Electromagnetic two-body currents of one- and two-pion range

Journal Article · Mon Dec 15 00:00:00 EST 2008 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.78.064002· OSTI ID:21199411

Pastore, S ^[1]; Schiavilla, R ^[1]; Goity, J L ^[2]

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1. Department of Physics, Old Dominion University, Norfolk, Virginia 23529 (United States)
2. Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)

Nuclear electromagnetic currents are derived in time-ordered perturbation theory within an effective-field-theory framework including explicit nucleons, {delta} isobars, and pions up to one loop, or next-to-next-to-next-to-leading order (N{sup 3}LO). The currents obtained at next-to-next-to-leading order (N{sup 2}LO), i.e., ignoring loop corrections, are used in a study of neutron radiative captures on protons and deuterons at thermal energies, and of A=2 and 3 nuclei magnetic moments. The wave functions for A=2 are derived from solutions of the Schroedinger equation with the Argonne v{sub 18} (AV18) or CD-Bonn (CDB) potentials, while those for A=3 are obtained with the hyperspherical-harmonics-expansion method from a realistic Hamiltonian including, in addition to the AV18 or CDB two-nucleon, a three-nucleon potential. With the strengths of the {delta}-excitation currents occurring at N{sup 2}LO determined to reproduce the n-p cross section and isovector combination of the trinucleon magnetic moments, we find that the cross section and photon circular polarization parameter, measured in n-d and n-vector-d processes, are underpredicted by theory; for example, the cross section is underpredicted by 11-38% as the cutoff is increased from 500 to 800 MeV. A complete analysis of the results, in particular their large cutoff dependence, is presented.

• OSTI ID: 21199411
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 78, Issue 6; Other Information: DOI: 10.1103/PhysRevC.78.064002; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
CROSS SECTIONS
DEUTERONS
EXCITATION
FIELD THEORIES
HAMILTONIANS
HARMONICS
ISOBAR MODEL
ISOVECTORS
MAGNETIC MOMENTS
MATHEMATICAL SOLUTIONS
MEV RANGE 100-1000
NEUTRONS
PERTURBATION THEORY
PHOTONS
PIONS
PROTONS
SCHROEDINGER EQUATION
TWO-BODY PROBLEM
WAVE FUNCTIONS