Last
Call for Predictions
Monday
May 14th to Friday June 8th 2007
Seminars
2. Tuesday May
15th 2007, 11am, TH Auditorium (4-3-005)
Author:
B. Sinha (VECC)
Title: Ratio of
Dileptons to Photons - Universal Signals of Quark Gluon Plasma
3. Wednesday May
16th 2007, 11am, TH Auditorium (4-3-005)
Author: Alex Kovner (Connecticut)
Title: Wannabe
dipoles and multigluon production at high energy
4. Friday May 18th
2007, 9.30am, TH Auditorium (4-3-005)
Author: Simon Wicks (Columbia)
Title:
Perturbative jet energy
loss mechanisms: Learning from RHIC,
extrapolating to LHC
Abstract: The WHDG model
combined DGLV radiative loss with a leading log calculation of
collisional energy loss. The essential physical contribution of the
collisional loss was thus included, with fluctuations given by a
gaussian width from the fluctuation-dissapation theorem. But there is
more to the physics of collisions in the QGP. As the expected number
of (hard) collisions of a jet with the medium is small, it is
necessary to evaluate the full fluctuation spectrum of a single
collision and the poissonian convolution of this for multiple
collisions. This collisional spectrum has interesting qualitative
features that have a quantitative effect, such as an energy gain
contribution, that are neglected in Bjorken-like calculations. The
comparison of the spectrum of momentum transfers with that for vacuum
propagators or the GW model reveals interesting contrasts, and also
gives an indication of theoretical uncertainties inherent in models
used.
5. Monday May 21st
2007, ALICE Club, 1.45pm,
room 160-1-009
Author: Peter Levai (RMKI Budapest)
Title:
Hadron Production
from Quark Coalescence at the LHC
6. Monday May 21st
2007, Heavy Ion Forum, 3.30pm, room 13-2-005
Author: William Horowitz (Columbia)
Title:
Possible String Theoretic
Deviations from pQCD in Heavy Quark
Energy Loss at the LHC
Abstract: For the first few
years of its running, pQCD techniques applied to high-pt jets at RHIC
were highly successful in explaining the observed normalization and
momentum dependence of jet suppression. However, there were signs
that the picture of a weakly coupled, perturbatively understandable
QGP was overly naive: the observed intermediate-pt azimuthal
anisotropy was too large; the number of nonphotonic electrons and the
viscosity over entropy ratio too small. Infinitely-coupled super
Yang-Mills calculations have been computed using string theoretic
approaches, first as applied to the eta over s ratio, and recently to
jet energy loss. Since none of the RHIC experiments currently has the
ability to discern the charm versus bottom quark contribution to the
nonphotonic electron spectrum, one cannot distinguish between the
possible pQCD versus string theoretic solutions to the heavy quark
quench puzzle. Nonetheless, pQCD gives very strong and specific
predictions for the momentum dependence of charm and bottom energy
loss. Deviations from this would point to new physics, and we provide
several possibilities of a different dependence given by string
theory calculations. The unique position of the LHC due to both its
particle identification abilities and its enormous momentum reach
should permit an observation of a possible discrepancy within the
first year of LHC running.
7. Tuesday May
22nd
2007, 11am, TH Auditorium
(4-3-005)
Author: Alejandro Ayala
Title: Collisional parton energy
loss in a finite QCD medium
revisited
8. Tuesday May
22nd
2007, Particle Physics Seminar, 4.30pm, Main Auditorium
Author: Helmut Satz (Bielefeld)
Title: Thermal
Hadron
Production and
Hawking-Unruh Radiation in QCD
Abstract: Multiparticle
production in high energy interactions, from $e^+e^-$ annihilation to
hadronic and heavy ion collisions, shows remarkable thermal features
in species abundances and transverse momentum spectra; these indicate
a universal temperature around 150 - 200 MeV. What is the common
basis for this behaviour? We conjecture that because of color
confinement, the physical vacuum forms an event horizon for quarks
and gluons. This can be crossed only by quantum tunneling, i.e.,
through the QCD counterpart of Hawking radiation from black holes.
Since such radiation cannot transmit information to the outside, it
must be thermal, of a temperature determined by the strong force at
the confinement surface; it also has to maintain color neutrality.
This phenomenon can provide a common mechanism for thermal hadron
production in all high energy interactions.
9. Wednesday May
23rd
2007, 11am, TH Auditorium (4-3-005)
Author: Igor M. Dremin (LPI Moscow)
Title: Cherenkov
gluons (predictions and proposals)
Abstract: Three predictions,
which stem from the idea about Cherenkov gluons, and proposals for
their verification are discussed. First experimental data about heavy
ion collisions favoring this idea are briefly described. Conclusions
about the properties of the nuclear medium at high energies are
presented.
10. Thursday May
24th
2007, 11am, TH Auditorium (4-3-005)
Author: Yuri M. Sinyukov (BITP Kiev)
Title:
Interferometry signatures of
new states of matter in
hydrodynamic picture of A+A collisions
Abstract: The
main advantage of hydrodynamic approach in nucleus-nucleus collisions
is possibility to analyze the evolution of the created matter
including the transitions from one forms (phases) of the matter to
others. To provide such an analysis for wide class of hydrodynamic
models we use “observables” which conserve their values during
the evolution. It was found that totally averaged phase-space density
(APSD) and specific entropy are integrals of motion at chemically
frozen evolution and their experimental values depend only on
temperature and chemical potential at freeze-out – final stage of
the hadronic matter evolution when the system decays. The plateau
found in the pion APSD behavior vs collision energy at Super Proton
synchroton (SPS) level is associated, apparently, with the
deconfinement phase transition at low SPS energies. A saturation of
this quantity at the energies available at BNL RHIC and CERN LHC will
indicate the limiting Hagedorn temperature for hadronic matter. The
behavior of the pion specific entropy demonstrate, probably, that the
critical temperature of the hadron-quark/gluon phase transition is
reached between SPS and RHIC energies. The results also shed light on
the HBT puzzle – unexpected behavior of the interferometry volumes
with energy.
11. Friday May
25th
2007, 11am, TH Auditorium (4-3-005)
Author: Rainer J. Fries (Texas A&M)
Title: Initial
Energy Density, Momentum and Flow in Heavy Ion Collisions
Abstract:
It is widely believed that the inital stage of a collision of
large nuclei at high center of mass energy is described by the color
glass condensate. Here we use this picture to compute the energy and
momentum densities produced in the earlierst stage of the collision.
We also present constraints for the initial energy density, pressure
and flow in the subsequent plasma phase. Phenomenological
consequences for RHIC and LHC are discussed.
12. Monday June
4th
2007, 11am, TH Auditorium
(4-3-005)
Author: W. Cassing (Giessen)
Title: Properties
of the sQGP at RHIC and LHC energies
13. Monday June
4th
2007, ALICE Club, 1.45pm,
room 160-1-009
Author: I. P.
Lokhtin (SINP MSU)
Title:
Monte-Carlo
simulation of jet quenching and high transverse
momentum observables at LHC
Abstract: The model to
simulate jet quenching effect in ultrarelativistic heavy ion
collisions is presented. The model is the fast Monte-Carlo tool
implemented to modify a standard PYTHIA jet event. The model has been
generalized to the case of the ``full'' heavy ion event (the
superposition of soft, hydro-type state and hard multi-jets) using a
simple and fast simulation procedure for soft particle production.
The model is capable of reproducing main features of the jet
quenching pattern at RHIC (the transverse momentum dependence of the
nuclear modification factor and the suppression of azimuthal
back-to-back correlations). The model is applied to probe jet
quenching in various new channels at LHC: jet nuclear modification
factor and jet anisotropy, jet fragmentation function measured by
leading particles, b-jets, dilepton-jet correlations, high-mass
dimuon and secondary charmonium spectra. The further development of
the model focusing on a more detailed description of low transverse
momentum particle production is in the progress.
14. Tuesday June 5th 2007, 11am, TH Auditorium (4-3-005)
Author: Ulrich Heinz (OSU)
Title:
Recent results on spectra
and v2 from (2+1)-d viscous
hydrodynamics
15. Tuesday June 5th 2007, 2pm, TH Auditorium (4-3-005)
Author: Jorge Casalderrey-Solana (LBL)
Title: Momentum
Broadening of Heavy Probes in Strongly Coupled Plasmas
Abstract:
We
compute the momentum broadening of a heavy fundamental charge
propagating through a $\mathcal{N}=4$ Yang Mills plasma at large t'
Hooft coupling. We do this by expressing the medium modification of the
probe's density matrix in terms of a Wilson loop averaged over the
plasma. We then use the AdS/CFT correspondence to evaluate this loop,
by identifying the dual semi-classical string solution. The calculation
introduces the type ``1'' and type ``2'' fields of the thermal field
theory and associates the corresponding sources with the two boundaries
of the AdS space containing a black hole. The transverse fluctuations
of the endpoints of the string determine $\kappa_T = \sqrt{\gamma
\lambda} T^3 \pi$ -- the mean squared momentum transfer per unit time.
($\gamma$ is the Lorentz gamma factor of the quark.) The result
reproduces previous results for the diffusion coefficient of a heavy
quark.
16. Wednesday June
6th 2007, 2pm, Wednesday Theory Colloquium, TH
Auditorium (4-3-005)
Author: Carlos Salgado (Rome La Sapienza)
Title: A new look
to heavy ion collisions:
preparing to the LHC
Abstract: A new way of
understanding the dynamics of high-density QCD is been developed thanks
to the reach of collider energies in heavy ions. In a general
presentation, I will review our present knowledge, in particular as
given by the interpretation of experimental data, as well as the new
theoretical developments where several fields begin to overlap. The new
regimes accessible at the LHC, where three of the four experiments have
a heavy-ion program, are qualitatively different from those reached at
present energies, opening new opportunities to understand the
properties of hot and dense QCD matter.
17. Thursday June
7th 2007, 11am, TH Auditorium (4-3-005)
Author: K. Werner (Subatech)
Title: The physics of
EPOS
Abstract: We discuss briefly how EPOS extends the
simple parton model by treating consistently multiple scattering and
by considering carefully projectile and target remnants. We then
discuss so-called nuclear effects due to splitting of parton ladders.
This is in particular important for proton-nucleus scattering, but it
also leads to important reductions of cross sections and particle
production in very high energy proton-proton collisions. We finally
discuss hydro-like collective phenomena, based on EPOS initial
conditions. Concerning results, we discuss mainly soft observables,
in particular their change from RHIC to LHC.
18. Friday June
8th 2007, 11am, TH Auditorium (4-3-005)
Author: A.M. Snigirev (SINP
MSU)
Title: Alignment
as a result from QCD jet
production or new still unknown physics at the LHC?
Abstract:
The hypothesis of the relation between the observed alignment
of spots in the x-ray film in cosmic ray emulsion experiments and the
features of events in which jets prevail at super high energies is
tested. Due to strong dynamical correlation between jet axis
directions and that between momenta of jet particles (almost
collinearity), the evaluated degree of alignment is considerably
larger than that for randomly selected chaotically located spots in
the x-ray film. It appears comparable with experimental data provided
that the height of primary interaction, the collision energy and the
total energy of selected clusters meet certain conditions. The Monte
Carlo generator PYTHIA, which basically well describes jet events in
hadron-hadron interactions, was used for the analysis. New physical
issues from the alignment phenomenon at the LHC is discussed.