The Two-Nucleon 1S0 Amplitude Zero in Chiral Effective Field Theory

Understand

We present a new rearrangement of short-range interactions in the $^1S_0$ nucleon-nucleon channel within Chiral Effective Field Theory.

• This is intended to reproduce the amplitude zero (scattering momentum $\simeq$ 340 MeV) at leading order, and it includes subleading corrections perturbatively in a way that is consistent with renormalization-group invariance.
• Systematic improvement is shown at next-to-leading order, and we obtain results that fit empirical phase shifts remarkably well all the way up to the pion-production threshold.
• An approach in which pions have been integrated out is included, which allows us to derive analytic results that also fit phenomenology surprisingly well.