Gerald Miller
University of Washington

Rolf Ent
Jefferson Lab

Carlos Munoz Camacho
LPC-Clermont, CNRS/IN2P3

Tony Thomas
Jefferson Lab

Program Coordinator:
Inge Dolan
(206) 685-4286

Agenda: 3-dimensional parton
structure of the nucleon encoded
in GPDs and TMDs

Agenda: dedicated workshop:
Hadron Spectroscopy

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The Jefferson Laboratory Upgrade to 12 GeV

September 14 - October 16 & October 26 - November 20

The goal of this program is to bring experimentalists and theorists together to explore important aspects of the exciting physics program which will be enabled by the Jefferson Laboratory 12 GeV Upgrade. This upgrade provides a unique opportunity through its combination of luminosity, duty factor and kinematic reach to make profound contributions to the study of hadronic matter.

Through its unprecedented polarized beam capabilities, JLab at 12 GeV allows detailed studies of both the spin and angular momentum distributions of quarks in nucleons, and low-energy weak neutral current processes through parity-violating electron scattering. Researchers will be able to obtain detailed maps of the distribution of valence quarks in both coordinate and momentum space. The links between coordinate space and momentum space maps will provide "3D" images of the substructure of the nucleons.

Measurements using nuclear targets will provide unprecedented access to the role of valence quarks in nuclei, and the dynamical process by which such quarks propagate through the nuclear medium and form hadrons. The EMC discovered some 25 years ago that the momentum distribution of quarks inside the nuclei was found to differ, notably in the valence region, from that of quarks in a free nucleon. While there are hundreds of papers on this subject, there is no universally accepted explanation. The valence quark region can be accessed in multiple ways using the high luminosity at 12 GeV, which would allow experimentalists and theorists to disentangle the effect. The effects of color transparency and short-range nucleon-nucleon correlations are closely related to these topics and form focus points of the program.

A new generation of hadron spectroscopy experiments and theoretical investigations will allow the search for exotic hadrons and investigate various puzzles involving mesonic and baryonic spectra. Finding exotic hadrons and determining their spectrum underline the role of gluon self-interactions in hadrons, and provide the basis for understanding the confinement mechanism that eternally locks quarks and gluons in hadrons. It is vital that theorists concerned with the physics of reaction mechanisms work with experimentalists to understand the relevant energy-dependent physics backgrounds that could mimic potential signals of a resonant state.

We organize this broad thrust into three categories:

9/14-18:3-dimensional parton structure of the nucleon encoded in GPDs and TMDs
9/14-10/16:Pdfs, gpds, tmds, valence quarks
10/26-11/06:Nuclear effects
**11/9-11/13:dedicated workshop: Hadron Spectroscopy
11/9-11/20:Search for exotics
**There is a mandatory workshop registration fee of $85, due at the time of registration.

  • Determining the spin and flavor dependence of the parton distribution functions, the generalized parton distributions and the transverse momentum distributions, of the valence quarks that reside in the nucleon. This would culminate in nucleon tomography measurements to discover the true three-dimensional structure of nucleons. Topics will include i) the control of the necessary resummation, target and quark mass, and higher-twist effects in the region of valence quarks, and how they can be disentangled from symmetry breaking effects; ii) linking form factor and valence quark measurements to nucleon models and Lattice QCD calculations; and iii) linking the roadmaps towards angular and orbital momentum of valence quarks that can come from form factor and quark longitudinal and transverse momentum distributions. Relevant fundamental symmetries will also be studies. This activity would occur during the period of 9/14 to 10/16, including a dedicated one-week workshop during the first week. The workshop held 9/14-18 will be organized by Harut Avakian, Delia Hasch, Charles Hyde, Andreas Metz, and Christian Weiss.

  • Accurate studies that allow researchers to disentangle the origin of the "nuclear EMC effect" in the valence quark region. This requires shedding light on the role valence quarks play in the deep structure and properties of atomic nuclei and how they interact with a dense nuclear medium. Topics will include the effect of the nuclear medium on valence and sea quark distributions, the interactions of quarks and gluons with the vacuum and the nuclear medium and any reaction involving a nuclear target. This activity would occur during the period of 10/26-11/06.

  • The search for exotic mesons using high energy photon-proton collisions. The fluctuations of the gluonic vacuum are an unavoidable part of the structure of mesons. The refinement of experimental and theoretical tools to establish such exotic mesons and make general progress in spectroscopy will be the topic of a dedicated workshop to be held Nov. 9-13, followed by another week of intense work.