We derive explicit anomaly-index formulas for four-dimensional Weyl fermions charged under the finite symmetries $\text{Spin}\times {\mathbb{Z}}_n$ and $\text{Spin}{\times }_{{\mathbb{Z}}_2^{\mathrm{F}}}{\mathbb{Z}}_{2m}^{\mathrm{F}}$. The strategy is to start from the standard perturbative anomaly indices for $\text{Spin}\times \mathrm{U}(1)$ and $\text{Spin}{\times }_{{\mathbb{Z}}_2^{\mathrm{F}}}\mathrm{U}(1)={\text{Spin}}^c$, and then restrict the continuous U(1) symmetry to a finite cyclic subgroup. On the level of invertible field theories this gives natural homomorphisms, ${\mathrm{TP}}_5(\text{Spin}\times \mathrm{U}(1))⟶{\mathrm{TP}}_5(\text{Spin}\times {\mathbb{Z}}_n),{\mathrm{TP}}_5({\text{Spin}}^c)⟶{\mathrm{TP}}_5(\text{Spin}{\times }_{{\mathbb{Z}}_2^{\mathrm{F}}}{\mathbb{Z}}_{2m}^{\mathrm{F}})$. We compute these maps explicitly by evaluating reduced $\eta$ invariants on geometric representatives of the finite anomaly groups. For $\text{Spin}\times {\mathbb{Z}}_n$, the relevant backgrounds are the five-dimensional lens-space bundle $X(n;1,1)$ and the product $L(n;1)\times \mathrm{K}3$. For $\text{Spin}{\times }_{{\mathbb{Z}}_2^{\mathrm{F}}}{\mathbb{Z}}_{2m}^{\mathrm{F}}$, the relevant backgrounds are $L(m;1,1,1)$ and, depending on the parity of $m$, either $L(m;1)\times \text{Enriques}$ or $L(m;1)\times \mathrm{K}3$. The output is a pair of integer-valued anomaly indices for each finite symmetry. These indices are normalized in the cyclic factors of the finite anomaly group, so they can be used directly in anomaly-cancellation checks for fermions with discrete gauge or global symmetries. They also provide the input for symmetry-extension applications to topologically ordered quantum dark matter: in Standard Model examples, the indices identify the discrete $\mathbf{B}+\mathbf{L}$ mixed gauge-gravitational anomaly left by missing sterile right-handed neutrinos and the finite $K$-gauge topological sector that can match it.

Displaced vertex (DV) signatures at colliders offer a powerful probe of new long-lived particles beyond the Standard Model. Among the best-motivated candidates are heavy neutral leptons (HNLs)—heavier counterparts of Standard Model neutrinos—which can account for the origin of neutrino masses and potentially produce di-leptonic DV signatures. In this study, we demonstrate how existing DV searches at the LHC can be extended to probe HNLs that couple predominantly to the tau-neutrino flavor. While current search strategies rely on identifying a prompt lepton alongside a displaced vertex, we show that analyzing events without a prompt lepton enables sensitivity to the process $pp\to W\to \tau N$, where the tau decays hadronically and the HNL subsequently decays to a lepton pair and a neutrino. We perform detailed Monte Carlo simulations of this process with HNLs decaying to ${\mu }^{+}{\mu }^{-}$ or $e^{+}{e}^{-}$ final states, apply ATLAS-inspired selection criteria, and optimize signal sensitivity. In particular, we demonstrate that appropriate cuts in the plane of dilepton invariant mass and DV radial position significantly enhance signal visibility. We propose several such optimized strategies and show that, even with Run 2 data ($139{\mathrm{fb}}^{-1}$), existing bounds can be improved by more than an order of magnitude. Future high-luminosity runs may strengthen sensitivity by up to 3 orders of magnitude compared to current limits.

We propose a method to accurately calculate the momentum distributions of the produced boson and fermion pairs and the phase distributions of pair-production probability amplitudes in a spatially homogeneous and time-dependent electric field. Applying this method to multiphoton pair production in a circularly polarized electric field rotating around the $z$-axis, we clarify that the topological charge appearing in the phase distributions of pair-production probability amplitudes reflects the orbital angular momentum (OAM) of the produced pairs rather than that of individual particles. On this basis, we demonstrate that, within the framework of the external-field approximation, the $z$-component of the total angular momentum of the field and the particles is conserved, whereas the conservation of total angular momentum cannot be verified. The results also reveal that pair production is constrained by $C$-parity conservation, and that pairs with smaller OAM are produced more favorably. These findings provide deeper insight into angular momentum transfer in pair production.

We investigate the enhanced dynamically assisted electron-positron pair production in differently polarized electric fields with frequency chirps within the real-time Dirac-Heisenberg-Wigner formalism. The combined influence of the chirp strength and the field polarization on the momentum distribution and the total number density of the created pairs is studied in detail for one-color fields as well as dynamically assisted two-color combined fields. Frequency chirps, applied in different field configurations, strongly reshape the momentum spectra by modifying the interference patterns and enhancing the peak momentum distribution. In the dynamically assisted case, the total number density can be enhanced significantly over 2–3 orders when large chirps are applied to both strong and weak fields. Furthermore, we observe that sensitivity of the number density to field polarization progressively diminishes as the chirp strength increases, a trend that holds for both one-color field and the assisted two-color combined fields. A comparison of different chirping scenarios shows that chirping only the weak field produces nearly the same enhancement in the pair yield as chirping both fields simultaneously, demonstrating that the weak-field chirp plays the dominant role in the chirp-induced enhancement of the dynamically assisted Schwinger mechanism. We also find the enhancement factor to be the largest near circular polarization in the chirp-free and weakly chirped regimes but is strongly suppressed with increasing weak-field chirp despite the continued growth of the absolute pair yield. These results provide new insight into the interplay among chirp, polarization, and dynamical assistance in strong-field quantum electrodynamics.

Hints of cosmic microwave background polarization rotation ($\mathrm{\Delta }\vartheta \sim {10}^{-3}\mathrm{rad}$) are commonly attributed to late-time dynamics of ultralight axions. We show that such ultralight degrees of freedom are not required. Polarization rotation naturally arises as a geometric interface phase acquired when photons cross interfaces between topologically distinct dark sector vacua. The effect is a discrete phase shift fixed by the normalization of a wall-supported electromagnetic Chern-Simons interaction and protected by an emergent 1-form symmetry of the low energy effective theory. This mechanism reproduces the familiar adiabatic rotation induced by light axion domain walls, but persists for arbitrarily thin walls where the axion is heavy or absent. In this regime the rotation manifests as a Pancharatnam phase localized at vacuum interfaces, independent of redshift and photon frequency below a natural ultraviolet cutoff. Cosmic birefringence thus emerges as a probe of vacuum structure in the dark sector, rather than of light-field dynamics.

We propose that a gravitational wave can be generated during leptogenesis in the early Universe, which occurs during heavy right-handed neutrino decay. Such a gravitational wave, as a remnant of leptogenesis, is shown to be associated with distinguishing signatures that not only act as a powerful probe to leptogenesis but also to the existence of heavy seesaw states, which otherwise remain difficult to validate despite their success in explaining the baryon asymmetry of the Universe, closely connected to the origin of neutrino mass.

Recent years have seen dramatic improvements in the sensitivity of electron-based direct detection experiments. Typically, the sensitivity to dark matter scattering is determined in the light and heavy mediator mass limits. In this paper we show that the light and heavy mediator mass limits are not separated by a single scale, but instead can be separated by up to 3 orders of magnitude in mediator mass for sub-GeV mass dark matter. We calculate the background-free sensitivity in Si and Ge targets, and a projected DAMIC-M sensitivity, to sub-GeV mass dark matter models with “intermediate-mass” mediators between the light and heavy mediator limits. This allows us to determine the precise range of mediator masses that electron-based direct detection experiments are sensitive to when the dark matter relic abundance is generated via freeze-in. We make the calculations presented here publicly available in an updated release of EXCEED-DM.

This article revisits the validity of tree-level statements regarding the Yukawa sector of various minimal-renormalizable $SU(5)$ frameworks at the loop level. It is well known that an $SU(5)$ model with only the $45_{\mathrm{H}}$ dimensional irreducible representation (irrep) contributing to the Yukawa sector is highly incompatible in yielding the low-energy observables. However, this study shows that when one-loop corrections from heavy degrees of freedom are included in the various Yukawa vertices, the model can reproduce the charged fermion mass spectrum and mixing angles within the assumed experimental uncertainty. The fitted Yukawa couplings remain within the perturbative range. The scenario also necessitates mass splitting among various scalars of $45_{\mathrm{H}}$ dimensional irrep, with some of the scalars’ mass deviating significantly from the matching scale $(M_{\mathrm{GUT}})$, collectively providing substantial threshold corrections. The effect of the lightest scalar on the renormalization group evolution of the standard model (SM) parameters has also been considered. It is shown that this scenario reproduces the SM spectrum at low energy. As an extension, the minimal $SU(5)$ model with only the $45_{\mathrm{H}}$ irrep is augmented with the $15_{\mathrm{H}}$-dimensional irrep, which also successfully reproduces the observed charged and neutral fermion mass spectra. Finally, the study considers an alternative $SU(5)$ model incorporating both $5_{\mathrm{H}}$ and $15_{\mathrm{H}}$ irreps, which also yields the desired fermion mass spectra and mixing angles. This work demonstrates the viability of a minimal $SU(5)$ Yukawa sector in different setups when quantum corrections are considered.

We develop a general-relativistic framework for two-component quantum dark fermion stars: equilibrium configurations of two degenerate fermion species governed jointly by gravity, a Yukawa-mediated dark fifth force, and a globally relevant Bohm quantum-pressure correction. The treatment retains the full covariant form of the nonlinear Klein–Gordon equation in the Schwarzschild interior, with closure relations valid at arbitrary compactness, from the ultralight baseline up to densities of order $0.16{\mathrm{fm}}^{-3}$ at which relativistic scalar densities and self-consistent effective fermion masses become unavoidable. Two Lagrangian parameters, the dark-fermion mass and the dimensionless ratio between the Yukawa channel and gravity, together fix the equilibrium structure; a joint measurement of mass and radius therefore constrains the dark-sector microphysics directly from gravitational-wave observables. For particle masses in the band ${10}^{-11}–{10}^{-10}\mathrm{eV}$, the configurations exhibit radii of 3–24 km and compactness in the range 0.14–0.34, behaving as dual mimickers: at moderate compactness they overlap with neutron stars in mass, radius, and inspiral frequency; at the most compact end ($\kappa \sim 0.34$, $R_T/R_S\simeq 1.5$) they cross the photon sphere and could masquerade as low-mass black holes in the mass-gap region. Tidal-deformability measurements discriminate against both populations simultaneously: the dimensionless tidal deformability is measurably smaller than the neutron-star value yet remains nonzero, unlike that of a genuine black hole. These objects populate the sensitivity bands of LISA, the Einstein Telescope, and Cosmic Explorer, producing astrometric microlensing signatures individually resolvable by Gaia. The framework thus provides a reproducible and falsifiable template for constraining dark-sector properties through multimessenger observations.

Quantum simulation offers a promising framework for quantum field theory calculations. Obtaining reliable results, however, requires careful characterization of systematic uncertainties. One important source is the boson truncation error, which arises from representing infinite-dimensional local Hilbert spaces with finite-dimensional ones. Previous studies have examined this problem from several perspectives. In particular, Jordan et al. [Science 336, 1130 (2012)] derived an energy-based bound applicable to generic low-energy states across a broad class of field theories. However, this approach often yields overly conservative bounds, especially at large volumes. In this work, we introduce a new methodology that significantly tightens the energy-based boson truncation bound through two complementary advances: an improved analytic derivation and a Monte Carlo-based numerical procedure. We demonstrate the method in ($1+1$)-dimensional scalar field theory and ($2+1$)-dimensional U(1) gauge theory in the dual formalism. Our approach substantially mitigates the volume dependence of the required truncation cutoff, achieving reductions nearly proportional to the volume in some cases and to the square root of the volume in others.

The mass spectrum of pseudoscalar and scalar mesons at finite temperature is studied within a nonlocal quark model with Polyakov loop extension. The analysis is performed in the leading order of the $1/N_c$ expansion. To suppress unphysical quark production thresholds in meson polarization loops in the hadronic phase, the quark propagator is modified after the inverse Laplace transform. In the deconfined phase, the quark pole is treated separately, while the same modification applies to the remaining part. For a consistent description of both confining and deconfining phases, an adjustment of the transformed propagator is proposed. At finite temperature, Lorentz symmetry breaking leads to the splitting of meson modes. The screening masses are computed over a wide temperature range, and the pole masses up to the deconfinement transition. The results are compared with lattice QCD data and show reasonable agreement.

This study examines the rare decay $B\to K_0^{*}(1430){\ell }^{+}{\ell }^{-}$ as a possible probe for new physics beyond the standard model (SM). We first analyze this channel within the SM and then include scalar leptoquark contributions. We provide predictions for key observables, like differential decay rate, branching ratio, ratio of branching fractions at different channels, forward-backward asymmetry and different lepton polarizations, and assess their sensitivity to leptoquark scenarios, highlighting $q^2$ regions less affected by the long-distance charmonium effects. The results can be useful for future Belle II and LHCb measurements.

We compute the complex heavy-quark potential in an anisotropic quark-gluon plasma (QGP) using kinetic theory with a Bhatnagar-Gross-Krook collision kernel. By incorporating momentum anisotropy and a finite collision rate into the medium dielectric response, we derive both the real and the imaginary parts of the in-medium potential. The real part of the inverse dielectric function is obtained from the retarded/advanced gluon propagator, while the imaginary part is determined from the Feynman (symmetric) propagator. We find that collisions have only a minimal impact on the real part of the potential, suggesting a similarly weak effect on the binding energy. In an anisotropic plasma, the Weibel instability induces a pinch singularity that can render the imaginary part of the potential ill-defined; we show that sufficiently large collision rates regularize this singularity, yielding a well-defined imaginary potential in the corresponding region of parameter space. In this well-defined regime, collisions significantly enhance the magnitude of the imaginary part and modify the effect of anisotropy. This enhancement leads to larger quarkonium thermal widths and dissociation rates in a nonequilibrium QGP, providing further insight into quarkonium suppression mechanisms.

We investigate the production of the $\mathrm{\Delta }(1232{)}^{++}$ resonance in the charmed baryon weak decay ${\mathrm{\Lambda }}_c^{+}\to K^{-}{\pi }^{+}p$, focusing on the ${\pi }^{+}p$ final-state rescattering mechanism. The direct $W^{+}$ exchange diagram is expected to be suppressed, hence we adopt the $W^{+}$ internal emission process ${\mathrm{\Lambda }}_c^{+}\to p{\overline{K}}^{*0}(892)$ followed by the subsequent decay ${\overline{K}}^{*0}\to K^{-}{\pi }^{+}$ as the dominant source of the final state particles. The $\mathrm{\Delta }(1232{)}^{++}$ resonance is then generated via ${\pi }^{+}p$ rescattering within a triangle loop mechanism. Our calculations incorporate both the tree-level ${\overline{K}}^{*0}(892)$ and the dynamically generated ${\overline{K}}_0^{*}(700)$ state arising from the $S$-wave $K\pi$ final state interaction. We find that our theoretical results can reproduce the bump and peak structures in the $K^{-}{\pi }^{+}$ invariant mass distributions for the ${\overline{K}}_0^{*}(700)$ and ${\overline{K}}^{*0}(892)$, respectively. Meanwhile, the peak for the $\mathrm{\Delta }(1232{)}^{++}$ in the ${\pi }^{+}p$ invariant mass distributions is also well described. The $\mathrm{\Delta }(1232{)}^{++}$ signal naturally emerges from rescattering effects, and adopting the pole parameters of $\mathrm{\Delta }(1232)$ resonance yields an improved description of the experimental data. In addition, we obtain a branching fraction ratio $\mathcal{B}[{\mathrm{\Lambda }}_c^{+}\to \mathrm{\Delta }(1232{)}^{++}{K}^{-}]/\mathcal{B}[{\mathrm{\Lambda }}_c^{+}\to p{\overline{K}}^{*0}(892)]\approx 0.5$, which is lower than the experimentally measured value. This discrepancy suggests that interference effects are likely significant in this decay process. Future high-precision measurements will further verify the proposed rescattering mechanism.

We investigate the stability and causality of relativistic spin hydrodynamics in the presence of a nonvanishing spin density background, assuming that the spin chemical potential ${\omega }^{\mu \nu }$ is of leading order (${\omega }^{\mu \nu }\sim \mathcal{O}(1)$) in the gradient expansion and is treated as a finite background in the linear perturbation analysis. It is found that within the first-order spin hydrodynamic framework, a finite spin density background modifies the dispersion relations, and modes propagating along different directions are controlled by distinct transport coefficients. Certain specific modes only appear in the $x$ direction. However, the modes in the large wave-vector limit exhibit acausal behavior. To address this issue, we subsequently adopt the framework of minimal causal spin hydrodynamics and derive the corresponding stability and causality conditions. The spin density background directly determines whether stability and causality can be satisfied simultaneously. In the small wave-vector limit, the results are similar to those of the first-order theory. In the large wave-vector region, however, significant differences emerge: the distinctions between different directions are no longer merely simple substitutions of transport coefficients, but involve more complex combinations. This indicates that the difference between modes in different directions increases with increasing wave vector.

In this work, a systematic investigation of the production of high-orbital-excitation kaons in $K^{-}p$ reactions is carried out within an effective Lagrangian model. The relevant $t$-channel processes are constructed, and the model is calibrated using a single adjustable parameter determined from existing experimental data. With this parameter, the measured production cross sections for the $K_3^{*}(1780)$, $K_2(1820)$, $K_2(1770)$, and $K_4^{*}(2045)$ states are successfully reproduced. Employing the same framework, the production cross sections for other high-orbital kaons are predicted. The results indicate that these states possess sizable cross sections and exhibit characteristically forward-peaked angular distributions, which is a typical feature of $t$-channel exchange, highlighting their great potential for observation in future experiments.

We investigate the charge transport properties of a relativistic drifting plasma using the kinetic theory within the relaxation time approximation. The collective drift induced by electromagnetic fields is described in terms of a suitably modified distribution function. The analysis is done for both constant and time-dependent field configurations. For constant electromagnetic fields, we obtain the Hall drift current that arises from the transverse motion of charged particles in electric and magnetic fields. Extending the framework to time-dependent electric fields, we show that their temporal variations give rise to polarization drift, which significantly alters the structure of the induced current and introduces additional components along both the conventional drift and polarization directions. We present a quantitative estimate of the Hall drift and polarization-induced contributions in the quark-gluon plasma and study the temperature dependence of the associated charge transport coefficients in the QCD.

We present a comprehensive study of the radiative decays of fully heavy tetraquarks ($T_{4c}$, $T_{4b}$) and mixed heavy-flavor tetraquarks ($T_{bc\overline{b}\overline{c}}$) into charmonium/bottomonium states, within the nonrelativistic QCD factorization framework. Numerical result indicates that the decay widths of fully charm tetraquark $T_{4c}$ into $\gamma J/\psi ({\eta }_c)$ are around 1 MeV. Crucially, the $\gamma J/\psi$ signal channel receives less experimental background near the $J/\psi J/\psi$ threshold, providing a compelling way to search for the possible tetraquark states X(6200). For $T_{4b}$, the decay width is highly suppressed by the bottom quark mass, just lying in the tens eV level. We further find that the decay widths of $T_{bc\overline{b}\overline{c}}\to \gamma \mathrm{\Upsilon }$ exceed those to $\gamma J/\psi$ by 3–4 orders of magnitude, indicating preferential $c\overline{c}$-pair annihilation over $b\overline{b}$. These radiative decay modes can be measured in the future experiments, and are helpful to understand the inner structure of the full heavy tetraquark.

Muon accelerators, a potential technology for enabling $\mathcal{O}(10\mathrm{TeV})$ parton center of mass energy collisions, would also source an intense, collimated beam of neutrinos at TeV energies. The energy and size of this beam would be excellently matched as a source for existing and planned neutrino telescopes: gigaton-sized detectors of astrophysical neutrinos at and above TeV energies. In this paper, we introduce the technical considerations and scientific reach of pairing a muon accelerator source of neutrinos with a neutrino telescope detector, a combination we dub the “Neutrino Kaleidoscope.” In particular, such a pairing would enable searches for non-standard oscillations of the beam neutrinos as they traverse the earth between source and detector. These nonstandard neutrino oscillations could be sourced by Lorentz invariance violation, which a neutrino kaleidoscope could probe up to the Planck scale. Such a search would also have a reach on sterile neutrinos orders of magnitude beyond existing terrestrial limits. Finally, we touch on the nonoscillation physics case for a neutrino kaleidoscope.

Measuring charge-parity ($CP$) violation in Higgs-fermion interactions is a key target of future precision Higgs programs. The decay $\mathbf{H}\to \tau \tau$ is particularly sensitive to the $CP$ structure of the Higgs Yukawa coupling via $\tau$ spin correlation, while the clean environment of $e^{+}{e}^{-}$ collisions at the Future Circular Collider (FCC) enables accurate reconstruction of $CP$-sensitive observables. In this letter, we study the sensitivity of FCC-ee to the Higgs $CP$ state using $\mathbf{H}\to \tau \tau$ events produced in associated $\mathbf{Z}\mathbf{H}$ production at $\sqrt{s}=240\mathrm{GeV}$. In the anomalous-coupling parametrization, we project a precision of $\mathrm{\Delta }{\varphi }_{\tau \tau }=\pm 2.5°$ at 68% CL, with the dominant contribution arising from one-prong hadronic $\tau$ decays. We further interpret the analysis in the effective field theory framework, deriving expected limits on the $CP$-odd operators, and compare them with electron and magnetic dipole moment measurements and the anomalous-coupling approach.