Spectral functions of nucleon form factors: Three-pion continua at low energies
- Technische Univ. Munchen, Garching (Germany)
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Indiana Univ., Bloomington, IN (United States)
We study the imaginary parts of the isoscalar electromagnetic and isovector axial form factors of the nucleon close to the 3 pi-threshold in covariant baryon chiral perturbation theory. At the two-loop level, the contributions arising from leading and next-to-leading order chiral pi N-vertices, as well as pion-induced excitations of virtual Delta(1232)-isobars, are calculated. It is found that the heavy baryon treatment overestimates substantially these 3 pi-continua. From a phenomenological analysis, that includes the narrow omega(783)-resonance or the broad a1-resonance, one can recognize small windows near threshold, where chiral 3 pi-dynamics prevails. However, in the case of the isoscalar electromagnetic form factors G$$s\atop{E,M}$$(t), the radiative correction provided by the pi0 gamma-intermediate state turns out to be of similar size.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC05-06OR23177
- OSTI ID:
- 1498268
- Report Number(s):
- JLAB-THY-18-2862; DOE/OR/23177-4576
- Journal Information:
- European Physical Journal. A, Vol. 55, Issue 2; ISSN 1434-6001
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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