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Title: Parity-violating interaction effects in the np system

Abstract

We investigate parity-violating observables in the np system, including the longitudinal asymmetry and neutron-spin rotation in n-vectorp elastic scattering, the photon asymmetry in n-vectorp radiative capture, and the asymmetries in deuteron photodisintegration d({gamma}-vector,n)p in the threshold region and electrodisintegration d(e-vector,e{sup '})np in quasielastic kinematics. To have an estimate of the model dependence for the various predictions, a number of different, latest-generation strong-interaction potentials - Argonne v{sub 18}, Bonn 2000, and Nijmegen I - are used in combination with a weak-interaction potential consisting of {pi}-, {rho}-, and {omega}-meson exchanges - the Desplanques-Donoghue-Holstein (DDH) model. The complete bound and scattering problems in the presence of parity-conserving, including electromagnetic, and parity-violating potentials are solved in both configuration and momentum space. The issue of electromagnetic current conservation is examined carefully. We find large cancellations between the asymmetries induced by the parity-violating interactions and those arising from the associated pion-exchange currents. In the n-vectorp capture, the model dependence is nevertheless quite small, because of constraints arising through the Siegert evaluation of the relevant E{sub 1} matrix elements. In quasielastic electron scattering these processes are found to be insignificant compared to the asymmetry produced by {gamma}-Z interference on individual nucleons. These two experiments, then, provide cleanmore » probes of different aspects of weak-interaction physics associated with parity violation in the np system. Finally, we find that the neutron-spin rotation in n-vectorp elastic scattering and asymmetry in deuteron disintegration by circularly polarized photons exhibit significant sensitivity both to the values used for the weak vector-meson couplings in the DDH model and to the input strong-interaction potential adopted in the calculation. This reinforces the conclusion that these short-ranged meson couplings are not in themselves physical observables; rather, the parity-violating mixings are the physically relevant parameters.« less

Authors:
; ;  [1]
  1. Jefferson Lab, Newport News, Virginia 23606, USA and Department of Physics, Old Dominion University, Norfolk, Virginia 23529 (United States)
Publication Date:
OSTI Identifier:
20695639
Resource Type:
Journal Article
Journal Name:
Physical Review. C, Nuclear Physics
Additional Journal Information:
Journal Volume: 70; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevC.70.044007; (c) 2004 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2813
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ASYMMETRY; BOSON-EXCHANGE MODELS; DEUTERONS; ELASTIC SCATTERING; ELECTRON-NEUTRON INTERACTIONS; ELECTRON-PROTON INTERACTIONS; ELECTRONS; MATRIX ELEMENTS; NEUTRONS; NUCLEAR FORCES; OMEGA-782 MESONS; P INVARIANCE; PARITY; PHOTONS; PHOTONUCLEAR REACTIONS; PIONS; POLARIZATION; POTENTIALS; PROTON-NEUTRON INTERACTIONS; QUASI-ELASTIC SCATTERING; RHO-770 MESONS; SPIN; STRONG INTERACTIONS; WEAK INTERACTIONS

Citation Formats

Schiavilla, R, Carlson, J, Paris, M, and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Parity-violating interaction effects in the np system. United States: N. p., 2004. Web. doi:10.1103/PhysRevC.70.044007.
Schiavilla, R, Carlson, J, Paris, M, & Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Parity-violating interaction effects in the np system. United States. doi:10.1103/PhysRevC.70.044007.
Schiavilla, R, Carlson, J, Paris, M, and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Fri . "Parity-violating interaction effects in the np system". United States. doi:10.1103/PhysRevC.70.044007.
@article{osti_20695639,
title = {Parity-violating interaction effects in the np system},
author = {Schiavilla, R and Carlson, J and Paris, M and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545},
abstractNote = {We investigate parity-violating observables in the np system, including the longitudinal asymmetry and neutron-spin rotation in n-vectorp elastic scattering, the photon asymmetry in n-vectorp radiative capture, and the asymmetries in deuteron photodisintegration d({gamma}-vector,n)p in the threshold region and electrodisintegration d(e-vector,e{sup '})np in quasielastic kinematics. To have an estimate of the model dependence for the various predictions, a number of different, latest-generation strong-interaction potentials - Argonne v{sub 18}, Bonn 2000, and Nijmegen I - are used in combination with a weak-interaction potential consisting of {pi}-, {rho}-, and {omega}-meson exchanges - the Desplanques-Donoghue-Holstein (DDH) model. The complete bound and scattering problems in the presence of parity-conserving, including electromagnetic, and parity-violating potentials are solved in both configuration and momentum space. The issue of electromagnetic current conservation is examined carefully. We find large cancellations between the asymmetries induced by the parity-violating interactions and those arising from the associated pion-exchange currents. In the n-vectorp capture, the model dependence is nevertheless quite small, because of constraints arising through the Siegert evaluation of the relevant E{sub 1} matrix elements. In quasielastic electron scattering these processes are found to be insignificant compared to the asymmetry produced by {gamma}-Z interference on individual nucleons. These two experiments, then, provide clean probes of different aspects of weak-interaction physics associated with parity violation in the np system. Finally, we find that the neutron-spin rotation in n-vectorp elastic scattering and asymmetry in deuteron disintegration by circularly polarized photons exhibit significant sensitivity both to the values used for the weak vector-meson couplings in the DDH model and to the input strong-interaction potential adopted in the calculation. This reinforces the conclusion that these short-ranged meson couplings are not in themselves physical observables; rather, the parity-violating mixings are the physically relevant parameters.},
doi = {10.1103/PhysRevC.70.044007},
journal = {Physical Review. C, Nuclear Physics},
issn = {0556-2813},
number = 4,
volume = 70,
place = {United States},
year = {2004},
month = {10}
}