Medium Modification of the Proton Form Factor.

Technical Information Center Oak Ridge Tennessee

关键词: Form factors;    Modifications;    Four momentum transfer;    Physics;   

RP-ID  :  DE2004824827

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

I argue that the double ratio of proton-recoil polarization-transfer coefficients, P(prime)(sub x) and P(prime)(sub z), of the quasielastic(sup 4)He(e,e(prime)p)(sup 3)H reaction with respect to the elastic(sup 1)H(e,e(prime)p) reaction is sensitive to possible medium modifications of the proton form factor in(sup 4)He. Recent measurements at both Mainz and Jefferson Lab of this double ratio at four-momentum transfers squared between 0.4 (GeV/c)(sup 2) and 2.6 (GeV/c)(sup 2) are discussed. I show that the data challenge state-of-the-art conventional meson-nucleon calculations, as these are unable to describe the results. The data hint at the need to include medium modifications of the proton form factor, as predicted by a quark-meson-coupling model, in the calculations. A recently approved follow-up experiment at a Q(sup 2) of 0.8 (GeV/c)(sup 2) and 1.3 (GeV/c)(sup 2) with unprecedented precision will provide one of the most stringent tests of the applicability of various calculations.