Relativistic Chiral Description of the 1 S 0 Nucleon–Nucleon ScatteringSupported by the China Scholarship Council, the National Natural Science Foundation of China (Grant Nos. 11375024, 11522539, 11735003, 11335002, and 11775099), NSFC and DFG through funds provided to the Sino-German CRC 110 “Symmetries and the Emergence of Structure in QCD” (NSFC Grant No. 11621131001, DFG Grant No. TRR110), the China Postdoctoral

Abstract

Recently, a relativistic chiral nucleon–nucleon interaction was formulated up to leading order, which provides a good description of the phase shifts of J ≤ 1 partial waves [Chin. Phys. C 42 (2018) 014103]. Nevertheless, a separable regulator function that is not manifestly covariant was used in solving the relativistic scattering equation. In the present work, we first explore a covariant and separable form factor to regularize the kernel potential and then apply it to study the simplest but most challenging 1 S 0 channel which features several low-energy scales. In addition to being self-consistent, we show that the resulting relativistic potential can describe quite well the unique features of the 1 S 0 channel at leading order, in particular the pole position of the virtual bound state and the zero amplitude at the scattering momentum ∼ 340 MeV, indicating that the relativistic formulation may be more natural from the viewpoint of effective field theories.