Pion-nucleon scattering in baryon chiral perturbation theory combined with the 1/ππ expansion
- Hampton Univ., Hampton, VA (United States)
- Hampton Univ., Hampton, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
This work implements the combined baryon chiral perturbation theory (BChPT) and 1/ππ expansions for pion-nucleon elastic scattering. The effective theory is based on the baryon sector dynamical spin-flavor πβ’πβ‘(4) symmetry emergent in the large ππ limit, whose breaking is controlled by the 1/ππ expansion. The noncommutativity of the chiral and 1/ππ expansions in unitarity corrections (loops) requires a linking of both expansions. As it was shown in the case of baryon masses and currents, the natural linking is the π expansion, in which πͺβ‘(π) = πͺβ‘(1/ππ) = πͺβ‘(π). The spin-flavor symmetry requires that the ground state baryons span an πβ’πβ‘(4) symmetric irreducible representation which implies that in particular π and Ξ are active degrees of freedom in the effective theory. The scattering amplitude is expanded to the next-to-next-to leading order in the π expansion, corresponding to the one-loop contributions with the leading-order Lagrangian. The results are given for generic ππ in order to demonstrate the consistency of the framework. The spin-flavor symmetry plays a central role in maintaining the consistency of the effective theory with respect to the 1/ππ expansion. This consistency manifests itself in an improvement in the convergence of the low energy expansion with respect to the case of the ordinary BChPT without an explicit dynamical Ξ, which is known to be inconsistent with the constraints of ππ scaling. Fits to the πβ’π β πβ’π, π, π, and π· partial wave amplitudes from the SAID data base are finally used to test the framework and to determine the energy range of its applicability.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); USDOE Office of Science (SC), Nuclear Physics (NP)
- Grant/Contract Number:
- AC05-06OR23177
- OSTI ID:
- 3011658
- Report Number(s):
- DOE/OR/23177--7870; JLAB-THY--25-4343; arXiv:2506.05224
- Journal Information:
- Physical Review. D., Journal Name: Physical Review. D. Journal Issue: 11 Vol. 112; ISSN 2470-0010; ISSN 2470-0029
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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