Disciplines / Research questions
Physics
691 research topics · 2739 questions
Double-row monodromy matrix3 questions
Commutativity and polynomiality of the Q-operator for the open XXZ spin chain with diagonal boundaries (Vlaar–Weston Conjecture 6.3)
Analytic theory of the rational -system for open spin- XXX chains: boundary-induced strings, -function ambiguity, and solution splitting
Correlation-function building blocks for the open XXZ spin-1/2 chain with general integrable boundaries: the overlap factor, form factors of local operators, and the inverse problem without U(1) symmetry
Double periodicity and quasi-periodicity3 questions
Elliptic eight-vertex model with domain wall boundary conditions: normalization-level identification of the domain wall partition function at generic parameters
Fractal structure of the Fibonacci Ising quasicrystal: uniform multifractality of Lee-Yang zeros and single-fermion spectrum at arbitrary couplings, and the topology of finite-fermion spectra below the interval threshold
Completeness of the Bethe ansatz for the dynamical elliptic (KZB) Bethe algebra and the global geometry of the elliptic Wronski map
Tetrahedron equation2 questions
Foundations of the state-integral construction of tetrahedron-equation solutions: analytic degeneration and the transpose pentagon hypothesis
Open problems of the tetrahedron duality: anomaly cancellation and the elliptic genus of the (0,2) brane box model, the oblique unit cell, and the reach of the construction
Four-spin interaction1 questions
Stochastic six-vertex model1 questions
Random tilings4 questions
Fluctuations of the uniformly random 3D dimer flow: convergence to the divergence-free projection of white noise
Open for about 3 yearsKenyon-Okounkov Gaussian free field convergence for uniformly weighted generalized tower graphs: upgrading gradient convergence to the full height field
Open for about 21 yearsLocal statistics of random domino tilings of L-shaped Aztec domains: unfrozen connecting paths and correlation kernels at the arctic curve and its cusps
Open for less than 1 yearScaling-limit theory for interacting k-tilings of the Aztec diamond: arctic curves, color coupling, and edge fluctuations
Open for about 3 years
Topological quantum computation5 questions
Completing a universal fault-tolerant gate set for Majorana braiding on the altermagnet–superconductor heterostructure platform
Open for about 1 yearScalable compilation of measurement-only topological gates in Majorana zero-mode arrays
Open for about 7 yearsMaking the universal topological gate set fault-tolerant: decoders, thresholds, and robust anyon-manipulation protocols under realistic noise including measurement errors
Open for about 1 yearExperimental and theoretical validation of STT-matrix-based braiding of vortex-hosted Majorana zero modes in two-dimensional topological superconductors
Open for about 2 yearsLeakage-controlled universal gates and a finite-tunneling readout analysis for the diagonal-coset Fibonacci-anyon quantum computer at filling factor 12/5
Open for about 2 years
Terahertz waves and their applications2 questions
Difficulties faced in terahertz electromagnetic wave transmission research2 questions
Exploiting the molecular absorption effect in terahertz communications: altitude-dependent spectral-window modeling, weather-adaptive VLC/THz cooperation, and closing the physical-layer-security insecure zones
Open for about 4 yearsWater-vapor continuum absorption in the terahertz atmospheric windows: determination of the self and foreign continuum coefficients, their temperature dependence, and the residual window discrepancies
Open for about 13 years
Can solar energy replace traditional energy sources?4 questions
Integrated system-level feasibility of a global PV-dominated electricity transition under full embodied-energy and material burdens
Open for about 16 yearsMinimum extended-boundary EROI for sustaining a complex modern society and the dynamic net-energy viability of the renewable energy transition
Open for about 17 yearsDetermining the minimum societal energy return on investment (EROI): the sustainable cut-off for net-energy-constrained solar resource accounting and the implications of falling below it
Open for about 17 yearsGenuine substitution of fossil generation by intermittent renewables in European electricity systems: empirical assessment across the generation, capacity and demand perspectives and the fossil backup requirement
Open for about 8 years
Extrasolar planetary systems: searching for distant worlds4 questions
The unseen planetary system of Fomalhaut: identifying the planets that sculpt its debris disk after Fomalhaut b proved to be a transient dust cloud
Open for about 21 yearsThe Formation Pathway of the HR 8799 Wide-Orbit Planetary System: Core Accretion versus Gravitational Instability
Open for about 17 yearsEstablishing the habitability of Hycean worlds and validating their atmospheric biosignatures
Open for about 5 yearsHow rare is the Solar System's architecture: the intrinsic occurrence rate of inner-depleted planetary systems with cold giant planets
Open for about 11 years
Exploring nucleon structure3 questions
The limit of the proton parton distribution ratio and the valence-quark dynamics it discriminates
Open for about 53 yearsProcess-independent observability of the gauge-invariant canonical orbital angular momentum in the nucleon spin decomposition
Open for about 13 yearsScheme-independent quark-gluon decomposition of the nucleon mass in QCD and the physical role of the trace anomaly
Open for about 31 years
Can gradient methods be used to solve the Dirac equation?6 questions
Convergence of the power-iteration and parameter-tuning scheme for self-consistent bound states of the Schrödinger and Dirac equations
Open for about 5 yearsVariational collapse in gradient-based minimization of the Dirac equation: a general selection mechanism for positive-energy eigenstates
Open for about 40 yearsRigorous error analysis of the Dirac-sVQA splitting variational quantum algorithm for the nonlinear Dirac equation
Open for less than 1 yearFully discrete convergence analysis of normalized-gradient-flow and min-max schemes for stationary states of nonlinear Dirac operators
Open for about 6 yearsRigorous error analysis, temporal sampling complexity, and long-time mass conservation for physics-informed neural network solvers of the time-dependent Dirac equation
Open for about 4 yearsConditioning versus preconditioning for gradient-based Dirac solvers in lattice QCD: net time-to-solution advantage at physical quark masses, production volumes, and many right-hand sides
Open for about 18 years
Iron-based high-temperature superconductivity and its mechanism2 questions
Nuclear isomers and possible gamma-ray lasers5 questions
Experimental validation of a current-driven thin-film Th vacuum-ultraviolet nuclear light source
Open for about 3 yearsStimulated de-excitation of the Re nuclear isomer in laser-produced plasma: reproducibility, mechanism, and the hypothesized second isomeric state in Re
Open for about 8 yearsOptical-range nuclear gamma-ray laser on the 229Th isomer transition: population inversion and stimulated-emission gain in a doped solid
Open for about 15 yearsExistence and charge-state-modulated decay of the conjectured isomer above the 8+ state in 92Zr
Open for about 1 yearUndemonstrated experimental program of the multi-photon stimulated graser: net gamma-ray amplification from laser-plasma gamma flashes with intense supplied photon fields
Open for about 2 years
Exploring the origin of the pseudogap in copper oxide high-temperature superconductors3 questions
Mutual relationship and common origin of the cuprate pseudogap and strange metal: testing the Mott-Slater localization / van-Hove-singularity coincidence scenario
Open for about 37 yearsMechanism of the non-monotonic temperature dependence of the cuprate normal-state pseudogap and of its spectral correspondence with incommensurate charge ordering in transition-metal dichalcogenides
Open for about 18 yearsNature of the quantum criticality at the pseudogap end point of hole-doped cuprate superconductors
Open for about 27 years
Gauge hierarchy problem in unified field theory8 questions
Is the electroweak hierarchy problem a physical problem? Scheme-independent naturalness from the distance to the electroweak critical surface
Open for about 45 yearsThreshold naturalness of the Higgs mass-squared: protective ultraviolet structures for the coexistence of the electroweak scale with high mass scales
Open for about 12 yearsRadiative and dynamical stability of scalar-tensor (equivalence-principle) solutions to the gauge hierarchy problem
Open for about 18 yearsLandscape and anthropic inputs for the weak-scale hierarchy: the Higgs-VEV and Yukawa distributions and the weak-to-weakless habitable-universe ratio
Open for about 5809 yearsConsistent quantization of internal fermionic (particle-ghost) symmetry as a solution to the gauge hierarchy problem
Open for about 12 yearsHigh-scale attraction at ultraviolet fixed points: can a large anomalous mass dimension in asymptotically safe gravity explain the gauge hierarchy?
Open for about 14 yearsDoes renormalization-group consistency enforce strong supercooling in classically scale-invariant extensions of the Standard Model?
Open for about 6 yearsCompleting the physical-tuning account of Higgs naturalness: the UV-tuned region, its origin in a UV completion, robustness of the Wilsonian flow, and observable tests
Open for about 4 years
Turbulence: models and computations10 questions
Closure of the Reynolds-averaged Navier–Stokes equations via constitutive relations or transport equations for the velocity-fluctuation fields
Open for about 130 yearsWell-posedness of the exterior turbulent flow boundary-value problem for RANS equations with two-equation turbulence models
Open for about 5 yearsExistence of weak solutions for the Jiang–Layton corrected eddy-viscosity turbulence model with an anisotropic time-derivative term
Open for about 11 yearsHow much domain knowledge must be embedded in machine-learned subgrid-scale closures for large-eddy simulation: invariance, cross-regime generalization, and computational cost
Open for about 7 yearsQuantifying the turbulent potential model's cost advantage over full Reynolds-stress closures and completing stress-transport model evaluation in complex flowfields
Open for about 27 yearsWeak uniqueness of mean outputs and dual stability for weak solutions of the Navier–Stokes equations in turbulent flow
Open for about 21 yearsPhysically consistent subgrid-scale models for large-eddy simulation: significance, compatibility, and realizability of model constraints
Open for about 10 yearsGuaranteed computability of high-Reynolds-number turbulent-flow outputs: the missing rigorous theory of dual (adjoint) stability
Open for about 22 yearsSystematic predictive and computational assessment of stress-transport turbulence closures versus two-equation eddy-viscosity models in complex flows
Open for about 19 yearsOpen problems in the mathematical theory of the NS-TKE and k-epsilon turbulence models: uniqueness, energy balance, and the realistic unbounded-eddy-viscosity regime
Open for about 12 years
Turbulent reactive flows9 questions
Regime-general turbulence–chemistry interaction closures for large-eddy simulation of premixed turbulent combustion
Open for about 19 yearsTurbulent flame speeds of non-equidiffusive () mixtures: a generalized scaling with Markstein/Lewis-number effects, the mechanism of stretch-affected local extinction, and a diffusivity-aware combustion regime diagram
Open for about 11 yearsCharacterizing turbulence within a premixed turbulent flame brush: separating intrinsic turbulence from reactant-product intermittency and mean-velocity-jump effects
Open for about 17 yearsA posteriori assessment of the flamelet regime diagram for non-premixed turbulent combustion LES: self-consistency of flamelet-model solutions and explicit-versus-implicit filtering
Open for about 9 yearsTurbulent diffusion of chemically reacting admixtures beyond first-order, constant-density assumptions: predictive theory for the effective turbulent chemical time and the turbulent diffusion coefficient at finite Reynolds and Damköhler numbers
Open for about 11 yearsQuantifying the statistical-independence factorization in assumed-PDF turbulence–chemistry closures for non-equilibrium reacting flows
Open for about 8 yearsA posteriori validation of sub-filter variance and unsteady NO-transport closures for predictive LES of NOx in gas-turbine combustors
Open for about 18 yearsPredictive turbulence-chemistry interaction modeling of MILD combustion: closing the CO and OH prediction gap in jet-in-hot-coflow flames
Open for about 14 yearsClosure of the zone-conditioned moment and PDF transport equations in the thin-reaction-zone framework for turbulent reacting flows at low Damköhler number
Open for about 6 years
Elliptic matrix2 questions
Elliptic parameters 1 questions
Elliptic modulus and complementary modulus 4 questions
Unproved arithmetic of Broadhurst's level-48 class invariants at discriminants N ≡ 3 (mod 8): the Chowla–Selberg unit λ and mod-64-signature generation of the Hilbert class field
Riffaut's conjecture: no singular modulus of degree at least 3 is a root of a rational trinomial (unconditional status)
Multiplicatively dependent triples of singular moduli: the Bilu–Gun–Tron classification conjecture
Integrality of singular values of the generalized lambda function in the excluded regime with or a prime power
Elliptic curves2 questions
Ferroelectric model in external fields2 questions
Perfect matching2 questions
Complete elliptic integrals 1 questions
Theory and experiments on the non-Gaussianity of the microwave background radiation spectrum6 questions
Non-Gaussianity of primordial isocurvature perturbations: detection-level observational determination and the model-to-bispectrum mapping
Open for about 18 yearsRobust inference of the primordial trispectrum from patch-to-patch variation of observed non-Gaussianity
Open for about 13 yearsThe post-inflationary CMB bispectrum of metric gravity: full second-order transfer, templates, and observational confrontation
Open for about 16 yearsObservational status of the predicted large equilateral/orthogonal non-Gaussianity in the two-field DBI inflation model of Nozari and Asadi (2016)
Open for about 10 yearsTesting scale-dependent primordial non-Gaussianity as the origin of the large-scale CMB anomalies: a joint bispectrum and power-modulation analysis beyond the Sachs-Wolfe approximation
Open for about 11 yearsPhysical origin of the spherical-harmonic phase non-Gaussianities detected in cleaned Planck and WMAP CMB temperature maps
Open for about 6 years
Experimental and theoretical studies of tensor modes in the microwave background radiation7 questions
Observationally discriminating the chiral gravitational-wave background of spectator axion-SU(2) inflation from the vacuum background: completing the CMB and laser-interferometer program
Open for about 9 yearsCan multi-field inflation produce a testably large tensor tilt for LiteBIRD: realistic model building and robust forecasts
Open for about 2 yearsForeground-robust inference of the tensor-to-scalar ratio with CMB-S4: residual-bias control, non-oracle debiasing, spatially adaptive component separation, and multi-pipeline validation for defensible primordial B-mode claims
Open for about 1 yearCMB -mode constraints on causal primordial gravitational-wave sources beyond the white-noise template
Open for less than 1 yearCompleting the gravitational-wave prediction for inflationary gauge-field sourcing: post-inflationary magnetic fields, reheating transitions, tensor non-Gaussianity, and renormalization
Open for less than 1 yearRobust end-to-end test of the single-field inflationary tensor consistency relation across CMB and laser-interferometer scales
Open for about 12 yearsPolarized foreground complexity and the robustness of CMB tensor-to-scalar-ratio constraints to foreground model mis-specification
Open for about 10 years
Differential and Integral Identities3 questions
Differential Galois group of the level-three cubic-theta differential field over Ramanujan's differential field
Riemann-Xi integral for the second error-function transformation, exact evaluations of its confluent-hypergeometric integrals, and the Delta/Nabla parity reversal (open questions of Dixit-Roy-Zaharescu)
Wan's first conjecture on moments of products of complete elliptic integrals: settling and determining the five remaining open even moments
Lattice-Boltzmann Simulation of Fluid Flow and Heat Transfer at Micro-Nano Scale5 questions
Generalizing the linearized double-distribution thermal lattice Boltzmann method: coupled shear–thermal noncontinuum flows, stable full-form equilibria, and complex geometries
Open for about 11 yearsParameter-free thermal lattice Boltzmann boundary treatment for rarefied gas microflow: maintaining accuracy beyond the first-order slip regime (Kn around 0.1 and above) at large Eckert and Prandtl numbers
Open for about 19 yearsKinetic lattice Boltzmann modeling of rarefied gas flow and heat transfer in the transition regime (): Knudsen-layer resolution, parameter-independent kinetic boundary conditions, and tractable discrete-velocity sets
Open for about 14 yearsGeneral validated effective-property models and the single-phase validity limit for nanofluid microchannel heat-transfer prediction
Open for about 21 yearsEffect of non-unity momentum and thermal accommodation coefficients on slip flow and heat transfer in an asymmetrically heated microchannel simulated by the thermal lattice Boltzmann method
Open for about 5 years
Phase Change Heat Transfer in Micro-Nano Channels5 questions
Experimental validation of slope- and curvature-dependent disjoining pressure in microchannel thin-film evaporation
Open for about 13 yearsPredictive design framework for subcooled flow boiling in microchannels with chemically patterned (wettability-patterned) surfaces
Open for about 7 yearsQuantitative synchronization criteria for flow boiling in parallel microchannels: coupling-coefficient thresholds, design mapping, measurement, and validated actuation
Open for about 6 yearsCritical heat flux limits of constructally optimized two-phase microchannel heat sinks
Open for about 6 yearsEvaporation-driven instability mechanism, thresholds, and predictive modelling for a meniscus in a heated flat micro-channel
Open for about 15 years
Liquid Transport in Micro-Nano Channels1 questions
Influence of Dimension on Properties of Strongly Correlated Electron Systems3 questions
Microscopic origin of the thickness-driven electronic evolution in SrRuO3/LaAlO3 superlattices (bad metal - weak localization - metal-insulator transition - strong 2D localization)
Open for about 13 yearsMicroscopic nature of the quantum criticality at the thickness-driven Mott transition in SrVO3 quantum wells: order parameter, emergent phases, and microscopic theory
Open for about 9 yearsDimensional crossover of weakly coupled Hubbard chains: charge-gap closing, spinon-confinement dynamics, and the ordering threshold beyond the quantum Monte Carlo window
Open for about 13 years
Why have about 40 hypernuclei been found experimentally, but only one hypernucleus?5 questions
Quark–quark hyperfine interactions and their medium modification in the Friedberg–Lee soliton model of nuclear matter and hypernuclei
Open for about 12 yearsThe unsettled Sigma (and Lambda) single-particle potentials in dense matter: constraining sign, isospin dependence, and momentum dependence from chiral EFT and hyperon directed flow
Open for about 48 yearsSigma-minus admixture in the Li hypernucleus and the production mechanism of neutron-rich hypernuclei in the reaction
Open for about 21 yearsCompleting the SU(3) chiral hyperon-nucleon interaction at N²LO: YNN three-baryon forces, charge-symmetry breaking, convergence, and empirical constraints
Open for about 7 yearsDetermining the interior radial shape and central repulsion of the Σ⁻-nucleus optical potential from Coulomb-assisted Σ⁻ bound states
Open for about 17 years
Why is spacetime four-dimensional?6 questions
Is the (3+1)-dimensional nature of the universe a thermodynamic necessity: robustness of the Helmholtz-free-energy selection and freezing of three spatial dimensions
Open for about 10 yearsCan the two assumptions of Deser's classical D = 4 selection argument — completeness of the second-order gravitational action and uniqueness of the stable vacuum — be derived from deeper principles rather than postulated?
Open for about 6 yearsMicroscopic foundation and quantitative predictions of the Afshordi–Stojkovic evolving-dimensions worldsheet model
Open for about 12 yearsDynamical foundations of the Machian integral formulation of Einstein's equations and the selection of 3+1 spacetime dimensions
Open for about 14 yearsReduction of the four-principle axiomatic basis for observed 3+1 spacetime dimensionality
Open for about 21 yearsDominant late-time phase and the emergence of commutative (3+1)-dimensional expanding spacetime in the Lorentzian type IIB matrix model
Open for about 13 years
Why can't strict many-body wave function calculations produce a superconducting state, while simple BCS mean-field calculations can?2 questions
Quantitative convergence and error control of particle-number-projected BCS wavefunctions versus exact many-body solutions for pairing correlations
Open for about 12 yearsd-wave superconductivity in the hole-doped two-dimensional Hubbard model: establishing the low-temperature, sign-problem-blocked regime by controlled computation and quantum simulation
Open for about 39 years