Data taken at the Relativistic Heavy Ion Collider (RHIC) over the last decade have shown
conclusively that the high temperature phase of QCD matter is a Quark-Gluon Plasma
(QGP) with the characteristics of a "nearly perfect" liquid. This conclusion has been confirmed
by measurements in Pb+Pb collisions at much higher energy at the CERN Large
Hadron Collider (LHC). In addition to the nearly inviscid liquid behavior of the QGP, the
RHIC and LHC experiments have shown that the QGP is highly opaque to energetic partons,
resulting in "strong jet quenching". The physics goal for the next decade is to characterize
the properties of this quark-gluon plasma liquid by quantitative extraction of fundamental
medium parameters from precision measurements of sensitive observables, including for example hadron
spectra, angular distributions and correlations, jet observables, heavy quarks
and electromagnetic probes.
This program will focus on the utilization of jets and heavy-quarks as probes of the QGP,
since these are the two areas with significant progress in recent years in terms of experimental
capabilities and improvements in theoretical tools. Both, jets and heavy quarks, are hard
probes that are being produced early on in the time-evolution of heavy-ion collisions in
processes that are well described using perturbative QCD. They interact strongly with the
surrounding QGP medium, and their measurable modifications in the final state distributions
with respect to vacuum expectations yield significant information on the properties of the
QGP medium. Of particular interest are the QGP transport coefficients, such as the jet
energy-loss parameters q̂ and ê as well as the heavy quark diffusion coefficients D. All of
these quantities are thought to exhibit a non-trivial temperature dependence, the extraction
of which will require high-precision data and advances in theory that are currently under
development. Since hard processes probe the QGP over a wide range of length scales this
program will also explore their use for determining the microscopic nature of the QGP as
well as the transition from weakly to strongly coupled parton energy loss.
The goal of the program is to bring together experts in the areas of of jet production, energy-
loss and heavy-quark dynamics to assess the progress made in utilizing these probes for the
characterization of the properties of the QGP medium, as well as to expose and bring into
focus unresolved questions and open issues that should be addressed via new theory efforts
or experimental measurements.
Key topics to be addressed include:
- survey of latest measurements at RHIC and LHC of
- open heavy flavor (D mesons, electrons,muons)
- heavy quarkonia (J/ψ, ψ(2S), ϒ(1S; 2S; 3S))
- jets and leading high-pT hadrons
- p(d)A jet measurements, energy loss in small QGP droplets
- theory of jet evolution in the QGP medium
- range of applicability for different calculational schemes
- leading particle observables vs. full jets
- hadronic final state interactions: relevant or negligible?
- sensitivity of hard probe theory calculations to the underlying QGP medium:
what medium features can be reliably probed?
- heavy-flavor dynamics in medium
- comprehensive analysis: do jets and heavy quarks provide a consistent picture?
- initial state and saturation physics - how important for hard probes?
- future roadmap: what are the most essential measurements and theory advances to be
Goals and Expected Outcomes
The goal of this program is twofold: (1) to educate young scientists in the state of the
art of jet and heavy quark physics as it pertains to the extraction of QGP properties and
(2) to review our current knowledge in that sector and develop a roadmap on how best to
utilize the newly available high quality data and novel theory advances for the high precision
extraction of QGP properties in the near to medium term future as well as how to utilize
the complementary of RHIC and LHC jet measurements in the longer term future enabled
by proposed experimental upgrades at RHIC.
Individual program weeks will be devoted to specific topics, with a comprehensive overarching workshop scheduled for the 2nd week of the program. In order to provide sufficient time for discussion during the regular program weeks, two seminar-style presentations will be given per day (in the morning) as well as a daily discussion session to follow up on topics and presentations as the need arises (in the afternoon). Depending on participant interest, the program in week #6 might be converted into a workshop-style setup.
- Week 1: Heavy Quarks in QCD matter
- Week 2: Workshop
- Week 3: Jet energy loss theory
- Week 4: Monte-Carlo approaches to Jet energy-loss
- Week 5: Onia
- Week 6: comprehensive picture & future of the field
Please note that a workshop registration fee of $45 will apply for attending the second week of the program.