Kai-Wen Li

Leading order relativistic chiral nucleon-nucleon interaction

Motivated by the successes of relativistic theories in studies of atomic/molecular and nuclear systems and the need for a relativistic chiral force in relativistic nuclear structure studies, we explore a new relativistic scheme to construct the nucleon-nucleon interaction in the framework of covariant chiral effective field theory. The chiral interaction is formulated up to leading order with covariant power counting and a Lorentz invariant chiral Lagrangian. We find that the relativistic scheme induces all six spin operators needed to describe the nuclear force. A detailed investigation of the partial wave potentials shows a better description of the and phase shifts than the leading order Weinberg approach, and similar to that of the next-to-leading order Weinberg approach. For the other partial waves with angular momenta , the relativistic results are almost the same as their leading order non-relativistic counterparts.

Strangeness S = − 1 hyperon-nucleon scattering in covariant chiral effective field theory

Motivated by the successes of covariant baryon chiral perturbation theory in one-baryon systems and in heavy-light systems, we study relevance of relativistic effects in hyperon-nucleon interactions with strangeness S = −1. In this exploratory work, we follow the covariant framework developed by Epelbaum and Gegelia to calculate the Y N scattering amplitude at leading order. By fitting the five low -energy constants to the experimental data, we find that the cutoff de pendence is mitigated, compared with the heavy-baryon approach. Nevertheless, the description of the experimental data remains quantitatively similar at leading order.

Leading order relativistic hyperon-nucleon interactions in chiral effective field theory

We apply a recently proposed covariant power counting in nucleon-nucleon interactions to study strangeness

Towards a relativistic formulation of baryon-baryon interactions in chiral perturbation theory

S=-1

Relativistic chiral description of the

\Lambda N-\Sigma N

^1S_0

interactions in chiral effective field theory. At leading order, Lorentz invariance introduces 12 low energy constants, in contrast to the heavy baryon approach, where only five appear. The Kadyshevsky equation is adopted to resum the potential in order to account for the non-perturbative nature of hyperon-nucleon interactions. A fit to the

nucleon-nucleon scattering

36

Relativistic baryon-baryon interactions in chiral perturbation theory

hyperon-nucleon scattering data points yields

Strangeness

\chi^2\simeq 16