Beyond the Standard Model: Hunting for Dark Matter in Pion Decay
![The PIENU experiment predicts the expected detection rate of [latex]\pi^{+}\to\mu^{+}\nu_{\mu}X[/latex] decays as a function of muon kinetic energy, demonstrating how varying the mass of the undetected particle <i>X</i> impacts signal prediction, with analyses at both low and high energies-corresponding to branching ratios of [latex]3\times 10^{-5}[/latex] and [latex]6\times 10^{-5}[/latex]-yielding results consistent with previously extracted residuals.](https://arxiv.org/html/2601.06254v1/x27.png)
A new analysis details how upcoming experiments leveraging pion decays could reveal the existence of sterile neutrinos and other particles composing the universe’s hidden dark sector.
Science
Entropic Memory in 3D Gauge Theory Defies Symmetry Breaking
New research reveals that three-dimensional Z2 lattice gauge theory exhibits a surprising robustness to symmetry breaking, driven by entropic effects that create a ‘classical memory’.
Squeezing Insights from Neutron Stars to Map Nuclear Forces
![Analysis of astrophysical data - incorporating gravitational-wave observations, maximum-mass constraints, and NICER results - refines prior estimates derived from nucleon-nucleon scattering, yielding updated posterior distributions for the six spectral LECs governing neutron matter, and further projecting anticipated sensitivities achievable with third-generation detectors for symmetric binary systems with component masses of [latex]1.0\,M_{\odot}[/latex] and [latex]1.4\,M_{\odot}[/latex].](https://arxiv.org/html/2601.05999v1/d7_current_injection.png)
New research leverages neutron star observations and machine learning to refine our understanding of the fundamental interactions governing matter at extreme densities.
Black Hole Secrets: Preserving Information in the Quantum Foam
New research offers a microscopic view of black hole evaporation, suggesting information isn’t lost but encoded in subtle quantum entanglement.
Seeing the Spin: EELS and the Future of Magnetic Materials Analysis
A new theoretical framework leverages inelastic electron scattering to precisely probe magnetic transitions and amplify subtle signals from spin-flip events.
Bending Light in a Flash: Sub-Cycle Control at Optical Frequencies
Researchers have achieved unprecedented control over light’s refractive index, demonstrating rapid modulation at timescales far exceeding the oscillation period of optical waves.
Mapping Materials’ Hidden Landscapes with AI-Powered Microscopy
Researchers have developed an autonomous system that uses artificial intelligence to efficiently explore the structure-property relationships within complex materials libraries.
Hunting for New Physics: Mapping the Limits of Lorentz Symmetry
A new analysis refines experimental strategies to comprehensively search for violations of fundamental symmetry principles in the realm of particle physics.
Mirror Images Under Light’s Control
New research shows how chiral optical cavities can manipulate and detect the fleeting dynamics of molecules with different ‘handedness’.
Waves of Order: Exploring Patterns in Quantum Fluids
![Bose-Einstein condensates exhibit tunable pattern formation-specifically, triangular density waves-through a two-stage modulation of the scattering length, a process driven by the spontaneous and collisional pairing of atoms with a specific momentum [latex]\mathbf{k}[/latex] of magnitude [latex]k_f[/latex], as demonstrated by a pattern recognition algorithm aligning randomly oriented condensate structures.](https://arxiv.org/html/2601.05576v1/x8.png)
This review examines how driving forces create striking patterns – from gentle ripples to chaotic turbulence – within the exotic realm of superfluidity.