Role of color neutrality in nuclear physics: Modifications of nucleonic wave functions

Abstract

The influence of the nuclear medium upon the internal structure of a composite nucleon is examined. The interaction with the medium is assumed to depend on the relative distances between the quarks in the nucleon consistent with the notion of color neutrality, and to be proportional to the nucleon density. In the resulting description the nucleon in matter is a superposition of the ground state (free nucleon) and radial excitations. The effects of the nuclear medium on the electromagnetic and weak nucleon form factors, and the nucleon structure function are computed using a light-front constituent quark model. Further experimental consequences are examined by considering the electromagnetic nuclear response functions. The effects of color neutrality supply small but significant corrections to predictions of observables.

Nucleon electromagnetic form factors

“…The resulting e.m. FF calculations reproduce reasonably well the power behavior of the FF at larger Q 2 . The WF of Schlumpf was also used by Frank, Jennings, and Miller [Fra96,Mil02a]. They found that such a light-front WF leads to a violation of hadron helicity conservation resulting in a F 2p /F 1p ratio which drops less fast than 1/Q 2 [Mil02a], in agreement with the G Ep /G M p polarization data.…”

Baryons as relativistic three-quark bound states

“…Nucleon form factors have been calculated in light-front constituent-quark models [517][518][519][520][521][522], also including dressed quark form factors which effectively add higher Fock components to the wave functions [523][524][525][526]. Light-front quark model calculations are also available for nucleon resonances [21,527,528].…”

Relativity, Chiral Symmetry, and the Nucleon Electromagnetic Form Factors

“…One could evaluate the form factors as Ψ|J + |Ψ and obtain the results. Actually the first results were obtained in 1995 [1], and are given as Figs. 10,11 in that reference.…”

“…[1,2], data are from Jones et al [9] for 2 ≤ Q 2 ≤ 3.5 GeV 2 and from Gayou et al [10]. for 3.5 ≤ Q 2 ≤ 5.5 GeV 2 .…”

“…Symmetries including Poincaré invariance and chiral symmetry will be the principal tool I'll use. This talk is based on three papers [1], [2], [3].…”