Abstract

We model interaction of photons, pseudoscalars and vector mesons within the resonance chiral symmetric theory with the SU(3) breaking. The couplings of the model are fitted to the experimental data. Within the developed model we predict the light-by-light contributions to the muon anomalous magnetic moment $a_{\mu}^P = (82.8 \pm 3.4)\times 10^{-11}$. The error covers also the model dependence within the class of models considered in this paper. The model was implemented into the Monte Carlo event generator Ekhara to simulate the reactions $e^+e^-\to e^+e^- P$, $P=\pi^0,\eta,\eta'$ and into the Monte Carlo event generator Phokhara to simulate the reactions $e^+e^-\to P\gamma(\gamma)$.

Highlights

  • During the last several years, many very accurate experimental data, which contain information about photonhadron interactions, emerged

  • The error covers the model dependence within the class of models considered in this paper

  • The model was implemented into the Monte Carlo event generator EKHARA to simulate reactions eþe− → eþe−P, P 1⁄4 π0; η; η0 and into the Monte Carlo event generator PHOKHARA to simulate reactions eþe− → PγðγÞ

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Summary

INTRODUCTION

During the last several years, many very accurate experimental data, which contain information about photonhadron interactions, emerged. The two main reasons for this effort, besides the pure interest in knowing better the microscopic world, are the discrepancy at the level of almost 4σ between the measured [2] and the calculated [3,4,5,6,7,8] anomalous magnetic moment of the muon (aμ) and the accuracy of the electromagnetic running coupling constant calculated at MZ [3], which is a limiting factor in future tests of the Standard Model In both cases, the hadronic contributions are the source of the uncertainties as electroweak corrections are well under control. We plan to extend our analysis to cover the eþe− → πþπ−; KþK−; K0K 0, and πþπ−π0 in a future publication This way it will be possible to study the model dependence of the obtained results comparing the hidden local symmetry and resonance chiral Lagrangian approach, which despite similarities are not identical.

THE MODEL
FITTING THE MODEL PARAMETERS TO THE EXISTING DATA
THE ASYMPTOTICS OF THE FORM FACTORS AND THE SLOPE OF THE FORM FACTORS AT
M2φi : ð50Þ
CONCLUSIONS

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