This is March’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
Bubble Misalignment Mechanism for Axions, J. Lee, K. Murai, F. Takahashi, W. Yin, https://arxiv.org/abs/2402.09501
We study the dynamics of axions at first-order phase transitions in non-Abelian gauge theories. When the duration of the phase transition is short compared to the timescale of the axion oscillations, the axion dynamics is similar to the trapped misalignment mechanism. On the other hand, if this is not the case, the axions are initially expelled from the inside of the bubbles, generating axion waves on the outside. Analogous to the Fermi acceleration, these axions gain energy by repeatedly scattering off the bubble walls. Once they acquire enough energy, they can enter the bubbles. The novel "bubble misalignment mechanism'' can significantly enhance the axion abundance, compared to models where the axion mass is either constant or varies continuously as a function of temperature. The increase in axion abundance depends on the axion mass, the duration of the phase transition, and the bubble wall velocity. This mechanism results in a spatially inhomogeneous distribution of axions, which could lead to the formation of axion miniclusters. It has potential implications for the formation of oscillons/I-balls, axion warm dark matter, cosmic birefringence, and the production of dark 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 in February (after they appear, with their arXiv numbers). The summary will be disseminated in the newsletter of February.
Send email to
Alessandro Lella alessandro.lella@ba.infn.it
Damiano Fiorillo damiano.fiorillo@nbi.ku.dk
with subject:
preprint summary for Cosmic Wispers newsletter
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