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Pion off-shell electromagnetic form factors: Data extraction and model analysis

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Author(s):
Choi, Ho-Meoyng ; Frederico, T. ; Ji, Chueng-Ryong ; de Melo, J. P. B. C.
Total Authors: 4
Document type: Journal article
Source: PHYSICAL REVIEW D; v. 100, n. 11, p. 12-pg., 2019-12-23.
Abstract

We investigate the pion electromagnetic half-off-shell form factors, which parametrize the matrix element of the charged pion electromagnetic current with one leg off mass shell and the other leg on mass shell, using an exactly solvable manifestly covariant model of a (3 + 1)- dimensional fermion field theory. The model provides a three-dimensional imaging of the two off-shell pion form factors F-1 and F-2 as a function of (Q(2), t), which are related to each other, satisfying the Ward-Takahashi identity. The normalization of the renormalized charge form factor F-1 is fixed by F-1 (Q(2) = 0, t = m(pi)(2)) = 1, while the other form factor F-2 vanishes; i.e., F-2 (Q(2), t = = 0 for any value of Q(2) due to the time-reversal invariance of the strong interaction. We define the new form factor g(Q(2), t) = F-2 (Q(2), t)/(t - m(pi)(2)) and find that g(Q(2), t) can be measurable in the on-mass-shell limit. In particular, g(Q(2) = 0, t = m(pi)(2)) is related with the pion charge radius. We also compare our form factors with the data extracted from the pion clectroproduction reaction for both the off-shell region (t < 0) and the on-shell limit (t -> m(pi)(2)). (AU)

FAPESP's process: 17/05660-0 - Theoretical studies of the structure and reactions of exotic nuclei and many-body systems
Grantee:Brett Vern Carlson
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 13/26258-4 - Superdense matter in the universe
Grantee:Manuel Máximo Bastos Malheiro de Oliveira
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 19/02923-5 - Hadronic physics with the light-front approach
Grantee:Joao Pacheco Bicudo Cabral de Mello
Support Opportunities: Regular Research Grants