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Article Dans Une Revue Journal of High Energy Physics Année : 2023

Forward light-by-light scattering and electromagnetic correction to hadronic vacuum polarization

Volodymyr Biloshytskyi
  • Fonction : Auteur
En-Hung Chao
  • Fonction : Auteur
Jeremy R. Green
  • Fonction : Auteur
Franziska Hagelstein
  • Fonction : Auteur
Harvey B. Meyer
  • Fonction : Auteur
Julian Parrino
  • Fonction : Auteur
Vladimir Pascalutsa
  • Fonction : Auteur

Résumé

Lattice QCD calculations of the hadronic vacuum polarization (HVP) have reached a precision where the electromagnetic (e.m.) correction can no longer be neglected. This correction is both computationally challenging and hard to validate, as it leads to ultraviolet (UV) divergences and to sizeable infrared (IR) effects associated with the massless photon. While we precisely determine the UV divergence using the operator-product expansion, we propose to introduce a separation scale $\Lambda\sim400\;$MeV into the internal photon propagator, whereby the calculation splits into a short-distance part, regulated in the UV by the lattice and in the IR by the scale $\Lambda$, and a UV-finite long-distance part to be treated with coordinate-space methods, thereby avoiding power-law finite-size effects altogether. In order to predict the long-distance part, we express the UV-regulated e.m. correction to the HVP via the forward hadronic light-by-light (HLbL) scattering amplitude and relate the latter via a dispersive sum rule to $\gamma^*\gamma^*$ fusion cross-sections. Having tested the relation by reproducing the two-loop QED vacuum polarization (VP) from the tree-level $\gamma^*\gamma^*\to e^+e^-$ cross-section, we predict the expected lattice-QCD integrand resulting from the $\gamma^*\gamma^*\to\pi^0$ process.
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Dates et versions

hal-03782731 , version 1 (12-09-2023)

Identifiants

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Volodymyr Biloshytskyi, En-Hung Chao, Antoine Gérardin, Jeremy R. Green, Franziska Hagelstein, et al.. Forward light-by-light scattering and electromagnetic correction to hadronic vacuum polarization. Journal of High Energy Physics, 2023, 03, pp.194. ⟨10.1007/JHEP03(2023)194⟩. ⟨hal-03782731⟩
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