Moments of the Neutron Charge Form Factor and the <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="italic">N</mi><mi></mi><mo>→</mo><mi></mi><mi>Δ</mi></math></span> Quadrupole Transition

P. Grabmayr; A. J. Buchmann

doi:10.1103/PhysRevLett.86.2237

Moments of the Neutron Charge Form Factor and the $N \to Δ$ Quadrupole Transition

P. Grabmayr and A. J. Buchmann

Phys. Rev. Lett. 86, 2237 – Published 12 March 2001

Abstract

Recent data allow a new parametrization of the neutron charge form factor $G_{E}^{n}$ . A parameter-free quark-model relation between $G_{E}^{n}$ and the $N \to Δ$ quadrupole form factor $G_{C 2}^{N \to Δ}$ is used to predict $G_{C 2}^{N \to Δ}$ from $G_{E}^{n}$ data. In particular, $〈 r_{n}^{2} 〉$ is related to $N \to Δ$ quadrupole moment $Q_{N \to Δ}$ , while $〈 r_{n}^{4} 〉$ connects to the $N \to Δ$ quadrupole transition radius $〈 r_{N \to Δ}^{2} 〉$ . From the latter we derive an experimental value for the charge radius of the light constituent quarks $r_{γ q} = 0.8 fm$ . Finally, the $C 2 / M 1$ ratio in pion electroproduction is predicted from the elastic neutron form factor data.