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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Axion flux monodromy discharges relax the cosmological constant

Abstract Linear axion monodromy models modulated with higher powers of fields naturally realize the quantum-mechanical flux discharge mechanism for relaxing the cosmological constant toward zero. Working with multiple copies of superposed linear and quadratic flux monodromies, each copy spanned by a pair of fluxes, we show that when the axion is very massive and so effectively decoupled, the membrane discharges relax the cosmological constant toward an attractor 0 < Λ/M 4 Pl ≪ 1. If we restrict the flux variations and the intermediate flux values to never venture beyond a finite flux range, the terminal value of the cosmological constant will be tiny but finite. We show how it can reproduce the observed scale of dark energy, and explain how to incorporate matter sector phase transitions.

Astronomy & Astrophysics↗
DOE OSTI2020

Axion structure formation – II. The wrath of collapse

ABSTRACT The first paper in this series showed that quantum chromodynamic axion dark matter, as a highly correlated Bose fluid, contains extra-classical physics on cosmological scales. The source of the derived extra-classical physics is exchange–correlation interactions induced by the constraints of symmetric particle exchange and interaxion correlations from self-gravitation. The paper also showed that the impact of extra-classical physics on early structure formation is marginal, as the exchange–correlation interaction is inherently non-linear. This paper continues the study of axion structure formation into the non-linear regime, considering the case of full collapse and virialization. The N-body method is chosen to study the collapse, and its algorithms are derived for a condensed Bose fluid. Simulations of isolated gravitational collapse are performed for both Bose and cold dark matter fluids using a prototype N-body code. Unique Bose structures are found to survive even the most violent collapses. Bose post-collapse features include dynamical changes to global structures, creation of new broad sub-structures, violations of classical binding energy conditions, and new fine structures. Effective models of the novel structures are constructed and possibilities for their observation are discussed.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

High-quality axion from exact SUSY chiral dynamics

We use supersymmetric chiral dynamics perturbed by anomaly-mediated supersymmetry breaking to obtain a high-quality, composite axion that solves the strong problem. The strong dynamics arises from a supersymmetric SU(10) chiral gauge theory with massless matter chiral superfields. This leads to a stable, nonsupersymmetric vacuum, calculated exactly, where a spontaneously broken global symmetry, identified with the Peccei-Quinn (PQ) symmetry, gives rise to a composite QCD axion. The chiral gauge theory also admits a discrete (or ) gauge symmetry that forbids PQ-violating operators up to dimension eight. An extension to an chiral gauge theory incorporates grand unification where the unification scale is identified with the PQ-breaking scale and PQ-violating operators are forbidden up to dimension 20. The supersymmetry breaking scale, near 100 TeV, ameliorates the Higgs hierarchy problem, while colored Nambu–Goldstone bosons may be detected at future colliders via decays to gluons or form heavy isotopes.

Gherghetta, Tony↗
DOE OSTI2020

Axion insulator state in ferromagnetically ordered CrI 3 /Bi 2 Se 3 /MnBi 2 Se 4 heterostructures

Ferromagnetic (FM) axion insulators may greatly simplify experimental explorations of the topological magnetoelectric effect, as the FM ordering can be stable in a broad range of magnetic field. Through density functional theory calculations and four-band model studies, we find that two-dimensional van der Waals FM CrI 3 and MnBi 2 Se 4 overlayers induce opposite-sign exchange fields in the topological surface states of Bi 2 Se 3 film when they are ferromagnetically ordered. As a consequence, the CrI 3 /Bi 2 Se 3 /MnBi 2 Se 4 heterostructure is a robust FM axion insulator, according to surface-resolved Berry curvature calculations. Our work opens up opportunities for the design of materials with the topological magnetoelectric effect.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Two-loop contributions of axion-like particles to electromagnetic and chromomagnetic form factors

Abstract Axions and axion-like particles emerge in many models for physics beyond the Standard Model. Thus, they have gained increasing research interest in both experimental and theoretical physics apart from their original proposition as a solution to the strong CP -problem. Among other aspects it has recently been shown that ALPs can potentially provide a solution to the long-lasting discrepancy between theory and experiment of the anomalous magnetic moment of the muon. Provided that the ALP has flavor-violating couplings to leptons, they can also mediate flavor-violating decays like $$\mu \rightarrow e\gamma $$ μ → e γ . Both processes are mediated through related form factors that we compute to two-loop order. We further show numerical implications of our calculations and how they might affect constraints on ALP couplings derived from experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

First Results from BREAD: Broadband Reflector Experiment for Axion Detection

We report R&D progress, as well as first dark photon search results with BREAD - a novel dish antenna for broadband ~$\mu$eV-eV wave-dark matter detection, which allows to utilize state-of-the-art high-field solenoidal magnets. Axions are converted non-resonantly to photons on a cylindrical metallic wall parallel to an external magnetic field. These photons are then focused using a novel reflector geometry onto a state-of-the-art high-sensitive photon detector. We recently demonstrated [PRL 128 (2022) 131801] that this concept using a $\sim 10\,{\rm m}^2$ conversion area in a $\sim 10\,{\rm T}$ solenoidal magnet has the potential to discover QCD axions spanning multiple decades in mass range. In this talk we discuss progress of our first stage pilot experiments - GigaBREAD and InfraBREAD - covering different mass ranges. We show first results of a room-temperature GigaBREAD prototype and discuss upscaling to larger, cryogenic and magnetized versions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Quality and Loss Factor Analysis of YBCO Superconducting Transmission Lines for Axion Dark Matter Detection

Axion haloscope experiments aim to detect the conversion of axions into microwave photons in a magnetic field, which produces extremely small signals requiring low-loss cryogenic transmission lines for readout to reduce noise and attenuation. Yttrium Barium Copper Oxide (YBCO) cables are a promising candidate. Unlike commonly used low-loss superconducting cables such as Niobium (Nb) and Niobium Titanium (NbTi), which have low critical fields, YBCO is a high-temperature superconductor that can remain stable in strong magnetic fields. We evaluate their suitability by characterizing the quality and loss factors of five stripline resonators (three YBCO, and copper and silver references) from the Brookhaven Technology Group at 77 K without an external field, and cooled to 30 mK in a 14 T magnet. For measurements at 77 K we recorded scattering parameter data and employed Lorentzian and circle-fitting analysis techniques. We identified the best-performing resonator and developed a cryogenic probe for future testing in the magnet at millikelvin temperatures.

Marinos, Zoe [UCLA]↗
DOE OSTI2023

Light Curves and Event Rates of Axion Instability Supernovae

Abstract It was recently proposed that exotic particles can trigger a new stellar instability that is analogous to the e − e + pair instability if they are produced and reach equilibrium in the stellar plasma. In this study, we construct axion instability supernova (AISN) models caused by the new instability to predict their observational signatures. We focus on heavy axion-like particles (ALPs) with masses of ∼400 keV–2 MeV and coupling with photons of g a γ ∼ 10 −5 GeV −1 . It is found that the 56 Ni mass and the explosion energy are significantly increased by ALPs for a fixed stellar mass. As a result, the peak times of the light curves of AISNe occur earlier than those of standard pair-instability supernovae by 10–20 days when the ALP mass is equal to the electron mass. Also, the event rate of AISNe is 1.7–2.6 times higher than that of pair-instability supernovae, depending on the high mass cutoff of the initial mass function.

Mori, Kanji (ORCID:0000000325951657)↗
DOE OSTI2025

First constraints on QCD axion dark matter using James Webb Space Telescope observations

I present the first constraints on QCD axion dark matter using measurements from the James Webb Space Telescope. By utilizing publicly available MIRI and NIRSpec blank-sky observations, originally collected for sky subtraction purposes, I derive strong limits on the axion-photon coupling constant $g_{a \gamma \gamma}$ in the mass range 0.1-4 eV. These constraints improve upon previous studies by more than two orders of magnitude for a range of masses. This analysis underscores the potential of blank-sky observations as a powerful tool for constraining dark matter models and demonstrates how astrophysical missions can be repurposed for particle physics research.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

High-Q Superconducting Lumped-Element Resonators for Low-Mass Axion Searches

Low-frequency superconducting lumped-element resonators have recently attracted significant attention in the context of axion dark matter searches. Here we present the design and implementation of a fixed-frequency superconducting resonator operating near $250~\mathrm{kHz}$, possessing an inductor volume of $\sim 1$ liter and achieving an unloaded quality factor $Q \approx 2.1\times10^{6}$. This resonator represents a significant improvement over the state of the art and informs the design of searches for low-mass axions.

FOS: Physical sciences↗
DOE OSTI2022

Engineering of Form Factor in Rotationally Symmetric Photonic Cavities for Faster Axion Searches

Form factor can be engineered in photonic cavities such that it dramatically increases the scan speed of axion haloscope detectors. Using higher-order modes of a photonic cavity, we can probe axions at larger mass ranges beyond the reach of current detectors that rely on conventional copper cavities. The main idea is to produce a higher-order mode with longitudinal field distribution that has relatively high amplitude away from both the cavity axis and the cavity walls such that it results in a relatively large form factor and maintains a high-quality factor. The detector scan speed significantly increases as it is proportional to the square of the form factor multiplied by the quality factor.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Probing Heavy Axion-like Particles from Massive Stars with X-rays and Gamma Rays

The hot interiors of massive stars in the later stages of their evolution provide an ideal place for the production of heavy axion-like particles (ALPs) with mass up to O(100 keV) range. We show that a fraction of these ALPs could stream out of the stellar photosphere and subsequently decay into two photons that can be potentially detected on or near the Earth. In particular, we estimate the photon flux originating from the spontaneous decay of heavy ALPs produced inside Horizontal Branch and Wolf-Rayet stars, and assess its detectability by current and future $X$-ray and gamma-ray telescopes. Our results indicate that current and future telescopes can probe axion-photon couplings down to $g_{a\gamma} \sim 4\times 10^{-11}$ GeV${}^{-1}$ for $m_a\sim 10-100$ keV, which covers new ground in the ALP parameter space.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Dynamical Heating from Dark Compact Objects and Axion Minihalos: Implications for the 21-cm Signal

The temperature of baryons at the end of the cosmic dark ages can be inferred from observations of the 21-cm hyperfine transition in neutral hydrogen. Any energy injection from the dark sector can therefore be detected through these measurements. Dark compact objects and dark-matter substructures can modify the baryon temperature by transferring heat via dynamical friction. In this work, we evaluate the prospects for detecting dynamical friction-induced heating from dark compact objects with a mass in the range $10^2 M_{\odot}$ to $10^5 M_{\odot}$, as well as from axion minihalos, using upcoming 21-cm experiments. We find that both the 21-cm global signal and power-spectrum measurements will be sensitive to dark compact objects that constitute about 10% of the dark matter, and will substantially improve our sensitivity to axion-like particles with masses in the range $10^{-18}$ eV to $10^{-9}$ eV.

Bhalla, Badal [Oklahoma U.] (ORCID:000000030488664↗
DOE OSTI2025

Mechanical Actuation Mechanism Design for Cryogenic Microwave Cavities in Axion Dark Matter Searches

Resonant Microwave Cavities are placed in a strong magnetic field at cryogenic temperatures (~.1K) in order to try to convert axions into detectable photons. A major challenge is to tune the cavity to allow no interference with the desired environment used for the experiment, which enables the system to operate near absolute zero and maintain superconductivity, thereby reducing noise as much as possible. My project focuses on developing and testing a low-thermal-conductivity gear reduction system with a 1000:1 ratio for cavity tuning. This gear system could significantly improve the thermal and electromagnetic interference of the tuning mechanism, helping ADMX scan for axions more accurately.

Ortega, Giancarlo [Marquette U.; Fermilab]↗
DOE OSTI2026

Quality and Loss Factor Characterization of YBCO Superconducting Transmission Lines for Axion Dark Matter Detection

Axion haloscope experiments aim to detect the conversion of axions into microwave photons under a strong magnetic field through resonant cavity techniques. The conversion produces an extremely small signal, requiring a cryogenic environment to reduce thermal noise, and low-loss superconducting transmission lines for minimal attenuation in the readout chain. Yttrium barium copper oxide (YBCO) cables are a promising candidate. Unlike commonly used low-loss cryogenic cables such as niobium (Nb) and niobium titanium (NbTi), which have low critical fields, YBCO is a high-temperature superconductor that can remain stable in strong magnetic fields. We characterized the quality and loss of five stripline resonators from the Brookhaven Technology Group: three YBCO, a copper reference, and a silver reference. Experimental methodology included collecting scattering parameter data on a vector network analyzer for the samples at 77 K along with room temperature baseline measurements, and employing both Lorentzian-fit and circle-fitting techniques to confirm the coupling regime and corroborate results. We achieved quality factors on the order of $10^3$ with corresponding loss factors on the order of $10^{-1}$ dB/m. Trends were comparable with literature data on Nb and NbTi at 4 K, which did have lower loss under these conditions, but suggested similar or perhaps better loss for YBCO when accounting for the temperature difference. We also developed a cryogenic probe for future measurements in a 14 T applied field at 30 mK. This will serve to directly evaluate YBCO's durability in magnetic fields, and we expect significantly improved performance at millikelvin temperatures.

Marinos, Z. [UCLA]↗
DOE OSTI2025

Bounds on Heavy Axions with an X-Ray Free Electron Laser

We present new exclusion bounds obtained at the European X-Ray Free Electron Laser facility (EuXFEL) on axionlike particles in the mass range 10 -3 eV ≲ m a ≲ 10 4 eV. Our experiment exploits the Primakoff effect via which photons can, in the presence of a strong external electric field, decay into axions, which then convert back into photons after passing through an opaque wall. While similar searches have been performed previously at a third-generation synchrotron [Yamaji et al., Phys. Lett. B 782, 523 (2018)], our work demonstrates improved sensitivity, exploiting the higher brightness of x-rays at EuXFEL.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Dark photons and axion-like particles at the electron-ion collider in China

The Electron-Ion Collider in China (EicC), a proposed high-luminosity facility with advanced charged particle and photon detection capabilities, provides unique opportunities to uncover new physics beyond the Standard Model. We analyze its sensitivity to dark photons produced through electron bremsstrahlung in coherent scattering. Thanks to its beam energy settings, it has the potential to comprehensively probe the previously unexplored parameter space between the constraints from meson decays and beam dumps below $\mathcal{O}(1)$ GeV with displaced-vertex search. Additionally, the EicC has the potential to probe axion-like particles (ALPs) in the mass range 0.1 GeV ≲ m a ≲ 5 GeV, with a coupling reach of Λ ≲ 10 6 GeV, by combining the prompt-decay and displaced-vertex searches. The projected sensitivities to ALPs exceed the current bounds.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Lepton-flavor violating axions at MEG II

We study the sensitivity of the existing MEG data to lepton flavor violating axion-like particles produced through μ + → e + a$\gamma$ and estimate the discovery potential for the upcoming MEG II experiment in this channel. The MEG II signal efficiency can be improved significantly if a new trigger can be implemented in a dedicated run with a reduced beam intensity. This search would establish the world leading measurement in this channel with only 1 month of data taking.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗