2025/04/01 by Estrada, Emilio J., Roig, Pablo
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2504.00448
We compute the tensor meson pole contributions to the Hadronic Light-by-Light piece of aμ in the purely hadronic region, using Resonance Chiral Theory. Given the differences between the dispersive and holographic groups determinations, we consider timely to present an alternative evaluation. In our approach, the lightest tensor meson nonet and two vector meson resonance nonets are considered in the chiral limit. Disregarding operators with derivatives, only the form factor F1T 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 decay widths. In this case, we obtain (in units of 10-11): a2-pole: -(1.02(10)\rm stat(+0.00-0.12)\rm syst), f2-pole: -(3.2(3)\rm stat(+0.0-0.4)\rm syst) and f2^′-pole: -(0.042(13)\rm stat), which add up to aμa2+f2+f2^′ \rm -pole=-(4.3+0.3-0.5), in close agreement with the holographic result when truncated to \mathcal F1T only. However, with an ad-hoc extended Lagrangian, that also generates \mathcal F3T, as in the holographic approach, we have found: a2-pole: +0.47(1.43)\rm norm(3)\rm stat(+0.06-0.00)\rm syst, f2-pole: +1.18(4.18)\rm norm(12)\rm stat(+0.24-0.00)\rm syst and f2^′-pole: +0.040(78)\rm norm(2)\rm stat, summing to aμa2+f2+f2^′ \rm - pole=+1.7(4.4), which agree with these recent determinations within uncertainties (dominated by the \mathcal F3T normalization). We point out that RχT generates all form factors, the contributions to aμ of \mathcal F2,4,5 cannot be evaluated in the current basis, preventing for the moment a complete calculation of aμ\rm T-poles within our framework.