The longitudinal asymmetry induced by parity-violating (PV) components in the nucleon-nucleon potential is studied in the charge-exchange reaction (3)He((n) over right arrow, p)(3)H at vanishing incident neutron energies. An expression for the PV observable is derived in terms of T-matrix elements for transitions from the (2S+1)L(J) = (1)S(0) and (3)S(1) states in the incoming n-(3)He channel to states with J = 0 and 1 in the outgoing p-(3)H channel. The T-matrix elements involving PV transitions are obtained in first-order perturbation theory in the hadronic weak-interaction potential, while those connecting states of the same parity are derived from solutions of the strong-interaction Hamiltonian with the hyperspherical-harmonics method. The coupled-channel nature of the scattering problem is fully accounted for. Results are obtained corresponding to realistic or chiral two-and three-nucleon strong-interaction potentials in combination with either the DDH or pionless EFT model for the weak-interaction potential. The asymmetries, predicted with PV pion and vector-meson coupling constants corresponding (essentially) to the DDH "best values" set, range from -9.44 to -2.48 in units of 10(-8), depending on the input strong-interaction Hamiltonian. This large model dependence is a consequence of cancellations between long-range (pion) and short-range (vector-meson) contributions and is of course sensitive to the assumed values for the PV coupling constants.
|Autori:||Viviani M; Schiavilla R; Girlanda L; Kievsky A; Marcucci L|
|Titolo:||Parity-violating asymmetry in the (3)He((n)over-right-arrow, p)(3)H reaction RID A-7123-2011|
|Anno del prodotto:||2010|
|Digital Object Identifier (DOI):||10.1103/PhysRevC.82.044001|
|Appare nelle tipologie:||1.1 Articolo in rivista|