Understanding the near-threshold structures in $$e^+e^-$$ annihilation from a unified $$N\bar{N}$$-interaction perspective

Abstract

Abstract Near-threshold structures have been observed in the cross sections for $$e^+e^-\rightarrow p\bar{p}$$ e + e - → p p ¯ , $$e^+e^-\rightarrow n\bar{n}$$ e + e - → n n ¯ , and several non-baryonic final states in the vicinity of the $$N\bar{N}$$ N N ¯ thresholds. We investigate whether these structures can be understood as manifestations of a common $$N\bar{N}$$ N N ¯ final-state interaction. The strong $$N\bar{N}$$ N N ¯ interaction is taken from the chiral EFT description of the coupled $${}^3S_1$$ 3 S 1 - $${}^3D_1$$ 3 D 1 system constrained by low-energy $$N\bar{N}$$ N N ¯ scattering data. With this interaction fixed, the $$p\bar{p}$$ p p ¯ and $$n\bar{n}$$ n n ¯ cross sections are described by fitting only short-distance electromagnetic production sources, which are assumed to vary slowly over the near-threshold region. T