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arXiv · 1906.12132

Non-derivative Axionic Couplings to Nucleons at large and small N

Francesco Bigazzi·Aldo L. Cotrone·Matti Järvinen·Elias Kiritsis
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Abstract

Among the possible CP-odd couplings of the axion to ordinary matter, the most relevant ones for phenomenology are the Yukawa couplings to nucleons. We analyze such non-derivative couplings within three different approaches: standard effective field theory, the Skyrme model and holographic QCD. In all the cases, the couplings can be related to the CP-odd non-derivative couplings to nucleons of the low-lying mesons and the $\eta'$. Using the effective field theory approach we discuss how to derive the expressions for the CP-odd interaction terms as functions of the parameters of the effective Lagrangian at generic number of colors $N_c$ and flavors $N_f$. Then, we compute the CP-odd couplings to nucleons of the axion, the $\eta'$ and the pseudo-Goldstone mesons in both the Skyrme and the holographic QCD model with $N_f=2,3$. We present model-independent expressions for the coefficients of the non-derivative axion-nucleon couplings. This allows us to provide quantitative estimates of these couplings.

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Francesco Bigazzi, Aldo L. Cotrone, Matti Järvinen, Elias Kiritsis. 2019-06-28. Non-derivative Axionic Couplings to Nucleons at large and small N. https://doi.org/10.1007/jhep01(2020)100

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