Question AXION GLUON MATTER AS DARK MATTER

[Harry Costas]

Properties of Axion matter hold the keys to how the universe functions.

[Submitted on 3 Apr 2025]

No Dark Matter Axion During Minimal Higgs Inflation​

Claire Rigouzzo, Sebastian Zell

We study minimal versions of Higgs inflation in the presence of a massless QCD axion. While the inflationary energy scale of the metric variant is too high to accommodate isocurvature bounds, it was argued that Palatini Higgs inflation could evade these constraints. We show, however, that an energy-dependent decay constant enhances isocurvature perturbations, implying that axions can at most constitute a tiny fraction <10−5 of dark matter. This conclusion can be avoided in Einstein-Cartan gravity by an additional coupling of the axion to torsion, albeit for a very specific choice of parameters. Analogous constraints as well as the possibility to alleviate them are relevant for all inflationary models with a non-minimal coupling to gravity.

 

[Harry Costas]

These are the days. that scientists are becoming aware of the properties of axion and Neutrino matter.

[Submitted on 8 Apr 2025]

Generalised Symmetries in Particle Physics​

Joe Davighi

In this talk I review various notions of generalised global symmetry: higher-form, higher-group, and non-invertible symmetry. All these notions have had profound impact on quantum field theory research in the last decade. I highlight various applications of these new symmetries in particle physics, focussing on theories beyond the Standard Model. Areas touched upon include axions, gauge unification, dark matter, neutrino masses, and flavour hierarchies.

 

[Harry Costas]

This is one more step forward to understanding the full potential of Axion Matter.

[Larger PBH abundances can be generated by axion-like particles. Alternatively, in scenarios where isocurvature constraints can be relaxed, we find that the totality of the DM can be produced by the QCD axion misalignment mechanism, accompanied by a O(10−3) DM fraction in PBHs of masses (105−106) M⊙. These can act as seeds for the formation of massive black holes at large redshifts, as suggested by recent JWST observations.]

[Submitted on 10 Apr 25]

Stupendously Large Primordial Black Holes from the QCD axion​

Miguel Faria, Ricardo Z. Ferreira, Fabrizio Rompineve

The inflationary diffusion of (pseudo-)scalar fields with discrete symmetries can seed the formation of a gas of closed domain walls after inflation, when the distance between degenerate minima in field space is not too far from the inflationary Hubble scale. Primordial black holes (PBHs) can then be formed once sufficiently heavy domain walls re-enter the Hubble sphere. In this scenario, inflation determines a distinctive PBH mass distribution that is rather flat and can thus lead to a sizable total abundance of PBHs, while avoiding some of the downsides of PBH formation from critical collapse. We show that generic QCD axion models, with decay constant close to the inflationary Hubble scale, can yield up to 1% of the dark matter (DM) today in the form of PBHs, while being compatible with isocurvature constraints from Cosmic Microwave Background observations. This occurs for values of axion decay constants around fa≃108 GeV, that is the region targeted by axion helioscopes and partially constrained by astrophysical observations. The resulting PBHs have \textit{stupendously} large masses, above 1011M⊙, and their existence can be probed by Large Scale Structure observations. Larger PBH abundances can be generated by axion-like particles. Alternatively, in scenarios where isocurvature constraints can be relaxed, we find that the totality of the DM can be produced by the QCD axion misalignment mechanism, accompanied by a O(10−3) DM fraction in PBHs of masses (105−106) M⊙. These can act as seeds for the formation of massive black holes at large redshifts, as suggested by recent JWST observations.

 

[Harry Costas]

AXION GLUON MATTER is important in understanding so-called dark matter. Its ability to be compacted close to the density of a singularity and mimic black hole properties allows us to think of its full potential.

[Submitted on 17 Apr 2025]

Observation of the Axion quasiparticle in 2D MnBi_2Te_4​

Jian-Xiang Qiu, Barun Ghosh, Jan Schütte-Engel, Tiema Qian, Michael Smith, Yueh-Ting Yao, Junyeong Ahn, Yu-Fei Liu, Anyuan Gao, Christian Tzschaschel, Houchen Li, Ioannis Petrides, Damien Bérubé, Thao Dinh, Tianye Huang, Olivia Liebman, Emily M. Been, Joanna M. Blawat, Kenji Watanabe, Takashi Taniguchi, Kin Chung Fong, Hsin Lin, Peter P. Orth, Prineha Narang, Claudia Felser, Tay-Rong Chang, Ross McDonald, Robert J. McQueeney, Arun Bansil, Ivar Martin, Ni Ni, Qiong Ma, David J. E. Marsh, Ashvin Vishwanath, Su-Yang Xu

In 1978, Wilczek and Weinberg theoretically discovered a new boson-the Axion-which is the coherent oscillation of the \theta field in QCD. Its existence can solve multiple fundamental questions including the strong CP problem of QCD and the dark matter. However, its detection is challenging because it has almost no interaction with existing particles. Similar \theta has been introduced to condensed matter and so far studied as a static, quantized value to characterize topology of materials. But the coherent oscillation of \theta in condensed matter is proposed to lead to new physics directly analogous to the high-energy Axion particle, the dynamical Axion quasiparticle (DAQ). In this paper, we present the direct observation of the DAQ. By combining 2D electronic device with ultrafast pump-probe optics, we manage to measure the magnetoelectric coupling \theta (\theta\propto\alpha) of 2D MnBi_2Te_4 with sub-picosecond time-resolution. This allows us to directly observe the DAQ by seeing a coherent oscillation of \theta at ~44 GHz in real time, which is uniquely induced by the out-of-phase antiferromagnetic magnon. Interestingly, in 2D MnBi_2Te_4, the DAQ arises from the magnon-induced coherent modulation of Berry curvature. Such ultrafast control of quantum wavefunction can be generalized to manipulate Berry curvature and quantum metric of other materials in ultrafast time-scale. Moreover, the DAQ enables novel quantum physics such as Axion polariton and electric control of ultrafast spin polarization, implying applications in unconventional light-matter interaction and coherent antiferromagnetic spintronics. Beyond condensed matter, the DAQ can serve as a detector of the dark matter Axion particle. We estimate the detection frequency range and sensitivity in the critically-lacking meV regime, contributing to one of the most challenging questions in fundamental physics.

 

[Harry Costas]

Intersting read

[Submitted on 2 May 2025]

Inflation from Anomalies​

Nick E. Mavromatos, Panagiotis Dorlis, Sotirios-Neilos Vlachos

We review a string-inspired model of inflation which is a consequence of condensates of chiral gravitational waves (GW) in the primordial Universe, leading in turn to a (approximately) constant condensate of a gravitational anomaly term of Chern-Simons (CS) type, present in the Lagrangian density that describes the dynamics of the very early Universe in the model. We discuss some mechanisms for the production of chiral GW, as well as the role of periodic modulations of the potential of the gravitational axion field, that couples to the CS anomaly term, in ensuring the correct inflationary slow-roll phenomenology of this model.

 

[Harry Costas]

Getting to know is becoming a dream come true.

[Submitted on 6 May 2025]

Cosmic strings and domain walls of the QCD quark condensate with and without a hidden axion​

Gia Dvali, Lucy Komisel, Anja Stuhlfauth

The chiral quark condensate of QCD, which spontaneously breaks the anomalous axial symmetry, gives rise to axionic type global string-wall systems. If a Peccei-Quinn type axion exists in the theory, the axionic strings are in general accompanied by winding of the QCD quark condensate. Depending on the axion model the winding can proceed either in the

or in the pion direction. This determines the structure of fermionic zero modes and the anomaly inflow which has important astrophysical consequences. We point out that

and pion string-wall systems exist in pure QCD, independently of the hidden axion. Strikingly, even if a hidden axion exists, the early cosmology can be entirely dominated by string-wall systems formed by the QCD quark condensate. We also discuss their role in the QCD phase transition and in heavy-ion physics.