Title: Precise determination of the proton magnetic radius from electron scattering data

Abstract

We extract the proton magnetic radius from high-precision electron-proton elastic scattering cross section data. Our theoretical framework combines dispersion analysis and chiral effective field theory and implements the dynamics governing the shape of the low- $Q^2$ form factors. It allows us to use data up to $Q^2\approx 0.5{\mathrm{GeV}}^2$ for constraining the radii and overcomes the difficulties of empirical fits and $Q^2\to 0$ extrapolation. We obtain a magnetic radius $r_M^p=0.850\pm 0.001$ ( $1\sigma$ fit uncertainty) ${}_{-0.004}^{+0.009}$ (full-range theory uncertainty) fm, significantly different from earlier results obtained from the same data using empirical fits, and close to our extracted electric radius $r_E^p=0.842\pm 0.002$ ( $1\sigma$ fit uncertainty) ${}_{-0.002}^{+0.005}$ (full-range theory uncertainty) fm.

Authors:

Alarcón, J. M. ;

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• Search DOE PAGES for ORCID "0000-0002-7764-9823"
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Higinbotham, D. W. ;

• Search DOE PAGES for author "Higinbotham, D. W."
• Search DOE PAGES for ORCID "0000-0003-2758-6526"
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Weiss, C.

Publication Date:

2020-09-21

Research Org.:

Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Nuclear Physics (NP); Spanish MECD

OSTI Identifier:

1664508

Alternate Identifier(s):

OSTI ID: 1666368

Report Number(s):

JLAB-THY-20-3149; DOE/OR/23177-4926; arXiv:2002.05167
Journal ID: ISSN 2469-9985; PRVCAN; 035203

Grant/Contract Number:  

AC05-06OR23177; FPA2016-77313-P

Resource Type:

Published Article

Journal Name:

Physical Review C

Additional Journal Information:

Journal Name: Physical Review C Journal Volume: 102 Journal Issue: 3; Journal ID: ISSN 2469-9985

Publisher:

American Physical Society

Country of Publication:

United States

Language:

English

Subject:

73 NUCLEAR PHYSICS AND RADIATION PHYSICS; Charge distributions; effective field theory; electroweak interactions in nuclear physics; Lepton induced nuclear reactions; photonuclear reactions; quantum electrodynamics; neutrons; protons; chiral symmetry; form factors; magnetic moment; nonperturbative methods