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Abstract |
We compute the tensor meson pole contributions to the Hadronic Light-by-Light piece of a μin the purely hadronic region, using Resonance Chiral Theory. Given the differences between the dispersive and holographic groups determinations and the resulting discussion of the corresponding uncertainty estimate for the Hadronic Light-by-Light section of the muon g – 2 theory initiative second White Paper, we consider timely to present an alternative evaluation. In our approach, in addition to the lightest tensor meson nonet, two vector meson resonance nonets are considered, in the chiral limit.Disregarding operators with derivatives, only the form factor FT 1 is non-vanishing, as assumed in the dispersive study. All parameters are determined by imposing a set of short-distance QCD constraints, and the radiative tensor decay widths. In this case, we obtain the following results for the different contributions (in units of 10-11): aa2-pole μ= – (1.02(10)stat(+0.00 -0.12) syst), af2-pole μ= – (3.2(3)stat(+0.0 -0.4) syst) and af' 2 -pole μ= -(0.042(13)stat), which add up to aa2+f2+ f' 2 -pole μ= – (4.3+0.3 -0.5), in close agreement with the holographic result when truncated to FT 1 only. However, with an ad-hoc extended Lagrangian, that also generates FT 3, as in the holographic approach, we have found: aa2-pole μ= +0.47(1.43)norm(3)stat(+0.06 -0.00)syst, af2-pole μ= +1.18(4.18)norm(12)stat(+0.24 -0.00) syst and af' 2 -pole μ= +0.040(78)norm(2)stat, summing to aa2+f2+ f' 2 -pole μ= +1.7(4.4), which agree with these recent determinations within uncertainties (dominated by the FT 3 normalization). We point out that R.T generates all five form factors, differently to previous approaches. The contributions to a μof F2,4,5 cannot be evaluated in the current basis, preventing for the moment a complete calculation of aT-poles μwithin our framework. |
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Address |
[Estrada, Emilio J.; Roig, Pablo] Ctr Invest & Estudios Avanzados Inst Politecn Nacl, Dept Fis, Apartado Postal 14-740, Mexico City 07360, Mexico, Email: emilio.estrada@cinvestav.mx; |
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