BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Multigluon correlations in the color glass condensate
DTSTART;VALUE=DATE-TIME:20120815T150000Z
DTEND;VALUE=DATE-TIME:20120815T152000Z
DTSTAMP;VALUE=DATE-TIME:20200405T074106Z
UID:indico-contribution-25255-308451@indico.cern.ch
DESCRIPTION:Speakers: Tuomas Lappi (U)\nMultiparticle correlations\, such
as the "ridge" effect in pp and AA collisions and forward dihadron correla
tions in pA collisions\, are an important probe of the strong color fields
that dominate the initial stages of a heavy ion collision. We argue that
the Color Glass Condensate framework provides the most natural way to unde
rstand them.\n\nWe describe recent progress in understanding two-particle
correlations in the dilute-dense system\, e.g. in forward dihadron produ
ction in deuteron-gold collisions. This requires computing the energy dep
endence of higher point Wilson line correlators from the JIMWLK renormali
zation group equation. We find that the large Nc approximation used so far
in the phenomenological literature is not very accurate. On the other han
d a Gaussian finite Nc approximation is a surprisingly close to the full r
esult.\n\nhttps://indico.cern.ch/event/181055/contributions/308451/
LOCATION: Empire
URL:https://indico.cern.ch/event/181055/contributions/308451/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Imprinting quantum fluctuations on hydrodynamic initial conditions
DTSTART;VALUE=DATE-TIME:20120815T154000Z
DTEND;VALUE=DATE-TIME:20120815T160000Z
DTSTAMP;VALUE=DATE-TIME:20200405T074106Z
UID:indico-contribution-25255-308513@indico.cern.ch
DESCRIPTION:Speakers: J. Scott Moreland (Duke University)\nThe precise val
ue of the QGP kinematic shear viscosity eta/s is a question of intense top
ical interest. Viscous hydrodynamic simulations are a tool for extracting
this information from experiment. The key observables are the anisotropic
flow coefficients v_n which (i) can be measured very precisely and (ii) ar
e very sensitive to eta/s which controls the "conversion efficiency" v_n/e
cc_n for turning initial fireball eccentricities of harmonic order n into
final flows of the same harmonic order. \n\nBoth ecc_n and v_n fluctuate s
trongly from collision to collision. These event-by-event fluctuations hav
e a key influence on the measurements [1] and must be properly taken into
account when extracting eta/s. Until recently\, most initial-state models
accounted only for the shape and density fluctuations arising from the flu
ctuating positions of the nucleons in the colliding nuclei. This leads to
fluctuations in the location of the newly produced matter\, and thus of th
e initial energy density profile of the expanding fireball and its eccentr
icities ecc_n\, but does not account for additional quantum fluctuations i
n the quark and gluon fields inside the nucleons that lead to fluctuating
numbers of secondary particles per nucleon-nucleon interaction. Several re
cent papers have addressed the implementation of these quantum fluctuation
s in the hydrodynamic initial conditions for the expanding collision fireb
all. \n\nStarting from the Monte Carlo Kharzeev-Levin-Nardi (MC-KLN) model
for generating fluctuating initial profiles for the gluon saturation mome
ntum Q_sat(x_T) in the transverse plane\, we have developed a Monte Carlo
algorithm that uses a Gaussian Random Field (GRF) generator [2] to generat
e a distribution of gluonic energy densities centered at the value corresp
onding to the field Q_sat(x_T)\, but fluctuating around this profile with
the two-point covariance function derived in [3] from the Glasma model. To
ensure that the energy density is everywhere positive the GRF is mapped t
o an appropriate negative binomial distribution (NBD) with the same varian
ce. NBD fluctuations have been recently shown to arise naturally from the
Glasma model and to describe the measured multiplicity distributions in pp
collisions at the LHC. The resulting density profile features ``hot spots
" as in the MC-KLN model overlaid with a fluctuating field texture charact
erized by an intrinsic length scale 1/Q_sat(x_T).\n \nWe show that inclusi
on of these additional gluonic quantum field fluctuations leads to only a
small (few percent) increase of the initial eccentricities ecc_n in centra
l collisions and to almost negligible effects at larger impact parameters.
These findings disagree with some of the results reported in [4]\, and we
will discuss possible origins for this discrepancy. Our results imply tha
t an earlier extraction of the QGP shear viscosity from a combined analysi
s of elliptic and triangular flow data from Pb-Pb collisions at the LHC [5
] is robust.\n\nReferences\n \n[1] Zhi Qiu and U. Heinz\, ``Event-by-eve
nt shape and flow fluctuations of relativistic heavy-ion collision firebal
ls\,'' Phys. Rev. C84\, 024911 (2011).\n\n[2] X. Emery and C. Lantuejoul\,
``TBSIM: A computer program for conditional simulation of 3-dimensional G
aussian random fields via the turning bands method\," Computers and Geosci
ences 32\, 1615 (2006).\n\n[3] B. Muller and A. Schafer\, ``Transverse ene
rgy density fluctuations in the Color Glass Condensate Model\,'' arXiv:111
1.3347 [hep-ph].\n\n[4] B. Schenke\, P. Tribedy and R. Venugopalan\, ``Flu
ctuating Glasma initial conditions and flow in heavy ion collisions\,'' ar
Xiv:1202.6646 [nucl-th]\; F. Gelis\, T. Lappi and L. McLerran\, ``Glitteri
ng Glasmas\,'' Nucl. Phys. A 828\, 149 (2009)\; A. Dumitru and Y. Nara\, `
`KNO scaling of fluctuations in pp and pA\, and eccentricities in heavy-io
n collisions\,'' Phys. Rev. C85\, 034907 (2012).\n\n[5] Z. Qiu\, C. Shen a
nd U. Heinz\, ``Hydrodynamic elliptic and triangular flow in Pb-Pb collisi
ons at sqrt(s)=2.76ATeV\,'' Phys. Lett. B707\, 151 (2012).\n\nhttps://indi
co.cern.ch/event/181055/contributions/308513/
LOCATION: Empire
URL:https://indico.cern.ch/event/181055/contributions/308513/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Forward azimuthal correlations in 200 GeV p+p and d+Au collisions
at STAR
DTSTART;VALUE=DATE-TIME:20120815T162000Z
DTEND;VALUE=DATE-TIME:20120815T164000Z
DTSTAMP;VALUE=DATE-TIME:20200405T074106Z
UID:indico-contribution-25255-308521@indico.cern.ch
DESCRIPTION:Speakers: Xuan Li (Shandong University)\nThe proton gluon dist
ribution function increases rapidly with decreasing x at fixed $Q^{2}$\, b
ut cannot increase indefinitely as x goes to 0. Gluon saturation is expect
ed at a low x value when gluon recombination balances gluon splitting. The
nuclear (with atomic mass number A) gluon distribution is approximately $
A^{1/3}$ larger than the nucleon gluon distribution function at the same x
[1]. STAR is sensitive to x between 0.001 and 0.02 for the nuclear gluon
distribution via di-jet measurements with calorimeter subsystems covering
-1 \n\nhttps://indico.cern.ch/event/181055/contributions/308521/
LOCATION: Empire
URL:https://indico.cern.ch/event/181055/contributions/308521/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Effect of longitudinal fluctuation in event-by-event (3+1)D hydrod
ynamics
DTSTART;VALUE=DATE-TIME:20120815T152000Z
DTEND;VALUE=DATE-TIME:20120815T154000Z
DTSTAMP;VALUE=DATE-TIME:20200405T074106Z
UID:indico-contribution-25255-308780@indico.cern.ch
DESCRIPTION:Speakers: Long-Gang Pang (l)\nHadron spectra and elliptic flow
in high-energy heavy-ion collisions are studied within a (3+1)D ideal hyd
rodynamic model with fluctuating initial conditions given by the AMPT Mont
e Carlo model and compared to experimental data. Fluctuation in the initia
l energy density comes from not only the coherent soft interaction of over
lapping nucleons but also the number of mini-jets within each binary nucle
on collision. Mini-jets produced via semi-hard parton scatterings are assu
med to be locally thermalized through a Gaussian smearing and give rise to
fluctuation in rapidity distribution along the longitudinal direction. Th
e longitudinal fluctuation is found to lead to sizable reduction of ellipt
ic flow at large transverse momentum.\n\nhttps://indico.cern.ch/event/1810
55/contributions/308780/
LOCATION: Empire
URL:https://indico.cern.ch/event/181055/contributions/308780/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The spectrum of quantum fluctuations and space-time evolution in t
he little bang
DTSTART;VALUE=DATE-TIME:20120815T160000Z
DTEND;VALUE=DATE-TIME:20120815T162000Z
DTSTAMP;VALUE=DATE-TIME:20200405T074106Z
UID:indico-contribution-25255-308814@indico.cern.ch
DESCRIPTION:Speakers: Raju Venugopalan (Brookhaven National Laboratory)\nW
e outline significant recent progress in a program to include quantum corr
ections to the evolution of the classical color fields produced in high-en
ergy ultra-relativistic heavy ion collisions. Previous work in this direct
ion for a scalar \\phi^4 theory [1] has now been extended to QCD. Leading
contributions from unstable quantum modes can be resumed to all loop order
s and expressed in terms of a gauge invariant spectrum of initial quantum
fluctuations\, which has been computed recently [2]. These fluctuations p
lay a key role in decoherence of the high occupancy fields\, and in their
possible isotropization and flow\, and in the matching of this initial dyn
amics to hydrodynamic flow\, thereby potentially eliminating a big source
of uncertainty in hydrodynamic simulations. We report on progress in the 3
+1-D numerical computations implementing these pre-equilibrium dynamics.\n
\n[1] K.~Dusling\, T.~Epelbaum\, F.~Gelis and R.~Venugopalan\,\n%``Role of
quantum fluctuations in a system with strong fields: Onset of hydrodynami
cal flow\,''\n Nucl.\\ Phys.\\ A {\\bf 850}\, 69 (2011)\; T.~ Epelbaum an
d F. Gelis\,\n %``Role of quantum fluctuations in a system with strong fi
elds: Spectral properties and Thermalization\,''\n Nucl.\\ Phys.\\ A {\\b
f 872}\, 210 (2011).\n\n[2] K.~Dusling\, F.~Gelis and R.~Venugopalan\, %``
The initial spectrum of fluctuations in the little bang\,''\n Nucl.\\ Phy
s.\\ A {\\bf 872}\, 161 (2011).\n\nhttps://indico.cern.ch/event/181055/con
tributions/308814/
LOCATION: Empire
URL:https://indico.cern.ch/event/181055/contributions/308814/
END:VEVENT
END:VCALENDAR