Parity-violating asymmetry in $gamma d to vec{n}p$ with a pionless effective theory

Nuclear parity violation is studied with polarized neutrons in the photodisintegration of the deuteron at low energies. A pionless effective field theory with di-baryon fields is used for the investigation. Hadronic weak interactions are treated by parity-violating di-baryon-nucleon-nucleon vertices, which have undetermined coupling contants. A parity-violating asymmetry in the process is calculated for the incident photon energy up to 30 MeV. If experimental data for the parity-violating asymmetry become available in the future, we will be able to determine the unknown coupling contants in the parity-violating vertices.

Parity-violating polarization in $np to dgamma$ with a pionless effective field theory

We consider the two-nucleon weak interaction with a pionless effective field theory. Dibaryon fields are introduced to facilitate calculations and ensure precision in the initial and final state propagators. Weak interactions are accounted for with the parity-violating dibaryon-nucleon-nucleon vertices, which contain unknown weak dibaryon-nucleon-nucleon coupling constants. We apply the model to the calculation of a parity-violating observable in the neutron-proton capture at threshold. Result is obtained up to the linear order in the unknown dibaryon-nucleon-nucleon coupling constants. We compare our result to the one obtained from a hybrid calculation, and discuss the extension to weak interactions in the few-body systems.

Parity violation in $d vec{gamma} -> np$ with pionless effective theory

We consider a pionless effective theory with dibaryon fields for the description of the weak process involving two nucleons. We construct leading order Lagrangians that contain nucleon-dibaryon weak coupling constants. We calculate the physical observable in the photodisintegration of the deuteron at threshold and obtain the result in terms of the nucleon-dibaryon weak coupling constants. Relation to existing calculations is discussed.

Parity-violating nucleon-nucleon interaction from different approaches

Two-pion exchange parity-violating nucleon-nucleon interactions from recent effective field theories and earlier fully covariant approaches are investigated. The potentials are compared with the idea to obtain better insight on the role of low-energy constants appearing in the effective field theory approach and the convergence of this one in terms of a perturbative series. The results are illustrated by considering the longitudinal asymmetry of polarized protons scattering off protons, $vec{p}+p -> p+p$, and the asymmetry of the photon emission in radiative capture of polarized neutrons by protons, $vec{n}+p -> d+gamma$.

The old and the new of parity-violating two-pion-exchange $NN$ potential

We consider the parity-violating two-pion-exchange potential obtained from the covariant formalism in the past and the state-of-the-art effective field theory approach. We discuss the behavior of the potential in coordinate space and its application to the parity-violating asymmetry in $vec{n} p to d gamma$ at threshold.