2017/04/30 by Hai-Qing Zhou, Shin Nan Yang · 13 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #hep-ph #nucl-ex #nucl-th
paper · pdf · doi:10.1103/physrevc.96.055210
published in Physical Review C 96(5) (American Institute of Physics) · 4 figures
openalex publication_date 2017/11/28 · arxiv created 2017/12/04 · openalex created_date 2017/12/04 · arxiv updated 2017/12/06 · openalex updated_date 2026/08/05
We evaluate the corrections of the two-photon exchange (TPE) process on the \ensuremathγ*N\mathrm\ensuremathΔ transition form factors. The contributions of the TPE process to eN\ensuremath→e\mathrm\ensuremathΔ(1232)\ensuremath→eN\ensuremathπ are calculated in a hadronic model with the inclusion of only the elastic nucleon intermediate states, to estimate its effects on the multipoles M_1+(3/2),\phantom\rule0.16em0exE_1+(3/2),\phantom\rule0.16em0exS_1+(3/2) at the \mathrm\ensuremathΔ peak. We find that TPE effects on GM* are very small. GE*, and GC* are also little affected at small Q2. For GE*, the TPE effects reach about 3--8% near Q2\ensuremath∼4\phantom\rule4pt0exGeV2, depending on the model, MAID or SAID, used to emulate the data. For GC*, the TPE effects decrease rapidly with increasing \ensuremathε while growing with increasing Q2 to reach \ensuremath∼6--15% with Q2\ensuremath∼4\phantom\rule4pt0exGeV2 at \ensuremathε=0.2. Sizeable TPE corrections to GE* and GC* found here point to the need to include TPE effects in the multipole analysis in the region of high Q2 and small \ensuremathε. The TPE corrections to REM and RSM obtained in our hadronic calculation are compared with those obtained in a partonic calculation for moderate momentum transfer of 2<Q2<4\phantom\rule4pt0exGeV2.