2013 Participants
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GAUSTEQ
Germany and U.S. Nuclear Theory Exchange Program
for QCD Studies of Hadrons and Nuclei
*************************** VISITOR REPORT ***************************
Please use the following template to prepare your report in plain text format. Short, itemized answers are preferred.
Send your report by E-mail to <gausteq@jlab.org> (as an attachment to
preserve formating).
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1) NAME AND HOME INSTITUTION OF TRAVELER (INCL. E-MAIL ADDRESS)
Chueng-Ryong Ji, Dept. of Physics, North Carolina State University
Email: ji@ncsu.edu
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2) POSITION OF TRAVELER (FACULTY/STAFF/POSTDOC/STUDENT)
Professor
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3) DATES OF TRAVEL
February 27, 2013 - March 17, 2013
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4) INSTITUTIONS VISITED (LIST PLACES AND TIME SPENT THERE)
1. DESY, Hamburg, 2 days (Feb. 28 - March 1)
2. JGU, Mainz, 4 days (March 2 - 5)
3. RUB, Bochum, 3 days (March 6 - 8)
4. VU, Amsterdam, 8 days (March 9 - 16)
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5) SCIENTIFIC CONTACTS AND COLLABORATORS (INDICATE NATURE OF CONTACTS,
LIKE "NEW COLLABORATION," "CONTINUING COLLABORATION," "USEFUL DISCUSSION," ETC.)
1. Markus Diehl, "useful discussion, host at DESY"
2. Marc Vanderhaeghen, "new collaboration, host at JGU"
3. Nico Stefanis, "useful discussion, host at RUB"
4. Maxim Polyakov, "new collaboration, co-host at RUB"
5. Ben Bakker, "continuing collaboration, host at VU"
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6) TOPICS DISCUSSED DURING VISIT
1. Kinematic Issues of GPDs in DVCS
2. General Tensor Structure of VCS 3. Four-fermion operator ideas in electromagnetic processes
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7) IMPACT ON TRAVELER'S OR HOST'S RESEARCH (INCL. EXPECTED PUBLICATIONS)
1. I've discussed with Markus Diehl, Marc Vanderhaeghen and Maxim Polyakov on the interface between the current theoretical framework based on GPDs and experimental measurements of DVCS observables. All of these experts in Germany shared our view that the present theoretical framework needs to be extended to cover the current and future DVCS experiments. In particular, we have discussed the new review article "CONCEPTUAL ISSUES CONCERNING GENERALIZED PARTON DISTRIBUTIONS" authored by myself and Ben Bakker, recently published in International Journal of Modern Physics E Vol. 22, No. 2 (2013) 1330002 (98 pages), where we presented the details of our reasoning for the need of extension from the present theoretical framework.
2. Marc Vanderhaeghen would like to continue our discussion on the bare-bone calculations presented in the above review article and analyze it using the general tensor structure of VCS that he and his collaborators presented, i.e. B. Pasquini, et al, Eur. Phys. J. A11, 185 (2001). Marc and I planned to meet again in the upcoming QCD evolution workshop at JLab, May 6-10, and continue to discuss this issue for a common project.
3. Maxim Polyakov would like to continue our discussion on the JLab kinematics for DVCS and analyze the values of -t/Q^2 in the kinematic regions that the JLab can provide with the 12 GeV upgrade. In particular, we agreed on the necessity of this analysis because the current theoretical framework based on GPDs relies crucially on the smallness of -t/Q^2 values. Ben Bakker and I have been analyzing the domain of kinematics available in JLab 12 GeV upgrade, and we will be in contact with Maxim for further discussion on this project.
4. Ben Bakker and I have completed our ongoing collaborative paper with other collaborateors entitled "Ideas of Four-Fermion Operators in Electromagnetic Form Factor Calculations"(arXiv:1303.3936) and submitted to PRD for publication.
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8) RELEVANCE TO JEFFERSON LAB OR GSI-FAIR (LIST RELEVANT PROGRAMS)
1. The improvement on the formulation of GPDs discussed with the German experts in this trip is highly relevant to the actual experimental region at JLab, particularly envisioned for the 12 GeV upgrade in DVCS.
2. The discussion on the general tensor structure of VCS is also relevant to the low-energy meson photo-production program in GSI-FAIR.
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9) SUGGESTIONS/RECOMMENDATIONS FOR PROGRAM ADMINISTRATORS (IF ANY)
GAUSTEQ is an excellent nuclear physics exchange program between Germany and US, and it might be beneficial for the program to cover the nearby countries in close proximity to Germany.
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10) SUPPORT PROVIDED BY HOSTS (INDICATE TYPE AND EXTENT OF SUPPORT, NOT EXACT AMOUNTS)
1. Hotels in Mainz for four nights (March 2-5) covered by HIM
2. Hotels in Bochum for three nights (March 6-8) covered by RUB
3. Train from Bochum to Amsterdam covered by RUB
4. Hotels in Amsterdam for seven nights (March 9-15) covered by VU
5. Train from Amsterdam to Muenster covered by VU
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11) ACKNOWLEDGMENTS
Although the preprint arXiv:1303.3936 didn't yet include this acknowledgment, we'll make sure to include it when the paper gets accepted for the publication.
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