Medium modification of the proton form-factor
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.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC05-84ER40150
- OSTI ID:
- 824827
- Report Number(s):
- JLAB-PHY-03-23; DOE/ER/40150-2730; nucl-ex/0308026; TRN: US0402231
- Resource Relation:
- Conference: Fourth International Conference on Perspectives in Hadronic Physics, Trieste (IT), 05/12/2003--05/16/2003; Other Information: PBD: 1 Feb 2004
- Country of Publication:
- United States
- Language:
- English
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