We extended the once-in-a-lifetime encounter (OILE) model to stochastic interactions among neutrinos. As in the original OILE model, the new model reproduces the mean-field behavior of a dense neutrino gas for time $t\lesssim (\mu \gamma {)}^{-1}$, where $\mu$ measures the strength of the mean-field neutrino self-interaction potential and is proportional to the neutrino density, and the dimensionless “impact parameter” $\gamma$ is a measure of the change in the flavor quantum state of a neutrino during interaction with another neutrino when the wave packets of the two neutrinos overlap. As in the mean-field case, the OILE model with random neutrino velocities experiences kinetic flavor decoherence as the flavor quantum states of the neutrinos diverge from each other. Unlike the mean-field case, however, the OILE model has a “collision term” due to the quantum entanglement among neutrinos. For $\gamma \ll 1$, this incoherent effect can drive the neutrinos into a quasisteady state that is similar to the collective precession mode in a homogeneous and isotropic neutrino gas in the mean-field approximation. Subsequently, the collision term drives the neutrino gas adiabatically through different quasisteady states and eventually to flavor equilibration. This process is an example of miscidynamic flavor evolution, with the mixing equilibria being the quasisteady precession states.

The cold, dense matter equation of state (EoS) determines crucial global properties of neutron stars (NSs), including the mass, radius and tidal deformability. However, a one-dimensional (1D), cold, and $\beta$-equilibrated EoS is insufficient to fully describe the interactions or capture the dynamical processes of dense matter as realized in binary neutron star (BNS) mergers or core-collapse supernovae (CCSNe), where thermal and out-of-equilibrium effects play important roles. We develop a method to self-consistently extend a 1D cold and $\beta$-equilibrated EoS of quark matter to a full three-dimensional (3D) version, accounting for density, temperature, and electron fraction dependencies, within the framework of Fermi-liquid theory (FLT), incorporating both thermal and out-of-equilibrium contributions. We compare our FLT-extended EoS with the original bag model and find that our approach successfully reproduces the contributions of thermal and compositional dependencies of the 3D EoS. Furthermore, we construct a 3D EoS with a first-order phase transition (PT) by matching our 3D FLT-extended quark matter EoS to the hadronic DD2 EoS under Maxwell construction, and test it through the general relativistic hydrodynamic simulations of the TOV-star and CCSN explosion. Both simulations produce consistent results with previous studies, demonstrating the effectiveness and robustness of our 3D EoS construction with PT.

The exclusive production of fully heavy tetraquarks ($T(bb\overline{b}\overline{b})$, $T(cc\overline{c}\overline{c})$, and $T(bc\overline{b}\overline{c})$) in association with a hard photon in electron-positron collisions is calculated within the framework of nonrelativistic QCD. Both inner structures of the moleculelike state and compact state with $J=0$, 1, 2 for the fully heavy tetraquark are discussed. We find that it is dismal to observe any fully heavy tetraquarks in either the compact configuration or the moleculelike configuration through such exclusive processes at either Belle II or future Z factories like the circular electron positron collider and the first stage of the future circular collider.

The Future Circular Hadron Collider (FCC-hh) will probe unprecedented energy regimes, enabling direct searches for new elementary particles at a scale of tens of TeV. FCC-hh is currently in the planning stage, and one of its primary physics goals is to search for physics beyond the Standard Model by exploring a previously inaccessible kinematic domain. While venturing into uncharted high-energy territories promises excitement, reconstructing objects with enormous transverse momenta will require overcoming major experimental challenges. This work investigates the identification of boosted $W$ bosons and boosted top quarks in the context of three beyond the Standard Model scenarios: heavy vectorlike quark ($B^{\prime }$), heavy neutral gauge boson ($Z^{\prime }$), and heavy neutral Higgs boson ($H$). We employ machine learning techniques, including extreme gradient boosting (XGBoost) and convolutional neural networks (CNN), to identify these ultraboosted objects in the collider from their SM background counterpart. We evaluate the performance of these techniques in distinguishing $W$ jets and top jets from quantum chromodynamics (QCD) jets at extremely high transverse momenta ($p_T$) values, demonstrating their potential for future FCC-hh analyses.

The hadronic light-by-light contribution to the muon anomalous magnetic moment is calculated in the framework of a nonlocal quark model with scalar-pseudoscalar and vector–axial-vector channels. The effect of the dressing of internal photons by vector mesons is found to be tiny. As a result, the contribution from the nonstrange quark loop is $a_{\mu }^{\mathrm{HLbL},\mathrm{Loop}}=(93\pm 9.9)\times {10}^{-11}$. The total value, including meson exchanges and the contribution of strange particles, is $a_{\mu }^{\text{HLbL}}=(154\pm 12.4)\times {10}^{-11}$.

We study the quantum chromodynamics (QCD) phase transitions in the complex chemical potential plane via the Dyson-Schwinger equation approach, incorporating a constant gluonic background field that represents the confining dynamics. We solve the quark gap equation and the background field equation self-consistently, which allows us to directly explore the confinement phase transition and furthermore, evaluate the impact of the back-coupling of confinement on chiral symmetry breaking. Moreover, within such a coupled framework toward the complex chemical potential region, we demonstrate the emergence of Roberge-Weiss (RW) symmetry and investigate the trajectory of Lee-Yang edge singularities (LYESs). Our analysis reveals that the LYESs scaling behavior is similar to our previous findings without the background field condensate. However, a significant difference from our earlier work is that the trajectory of LYESs terminates when the imaginary part of the singularity becomes $1/3\pi T$. We elaborate that this cutoff behavior is caused by the RW symmetry that is symmetric to the imaginary chemical potential $\mathrm{Im}\mu =1/3\pi T$.

Color transparency (CT) is a fundamental phenomenon in QCD in which hadrons produced in high-energy exclusive processes traverse nuclear matter with minimal interactions. Nuclear transparency, which quantifies this attenuation suppression, is a quantity with high sensitivity to CT effects and provides critical insights into QCD dynamics in nuclear environments. In this study, we revisit nuclear transparency using the framework of generalized parton distributions (GPDs). By constructing nuclear GPDs (nGPDs) through the incorporation of nuclear parton distribution functions, we calculate the nuclear transparency $T(Q^2)$ for the carbon nucleus as a function of momentum transfer $Q^2$ considering various definitions and compare the results obtained with available experimental data. Our finding highlights the importance of choosing a physically motivated definition of nuclear transparency. Moreover, we emphasize that a more reliable determination of nGPDs requires a dedicated global analysis incorporating nuclear data. Such an approach is essential for improving the theoretical understanding of CT and for achieving consistency with experimental observations in the high-$Q^2$ regime.

We study for the first time the transverse momentum transfer distributions $d\sigma /dt$ in coherent production of charmonia in nuclear ultraperipheral and electron-ion collisions within the QCD color dipole approach based on a rigorous Green function formalism. This allows us to treat properly the color transparency effects, as well as the higher and leading-twist shadowing corrections associated with the $|Q\overline{Q}⟩$ and $|Q\overline{Q}nG⟩$ Fock components of the photon. While the multigluon photon fluctuations represent the dominant source of nuclear shadowing at kinematic regions related to the recent LHC and its future upgrade to LHeC, the upcoming electron-ion collider at RHIC will additionally require the proper incorporation of reduced quark shadowing. The latter effect leads to a significant decrease in the differential cross sections $d\sigma /dt$ compared to standard calculations based on the eikonal form for the dipole-nucleus amplitude. The leading-twist shadowing corrections, corresponding to a nonlinear QCD evolution of a partial dipole-nucleus amplitude, reduce substantially charmonium $t$-distributions in the LHeC energy range. We predict a nonmonotonic energy dependence of $d\sigma /dt$ suggesting so possible gluon saturation effects with increased onset at larger $t$-values. In addition to shadowing corrections, we study how the color transparency effects affect the shape of $t$-dependent nuclear modification factor.

Tunneling processes offer a promising path for finding signatures of quantum gravity. While tunneling of geometry has long been recognized in the literature, few detailed analyses in covariant loop quantum gravity have been carried out. We investigate spinfoam transitions in the holonomy representation, which naturally encodes the extrinsic curvature of boundary states. To reduce technical complications to a minimum, we study these amplitudes within the simple framework of the Ponzano-Regge spinfoam model for three-dimensional Euclidean quantum gravity. We identify the geometries dominating the spinfoam path integral in the classically forbidden regime when formulated in terms of dihedral angles as boundary data. We characterize these nonclassical geometries and show that their contributions to the spinfoam amplitude are exponentially suppressed in the semiclassical limit via analytic continuation of the discrete gravity action. We argue that they satisfy all the desired properties of tunneling processes. We also shed light on quantum black-to-white hole transitions, in particular clarifying the origin of the exponential suppression of various quantum amplitudes, while at the same time laying the basis for a future complete calculation of the amplitude in covariant loop quantum gravity.

Extreme mass ratio inspirals, compact objects spiraling into massive black holes, represent key sources for future space-based gravitational-wave detectors such as LISA. The inspirals will occur within rich astrophysical environments containing gravitating matter. Motivated by this, we develop a fully relativistic framework for inspirals under the gravitational influence of matter environments. Our approach employs a two-parameter perturbation expansion in the mass ratio and an environmental parameter. This yields a modified Teukolsky equation capturing the leading cross-order. We then implement a simple pole-dipole approximation of an axisymmetric environment through a thin matter shell and restrict to nonrotating black holes. As a result, we obtain a piecewise type D spacetime. This enables the use of Teukolsky-based methods while accounting for junction physics. The presence of the matter shell leads to effectively nonseparable boundary conditions for the Teukolsky scalar and introduces mode mixing between adjacent multipoles. Additionally, the shell oscillates under the wave perturbation of the inspiral, contributing to the overall flux. The framework provides novel insights into the global dynamics of gravitational radiation in tidal environments. Furthermore, it represents a complete theoretical foundation for a future computation of inspirals and waveforms in our environmental model.

Observations of energy-dependent photon time delays from distant flaring sources provide significant constraints on Lorentz invariance violation (LIV). Such effects originate from modified vacuum dispersion relations causing differences in propagation times for photons emitted simultaneously from gamma-ray bursts, active galactic nuclei, or pulsars. These modifications are often parametrized within a general framework by an effective quantum gravity energy scale $E_{QG,n}$. While such general constraints are well established in the LIV literature, their translation into specific coefficients of alternative theoretical frameworks, such as the Standard-Model extension (SME), is rarely carried out. In particular, existing bounds on the quadratic case ($n=2$) of $E_{QG,n}$ can be systematically converted into constraints on the nonbirefringent, $CPT$-conserving SME coefficients $c_{(I)jm}^{(6)}$. This work provides a concise overview of the relevant SME formalism and introduces a transparent conversion method from $E_{QG,2}$ to SME parameters. We review the most stringent time-of-flight-based bounds on $E_{QG,n}$ and standardize them by accounting for systematics, applying missing prefactors, and transforming results into two-sided Gaussian uncertainties where needed. We then use these standardized constraints, along with additional bounds from the literature, to improve bounds on the individual SME coefficients of the photon sector by about an order of magnitude. A consistent methodology is developed to perform this conversion from the general LIV framework to the SME formalism.

We present updated constraints on the parameters of an axion dark energy model, for which we took into account the properties of its characteristic potential and its full cosmological evolution. We show that the values of the axion parameters appear sufficiently constrained by the data, including the latest DESI DR1, and are consistent with the theoretical expectations of a field mass $m_a$ in the ultralight regime $\log (m_a{c}^2/\mathrm{eV})\simeq -32.60\pm 0.12$, and an effective energy scale $f_a$ close to the reduced Planck energy $\log (f_a/M_{\mathrm{Pl}})\simeq -0.28\pm 0.19$. Our results also support the idea of dynamical dark energy, although Bayesian evidence still favors the phenomenological dark energy model $w_0{w}_a$ over the axion dark energy, with the Bayes factor indicating moderate and weak strength of the evidence, respectively, when the models are compared to the cosmological constant $\mathrm{\Lambda }$. However, the results suggest that axion dark energy remains a well-motivated model and its parameters may be better constrained if the upcoming DESI data show further evidence for dynamical dark energy.

Matched filtering is a long-standing technique for the optimal detection of known signals in stationary Gaussian noise. However, it has known departures from optimality when operating on unknown signals in real noise and suffers from computational inefficiencies in its pursuit of near-optimality. A compelling alternative that has emerged in recent years to address this problem is deep learning. Although it has shown significant promise when applied to the search for gravitational-waves in detector noise, we demonstrate the existence of a multitude of learning biases that hinder generalization and lead to significant loss in detection sensitivity. Our work identifies the sources of a set of 11 interconnected biases present in the supervised learning of the gravitational-wave detection problem and contributes mitigation tactics and training strategies to concurrently address them. In light of the identified biases, we demonstrate that existing detection sensitivity metrics are not reliable for machine-learning pipelines and discuss the trustworthiness of previous results. We use gravitational-wave domain knowledge to build a bespoke machine-learning-based binary black hole search pipeline called Sage that addresses these biases. Via the injection study presented in the Machine-Learning Gravitational-Wave Search Challenge, we show that Sage detects $\approx 11.2\%$ more signals than the benchmark pycbc analysis at a false-alarm rate of one per month in O3a noise. Moreover, we also show that it can detect $\approx 48.29\%$ more signals than the previous best-performing machine-learning pipeline on the same dataset. We empirically prove that Sage can (i) effectively handle out-of-distribution noise power spectral densities, (ii) strongly reject non-Gaussian transient noise artifacts, and (iii) achieve higher detection sensitivities using less data than network architectures of a similar size. By studying machine-learning biases and conducting empirical investigations to understand the reasons for performance improvement or degradation, we aim to address the need for interpretability of machine-learning methods for gravitational-wave science. All code and implementations are available.

We describe the effort to characterize gravitational-wave searches and detector sensitivity to different types of compact binary coalescences during the LIGO-Virgo-KAGRA Collaborations’ fourth observing run. We discuss the design requirements and example use cases for this data product, constructed from $>4.33\times {10}^8$ injections during O4a alone. We also identify subtle effects with high confidence, like diurnal duty cycles within detectors. This paper accompanies a public data release of the curated injection set, and the Appendixes give detailed examples of how to use the publicly available data.

For coupled channels $D^0{K}^{+}$, $D^{+}{K}^0$, $D_s^{+}\eta$, and $D_s^{+}{\pi }^0$, the $S$-wave scattering amplitudes are constructed taking into account the mixing of the isoscalar resonance $D_{s0}^{*}(2317{)}^{+}$ with nonresonance amplitudes with isospin $I=1$. The phenomenological approach we use allows us to quite simply clear up the general structure of the $D_{s0}^{*}(2317{)}^{+}\to D_s^{+}{\pi }^0$ decay amplitude violating isospin. We show that the phase of this amplitude coincides with the phase of the nonresonanct $D_s^{+}{\pi }^0$ scattering amplitude in agreement with the Watson theorem. Its modulus squared, as it should be, determines the width of the resonance peak in the $D_s^{+}{\pi }^0$ channel. Taking into account the ${\pi }^0-\eta$ mixing in internal lines up to the second order inclusively ensures that the unitarity condition is fulfilled. The presented analysis complements the description of the $D_{s0}^{*}(2317{)}^{+}\to D_s^{+}{\pi }^0$ decay based on the coupled channel unitarized chiral perturbation theory. The numerical estimates obtained by us for the $D_{s0}^{*}(2317{)}^{+}\to D_s^{+}{\pi }^0$ decay width do not contradict those available in the literature.

Using the renormalization group procedure for effective particles we calculate the effective Hamiltonians in the theory of a fermion field coupled to a scalar field via the Yukawa interaction. The theory is renormalized by the addition of counterterms. Necessary counterterms are determined by computing matrix elements of the effective Hamiltonian. All calculations are performed up to the second order in the expansion in powers of the coupling constant. Renormalized effective Hamiltonians are well-defined symmetric forms acting in the Fock space as opposed to the renormalized bare Hamiltonian, which is not well defined without regularization. We introduce computational techniques that should streamline higher-order calculations and may be of independent interest.

Over the past two decades, intense experimental efforts have focused on measuring observables that contribute to a three-dimensional description of the nucleon. Generalized parton distributions provide complementary insights into the internal structure and dynamics of hadrons, including information about the orbital angular momentum carried by quarks. The most direct process to access these distributions is deeply virtual Compton scattering, in which the cross section can be expressed in terms of Compton form factors. These quantities are defined as convolutions of the generalized parton distributions with coefficient functions derived in perturbative quantum chromodynamics. We extract the Compton form factors from deeply virtual Compton scattering data collected at Jefferson Lab, including the most recent measurements in Hall A, using a novel local fitting technique based on ${\chi }^2$ mapping to constrain the real parts of the Compton form factors $\mathcal{H}$, $\mathcal{E}$ and $\tilde{\mathcal{H}}$. They are determined independently in each kinematic bin for the unpolarized beam-target configuration under the twist-2 approximation, following the formalism developed by Belitsky, Müller, and Kirchner. The extracted Compton Form Factors are then used to train and regularize a deep neural network, enabling a global determination of their behavior with minimal model dependence. This procedure is validated and systematically studied using pseudodata generated with kinematics matching those of the experimental measurements.

We demonstrate that a pseudo-Nambu-Goldstone boson (pNGB) with an initial misalignment angle can drive successful spontaneous baryogenesis and serve as a dark matter (DM) candidate, provided the corresponding global symmetry is nonrestored at high temperature. A key feature of this mechanism is the presence of a slowly sliding phase in the pNGB’s motion, during which it traverses rapidly diminishing potential barriers, generating and freezing the baryon asymmetry, while transitioning into the kination phase and then an oscillatory phase. Just before the would-be oscillation temperature, parametric resonance effectively fragments the homogeneous mode into fluctuations that ultimately constitute the final DM abundance. By considering a dimension-five explicit breaking operator, we find that the predicted pNGB mass and decay constant are approximately 5 eV and $3\times {10}^6\mathrm{GeV}$, respectively, while the radial mode has a light mass $\mathcal{O}(10)\mathrm{MeV}$ and a small mixing $\mathcal{O}({10}^{-4})$ with the Higgs boson. Applied to the Majoron in the type-I seesaw model, this scenario requires the heaviest right-handed neutrino to be as light as 0.1 to 100 GeV. These predictions can be tested through kaon experiments, heavy neutral lepton searches, the LHC, and future colliders.

Recent theoretical and experimental studies of the muon magnetic moment indicate the absence of the previously reported discrepancy, providing a vital opportunity to constrain potential beyond the Standard Model (BSM) physics. In this work, we explore the MeV-GeV mass range, where existing exclusion limits remain relatively loose. We analyze both scalar and pseudoscalar as well as vector and axial vector mediators. We demonstrate that the new bounds are not only comparable to—but in several cases, significantly more stringent than—the constraints obtained from previous collider experiments, even when near-future projections are considered.