Coherent-Nuclear Pion Photoproduction and Neutron Radii

Abstract

{ {\bf Background:} Knowing the difference between the neutron and proton densities of nuclei is a significant topic because of its importance for understanding neutron star structures and cooling mechanisms. The coherent-nuclear photoproduction of pions, $({\g,π^0})$, combined with elastic electron scattering, has been suggested to be a very accurate probe of density differences. {\bf Purpose:} Study the ${(\g,π^0})$ reaction mechanism so as to better access the uncertainties involved in extracting the neutron density. {\bf Methods:} Include the effects of final-state pion-nucleus charge-exchange reactions on the cross section and study the influence of the non-zero spatial extent of the proton. {\bf Results:} The effects of final-state charge-exchange increase the cross section between 6\% and 5\%, generally decreasing as the momentum transfer increases. This leads to an increase of the extracted neutron skin distance by about 50\%. The validity of the previous treatments of the proton size is confirmed. {\bf Conclusion:} The model dependence of the theoretically computed cross section increases the total systematic uncertainty (experiment plus theory) in extracting the neutron skin from the ${(\g,π^0})$ cross section by at least a factor of three. }

arXiv comment9 pages. 5 figures

References in corpus (26)

• Recent Progress and New Challenges in Isospin Physics with Heavy-Ion Reactions
• Isospin Asymmetry in Nuclei and Neutron Stars
• The Equation of State from Observed Masses and Radii of Neutron Stars
• Neutron Star Structure and the Neutron Radius of 208Pb
• Constraints on the symmetry energy and neutron skins from experiments and theory
• Neutron-Rich Nuclei in Heaven and Earth
• Constraints on the density dependence of the symmetry energy
• Nuclear symmetry energy probed by neutron skin thickness of nuclei
• A unitary isobar model for pion photo- and electroproduction on the proton up to 1 GeV
• Complete electric dipole response and the neutron skin in 208Pb
• Constraints on neutron star radii based on chiral effective field theory interactions
• Muonic hydrogen and the proton radius puzzle
• Constraints on the symmetry energy and on neutron skins from the pygmy resonances in 68Ni and 132Sn
• Density slope of the nuclear symmetry energy from the neutron skin thickness of heavy nuclei
• The Proton Radius Puzzle
• Nuclear constraints on properties of neutron star crusts
• Neutron skin of ${}^{208}$Pb from Coherent Pion Photoproduction
• Neutron density distributions from antiprotonic 208Pb and 209Bi atoms
• Super-soft symmetry energy encountering non-Newtonian gravity in neutron stars
• Effects of Neutron Spatial Distributions on Atomic Parity Nonconservation in Cesium
• Rescattering effects in coherent pion photoproduction on the deuteron in the $\Delta$ resonance region
• Medium Effects in Coherent Pion Photo- and Electroproduction on 4He and 12C
• Coherent pi0-photoproduction from atomic nuclei
• Coherent Photoproduction of Pions on Spin-Zero Nuclei in a relativistic, non-local Model
• Neutron rich matter in heaven and on Earth
• Nuclear mass form factors from coherent photoproduction of ${\pi }^0$ mesons

Cited by in corpus (5)

• Expanding Nuclear Physics Horizons with the Gamma Factory
• The nuclear symmetry energy from neutron skins and pure neutron matter in a Bayesian framework
• Ab initio computations of the fourth-order charge density moments of ${}^{48}$Ca and ${}^{208}$Pb
• Probing small neutron skin variations in isotope pairs by hyperon-antihyperon production in antiproton--nucleus interactions
• Nuclear coherent ${\pi }^0$ photoproduction with charge-exchange and spin-flip rescattering