dynamics more complicated!
J/y Elliptic Flow!
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
H. Yang APW
J/y m+m- in ALICE Muon Arm
finite v2 observed
Most central bin
dominated by fluctuations
H. Yang APWFor different bkgds.
J/y m+m- in ALICE Muon
Arm
20 – 60 % centrality
v2 (pT) dependence
J/y Elliptic Flow!
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
H. Yang APWFor different bkgds.
J/y m+m- in ALICE Muon Arm
finite v2 observed
Most central bin
dominated by fluctuations
J/y e+e- in STAR
20 – 60 % centrality
no v2 signal!
J/y m+m- in ALICE Muon
Arm
20 – 60 % centrality
v2 observed 1.5 < pT < 4
GeV/c
Direct g Elliptic Flow..
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
v2inc = v2 of inclusive g
from conversions
V2decays = v2 of decay g’s
D. Lohner, reported by C. Loizides APW
v2dir = v2
inc +v2
inc – v2decays
Rg –
1(Rγ = Ninc/Ndecays)
Next step: extract -g dirv2
Direct g Elliptic Flow from PHENIX
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Au+Au at 200 GeV PHENIX, arXiv:1105.4126
-g dirv2 using technique outlined on previous slide
Large -g dirv2 at lower pT ~ v20p
Too large for theory!
-g dirv2 at higher pT ~ hard
scattering?
Theorists Working on Shear Viscosities
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Hydro: Qui, Shen, Heinz, Phys. Lett. B707 (2012) 151.
Zeroing in on h/s and initial conditions?
Shear Viscosity from v2 & v3
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Hydro: Schenke, Jeon, Gale, Phys. Lett. B702 (2011) 59.
Sensitivities of h/s and initial conditions to vn
Elliptic Flow at Large pT
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
High pT v2 from jets?
Elliptic Flow at Large pT
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
CMS, arXiv:submit/0450742
CMS and ATLAS high pT results
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
“We understand the shear viscosity, sound
velocity, EOS, other properties of the Medium!”
e.g. – constituents?
c-symmetry?
deconfinement?
Should ask ourselves
“What Will it Take to Be Able to Say…?”
e+e- in PHENIX….. Properties of the Medium
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Min. Bias Au+Au
PHENIX, PRC81, 034911(2010), arXiv:0912.0244
Low mass di-leptons
The original case for
medium effects!
Space-time evolution?Shuryak, arXiv:1203.1012v1
Au + Au e+e- in STAR
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Inconsistent with PHENIX?Still work to be done!
Au + Au e+e- vs Centrality in PHENIX
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Centrality dependence:
PHENIX, PRC81, 034911(2010), arXiv:0912.0244
Low mass di-leptonEnhancement!
Increases with centrality.
Central Au + Au e+e- in STAR
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Difficult…consistency…!
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Vector Meson Studies in ALICE pp
ALICE, Phys. Lett. B710 (2012) 557.
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Cocktail not quite complete…. “enhancement apparent”
ALICE Central Collision e+e- data, C. Baumann APW
Towards Properties of the Medium (ALICE)
Towards Properties of the Medium (ALICE)
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
ALICE 20 – 80 % centrality e+e- data, C. Baumann APW
Clearly a difficult task! Much can be done prior to upgrades!
Suppression of High pT Particles
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
/AA
AA /coll pp
NR
N N
γ
γ
CMS, arXiv:1202.2554v1
Suppression of High pT Particles
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
/AA
AA /coll pp
NR
N N
γ
γ
RAA at LHC theory:
pQCD behavior!
Inconsistent with CGCinitial conditions.
Requires running coupling constant!
Isn’t this now purely pQCD with running a?
B. Betz and M. Gyulassy, arXiv:1201.0281
Suppression of “Intermediate pT” Particles
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
/AA
AA /coll pp
NR
N N
γ
γ
RAA at LHC theory:
pQCD behavior!
A few more details left.
B. Betz and M. Gyulassy, arXiv:1201.0281
Begs for RAA for all i.d.’ed particles – to confront theory!
Suppression of “Intermediate pT” Pions
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012ALICE, P. Christiansen APW
Suppression of “Intermediate pT” Kaons
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012ALICE, P. Christiansen APW
Suppression of “Intermediate pT” Protons
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012ALICE, P. Christiansen APW
Suppression of “Intermediate pT” p0
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Work of Dmitri Peresunko, reported by C. Loizides APW
Consistent with charged pions. Progress!
More to do on Photons!
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
RAAdir-g vs pT
PHENIX, PRL 96 (2006) 202301
PHENIX, PRL 104 (2010) 132301
“Enhanced production of Direct g ...
Implications for Initial Temperature”!
Tinit ~ 370 MeV
T = 221 +/- 19 +/- 19 MeV
Parton Energy Loss in the Medium
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Heavy Flavor production, flow and propagation (RAA)
Muller, Schukraft & Wylsouch, arXiv:1202.3233
To understand:
quark, gluon & flavor
dependence.
Looks like ~pQCD at pT > 10 GeV/c…except need…
Heavy Quark Energy Loss in the Medium
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Will B-quarks Behave as pQCD predicts?
WHDG prediction for B
M. Gyulassy, BNL Seminar 2012
Heavy Quark Energy Loss in the Medium
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
ALICE, arXiv:1203.2160 “Suppression of high pT D mesons in central Pb-Pb at √sNN = 2.76 TeV”
pQCD with parton E-loss describes both charm & light hadrons!…….with little nuclear shadowing! Extend pT range !
Aside – J/y in pp at 7 TeV!
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Mid-rapidity J/y more likely produced in high multiplicity pp events!Theory in a quandary!?
J/ Y Suppression at SPS & RHIC
J/ψ – more suppressed forward.Partly due to cold nuclear matter!
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
J/ψ suppressed at RHIC ~ SPS!
Increases with centrality(not shown here).
J/ Y Suppression at RHIC & LHC
CMS, PRL 107 (2011) 052302
High pT J/ψ near ycm more suppressed than at RHIC
→ energy loss of charm quark
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
J/ψ less suppressed than at RHIC
Recent Word by PHENIX – J/ Y Suppression at RHIC
Suppression of J/y at forward rapidity stronger than at midrapidity.
Have compared to recent calculations that include
gluon saturationgluon shadowinginitial-state parton energy losscold nuclear matter breakupcolor screeningcharm recombination.
J/y suppressed beyond cold-nuclear-matter effects.
Disagreement between models and d+Au data precludes using these models to quantify hot nuclear matter suppression.
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
PHENIX, arXiv:1103.6269v1
ALICE – Emphasizes importance of p-Pb and Pb-p this year!
U Suppression at RHIC & LHC
U(2s), U(3s) suppressed wr to U(1s),& relative to p+p collisions
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
CMS, PRL 107 (2011) 052302
U Suppression at RHIC & LHC
U(2s), U(3s) suppressed wr to U(1s),& relative to p+p collisions
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
ALICE – Progress! Should also be able to analyze Y in e+e- channel in EMCal!
ALICE, J. Castillo, reported by D. Das APW
Mmm (GeV/c2)
ALICE in progress!
CMS, PRL 107 (2011) 052302
Jets at the LHC – Di-Jet Energy Imbalance!
Azimuthal Angular Correlations
Triggerjet
Away-side jet
Energy Asymmetry: AJ = ET1 – ET2 / ET1 + ET2
for > Df p/2
ET1 > 100 GeV ET2 > 25 GeV
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Where does the Energy Go? – CMSdevPRC 84 (2011) 024906
Energy/momentum balance in event is carried bylow momentum particles at large angles to jets!
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
pQCD, vacuum fragmentation, thermalization of lost energy?
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Must understand parton propagation energy loss processes in the medium!
A Lot to Do & Still to Come from Jets in ALICE
Jets – (relative to reaction plane for geometry / pathlength selection)
(relative to pp)
spectra (understand soft background in Pb-Pb)
changes in intra-jet structure
correlations & energy balance
jet-hadron
hadron-jet
g-jet
di-jet
B-jets (for quark propagation in medium)
vn of jet (impact on flow analyses)
Use some of above for event selection criteria
e.g. di-jet energy imbalance
More on Spacetime Evolution
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012
Tremendous effort on many different analyses! Need to consider physics message papers across analyses
(e.g. v2,3,…, RAA for ID’ed particles)
- How does the system evolve and thermalize from its initial state?
What is the initial state (CGC?)?
- What are the properties & constituents (vs. T) of the QGP?
- Can we understand parton propagation & energy loss at fundamental level?
What can we learn about the medium response?
- How does hadronization take place?
- Can we understand & extract all contributions to quarkonium suppression?
What does it tell us?
- Is the QCD Phase Diagram featureless above Tc? Coupling strength vs T….
- Are there new phenomena? Whatever happened to c-symmetry?....
- Can there be new developments in theory (lattice, hydro, parton E-loss,
string theory…) and understanding……across fields……?
Big Questions – QGP at RHIC & LHC
John Harris (Yale) AIM Session, ALICE Physics Week, April 19, 2012