Department of Physics, Kyungpook National University
경북대학교 물리학과

KNU Physics Seminars

Exploring the 3D structure of nucleon resonances based on transition GPD measurements at JLAB

by Dr Stefan Diehl (U. Giessen & U. Connecticut)

Seminar Room 320 (BLDG #219)

Seminar Room 320

BLDG #219


The study of transition GPDs is a unique tool to understand the 3 dimensional structure and the mechanical properties of nucleon resonances for the first time. To extract transition GPDs, for example the non-diagonal DVCS process can be used. In this process a pion-nucleon system, originating from the decay of an $N^*$ resonance, is produced in addition to a real photon. In addition transition GPDs, especially the chiral-odd sector can be studied by non-diagonal meson production like the hard exclusive $\pi^- \Delta^{++}$ process. Because the factorisation of these process amplitude requires the constraints on Mandelstam variable $t$ and photon virtuality $Q^2 (-t/Q² \ll 1)$ and several final state particles have to be detected for a clean identification, CLAS12 in combination with the upgraded CEBAF accelerator at JLAB provides a unique opportunity to study these processes.
The talk will introduce the topic and present an on-going analysis effort on the recently collected CLAS12 data. In addition perspectives for a 20+ GeV JLAB energy upgrade will be discussed. The results will be discussed in the context of theoretical predictions for the $N \to \Delta^{++}$ transition GPDs which can help us to gain insights into the 3D structure of the $N$ to $\Delta$ transition. 


Host: Yongseok Oh and Kirill Semenov-Tyan-Shansky

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