Organizers:
Sean Fleming
University of Arizona
fleming@physics.arizona.edu
Thomas Mehen
Duke University
mehen@phy.duke.edu
Anna Stasto
Pennsylvania State University
astasto@phys.psu.edu
Program Coordinator: Inge Dolan
inge@u.washington.edu
(206) 6854286
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INT Program INT113
Frontiers in QCD
September 19  November 18, 2011
OVERVIEW
This nine week program will focus on a variety of different aspects of QCD based
research in which there has been a tremendous amount of recent progress, namely
 Soft Collinear Effective Theory (SCET),
 Analytic construction of amplitudes in field theory,
 Smallx physics,
 The AdS/CFT correspondence.
Many of the advances in each of these fields have occurred independently of each
other, though there is significant overlap between all of them. The aim of this
program is to bring together experts working in each area in order to exchange
information about these recent advances, to provide an interface between highenergy
and nuclear physics, and to explore the possibility of applying these methods in new
contexts.
ORGANIZATION
The program will be divided into three sections that are three weeks in length.
During each session the focus will be
 Weeks 13 (9/1910/7): Frontiers of Perturbative QCD including
factorization, resummation, SCET approaches, and advanced methods for
computing gauge theory amplitudes;

Week 2 Workshop
Advances in QCD: Effective Field Theory and Recursive Analytic Methods
The past decade has seen a number of advances in treatments of gauge theories including effective theory approaches and the use of analytic methods to understand scattering amplitudes. In some cases these advances have turned hard problems into trivial problems. This workshop aims to explore these topics by focusing on soft collinear theory and recursive analytic methods in field theory.
There will be a followup workshop on recursive analytic methods in field theory later in the fall.
Amplitudes 2011
 Weeks 46 (10/1010/28): Smallx physics including resummation, high
parton densities, nonlinear phenomena in parton evolution, multiple scattering and applications to high energy collisions;
 Weeks 79 (10/3111/18): AdS/CFT and applications to QCD, gauge
theory, and other strongly interacting systems.

Week 7 will be a "focus week" dedicated to applying the AdS/CFT correspondence to the quark gluon plasma
Though each section will have its point of emphasis, we hope there will be interaction
between experts all across the QCD community throughout the workshop.
CONTENT
Examples of questions that we hope to address during the program include:
 Can the new onshell methods be directly applied to study nuclear
physics?
Since the new onshell methods only rely on physical properties of the underlying quantum field theory, it may be possible to apply them in a wider
context than previously considered, including the study of nuclear phenomena
which allow a perturbative description.
 Can resummation via SCET be interfaced with the automatized
implementations of onshell methods such as BlackHat, Rocket, or CutTools?
In SCET, one expands the QCD Lagrangian in terms of various modes that
contribute at different energy scales. With the SCET Lagrangian in hand,
one could envisage building computer code that automatically resums large
logarithmic corrections to multiparton scattering processes which go beyond
the standard leadinglogarithmic parton shower algorithms implemented in
commonly used event generators such as Pythia or Herwig.
 What can we learn from multiparton scattering processes at low x
at the LHC? Conversely, can new developments in smallx physics
be used to further constrain parton distribution functions (PDFs)
at low x which give large contributions to certain processes at the
LHC?
The LHC probes the small x region which is dominated by the gluon density.
However, the gluon PDF is only constrained in a limited kinematical regime
by deep inelastic scattering data. Therefore it suffers from large uncertainties
when extrapolated to the smaller values of x which are available at the LHC.
The production of heavy quarks and also Higgs production at the LHC is quite
sensitive to the gluon PDF at low x. Do early data from LHC possibly hint at
an increasing role of multiple parton interactions and nonlinear phenomena at
these energies? Bringing together nuclear and highenergy physicists at this
workshop will allow to advance the understanding of smallx physics from
both viewpoints.
 Can lowx resummation methods shed light on operator structure
in SCET?
In principle SCET includes the lowx kinematic regime, and logarithms of x should be summable via the renormalization group equations.
However, the problem of resummation of small x logarithms using SCET has
remained elusive, and the connection between SCET and lowx methods is
not clear. Can a bridge between lowx methods and SCET be built? And
can SCET be used to elucidate the nonperturbative structure of the lowx
regime?
 Can AdS/CFT or its generalizations give us quantitative/qualitative
insight into aspects of QCD which are not amenable to either perturbative or lattice QCD methods?
The AdSCFT correspondence can
elucidate the dynamics of strongly coupled gauge theories. Unlike lattice
QCD, it can be to applied to problems which can only be formulated in
Minkowski space. Because of this it can be applied to problems like the thermalization/equilibration of the Quark Gluon Plasma and transport processes
that are directly relevant to heavy ion experiments. It would also be interesting to search for gravity duals that more closely resemble QCD as well as
systematically incorporate 1/N_{c} corrections.
