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1. Nonequilibrium dynamics of axionlike particles: The quantum master equation

   https://doi.org/10.1103/PhysRevD.107.063518  

   Cao, Shuyang; Boyanovsky, Daniel (March 2023, Physical Review D)

   We study the nonequilibrium dynamics of axionlike particles (ALP) coupled to Standard Model degrees of freedom in thermal equilibrium. The quantum master equation (QME) for the ALP reduced density matrix is derived to leading order in the coupling of the ALP to the thermal bath, but to all orders of the bath couplings to degrees of freedom within or beyond the Standard Model other than the ALP. The QME describes the damped oscillation dynamics of an initial misaligned ALP condensate, thermalization with the bath, decoherence, and entropy production within a unifying framework. The ALP energy density features two components: a “cold” component from the misaligned condensate and a “hot” component from thermalization with the bath. 

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2. Predicting Licenses for Changed Source Code

   https://doi.org/10.1109/ASE.2019.00070  

   Liu, Xiaoyu; Huang, LiGuo; Ge, Jidong; Ng, Vincent (November 2019, Proceedings of the 34th IEEE/ACM International Conference on Automated Software Engineering)

   null (Ed.)

   Open source software licenses regulate the circumstances under which software can be redistributed, reused and modified. Ensuring license compatibility and preventing license restriction conflicts among source code during software changes are the key to protect their commercial use. However, selecting the appropriate licenses for software changes requires lots of experience and manual effort that involve examining, assimilating and comparing various licenses as well as understanding their relationships with software changes. Worse still, there is no state-of-the-art methodology to provide this capability. Motivated by this observation, we propose in this paper Automatic License Prediction (ALP), a novel learning-based method and tool for predicting licenses as software changes. An extensive evaluation of ALP on predicting licenses in 700 open source projects demonstrate its effectiveness: ALP can achieve not only a high overall prediction accuracy (92.5% in micro F1 score) but also high accuracies across all license types. 

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3. Frequency‐Scanning Considerations in Axionlike Dark Matter Spin‐Precession Experiments

   https://doi.org/10.1002/andp.202300223  

   Zhang, Yuzhe; Tumturk, Deniz Aybas; Bekker, Hendrik; Budker, Dmitry; Kimball, Derek F. Jackson; Sushkov, Alexander O.; Wickenbrock, Arne (November 2023, Annalen der Physik)

   Abstract Galactic dark matter may consist of axionlike particles (ALPs) that can be described as an “ultralight bosonic field” oscillating at the ALP Compton frequency. The ALP field can be searched for using nuclear magnetic resonance (NMR), where resonant precession of spins of a polarized sample can be sensitively detected. The ALP mass to which the experiment is sensitive is scanned by sweeping the bias magnetic field. The scanning either results in detection of ALP dark matter or rules out ALP dark matter with sufficiently strong couplings to nuclear spins over the range of ALP masses corresponding to the covered span of Larmor frequencies. In this work, scanning strategies are analyzed with the goal of optimizing the parameter‐space coverage via a proper choice of experimental parameters (e.g., the effective transverse relaxation time). 

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4. Predictions for axion couplings from ALP cogenesis

   https://doi.org/10.1007/JHEP01(2021)172  

   Co, Raymond T.; Hall, Lawrence J.; Harigaya, Keisuke (January 2021, Journal of High Energy Physics)

   null (Ed.)

   A bstract Adding an axion-like particle (ALP) to the Standard Model, with a field velocity in the early universe, simultaneously explains the observed baryon and dark matter densities. This requires one or more couplings between the ALP and photons, nucleons, and/or electrons that are predicted as functions of the ALP mass. These predictions arise because the ratio of dark matter to baryon densities is independent of the ALP field velocity, allowing a correlation between the ALP mass, m a , and decay constant, f a . The predicted couplings are orders of magnitude larger than those for the QCD axion and for dark matter from the conventional ALP misalignment mechanism. As a result, this scheme, ALP cogenesis, is within reach of future experimental ALP searches from the lab and stellar objects, and for dark matter. 

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5. Searching for axion-like particles through CMB birefringence from string-wall networks

   https://doi.org/10.1088/1475-7516/2022/10/090  

   Jain, Mudit; Hagimoto, Ray; Long, Andrew J.; Amin, Mustafa A. (October 2022, Journal of Cosmology and Astroparticle Physics)

   Abstract Axion-like particles (ALPs) can form a network of cosmic strings and domain walls that survives after recombination and leads to anisotropic birefringence of the cosmic microwave background (CMB). In addition to studying cosmic strings, we clarify and emphasize how the formation of ALP-field domain walls impacts the cosmic birefringence signal; these observations provide a unique way of probing ALPs with masses in the range 3 H 0 ≲ m a ≲ 3 H cmb . Using measurements of CMB birefringence from several telescopes, we find no evidence for axion-defect-induced anisotropic birefringence of the CMB. We extract constraints on the model parameters that include the ALP mass m a , ALP-photon coupling 𝒜 ∝ g aγγ f a , the domain wall number N dw , and parameters characterizing the abundance and size of defects in the string-wall network. Considering also recent evidence for isotropic CMB birefringence, we find it difficult to accommodate this with the non-detection of anisotropic birefringence under the assumption that the signal is generated by an ALP defect network. 

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