Rosenbluth separation of the $\pi^0$ electroproduction cross section - INSPIRE

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Rosenbluth separation of the $\pi^0$ electroproduction cross section

Jefferson Lab Hall A

Collaboration

•

M. Defurne
(
- DAPNIA, Saclay
)

Aug 2, 2016

6 pages

Published in:

Phys.Rev.Lett. 117 (2016) 26, 262001

Published: Dec 23, 2016

e-Print:

1608.01003 [hep-ex]

DOI:

10.1103/PhysRevLett.117.262001

Report number:

JLAB-PHY-16-2309

Experiments:

JLAB-E-07-007

View in:

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Abstract: (APS)

We present deeply virtual π0 electroproduction cross-section measurements at xB=0.36 and three different Q2 values ranging from 1.5 to 2 GeV2, 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 σLT. 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. 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-Q2 regime.

Note:

Submitted to Physical Review Letters

deep inelastic scattering
generalized parton distribution: transversity
pi0: electroproduction
nucleon: generalized parton distribution
pi: distribution amplitude
parton: distribution function
longitudinal
transverse
quantum chromodynamics: perturbation theory
scattering amplitude

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