We introduce the fuzzy dark sector (FDS) scenario as a rich, interacting system and candidate for dark matter. This serves as a natural extension of the single-component, noninteracting fuzzy dark matter (FDM) paradigm. Concretely, we consider an ultralight Abelian-Higgs model, with interacting Higgs and dark photon degrees of freedom. We find that the transfer function and hence the imprint on the cosmic microwave background and large-scale structure (LSS) are characterized by a single characteristic scale of the interacting fuzzy dark sector, allowing us to recover the LSS signature of single-field FDM, dependent on the FDS parameters. In contrast, galactic halos present a great diversity, unlike with the universality of single-field FDM, owing to the interaction between fields. This interaction introduces an instability that is not otherwise present for the case of four decoupled scalars. Finally, we comment on primordial production and portals to the Standard Model and introduce another simple realization of the fuzzy dark sector paradigm with a kinetic coupling.

We investigate the observational constraints on $\alpha$-attractor inflationary models and their postinflationary reheating dynamics in light of the latest cosmic microwave background (CMB) data from ACT DR6 combined with Planck18, $\mathrm{BICEP}/Keck$ 2018, and DESI (collectively denoted P-ACT-LB-BK18). Focusing on both E- and T-type attractor potentials, we analyze how inflationary observables, namely the scalar spectral index $n_s$ and the tensor-to-scalar ratio $r$, are indirectly influenced by reheating parameters such as the reheating temperature $T_{\mathrm{RH}}$, the inflaton equation of state $w_{\varphi }$, and consequently the inflaton’s couplings to Standard Model (SM) particles. We incorporate constraints from primordial gravitational wave (PGW) overproduction via $\mathrm{\Delta }{N}_{\mathrm{eff}}$ bounds, which are particularly relevant for stiff postinflationary dynamics. Additionally, we include theoretical constraints from Coleman-Weinberg (CW) one-loop radiative corrections, which impose an upper bound on the couplings, as well as inflaton self-resonance, a nonperturbative effect that can occur even in the absence of inflaton-SM interactions and imposes a strong lower limit, particularly significant for $1/3\lesssim w_{\varphi }\lesssim 0.7$. Our analysis shows that E-models allow a broad range of reheating scenarios, including matter-like reheating ($w_{\varphi }=0$), whereas the T-model yields more restrictive results and remains viable only for $w_{\varphi }>1/2$ for all three nongravitational interaction channels, $\varphi \to \overline{f}f$, $\varphi \to bb$, and $\varphi \varphi \to bb$ are considered. For stiffer equations of state, an intermediate coupling window survives, bounded from above by CW corrections or $2\sigma$ observational limits, and from below by the combined PGW and self-resonance constraints. We derive updated bounds on inflaton couplings for both decay and scattering channels and identify parameter regions consistent with successful perturbative reheating. These results establish a robust connection between inflationary dynamics, reheating physics, and particle interactions, and provide concrete targets for upcoming precision CMB observations.

We use diffuse Galactic high energy gamma ray data from LHAASO and Fermi-LAT to constrain gravitationally produced decaying dark matter (DM). Focusing on four benchmark candidates: a dark photon, a heavy right-handed neutrino (RHN), a pseudo-Nambu-Goldstone boson (pNGB), and a nonminimally coupled scalar we derive bounds on the DM mass and its couplings to the visible sector. For dark photons, RHNs, and pNGBs, the combined data constrain the effective interaction strength to $\lesssim \mathcal{O}({10}^{-30})$ for DM masses $\gtrsim \mathcal{O}(\mathrm{TeV})$. For the nonminimally coupled scalar, this interaction strength is limited to $\lesssim \mathcal{O}({10}^{-10})$, for the same DM mass range. Moreover, photon-dark photon oscillations yield strong constraints for massive dark photon beyond 10 GeV, closing a region of parameter space previously left unconstrained.

We present a framework to probe intrinsic stochastic fluctuation in the orbital phase evolution of long-lived double white dwarf binaries through gravitational-wave observations with LISA. To capture the essential structure of the fluctuation, we introduce a minimal quadratic statistic that isolates its temporal correlation. We derive a simple analytic scaling relation for the signal-to-noise ratio of this correlation statistic, explicitly showing its dependence on the total observation time and the intrinsic phase correlation time.

We study the Hamiltonian truncation for the two-dimensional $\lambda {\varphi }^4$ theory within the framework of Hamiltonian truncation effective theory, where truncation artifacts are mitigated through a systematic inclusion of corrective terms organized in inverse powers of the ultraviolet energy cutoff $E_{\max }$. Building on the leading-order matching program, we develop two complementary extensions. First, we derive compact all-order expressions for the local matching corrections to the mass and quartic coupling by resumming infinite classes of diagrams sharing fixed topologies within the local approximation. Second, we extend the nonlocal sector by computing the next-to-next-to-local corrections contributing at $\mathcal{O}(E_{\max }^{-4})$, following a continuum-first matching procedure, in which the effective corrections are computed in infinite volume and the spatial direction is subsequently recompactified to obtain a discrete basis of free-Hamiltonian eigenstates on which the truncated operator construction is implemented. Our results show that an increasingly rich operator basis is necessary to describe the theory beyond leading order.

Tree-level lepton-flavor violating decays induced by Lorentz-violating effects within the Yukawa sector of the standard model extension are studied. These new-physics effects are parametrized by the $(Y_f{)}_{\mu \nu }^{AB}$ tensor, with $\mu$ and $\nu$ denoting Lorentz indices and $A$, $B$ being indices in the flavor space. Since this tensor is antisymmetric under the interchange of Lorentz indices, in analogy with the electromagnetic tensor $F_{\mu \nu }$, $(Y_f{)}_{\mu \nu }^{AB}$ can be expressed in terms of six components associated with two complex three-vectors denoted by ${\mathbf{e}}_l^{AB}$ and ${\mathbf{b}}_l^{AB}$. On the assumption that these three-vectors are purely real or purely imaginary and mutually orthogonal, constraints on their magnitudes via experimental bounds on lepton-flavor violating processes $\mathrm{Br}(l_B\to \gamma l_A)$ and $\mathrm{Br}(l_B\to l_A{l}_C{\overline{l}}_C)$ are estimated. Thus, the $l_B\to \gamma l_A$ decay provides the following upper bounds: $|{\mathbf{e}}_l^{\mu \tau }|<1.51\times {10}^{-11}$, $|{\mathbf{e}}_l^{e\tau }|<1.34\times {10}^{-11}$, $|{\mathbf{e}}_l^{e\mu }|<3.65\times {10}^{-18}$, $|{\mathbf{b}}_l^{\mu \tau }|<1.95\times {10}^{-11}$, $|{\mathbf{b}}_l^{e\tau }|<1.73\times {10}^{-11}$, $|{\mathbf{b}}_l^{e\mu }|<4.71\times {10}^{-18}$. Conversely, by assuming that the Lorentz-violating coefficients are purely real, for the $l_B\to l_A{l}_C{\overline{l}}_C$ process it is found that $|{\mathbf{e}}_l^{\mu \tau }|<2.87\times {10}^{-12}$ and $|{\mathbf{b}}_l^{\mu \tau }|<4.05\times {10}^{-12}$. These results offer more restrictive bounds than those previously reported in the literature.

We propose a novel approach for extracting symmetry breaking effects from symmetry conserving three-body decays. The method is based on mapping the Dalitz plot to a unit disk, and the difference of the disk distributions of two related decays isolates purely symmetry breaking effects. We demonstrate this method by extracting the fundamental parameter $Q$, an isospin breaking ratio of light quark masses defined as $Q^2\equiv (m_s^2-{\widehat{m}}^2)/(m_d^2-m_u^2)$ with $\widehat{m}$ the average of up and down quark masses, from the decays ${\eta }^{\prime }\to \eta {\pi }^{+}{\pi }^{-}$ and ${\eta }^{\prime }\to \eta {\pi }^0{\pi }^0$. With the Dalitz plot distributions for these two decays reported by BESIII, we illustrate the method and obtain $Q=22.5\pm 1.0$, which is consistent with previous determinations and has a comparable uncertainty. With the full BESIII dataset, which is eight times larger than the one used here, a more precise determination of $Q$ should become possible. This promising and novel method can be generalized to other three-body decays to extract symmetry breaking effects.

As the lightest isovector vector meson, the $\rho$ meson is an important object for investigating the structure of resonant states in strong interactions. Owing to its strong coupling to the $\pi \pi$ channel and its large decay width, the conventional constituent quark model treatment, in which it is simply regarded as a pure $q\overline{q}$ bound state while the hadronic-channel coupling effects are neglected, is insufficient to fully characterize its physical properties. To this end, in the present work we establish a unified framework for studying the structure and resonant properties of the $\rho$ meson by combining the quark-gluon and hadronic degrees of freedom. At the quark-gluon level, we first determine the parameters of the chiral quark model by refitting a set of narrow mesons for which open Okubo-Zweig-Iizuka-allowed strong-decay channels are absent or strongly suppressed. With these parameters fixed, the bare mass of the $\rho$ meson is obtained and used as the input for the subsequent hadronic-level analysis. At the hadronic level, based on inverse-scattering theory, we construct a model including the coupling between the bare state and the $\pi \pi$ continuum, extract the ${\rho }_0-\pi \pi$ interaction using the $P$-wave $\pi \pi$ scattering phase-shift data, and further calculate the width of the $\rho$ meson as well as the bare-state component in the physical state. The present work also provides a generalizable analytical framework for further studies of other hadronic resonances with significant coupled-channel effects.

Employing the well-known unitary equivalence between Fokker-Planck operators and Schrödinger Hamiltonians, we compute the quasinormal-mode spectrum of ultrarelativistic kinetic theories with momentum-space diffusion. We show that the collision operator reduces to a Dirac-delta Schrödinger problem in one spatial dimension, and to a Coulomb Schrödinger operator with hydrogenic spectrum in three dimensions. A finite spatial wave number appears as a perturbation of the associated quantum potential. The hydrodynamic mode is found to obey exact Fick-type diffusion at all real wave numbers, whereas relativistic kinematics generically produces a continuous ballistic band in the nonhydrodynamic sector, a feature absent in the Newtonian regime.

We compute the complete two-loop unrenormalized electroweak corrections to the Higgsstrahlung process $e^{+}{e}^{-}\to HZ$ at future Higgs factories. Our result for a given center-of-mass energy is expressed as a piecewise function defined by several deeply expanded power series, which has high precision and can be further manipulated efficiently. We find that the finite part of the unrenormalized two-loop electroweak corrections can contribute a few thousandths, which might indicate their importance to match the precision of future Higgs factories. This work represents the first complete calculation of the unrenormalized two-loop electroweak corrections for processes with four external particles.

We present a systematic study of the effects of ultralight dark matter (ULDM) on neutrino oscillations using the latest long-baseline data from the T2K and $\mathrm{NO}\nu \mathrm{A}$ experiments. Our analysis covers both flavor-universal and flavor-general scalar interactions as well as vector interactions associated with the $L_e-L_{\mu }$ and $L_{\mu }-L_{\tau }$ gauge symmetries. Importantly, we explicitly consider the coherence properties of the ULDM by incorporating the resulting stochastic fluctuations into our statistical analysis. We find that in the low-mass regime, $m_{\varphi }\lesssim {10}^{-17}\mathrm{eV}$, where the stochastic effects are maximal, the constraints on the ULDM couplings are relaxed by roughly an order of magnitude compared to those in the high-mass regime, $m_{\varphi }\gtrsim {10}^{-15}\mathrm{eV}$, where such fluctuations are effectively averaged out. While the combined T2K and $\mathrm{NO}\nu \mathrm{A}$ datasets impose nontrivial exclusion limits on the ULDM interactions, we do not find statistically significant evidence that these effects can alleviate the current tension in determining the charge-parity ($CP$) violating phase ${\delta }_{CP}$ between the two experiments. Therefore, it will be essential for future high-precision facilities to further probe the ULDM scenarios and achieve a definitive measurement of ${\delta }_{CP}$.

Accurate determination of the neutrino energy is central to precision oscillation measurements. In this work, we introduce the $W^2$-based estimator, a new neutrino energy estimator based on the measurement of the final-state hadronic invariant mass. This estimator is particularly designed to be employed in liquid-argon time-projection chambers exposed to broadband beams that span the challenging transition region between shallow inelastic scattering and deep inelastic scattering. The performance of the $W^2$-based estimator is compared to four other commonly used estimators. The impact of the estimator choice is evaluated by performing measurements of ${\delta }_{CP}$ and $\mathrm{\Delta }{m}_{23}^2$ in a toy long-baseline oscillation analysis. We find that the $W^2$-based estimator shows the smallest bias as a function of true neutrino energy and it is particularly stable against the mismodeling of lepton scattering angle and momentum, missing energy, hadronic invariant mass and final state interactions. However, studies of the resolution of each estimator as a function of true neutrino energy show this is somewhat offset by worse energy resolution when perfect modeling of these quantities is assumed. This estimator is valid for events with at least one proton and any number of pions; an inclusive channel that complements the strength of more exclusive methods that optimize the energy resolution. By providing a detailed analysis of the strengths, weaknesses and domain of applicability of each estimator, this work informs the combined use of energy estimators in any future LArTPC-based oscillation analysis.

Unsupervised learning has been widely applied to various tasks in particle physics. However, existing models lack precise control over their learned representations, limiting physical interpretability and hindering their use for accurate measurements. We propose the histogram autoencoder (HistoAE), an unsupervised representation learning network featuring a custom histogram-based loss that enforces a physically structured latent space. Applied to silicon microstrip detectors, HistoAE learns an interpretable two-dimensional latent space corresponding to the particle’s charge and impact position. After simple postprocessing, it achieves a charge resolution of $0.25e$ and a position resolution of $3\mathrm{\mu }\mathrm{m}$ on beam-test data, comparable to the conventional approach. These results demonstrate that unsupervised deep learning models can enable physically meaningful and quantitatively precise measurements. Moreover, the generative capacity of HistoAE enables straightforward extensions to fast detector simulations.

We compute three-loop QCD corrections to the scattering amplitude of a Higgs boson and three partons interfered with its tree level counterpart. Specifically, we derive our results in the generalized leading color limit. Our results are represented in terms of so-called multiple polylogarithms and thus are ready for use in phenomenological predictions. We provide the three-loop amplitudes necessary to compute the production cross section of a Higgs boson and a hadronic jet at hadron colliders and the decay probability of a Higgs boson to three hadronic jets at lepton colliders.

We consider hidden symmetries arising from U duality in the dimensional reduction of nonmaximal higher-derivative supergravities to three dimensions. In particular, we consider the $G_{2(2)}$ symmetry of minimal five-dimensional supergravity and the $O(d+p+1,d+1)$ symmetry of bosonic and heterotic string theory on $T^d$. Using a group theory argument, we show that the higher-derivative corrections explicitly break all hidden symmetry enhancements. As special cases, this also implies that higher-derivative corrections prevent the symmetry enhancement to $SL(3,\mathbb{R})$ in pure five-dimensional gravity and $O(4,4)$ in the STU model.

We investigate the quantum coherence dynamics of a three-level atom undergoing noninertial motion. Using an open-quantum-system approach, we derive a master equation for an atom coupled to a massless scalar field in vacuum and compare uniform linear acceleration with circular acceleration. For a degenerate $\mathrm{\Lambda }$-type configuration, we show that steady-state coherence can emerge and its value depends not only on the acceleration, but also on the initial atomic state. In the intermediate-acceleration regime, circular acceleration leads to a systematically larger steady-state coherence than uniform linear acceleration, whereas in both the small- and large-acceleration limits the two cases become essentially indistinguishable. Extending the analysis to $V$-type and $\mathrm{\Xi }$-type configurations, we find that the $V$-type system exhibits coherence dynamics closely analogous to the $\mathrm{\Lambda }$-type case, whereas the $\mathrm{\Xi }$-type system behaves qualitatively differently: Its relevant off-diagonal density matrix elements decay exponentially, precluding any steady-state quantum coherence. These results reveal how the noninertial trajectory, acceleration scale, initial-state preparation, and level configuration jointly govern coherence generation and survival in accelerated three-level atoms.

We investigate exact solutions of the Einstein-Maxwell equations with the cosmological constant where the source of the gravitational field consists of a magnetic field and dust. In particular, we restrict our study to the case of Bianchi type III models. All these solutions either start with a singularity and then expand, or they are initially collapsing and end at a singularity. We discuss the physical meaning of the parameters appearing in the metrics and examine the possible subcases and the relative importance of the dust and the magnetic field throughout the evolution of the solution.

The Laser Interferometer Space Antenna (LISA) will observe massive black hole binaries (MBHBs) with astoundingly high signal-to-noise ratio, leaving parameter estimation with these signals susceptible to seemingly small waveform errors. Of particular concern for MBHBs are errors due to neglected higher-order modes. We extend Yi et al. [Phys. Rev. D 112, 124063 (2025)] to examine errors due to neglected higher-order modes for MBHBs with nonzero (aligned) progenitor spins and total mass up to ${10}^8{M}_{\odot }$. For these very massive systems, there can be regions of parameter space in which the $(\ell ,|m|)=(2,2)$ modes are no longer dominant with respect to higher-order ones. We find that the extent of systematic bias can change significantly when varying the progenitor spins of the binary. We also find that for the heaviest, and therefore shortest, MBHB signals, slight systematic errors can cause severe misinference of the sky localization parameters. We propose an improved likelihood optimization scheme with respect to previous work as a way to predict these effects in a computationally efficient manner.

We study a simple theory based on general relativity, minimally coupled to a constrained scalar triplet and to an auxiliary nonpropagating three-form sector. Within a spherically symmetric hedgehog ansatz, the theory admits a continuous exact family of asymptotically flat geometrically regular black holes. For a simple choice of kinetic function, the solutions possess a de Sitter core and approach Schwarzschild with the first correction appearing only at order $r^{-4}$. We analyze their horizon structure, thermodynamics, and main strong-field properties. The black holes carry topological scalar hair and a continuous secondary parameter, but no scalar charge. The regularity established here is geometric: the curvature invariants remain finite, although the matter sector is not completely smooth at the center.

We introduce a new factorized and resummed waveform for circularized, nonspinning, compact binaries that leverages on the solution of the Teukolsky equation once mapped into a confluent Heun equation. The structure of the solution allows one to identify new resummed factors that completely absorb all test-mass logarithms and transcendental numbers via exponentials and $\mathrm{\Gamma }$-functions at any post-Newtonian (PN) order. The corresponding residual relativistic and phase corrections are thus polynomial with rational coefficients, that are in fact PN-truncated hypergeometric functions. Our approach complements the recent proposal of Ivanov et al. [Phys. Rev. Lett. 135, 141401 (2025)], notably recovering the corresponding renormalization group scaling of multipole moments from first principles and fixing the scaling constant. In the test mass limit, our approach (pushed up to 10PN) yields waveforms and fluxes that are globally more accurate than those obtained using the standard factorized approach of Damour et al. [Phys. Rev. D 79, 064004 (2009)]. The method generalizes straightforwardly to comparable mass binaries implementing the new concept of universal anomalous dimension of multipole moments and might be eventually useful to improve current state of the art effective-one-body waveform models for coalescing binaries.