Organizers:John Negele negele@mitlns.mit.edu David Richards dgr@jlab.org Martin Savage savage@phys.washington.edu Edward Shuryak shuryak@tonic.physics.sunysb.edu Program Coordinator: Laura Lee lee@phys.washington.edu (206) 685-3509 Application form Workshop on the Fourth Root of the Staggered Fermion Determinant Workshop on Synergy Between Experiment and Lattice QCD in Exploring Hadron Structure |
March 6 - May 26, 2006
This program will bring together for an extended period theorists and experimentalists interested in the following five areas to deepen each others' appreciation of the issues involved, to coordinate effort, and to brainstorm new approaches:
Beyond the obvious challenge of quantitative comparison with experiment, high energy probes of hadron structure raise fundamental questions that can be clarified by lattice exploration, such as the origin of the nucleon spin, how quark and gluon substructure gives rise to scaling observed in form factors, and the transverse structure of the nucleon light cone wave function. Similarly, spectroscopy poses questions such as the role of diquark degrees of freedom in the baryon spectrum, including pentaquarks, and the role of flux tubes and their excitations.
In addition to the conventional spectroscopy of isolated hadrons, there
is also a new spectroscopy in the quark-gluon plasma at high J/y survives until about T=(2-3)T, giving rise
to a
new picture of a strongly coupled Quark-Gluon plasma, including colored
_{c}(qq,qg,gg) states, which are responsible for a large fraction of the
pressure and entropy.
One can also explore hadron phenomenology based on topological objects in
QCD. In the past, many aspects of the instanton liquid phenomenology have
been observed in lattice calculations. One can similarly investigate the
role of topological objects at high T g T.
_{c}Participants with expertise in these and related areas of phenomenology will play an essential role in exploring new ways to use lattice QCD to obtain new insight into these issues.
Chiral perturbation theory is an essential tool for lattice QCD. Since the
cost of lattice calculations in a box sufficiently large to contain a pion
grows as Since the technologies for large scale lattice calculations and for detailed chiral perturbation calculations are each so different and so demanding, the same theorists generally do not pursue both aspects. Hence, it will be valuable to get the practitioners of both aspects of lattice calculations together for an extended period.
Calculation of physical observables in lattice field theory requires extensive calculation of renormalization factors and matching of lattice regularization to some continuum regularization scheme used to analyze experimental data, such as . In addition, since some renormalization factors can be calculated nonperturbatively by numerical lattice calculations, it is valuable to plan a thorough program of cross-checks of perturbative and non-perturbative renormalization. Again, the technology of perturbative renormalization is so demanding that these calculations are done by different theorists than those who undertake large scale lattice calculations or chiral perturbation theory, so key members of this community will be an important component of the program.
Theorists directly involved in large scale lattice calculations will benefit greatly from extended interaction with phenomenologists who are interested in how lattice QCD can contribute to understanding hadron structure and testing phenomenological models and with theorists interested in chiral perturbation theory and renormalization. In addition, there are many technical aspects of lattice calculations that will be beneficial to discuss. Finally, it will be valuable to brainstorm new approaches to some of the salient unsolved problems in lattice QCD, such as measuring gluon observables, calculating high moments of parton distributions, calculating form factors at high momentum transfer, and the fermion sign problem.
Given current and planned experiments at Bates, JLab and RHIC, such as measuring electromagnetic and strangeness form factors, generalized parton distributions, the nucleon spin structure, and nucleon-delta transition form factors; searching for pentaquarks and other exotics; and exploring bound states in the quark-gluon plasma, lattice QCD has potential for high impact on nuclear physics experiments. Hence, an essential component of this program will be visits and seminars by key experimentalists to explore how lattice calculations can most effectively complement and guide experiment. |