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This is April’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.
A.Yu. Kotov, M.P. Lombardo, A. Trunin
https://arxiv.org/pdf/2502.15407
QCD topology plays a significant role in the study of the properties of the QCD axion. The topological susceptibility is related with the axion mass, and the Free Energy with the axion potential. In recent years lattice simulations have provided many results for the former, however a complete agreement among different results is still missing, in particular in the high temperatures regime (T ≳ 1 GeV) relevant for axion physics. In this study we provide further insight in the complicated lattice topology systematics, and present the first results for the QCD Free Energy around and above the QCD transition temperature.
D. F. G. Fiorillo, T. Pitik , E. Vitagliano
https://arxiv.org/pdf/2503.15630
We revisit the production of axion-like particles (ALPs) coupled to electrons at tree-level in a relativistic plasma. We explicitly demonstrate the equivalence between pseudoscalar and derivative couplings, incorporate previously neglected processes for the first time—namely, semi-Compton production (γe−→ae−) and pair annihilation (e+e−→aγ)—and derive analytical expressions for the bremsstrahlung (e−N →e−Na) production rate, enabling a more computationally efficient evaluation of the ALP flux. Additionally, we assess uncertainties in the production rate arising from electron thermal mass corrections, electron-electron Coulomb interactions, and the Landau-Pomeranchuk-Migdal effect. The ALP emissivity is made available in a public repository as a function of the ALP mass, the temperature, and the electron chemical potential of the plasma. Finally, we examine the impact of ALP production and subsequent decays on astrophysical observables, deriving the leading bounds on ALPs coupling to electrons. At small couplings, the dominant constraints come from the previously neglected decay a →e+e−γ, except for a region of fireball formation where SN 1987A X-ray observations offer the best probe. At large couplings, bounds are dominated by the energy deposition argument, with a recently developed new prescription for the trapping regime.
D. F. G. Fiorillo, T. Pitik , E. Vitagliano
https://arxiv.org/pdf/2503.13653
Feebly interacting particles, such as sterile neutrinos, dark photons, and axions, can be abundantly produced in the proto-neutron star (PNS) formed in core-collapse supernovae (CCSNe). These particles can decay into photons or charged leptons, depositing energy outside the PNS. Strong bounds on new particles can thus be derived from the observed luminosity of CCSNe, with even tighter bounds obtained from low-energy SNe observations. For the first time we highlight that, at sufficiently large couplings, particle production outside the PNS must also be considered. Using the prototypical case of axions coupling to two photons, we show that at large couplings the energy transfer from PNS to its surroundings is diffusive rather than ballistic, substantially reducing the deposited energy. Our findings have implications for the parameter space of particles probed in beam dump experiments and for dark matter models involving a sub-GeV mediator.
Francesca Lecce, Alessandro Lella, Giuseppe Lucente, Vimal Vijayan, Andreas Bauswein, Maurizio Giannotti, Alessandro Mirizzi
https://arxiv.org/pdf/2504.02032
Axion-like particles (ALPs) can be copiously produced in binary neutron star (BNS) mergers through nucleon-nucleon bremsstrahlung if the ALP-nucleon couplings gaN are sizable. Furthermore, the ALP-photon coupling gaγ may trigger conversions of ultralight ALPs into photons in the magnetic fields of the merger remnant and of the Milky Way. This effect would lead to a potentially observable short gamma-ray signal, in coincidence with the gravitational-wave signal produced during the merging process. This event could be detected through multi-messenger observation of BNS mergers employing the synergy between gravitational-wave detectors and gamma-ray telescopes. Here, we study the sensitivity of current and proposed MeV gamma-ray experiments to detect such a signal. We find that the proposed instruments can reach a sensitivity down to gaγ ≳ few × 10−13 GeV−1 for ma ≲ 10−9 eV, comparable with the SN 1987A limit.
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.
Postdoctoral position in Axion dark matter searches, Berkeley link
Research associate on the DarkSide experiment, Rutherford link
Research associate on the QUEST-DMC dark matter experiment, Rutherford link
Expression of interest for a postdoc position in La Sapienza, Rome link
Expression of interest for a Marie Skłodowska-Curie fellowship in Particle Cosmology, UCM Madrid link
Postdoctoral position in astrophysics and quantum technology, Zaragoza link
5th Annual EuCAPT Symposium link
Summer Conference on High Energy Physics & Astrophysics link
Dark matter and neutrinos link
NEHOP’25 - New Horizons in Primordial Black Hole Physics link
Planck 2025 link
Tabletop Scale Cosmology 2025 link
Dark Matter 2025: From the Smallest to the Largest Scales (DM2025) link
UK-Astroparticle Physics Phenomenology: Spring 2025 (UK-APP) link
Valencia Workshop on the Small-Scale Structure of the Universe and Self-Interacting Dark Matter link
Making Neutron Stars a Laboratory for New Physics link
Dark tools link
Axions in Stockholm link
Les Houches Summer School 2025: The Dark Universe link
Dark Side of the Universe 2025 (DSU-2025) link
International Conference "Dark Matter and Stars: Multi-Messenger Probes of Dark Matter and Modified Gravity" (ICDMS2025) link
11th Summer School in Particle and Astroparticle Physics (GRASPA2025) link
30th International Symposium on Particles, Strings and Cosmology (PASCOS 2025) link
Windows into New Physics in the Sky link
3rd General Meeting of the COST Action: Cosmic WISPers (CA21106) link
3rd Training School of the COST Action: Cosmic WISPers (CA21106) link
Light Dark World 2025 (LDW 2025) link
20th Patras Workshop on Axions WIMPs and WISPs link
28th International Conference on Particle Physics & Cosmology (COSMO 2025) link
Strings & Cosmology Meeting link