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1QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
QGP Winter School
Jaipur, India, Feb. 1st 3rd 2008
David d’EnterriaCERN
HighpHighpTT hadrons & jets in hadrons & jets inhighenergy nuclear collisionshighenergy nuclear collisions
2QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
OverviewOverview
qhat = ?dNg/dy = ?cs =?
■ Suppressed highpT hadron spectra:
■ Modified highpT dihadron correlations:
■ Full jet reco, jet, modified FFs:
FastkT (D=0.4),area substraction
Hot/dense QCD matter properties via “jet quenching”
3QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
QCD matter with heavyions: physics menuQCD matter with heavyions: physics menu
ε /T4
T/Tc
▪ Highdensity QCD at smallx: CGC
▪ QCD at hightemperature: QGP
▪ Gaugegravity duality: AdS/QCD
N = 4
SU(Nc)
BH in
AdS5 x S 5
(s tack of 4 D3 bran es)
✱ (de)confinement✱ chiral symm. restoration✱ early Universe thermodyn.
4QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Early-time probes of QGPEarly-time probes of QGP
▪ HE AA colls. produce expanding QGP: V~O(103 fm3) for ~10 fm/c▪ Collision dynamics: Diff. observables sensitive to diff. reaction stages
Tim
e
Penetrating
probes t~0.1 fm/c
t ~ 10 fm/c
t ~ 107 fm/c
Final state probes
Penetrating probes
5QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Hard probes of hot/dense QCD matterHard probes of hot/dense QCD matter
Z,
“Jet quenching”
J/Ψ & Υ suppression
direct , *, Z(control)
▪ Hard probes: largeQ2 (Q>2 GeV/c), earlytime production (~1/Q<0.1 fm/c) ▪ “Selfgenerated tomographic probes of the hottest and densest phases of AA collisions, well controlled experimentally & theoretically.”
6QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
““Jet quenching” as a QGP probeJet quenching” as a QGP probe
� gluonsstrahlung�
∆Eloss(g) > ∆Eloss(q) > ∆Eloss(Q) (color factor) (mass effect)
∝ (q, gluon density, L2)GLV
BDMPS
ˆ
▪ Parton energy loss: multiple nonAbelian (=gluon) radiation off the produced hard parton induced by the dense QCD medium:
▪ Parton energy loss ➠ Medium properties:
▪ transport coefficient:
▪ Flavourdependent energy loss:
▪ Energy lost carried away by gluons in broadened jet cone:
µ
λµ22
ˆ ≈=Lk
q T : Debye mass: mean freepath λ
q̂
7QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
25-years of � jet quenching� phenomenology25-years of � jet quenching� phenomenology
▪ Mono-jets:
▪ Jet broadening in :
XNWang&Gyulassy PRL 68, 1480 (1992)
Armesto et alhepph/0405301
▪ Leading hadron suppression:
▪ Medium-modified FFs:
X.N.Wang,A.MajumderSalgado&Wiedemann;Arleo, ...
Bjorken, FERMILABPUB82059THY.1982
▪ Mach-cones in :
θM Trigger
cos M scθ =
Stoecker et al. hepph/0505245.Casalderrey, Shuryak, hepph/0411315
Cerenkov angles, ...
...
Nchjet increases
<zjet> decreases
8QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
I. HighpI. HighpTT single inclusive single inclusive hadron spectrahadron spectra
9QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pTT (leading) hadrons (leading) hadrons
pT< 2 GeV/c: Expo. (Ed3σ/d3p ~ e-6pT) w/ constant inv. slope: ~ 160 MeV ~ Tcrit
Thermallike soft hadrons: e6pT √sindep.
Hard scatt.: 1/pT
n (√sdepend.)
pT~2GeV/c
■ Above pT~ 2 GeV/c: single spectra dominated by fragmentation hadrons
carrying a large fraction of parent parton pT (<z>=phad/pparton~0.7 @ RHIC)
10QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High-pHigh-pTT hadrons: pQCD factorization theorem hadrons: pQCD factorization theorem
(1) Hadron = collection of partons described by PDFs(x,Q2):
■ Production cross section computable as a convolution of 3 terms: 1 short-
distance (pQCD parton-parton) & 2 long-distance (PDF, FF)
(2) High-Q2 parton-parton x-sections computed
perturbatively at a given O(s):
(3) Parton (jet) fragmentation into hadrons described by a FF(z,Q2):
x1
x2
hadronjet
11QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High-pHigh-pTT hadron spectra: p-p hadron spectra: p-p @ @ 200 GeV200 GeV
■ High pT hadron spectra very well described by NLO pQCD:
PHENIX Collab.
PRD76, 051106(R) (2007)
■ Data sensitive to different parametrizations of gluon FF
M. Ru sscher , QM06
12QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Hard yields in p-A, A-A collisions (no medium effects)Hard yields in p-A, A-A collisions (no medium effects)
A
B
dσAB → hard = A∙B∙dσpp → hard
dNAB → hard (b) = TAB(b)∙dσpp → hard
Nuclear Modification Factor:
At impact parameter b:
geom. nuclear overlap at b nonpQCD prod.
TAB ~ Ncoll (# of nucleonnucleon colls at b)
AB = “simple superposition of pp collisions”⇒ nPDF: independent sum of “free” partons:
dσpA → hard = A∙dσpp → hard
■ Factorization theorem for nuclear collisions:
■ "Ncoll scaling� :
13QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pTT hadron spectra: d-Au hadron spectra: d-Au @ 200 GeV@ 200 GeV
π0
PHENIX, nucl-ex/0610036
η
PHENIX,
nucl-ex/0611006
■ Small "cold nuclear matter" modifications (Cronin, shadowing): ~20%
π,h
■ Only protons (factor ~2 enhancement)
deviate from "vacuum" production
STAR: nucl-ex/0604018
p,p_
14QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pTT pion spectra: Au-Au pion spectra: Au-Au @ 200 GeV@ 200 GeV
Au+Au→ π0 X (peripheral) Au+Au→ π0 X (central)
Peripheral data agree well with Strong suppression in
p+p (data&pQCD) plus Ncoll scaling central Au+Au collisions
15QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
AuAu (dAu) @ 200 GeV:AuAu (dAu) @ 200 GeV: high phigh p
TT (un)suppression ! (un)suppression !
x45 suppression
■ RAA << 1: well belowpQCD expectations for hard scattering xsections in vacuum
π0,h ±
■ AuAu suppression due to finalstate interactions absent in “control” dAu colls.
PRL 91, 0723ii (2003)
PHENIX, PRL 88, 022301 (2002)
16QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T suppression suppression ⇒⇒ QCD medium properties QCD medium properties■ Medium properties via data vs. � jet quenching� models:
Initial gluon densities (GLV):
dNg/dy = 1400+270
Transport coefficients
■ Other models: Temperatures [AMY]: T ~ 0.4 GeV [G. Moore], Opacities: <n> = L/λ ≈ 3 � 4 [Levai et al.]
Energy losses: dE/dx≈ 0.25 GeV/fm (expanding), dE/dx|eff ≈ 14 GeV/fm (static) [X.N.Wang]
Large opacities imply fast thermalization.
All these values imply energy densities well above εcrit QCD in thermalized syst.
[BDMPS/PQM]
<q0> ~ 13.2+2.1 GeV2/fm
[Vitev & Gyulassy]
PHENIX, arxiv:0801.1655
-150
-3.2
17QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T suppression (I): hadron “universality”suppression (I): hadron “universality”
■ Photons are unsuppressed but π0,η,h± show a common suppression pattern (magnitude, pT, centrality, ...):
■ Same flat RAA ~ 0.2 up to 10 GeV/c
■ Universal suppression for light mesons consistent with quenching at partonic level prior to q,g fragmentation into leading meson according to vacuum FFs.
PRL 96, 202301 (2006)
✔✔
18QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T suppression (II): psuppression (II): pTTdependencedependence
■ Flat pTdependence described by parton energy loss models:
■ Underlying LPM interference for single gluon bremsstrahlung would give: ∆Eloss ~ log(pT)
■ Combination of diff. effects (convolution w/ realistic parton radiation energy distrib., local parton pT slope, nuclear PDFs ...) yields constant quenching factor.
PQM – A. Dainese, C. Loizides, G. PaicEPJ C 38, 461(2005)
GLV – I. Vitev 2005
✔✔
19QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T suppression (III): Excitation functionsuppression (III): Excitation function
■ c.m. energy dependence in agreement with parton energy loss in increasingly dense medium:
RAA ~ 1 @ √s ~ 20 GeV ⇒ dNg/dy ~ 400 , <q0> ~ 3.5 GeV2/fmRAA ~ 0.3 @ √s = 62 GeV ⇒ dNg/dy ~ 650 , <q0> ~ 7 GeV2/fmRAA ~ 0.2 @√s =200 GeV ⇒ dNg/dy ~ 1100 , <q0> ~ 14 GeV2/fm
[RAA @ SPS uses “revised” pp ref.]
Initial gluon density: Medium transport coeff.: SPSRHICRHIC
D.d'E., EJP C 43 (2005)295PHENIX, arXiv:0801.iii
AuAuCuCu
(less suppression in lighter systems)
✔✔
20QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T suppression (IV): centralitydependencesuppression (IV): centralitydependence
PQM – Loizides EPJ C 38, 461(2005)
■ Increasing centrality i.e. Npart ⇒ increased L, ρ ⇒ larger suppression ■ Theory predicts: log(RAA) ∝Npart
−2/3
■ Agreement data ↔ models as expected for diff. suppressions at diff. (geometrical) parton production points.
PHENIX, arXiv:0801.iii
nEXP~0.58±0.1 consistent with nTH~2/3
✔✔
21QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T suppression (V): pathlength dependencesuppression (V): pathlength dependence
∆φ = 0°
∆φ = 90°
No apparent Eloss for L< 2 fm“Corona effect” effect? V. Pantuev hepph/0506095
Lε
■ Parton Eloss pathlength ∝ L2 (static), L (expanding):
matter thickness
Less suppression inplane (“short” direction) More suppression outofplane (“long” direction)
~2 fm
Eloss approx. linear with L formost centralities,
PRC76, 034904 (2007)
✔✔
22QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T suppression (VI): nonAbelian naturesuppression (VI): nonAbelian nature
■ Gluons radiate ✕2 more than quarks:
■ TEST 1: At fixed pT & increasing √s (i.e. at lower x): increased fraction of gluons ⇒ increased quenching
NonAbelian energy loss modelpreferred over “nonQCD” (qloss=gloss)
Gluon: CA = Nc = 3Quark: CF =(Nc
21)/2Nc = 4/3
pT = 5 GeV/c, √s = 105500 GeV
CA /CF=2.25}
SPS=q
RHIC=q,g
LHC=g D.d'E., EJP C 43 (2005)295qrich
q,g~50%
✔✔
23QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T suppression (VI): nonAbelian nature ?suppression (VI): nonAbelian nature ?
■ TEST 2: A large fraction of highpT (anti)protons from gluonfragmentation ⇒ increased p over quenching
STAR, PRL 97, 152301 (2006)
■ But above 6 GeV/c, similar ,p suppression: no apparent stronger gluon energy loss
(Need new calculations, with latest baryon FF: AKK, DSS)
pT (GeV/ c)
p/ π
40% from gluons
90% p,p from gluons_
dAu
■ However, (anti)proton production not well “calibrated”: enhanced in “cold QCD matter” (extra nonpQCD mechanism ?)
✔✔
24QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T suppression (VII): Mass effect ?suppression (VII): Mass effect ?
⇒ HeavyQ expected to lose less energy than lightq.■ HighpT e± from heavyquark decays equally suppressed as pions: RAA~0.2 above ~6 GeV/c. Radiative energy loss fails to reproduce data.
■ less bottom fraction ? Additional quenching from collisional energy loss ? ⇒ need to directly reconstruct D (and B) mesons.
■ “Deadcone” effect: Massive quarks cannot radiate gluons at low angles (causality requirement: since vQ<c)
STAR, PRL (2006)
PHENIX, PRL (2006)
[Dokshitzer & Kharzeev]
25QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T single hadron suppression: summarysingle hadron suppression: summary
▪ Hadrons (but not ) above pT~5 GeV/c suppressed in central AuAu by a factor of ~5 wrt. “vacuum” (pp) or “cold QCD matter” (dAu) parton fragmentation.
▪ Magnitude of quenching consistent with parton energy loss model predictions in a very opaque system: dNg/dy~1400 or q~13 GeV2/fm
❤ Most observed properties of the quenching factor consistent with radiative Eloss: pT, centrality, √s, pathlength, “nonAbelianity”, ...
A few “glitches” in the canonical interpretation: ♦ no deadcone effect for heavyQ (collisional Eloss ?) ♦ ~2fm pathlength “unsuppression” (“corona” effect ?) ♦ (anti)protons not from gluon fragmentation (extra production ?)
26QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T suppression: outlook (CMS @ LHC)suppression: outlook (CMS @ LHC)
▪ Physics reach (PbPb @ 5.5 TeV, 0.5 nb1, HLT): spectra, RAA
pT~300 GeV/c (Slower rise in BDMPS than in GLV)
▪ RAA at the LHC not independent of pT: more sensitivity to energy loss distribution
27QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
II. HighpII. HighpTT dihadron dihadron correlations correlations
28QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Jet reconstruction in Au-Au at RHIC ?Jet reconstruction in Au-Au at RHIC ?
▪ Full jet reconstruction w/ std algorithms is unpractical (but possible?) at
RHIC due to (i) low jet yields, (ii) large soft background (� underlying event� ):
p+p →jet+jet [√s = 200 GeV] Au+Au → X [√sNN = 200 GeV]
29QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
�� Jet physics� in Au-Au at RHICJet physics� in Au-Au at RHIC
▪ Alternative I : Study energy modifications suffered by the highest pT hadrons in (“leading” hadron of the jet) in AA compared to pp:
p+p →jet+jet [√s = 200 GeV] Au+Au → X [√sNN = 200 GeV]
30QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
�� Jet physics� in Au-Au at RHICJet physics� in Au-Au at RHIC
▪ Alternative II : Study the azimuthal correlations in AA relative to pp between highest pT hadron (“trigger”) & any other “associated” hadron:
p+p →jet+jet [√s = 200 GeV] Au+Au → X [√sNN = 200 GeV]
31QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
�� Jet physics� in Au-Au at RHICJet physics� in Au-Au at RHIC
▪ Alternative II : Study the azimuthal correlations in AA relative to pp between highest pT hadron (“trigger”) & any other “associated” hadron:
p+p →jet+jet [√s = 200 GeV] Au+Au → X [√sNN = 200 GeV]
32QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Dijets via di-hadron Dijets via di-hadron ∆φ∆φ correlations: pp, dAu correlations: pp, dAu
▪ Study dijet events “statistically”: via typical backtoback azimuthal correlations of produced hadron pairs (h± – h±, π0,± – h±):
▪ Clear near-side (∆φ ~ 0) and
away-side (∆φ ~ π) jet signals: 35 GeV/c
d+Au
Nearside
awayside
23 GeV/c
p+p
dAu
pp
pTassoc = 23 GeV/c pT
assoc = 35 GeV/c
▪ Trigger: highest pT (leading) hadron.
▪ Associated ∆φ distribution (e.g. ”assorted”: 2 GeV/c < pT
assoc < pTtrigger)
33QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Dijets via dihadron Dijets via dihadron ∆φ∆φ correlations: central AuAu correlations: central AuAu
▪ AuAu: trigger hadron: from parton at surface awayside hadron: from quenched parton
▪ Same analysis as in pp, dAu but: larger underlying event elliptic flow subtraction
▪ Main experimental findings:
“punchthrough” at high pT
Nearside: approx. unmodified
Awayside: “disappearance” at semihard pT
broadening/softening at low pT
“splitting” at intermediate pT
34QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
AuAu dihadron AuAu dihadron ∆φ∆φ correlations: semi-hard, low- p correlations: semi-hard, low- pTT
▪ “Jet remnants” reappear at low pT
as a broader/softened structure:pT trigg= 4 – 6 GeV/cpTassoc = 0.15 – 4 GeV/c
STAR, PRL90, 082302 (03)
1/N t
rigge
r dN/
d(∆φ
)
pT trigg= 4 – 6 GeV/cpTassoc > 2 GeV/c
1/N t
rigge
r dN/
d(∆φ
) ∆φ (radians)
STAR, PRL95,152301(05)
▪ Awayside peak disappears: “monojet” like topology:
<pT> awayside hadrons (pp) ~ 1. GeV/c<pT> awayside hadrons (AuAu) ~ 0.7 GeV/c<pT> inclusive hadrons (AuAu): ~0.6 GeV/c
35QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
AuAu dihadron AuAu dihadron ∆φ∆φ correlations: away-side splitting correlations: away-side splitting
▪ Strongly modified awayside correlations at intermediate pT's : (1) Awayside “dip” at (2) Excess of activity (“double peak”, “shoulders”) at: ±1.1 rad
arXiv:0801.iii
0-12%
012%2.5 < pT,trig < 4.0 GeV/c1.0 < pT,assoc < 2.5 GeV/c
▪ Splitting angle doesn't vary much in wide range of centralities
(rads)
arXiv:0801.iii
36QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
AuAu dihadron AuAu dihadron ∆φ∆φ correlations: splitting interpretations correlations: splitting interpretations
▪ Large angle gluon rad.
A. Polosa, C. Salgado
Also: Vitev, Phys. Lett. B630 (2005)
Quenchedjet scatters through medium radiates largeangle gluon (“Mercedes” topology)
▪ But also: deflected jets ...
▪ Mach cone
T. Renk, J. Ruppert
hepph/0411315 Casalderrey,Shuryak,Teaneynuclth/0406018 Stoeckerhepph/0503158 Muller,Ruppertnuclth/0503028 A. K. Chaudhuri
▪ Cerenkov radiation
I. Dremin;V. Koch,A. Majumder, XN. Wangnuclth/0507063
Quenchedjet generates a sonic shockboom whilepropagating thru medium. Speedofsound accessible:
Quenchedjet radiates at fixed angle when traversing the medium at v > c. Gluondielectric coeffic. accessible:
( ) nem1cos =θ
cos M scθ =
37QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
AuAu dihadron 3-particle AuAu dihadron 3-particle ∆φ∆φ correlations: splitting correlations: splitting
∆φ1
3
∆φ12
0 π 2π
π
2π
Conelike structure
in each event
▪ 3particle help discriminate among various physics mechanisms:
However: Large backgrounds , background shapes not s im p le
Mediumaw ay
near
deflected jets
aw ay
near
Medium
Mach cone
∆φ12
0 π 2π
2π∆φ1
3
πEventbyevent deflection of jets
[M.v Leeuwen, QM06]
38QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
AuAu dihadron 3-particle AuAu dihadron 3-particle ∆φ∆φ correlations: results correlations: results
Au+ Au 0- 12%
(∆φ12- ∆φ13)/ 2
(∆φ12+ ∆φ13)/ 2- π
PHENIX Preliminary
C. Prun eau , J. UleryC. Zh an g, N. Ajitan an d
∆ϕ1
3
Cumulant analysis:ModelindependentNonzero 3particle structure
Jet+background analysis:Modeldependent, more sensitiveOffdiagonal peaks consistent with conical emission
(Different coordinates)No ‘deflectedjet peak’consistent with conical emission
∆ϕ12
Conelike emission favoured
3 < pT,t r ig < 4 GeV/ c
1 < pT,as s oc < 2 GeV/ c
[M.v Leeuwen, QM06]
39QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Jet fragmentation: azimuthal � charge ordering�Jet fragmentation: azimuthal � charge ordering�
▪ Strong dynamical charge correlations are expected in jet fragmentation:
▪ Compare ++ and correlations to +
▪ Similar charge ordering observed in pp, AuAu & jetfragmentation MC.
pT > 4 GeV/c: same hadron production mechanism in central AuAu & pp
STAR, PRL , (2002)
40QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
High pHigh pT T dihadron correlations: summarydihadron correlations: summary
▪ HighpT 2,3 hadron correlations: allow access mediummodified dijets
▪ Jetlike correlations clearly present: nearside shape, charge ordering
▪ Awayside associated hadrons strongly modified: Low pT: yield strongly enhanced, softened & broadened MidpT: doublepeak structure with conicallike emission at ~1.1 rad Semihard pT: awayside peak strongly suppressed HighpT (pT~8 GeV/c): awayside peak reappears (“punchthrough”)
▪ Rich phenomena at intermediate pT: Tantalizing connections to collective medium response to hard partons (speed of sound, index of refraction, ...) but theorydata comparison challenging.
41QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
III. Jet reconstruction, III. Jet reconstruction, jet, jet, fragmentation functionsfragmentation functions
43QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
d+Au, 40100%
Au+Au, 05%
STAR preliminary
3 < pT(trig) < 6 GeV2 < pT(assoc) < pT(trig)
[D. Magestro, HP'04]
Dihadron Dihadron ∆η∆η correlations: AuAu (200 GeV) correlations: AuAu (200 GeV)
Significant broadening of pseudo-rapidity
correlations in AuAu compared to pp,dAu. (“stretching” of jet cone along η).
Coupling of g radiation w/ longitud. expanding medium?STAR preliminary p+p
Au+Au, 05%
nearside width
44QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Dijets via dihadron Dijets via dihadron ∆φ∆φ correlations: central AuAu correlations: central AuAu
Ajitanand, ICPAQGP'04and nuclex/0501025
▪ Delicate subtraction procedure (esp. in finite acceptances).
▪ Same dNpair/d analysis as in pp (dAu) but 2 extra � complications�:
(1) Increased � underlying event� background
(2) Collective elliptic flow (harmonic) contribution
45QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Dihadron Dihadron ∆φ∆φ correlations: AuAu away-side splitting correlations: AuAu away-side splitting
PHENIX (nucl-ex/0507004)
p er ip hera l: norm a l je t p a t tern
Emergence of a Volcano Shape
Correlation of soft ~1-2 GeV/c jet partnersCorrelation of soft ~1-2 GeV/c jet partners
46QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Dihadron Dihadron ∆φ∆φ correlations: splitting correlations: splitting
Double peak structure at π ± 1.2 rad reminiscent of Mach wave conical shock (“sonic boom”) in medium ⇒ speed of sound accessible
33.0)(1∫ ττ
τ sf
avs cdc
cos M scθ =
θM Trigger
Mach cone:
θ = arccos(<cs>) ~ 1.2 rad
(timeaveraged)
~ θexp
→ HRG (cs~√0.2)
→ phase transition (cs~0.)
→ QGP (cs~1/√3)
= ~<cs>
47QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Jet properties from dihadron correlationsJet properties from dihadron correlations
Jet “width” j T :
Dijet acoplanarity k T:
(1) 2hadron correlation function:
(2) Fit to 2gaussians: nearside σN, farside σF widths
(3) Extraction of jT, kT from σN, σF via [*], [**] (and dN/dxE from YieldN,F)
⇒
[*]
[**]
nearside farside
[details in J.Jia, nuclex/0409024]
48QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Mean transverse momentum of jet hadrons Mean transverse momentum of jet hadrons (j(jTT): pp, dAu): pp, dAu
Jet (nearangle) “width” jT :jT
p+p
Pythia + GEANT
< jT> ~ 500 MeV/c (from full jet reco) p+p
< jTy> ~350 MeV/c ≡ < jT> ~ 500 MeV/c
• < jT> ~ 500 MeV/c: Agreement between RHIC and ISR data.
• No apparent difference between dAu and pp.
• Fragmentation not affected by cold QCD medium.
[J.Rak, QM'04]
49QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Di-jet acoplanarity (� intrinsic� kDi-jet acoplanarity (� intrinsic� kTT) : pp, dAu) : pp, dAu
Intrinsic kT (dijet acoplanarity):
Tk
Jet 2
Jet 1
∆ϕ
⟨z⟩ = 0.75 taken as constant
• Nonnegligible pp kT broadening: <kTy> ~ 1.1 GeV/c (not observed in high pT spectra <kT>pair≠<kT>incl)
• Nonnull (but small) dAu <kT>nuclear
(constraints models of multiple scattering in cold nuclear medium)
nuclearTppTdAuT kkk 222
R=0.35
d+Au
= +
∆φ=0.22±0.02±0.06
∆φ=0.31±0.05±0.06
(from full jet reco: ET~13 GeV)
50QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Di-jet acoplanarity (� intrinsic� kDi-jet acoplanarity (� intrinsic� kTT): Excitation function (pp)): Excitation function (pp)
Dihadron in pp @ RHIC<kT> ~ 1.8 GeV/c
sqrt(s)dependence of <kT>pair:
(Logarithmic) increase with sqrt(s) consistent with growing gluon radiation contribution (not just intrinsic parton Fermi motion).
51QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Jet properties (jJet properties (jTT, k, k
TT): AuAu (200 GeV)): AuAu (200 GeV)
Preliminary
pp <z><|kTy|>
pp <|jTy|>
pTtrigg =2.5 – 4.0 GeV/c , pTassoc = 1.0 – 2.5 GeV/c
Centrality dependence of ⟨|jTy|⟩ and ⟨z⟩ ⟨|kTy|⟩ in Au+Au:
<jT>AuAu~ <jT>pp: nearside fragmentation unaffected by QCD medium.
Significant kT broadening (kT~3 GeV/c) in AuAu (strongly centrality dependent) indicating substantial finalstate rescattering of awayside fragmenting parton.
[J.Rak, QM'04]
52QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
AdS/CFT correspondence and sQGP propertiesAdS/CFT correspondence and sQGP properties
Classical gravity limit
NN = 4 Super-Yang-Mills theory in 4d with SU(NC)
Ap p ly to both d ynam ical and therm od ynam ic observables .
YM observables at in fin ite NC and in fin ite coup ling can be com p uted us ing class ical gravity
A s t r ing theory in 5d Ad S
Fin ite tem p eratu reLarge NC and
s t rong coup ling lim it
Black hole in Ad S5
53QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
BDMPS transport coefficient (q) in N=4 SYMBDMPS transport coefficient (q) in N=4 SYM
( )( )
33
45
432/3
69.26ˆ TNTq cSYMSYM αλπ ≈Γ
Γ=
/fm.GeV 4.5ˆ 2=SYMq MeV TCN s 300 ,21 ,3 === α• Take:
Black hole in AdS spacetime: radial coordinate r,• horizon: r=r0
• constant r surface: (3+1)dim Minkowski spacetime
horiz on
€
r0€
r=∞
Recipe: (i) Non pQCD definition of qhat:(ii) Compute qhat in strongly coupled SuperYangMills theory using AdS/CFT
Our (3+1)dim world, Wilson loop C in our world
: area of string worldsheet with boundary C
€
S(C)
54QGPWS, Jaipur, 1st – 3rd Feb 2008 David d'Enterria (CERN)
Drag force for heavy quarks in N=4 SYMDrag force for heavy quarks in N=4 SYMHerzog, Karch, Kovtun, Kozcaz, Yaffe; Gubser, …….
Drag force for a heavy quark moving in the medium:
CasalderreySolana, Teaney
Fluctuationdissipation theorem
Diffusion coefficient:
Note: D can not be used to find q̂
It is possible to analyze the energy flow pattern (indications of conical flow)
Fluctuationdissipation theorem assumes the quark is in equilibrium with the medium: does not apply to high energy jet
J. J. Friess, S. S. G ubser and
G . M ichalogiorgakis,arXiv:hepth/0605292.