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Title: Rosenbluth Separation of the π 0 Electroproduction Cross Section

In this paper, we present deeply virtual $$\pi^0$$ electroproduction cross-section measurements at $$x_B$$=0.36 and three different $Q^2$ values ranging from 1.5 to 2 GeV$^2$, obtained from Jefferson Lab Hall A experiment E07-007. The Rosenbluth technique is used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component and, thus, is far from the asymptotic limit predicted by perturbative quantum chromodynamics. Nonetheless, an indication of a nonzero longitudinal contribution is provided by the measured interference term $$\sigma_{LT}$$. Results are compared with several models based on the leading-twist approach of generalized parton distributions (GPDs). In particular, a fair agreement is obtained with models in which the scattering amplitude includes convolution terms of chiral-odd (transversity) GPDs of the nucleon with the twist-3 pion distribution amplitude. Finally, this experiment, together with previous extensive unseparated measurements, provides strong support to the exciting idea that transversity GPDs can be accessed via neutral pion electroproduction in the high-Q 2 regime.
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Publication Date:
Report Number(s):
JLAB-PHY-16-2309; DOE/OR/23177-3891; arXiv:1608.01003
Journal ID: ISSN 0031-9007
Grant/Contract Number:
AC05-06OR23177
Type:
Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 117; Journal Issue: 26; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Research Org:
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); National Science Foundation (NSF); National Center for Scientific Research (CNRS) (France); National Research Agency (ANR) (France)
Contributing Orgs:
Jefferson Lab Hall A Collaboration
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; deep inelastic scattering; photon & charged-lepton interactions with hadrons; mesons; protons
OSTI Identifier:
1337925
Alternate Identifier(s):
OSTI ID: 1337448