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Article
Report number	arXiv:1907.06575 ; CERN-TH-2019-118 ; DESY-19-194
Title	Axion-electron decoupling in nucleophobic axion models
Author(s)	Björkeroth, Fredrik (LNF, Dafne Light) ; Di Luzio, Luca (INFN, Pisa ; Pisa U.) ; Mescia, Federico (ICC, Barcelona U.) ; Nardi, Enrico (LNF, Dafne Light) ; Panci, Paolo (INFN, Pisa ; Pisa U. ; CERN ; Gran Sasso) ; Ziegler, Robert (CERN)
Publication	2020-02-20
Imprint	2019-07-15
Number of pages	5
Note	5 pages, 1 figure
In:	Phys. Rev. D 101 (2020) 035027
DOI	10.1103/PhysRevD.101.035027
Subject category	hep-ph ; Particle Physics - Phenomenology
Abstract	The strongest upper bounds on the axion mass come from astrophysical observations like the neutrino burst duration of SN1987A, which depends on the axion couplings to nucleons, or the white-dwarf cooling rates and red-giant evolution, which involve the axion-electron coupling. It has been recently argued that in variants of DFSZ models with generation-dependent Peccei-Quinn charges an approximate axion-nucleon decoupling can occur, strongly relaxing the SN1987A bound. However, as in standard DFSZ models, the axion remains in general coupled to electrons, unless an ad hoc cancellation is engineered. Here we show that axion-electron decoupling can be implemented without extra tunings in DFSZ-like models with three Higgs doublets. Remarkably, the numerical value of the quark mass ratio $m_u/m_d\sim 1/2$ is crucial to open up this possibility.
Copyright/License	preprint: (License: CC-BY-4.0) publication: © 2020-2025 authors (License: CC-BY-4.0)

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