Newsletter July 2025

Monday 28 Jul 2025, 10:00 → 12:00 Europe/Rome

This is July’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.

 

 

Cosmic Wispers preprints

Deep Neural Networks Hunting Ultra-Light Dark Matter

Pavel Kůs, Diana López Nacir, Federico R. Urban

 https://arxiv.org/abs/2506.04100

ULDM induces measurable, characteristic signals in pulsar-timing data because it causes the orbits of pulsars in binary systems to osculate. We investigate the potential of machine learning techniques to detect such ULDM signals with three types of neural networks: an autoencoder, a binary classifier, and a multiclass classifier. We apply these methods to scalar, vector and tensor ULDM and find that the sensitivity achieved using machine learning methods is comparable to that of a semi-analytical Bayesian approach.

 

Resolving the QCD Axion Domain Wall Problem by a Light Axion

Junseok Lee, Kai Murai, Fuminobu Takahashi, Wen Yin

https://arxiv.org/abs/2507.07075

We show that the QCD axion domain wall problem can be resolved by introducing an additional massless or light axion that also couples to gluons. The underlying mechanism is straightforward: the domain walls associated with the QCD axion can terminate on strings of this auxiliary axion, causing the network to collapse into string bundles that behave as ordinary cosmic strings. This scenario predicts the formation of stable string bundles, which can leave observable signatures such as gravitational waves, cosmic birefringence, and anisotropies in the cosmic microwave background. The simultaneous detection of QCD axion dark matter and any of these signals would provide a smoking-gun signature of this mechanism.

 

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

• August

• Postdoctoral Position at TU Dortmund in Dark Matter/Axion Research and X-ray Optics, Dortmund. link

• Postdoctoral Position on MADMAX, Garching. link

• Postdoctora research associate in Beyond the Standard Model phenomenology, DAMTP, Cambridge. link

• September

• "La Caixa" postdoctoral positions at UAM & IFT, Madrid. link

• Postdoctoral Researcher in XENONnT & XLZD, Nagoya. link

• Postdoctoral Research Associate on Neutrino Physics, IFIC, Valencia. link

• October

• Postdoctoral position on Hyper-Kamiokande, LPNHE, Paris. link

 

 

Conferences

• August

• Black Holes & Cosmology 2025 (BHCos '25) link

• New Ways to Discover Light New Physics link

• Dark Matter and Neutrino Focus Week link

• TAUP 2025 link

• September

• Invisibles25 Workshop 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

• 1st UNDARK workshop: Astrophysical searches of dark sectors with radio wave observations link

• October 

• 28th International Conference on Particle Physics & Cosmology (COSMO 2025) link

• November

• Theoretical Tools for Gravitational Wave Physics link

• December

• Strings & Cosmology Meeting link