RT Journal Article
T1 Pseudoscalar pole light-by-light contributions to the muon (g − 2) in resonance chiral theory
A1 Guevara, A.
A1 Roig Picazo, Pilar
A1 Sanz Cillero, Juan José
AB We have studied the P → γ⋆γ⋆ transition form-factors (P = π0, η, η′) within a chiral invariant framework that allows us to relate the three form-factors and evaluate the corresponding contributions to the muon anomalous magnetic moment aμ = (gμ−2)/2, through pseudoscalar pole contributions. We use a chiral invariant Lagrangian to describe the interactions between the pseudo-Goldstones from the spontaneous chiral symmetry breaking and the massive meson resonances. We will consider just the lightest vector and pseudoscalar resonance multiplets. Photon interactions and U(3) flavor breaking effects are accounted for in this covariant framework. This article studies the most general corrections of order m 2 P within this setting. Requiring short-distance constraints fixes most of the parameters entering the form-factors, consistent with previous determinations. The remaining ones are obtained from a fit of these form-factors to experimental measurements in the space-like (q2 ≤ 0) region of photon momenta. No time-like observable is included in our fits. The combination of data, chiral symmetry relations between form-factors and high-energy constraints allows us to determine with improved precision the on-shell P -pole contribution to the Hadronic Light-by-Light scattering of the muon anomalous magnetic moment: we obtain aP,HLbLμ=(8.47±0.16) ⋅ 10−10 for our best fit. This result was obtained excluding BaBar π0 data, which our analysis finds in conflict with the remaining experimental inputs. This study also allows us to determine the parameters describing the η−η′ system in the two-mixing angle scheme and their correlations. Finally, a preliminary rough estimate of the impact of loop corrections (1/NC ) and higher vector multiplets (asym) enlarges the uncertainty up to aP,HLbLμ=(8.47±0.16sta±0.091/NC+0.5−0asym)⋅10−10.
PB Springer
SN 1029-8479
YR 2018
FD 2018-06-27
LK https://hdl.handle.net/20.500.14352/12866
UL https://hdl.handle.net/20.500.14352/12866
LA eng
NO Ministerio de Economía y Competitividad (MINECO)
NO CONACYT Projects
NO Spanish Consolider-Ingenio 2010 Programme CPAN
DS Docta Complutense
RD 18 dic 2025