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Newsletter September 2025
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Description
This is September’s edition of the newsletter of the COST action. The aim is to keep you updated on recent and upcoming conferences and postdoc positions on subjects related to WISPs.
Winners of the prize for the best three students’ talks
We are happy to announce that
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Marta Fuentes Zamoro, Tackling ALP searches in meson decays with ALPaca: a phenomenological approach
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Sophia Hollick, A combined search for dark matter with COSINE-100 and ANAIS-112
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Noelia Maria Sanchez Gonzalez, Dynamical systems and superstring phases in the early universe
have been awarded with the prize for the best three students’ talks at the CA21106 3° Training School, held in Annecy on 16-19 September 2025.
Congratulations on behalf of the whole COST Action Cosmic WISPers!
Cosmic Wispers preprints
Comprehensive ALP Searches in Meson Decays
Jorge Alda, Marta Fuentes Zamoro, Luca Merlo, Xavier Ponce Díaz, Stefano Rigolin
https://arxiv.org/abs/2507.19578
We present a comprehensive study of axion-like particles (ALPs) in meson decays, combining effective field theory and ultraviolet models within the open-source tool ALPaca. The analysis accounts for running and matching effects across energy scales, including non-perturbative QCD corrections via chiral perturbation theory. We discuss several benchmark models, both flavour-universal and non-universal, using the most up-to-date theoretical computations for ALP decays and branching ratios. Experimental signatures such as prompt, displaced, and invisible decays are included. A dedicated analysis of B-physics is performed.
ALPaca: The ALP Automatic Computing Algorithm
Jorge Alda, Marta Fuentes Zamoro, Luca Merlo, Xavier Ponce Díaz, Stefano Rigolin
https://arxiv.org/abs/2508.08354
The ALP Automatic Computing Algorithm, ALPaca, is an open source Python library devoted to studying the phenomenology of Axion-Like Particles (ALPs) with masses in the ranges ma ∈ [0.01−10] GeV. ALPaca provides a flexible and comprehensive framework to define ALP couplings at arbitrary energy scales, perform Renormalisation Group evolution and matching down to the desired low energy scale, and compute a large variety of ALP observables, with particular care to the meson decay sector. The package includes support for UV completions, experimental constraints, and visualisation tools, enabling both detailed analyses and broad parameter space exploration.
Axion-photon conversion in transient compact stars: Systematics, constraints, and opportunities
Damiano F. G. Fiorillo, Ángel Gil Muyor, Hans-Thomas Janka, Georg G. Raffelt, Edoardo Vitagliano
https://arxiv.org/abs/2509.13322
We study magnetic conversion of ultra-relativistic axion-like particles (ALPs) into photons in compact-star environments, focusing on the hot, transient conditions of core-collapse supernova (SN) remnants and neutron-star mergers (NSMs). We address previously overlooked uncertainties, particularly the suppression caused by ejected matter near the stellar surface, a region crucial to the conversion process. We derive analytical expressions for the transition rate; they reveal the influence of key parameters and their uncertainties. We update constraints using historical gamma-ray data from SN 1987A and find $g_aγ<5×10^{−12}$ GeV−1for $m_a≲10−9 meV$. We also forecast sensitivities for a future Galactic SN and for NSMs, assuming observations with Fermi-LAT or similar gamma-ray instruments. We distinguish ALPs -- defined as coupling only to photons and produced via Primakoff scattering -- from axions, which also couple to nucleons and emerge through nuclear bremsstrahlung. We omit pionic axion production due to its large uncertainties and inconsistencies, though it could contribute comparably to bremsstrahlung under optimistic assumptions. For the compact sources, we adopt time-averaged one-zone models, guided by numerical simulations, to enable clear and reproducible parametric studies.
Small Progenitors, Large Couplings: Type Ic Supernova Constraints on Radiatively Decaying Particles
Francisco R. Candón, Damiano F. G. Fiorillo, Hans-Thomas Janka, Bart F. A. van Baal, Edoardo Vitagliano
https://arxiv.org/abs/2509.18253
Supernova (SN) 1987A is a celebrated laboratory in searches for gamma-ray flashes produced by the radiative decay of sub-GeV particles such as axion-like particles (ALPs), sterile neutrinos, and novel gauge bosons. At large couplings, however, particles decay rapidly inside the stellar envelope, which results in a suppression of the signal. Focusing on the prototypical example of ALPs with a photon coupling, we show that core-collapse SNe of Type Ic are much less affected by this attenuation, thanks to the compactness of their progenitors ensuing from the loss of their envelope. While Fermi-LAT may miss the brief gamma-ray flash from a single Type Ic SN, their high rate allows for a statistical approach: by stacking many events, we can obtain constraints that significantly surpass those from SN 1987A at large couplings. Our approach can be extended to any feebly interacting particle featuring a decay channel into photons.
We encourage participants in the COST action to send us a small summary, typically smaller than the abstract, of their own articles that will appear in the arXiv (after they appear, with their arXiv numbers). The summary will be disseminated in the newsletter.
Send email to
Alessandro Lella alessandro.lella@ba.infn.it
Damiano Fiorillo damianofg@gmail.com
with subject: preprint summary for Cosmic WISPers newsletter.
PhD/Postdoc/Junior Positions
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September
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Postdoctoral Research Associate on Neutrino Physics, IFIC, Valencia. link
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Postdoctoral Research Associate In Dark Matter/SuperCDMS Experiment link
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October
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Postdoctoral position on Hyper-Kamiokande, LPNHE, Paris. link
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Postdoctoral research position in JUNO link
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PhD position in Theoretical Particle Cosmology link
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PhD positions in experimental and theoretical particle physics link
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Postdoctoral Position in Neutrino Physics at TAMBO link
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Three PhD positions in astroparticle physics, to start at the earliest convenience link
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PhD in Experimental Space Astroparticle Physics (DAMPE & HERD) link
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November
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Multiple PhD Positions in Fundamental Physics and Quantum Dynamics link
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Postdoctoral Research Associate - Liquid Noble Dark Matter Detection link
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PhD positions in Astrophysics, Cosmology and Gravitation link
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Postdocs in High-Energy Particle Physics and Cosmology link
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December
Conferences
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October
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28th International Conference on Particle Physics & Cosmology (COSMO 2025) link
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Beyond Standard Model: From Theory to Experiment ( (BSM- 2025) link
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November
- Theoretical Tools for Gravitational Wave Physics link
- Axions in Japan link
- Light Dark Sectors @ LNF link
- Theory meets Experiments 2025: School on Direct Detection across Dark Matter mass ranges link
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December
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Strings & Cosmology Meeting link
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June
