New axion contribution to the two-photon decays of neutral pions

Fuente: arXiv
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Autores principales: Lu, Zhen-Yan, Huang, Yang, Cheng, Ji-Gui, Lu, Qi, Wang, Shu-Peng
Formato: Preprint
Publicado: 2025
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author Lu, Zhen-Yan
Huang, Yang
Cheng, Ji-Gui
Lu, Qi
Wang, Shu-Peng
author_facet Lu, Zhen-Yan
Huang, Yang
Cheng, Ji-Gui
Lu, Qi
Wang, Shu-Peng
contents The presence of axions introduces new diagrams at one-loop order to the two-photon decays of the neutral pion through axion-pion mixing. In this work, we calculate this correction, missing in all current calculations, in the framework of SU(2) chiral perturbation theory. We show that the correction is proportional to the axion-photon coupling and the square of axion mass, which in turn is strongly suppressed by the axion decay constant for the classical space window but may not be negligible for the QCD axion in the MeV or even larger mass range. On the other hand, in combination with the experimental measurement of the decay width of $π^0\rightarrowγγ$ process, this result rules out the standard QCD axion as an explanation for the possible discrepancy between the chiral perturbation theory prediction and the experimental data.
format Preprint
id arxiv_https___arxiv_org_abs_2502_04060
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle New axion contribution to the two-photon decays of neutral pions
Lu, Zhen-Yan
Huang, Yang
Cheng, Ji-Gui
Lu, Qi
Wang, Shu-Peng
High Energy Physics - Phenomenology
High Energy Physics - Experiment
The presence of axions introduces new diagrams at one-loop order to the two-photon decays of the neutral pion through axion-pion mixing. In this work, we calculate this correction, missing in all current calculations, in the framework of SU(2) chiral perturbation theory. We show that the correction is proportional to the axion-photon coupling and the square of axion mass, which in turn is strongly suppressed by the axion decay constant for the classical space window but may not be negligible for the QCD axion in the MeV or even larger mass range. On the other hand, in combination with the experimental measurement of the decay width of $π^0\rightarrowγγ$ process, this result rules out the standard QCD axion as an explanation for the possible discrepancy between the chiral perturbation theory prediction and the experimental data.
title New axion contribution to the two-photon decays of neutral pions
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
url https://arxiv.org/abs/2502.04060