E99-107 CLAS experiment for generalized form factor near threshold

Spokespersons

V. D. Burkert, R. Minehart

Year

2005

Abstract

We report the first extraction of the pion-nucleon multipoles near the production threshold for the $n\pi^+$ channel at relatively high momentum transfer ($Q^2$ up to 4.2 $\rm{GeV^2}$). The dominance of the $s$-wave transverse multipole ($E_{0+}$), expected in this region, allowed us to access the generalized form factor $G_1$ within the light-cone sum rule (LCSR) framework as well as the axial form factor $G_A$. The data analyzed in this work were collected by the nearly $4\pi$ CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754 $\rm{GeV}$ electron beam on a proton target. The differential cross section and the $\pi-N$-multipole $E_{0+}/G_D$ were measured using two different methods, the LCSR and a direct multipole fit. The results from the two methods are found to be consistent and almost $Q^2$ independent.

Publication

1. K.Park, R.W.Gothe, and CLAS Collaboration Measurement of the generalized form factors near threshold via γ^* p -> nπ⁺ at high Q² // Phys. Rev. C 85, 035208 (2012); arXiv:1201.0903v1

Quantities

dσ/dΩ

Measurements