Primordial Magnetogenesis and Gravitational Waves from ALP-assisted Phase Transition

[2604.20768] Primordial Magnetogenesis and Gravitational Waves from ALP-assisted Phase Transition Skip to main content Search Submit Donate Log in High Energy Physics - Phenomenology arXiv:2604.20768 (hep-ph) [Submitted on 22 Apr 2026 ( v1 ), last revised 27 Aug 2026 (this version, v2)] Title: Primordial Magnetogenesis and Gravitational Waves from ALP-assisted Phase Transition Authors: Pankaj Borah , P. S. Bhupal Dev , Anish Ghoshal View PDF HTML (experimental) Abstract: Sufficiently strong first-order phase transitions (FOPTs) in the early Universe can simultaneously produce an observable stochastic gravitational wave background (SGWB) and a large-scale primordial magnetic field (PMF). The recent $3.8\sigma$ evidence for a non-zero intergalactic magnetic field from anisotropic pair-halo searches using \textit{Fermi}-LAT data further motivates a cosmological origin. We investigate an FOPT-origin of both cosmic signatures, namely, PMF and SGWB, and their correlation, within a minimal axion-like particle (ALP) framework in which a global $U(1)$ symmetry is spontaneously broken through radiative corrections, with the ALP sector coupled to the Standard Model (SM) via a Higgs-portal. We compute the present-day PMF amplitude and coherence length for both maximally helical and non-helical configurations, accounting for inverse cascade effects. For maximally helical configurations, we find peak field strengths up to $B_0 \sim 10^{-9}$ G at coherence length $\lambda_0 \sim 10^{-3}-10^{-1}$ Mpc, consistent with lower bounds on the IGMF inferred from blazar observations by MAGIC, H.E.S.S. and {\it Fermi}-LAT. We show that the ALP parameter region consistent with $\gamma$-ray blazar data (assuming maximally helical fields) simultaneously produces stochastic GW signals detectable at future space-based interferometers, such as LISA, etc., over the ALP decay constant range $10^3~\text{GeV} \lesssim f_a \lesssim 10^5~\text{GeV}$. We demonstrate that these correlated constraints can be directly mapped onto effective ALP couplings to SM particles, e.g., photons, gluons, and fermions. This establishes a multi-messenger complementarity between cosmological observables and laboratory/astrophysical ALP searches, with combined constraints preferring relatively heavy ALPs, $m_a \gtrsim 0.1~\text{GeV}$, accessible to next-generation intensity and energy-frontier experiments. Comments: 42 pages, 7 figures. Minor revision and references added. Version accepted for publication in JCAP Subjects: High Energy Physics - Phenomenology (hep-ph) ; Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th) Cite as: arXiv:2604.20768 [hep-ph] (or arXiv:2604.20768v2 [hep-ph] for this version) https://doi.org/10.48550/arXiv.2604.20768 Focus to learn more arXiv-issued DOI via DataCite Journal reference: JCAP 09 (2026) 118 Related DOI : https://doi.org/10.1088/1475-7516/2026/09/118 Focus to learn more DOI(s) linking to related resources Submission history From: Pankaj Borah [ view email ] [v1] Wed, 22 Apr 2026 16:57:22 UTC (6,259 KB) [v2] Thu, 27 Aug 2026 09:25:11 UTC (6,279 KB) Full-text links: Access Paper: View PDF HTML (experimental) TeX Source view license Current browse context: hep-ph < prev | next > new | recent | 2026-04 Change to browse by: astro-ph astro-ph.CO hep-th References & Citations INSPIRE HEP SciX Google Scholar Semantic Scholar export BibTeX citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer ( What is the Explorer? ) Connected Papers Toggle Connected Papers ( What is Connected Papers? ) Litmaps Toggle Litmaps ( What is Litmaps? ) scite.ai Toggle scite Smart Citations ( What are Smart Citations? ) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv ( What is alphaXiv? ) Links to Code Toggle CatalyzeX Code Finder for Papers ( What is CatalyzeX? ) DagsHub Toggle DagsHub ( What is DagsHub? ) GotitPub Toggle Gotit.pub ( What is GotitPub? ) Huggingface Toggle Hugging Face ( What is Huggingface? ) ScienceCast Toggle ScienceCast ( What is ScienceCast? ) Demos Demos Replicate Toggle Replicate ( What is Replicate? ) Spaces Toggle Hugging Face Spaces ( What is Spaces? ) Spaces Toggle TXYZ.AI ( What is TXYZ.AI? ) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower ( What are Influence Flowers? ) Core recommender toggle CORE Recommender ( What is CORE? ) IArxiv recommender toggle IArxiv Recommender ( What is IArxiv? ) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. 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