arXiv subjects

Matthew J. Baldwin

Publications and source records attributed to Matthew J. Baldwin.

5 recordsLinked to original sources

arXiv2026

Accidentally Stable Dark Matter in a Parity Solution to the Strong CP Problem

Parity symmetry, with an extended gauge group $SU(3)_c \times SU(2)_L \times SU(2)_R \times U(1)_X$, can solve the strong CP problem. In particular, the model where $SU(2)_R\times U(1)_X$ is broken by the Parity partner of the Standard Model Higgs solves the strong CP problem without the necessity of introducing extra symmetry. We discuss the possibility of accidentally stable dark matter in this framework and show that $SU(2)_L \times SU(2)_R$ bi-triplet fermions can be stable over cosmological timescales. We compute the relic abundance of the bi-triplet dark matter and derive constraints on the parameter space from collider, direct-detection, and indirect-detection experiments. The $SU(2)_R\times U(1)_X$ symmetry breaking scale is required to be below 150 TeV, and most of the parameter space can be probed by near-future indirect-detection experiments.

hep-ph↗

arXiv2026

Probing the Cosmic Axion Background via Axion-Photon Conversion in Filaments

The cosmic axion background (CaB) is a hypothetical population of relativistic axions produced in the early universe. If the CaB is produced from dark matter decays, the axions in this population can convert to photons in the magnetic fields of cosmological filaments, resulting in an isotropic gamma ray background flux. We present new indirect detection constraints on the axion mass and axion-photon coupling, for GeV-TeV dark matter with a decay lifetime below $10^{30}$ sec, by comparing this flux against experimental data. We exclude significant parameter space for axion masses below $10^{-5}$~eV for a broad range of dark matter masses and lifetimes, assuming conservative filament magnetic field strengths ($\sim 1$ nG). For large filament fields ($\sim 100$ nG), our strategy also constrains a portion of the QCD-axion parameter space for TeV-scale dark matter masses.

hep-ph↗

arXiv2025

Upper Bound on Parity Breaking Scale for Doublet WIMP Dark Matter

We consider weakly interacting massive particle (WIMP) dark matter in a Parity solution to the strong CP problem. The WIMP phenomenology can be drastically affected by the presence of Parity partners of the WIMP and electroweak gauge bosons. We focus on a Parity extension of $SU(2)_L$-doublet fermion dark matter, identify the viable parameter space, and derive the predictions of the theory. We find that the Parity symmetry breaking scale is bounded from above, with the bound given by $25-60$ TeV, depending on whether or not dark matter and its Parity partner coannihilate with each other. The High-Luminosity Large Hadron Collider, future colliders, and direct and indirect detection experiments can probe the parameter space further, with correlated signal rates.

hep-ph↗

arXiv2025

Electrically insulating materials for centrifugal mirrors

The centrifugal mirror confinement scheme incorporates supersonic rotation into a magnetic mirror device, which stabilizes and heats the plasma. This concept is under investigation in the Centrifugal Mirror Fusion Experiment (CMFX) at the University of Maryland. Plasma rotation is driven by an axial magnetic field and a radial electric field that lead to velocity drifts in the azimuthal direction. An electrically insulating material is required to prevent the applied voltage from shorting on the grounded chamber. Hexagonal boron nitride (hBN) is a promising candidate material for plasma-facing components in future centrifugal mirrors due to its exceptional thermal and electrical properties. However, its performance under intense particle and heat fluxes characteristic of the plasma edge in fusion devices remains largely unexplored. Computational modeling for ion- and neutron-material interactions was carried out with RustBCA and OpenMC, respectively, and predicts relatively good performance in comparison to other insulating materials. Material coupons were then exposed to plasma in PISCES-A at UCSD and CMFX. A load-locked sample feedthrough was constructed and installed on CMFX to test coupons. Two erosion mechanisms were identified -- sputtering and grain ejection -- both of which were more apparent in silicon carbide than hBN.

physics.plasm-ph↗

arXiv2024

Electroweak-Charged Dark Matter and SO(10) Unification with Parity

We consider electroweak-charged dark matter in an $SO(10)$ unified theory that solves the strong $CP$ problem via Parity. Electroweak-charged dark matter has a colored $SO(10)$ partner, whose mass should be much above the dark matter mass to avoid cosmological problems arising from the decay of the colored partner. The mass hierarchy can be naturally achieved by an $SO(10)\times CP$ symmetry breaking Higgs that has a missing vacuum expectation value. The mass hierarchy, via quantum corrections to the gauge coupling constants, lowers the unification scale and enhances the proton decay rate. Hyper-Kamiokande will probe the parameter space with precise gauge coupling unification. We derive the range of the top quark mass and the strong coupling constant preferred by radiative Parity breaking by the Higgs Parity mechanism.

hep-ph↗