We present the calculation of next-to-next-to-leading-order (NNLO) QCD corrections to hadron multiplicities in light-quark jets at lepton colliders, employing the “projection-to-Born” (P2B) method implemented in the FMNLO program. Taking the next-to-leading-order result as an example, we rigorously establish the validity of our P2B-based calculation. We then present NNLO predictions for the normalized asymmetry $D_{K^{-}}$ between hadron and antihadron production in light-quark jets and compare them with SLD data. We find that a suppression of these SLD measurements relative to NPC23 predictions for $D_{K^{-}}$ emerges in the intermediate $z_h$ domain ($0.2\lesssim z_h\lesssim 0.7$). We expect that incorporating these SLD data into global QCD fits will enable improved determination of fragmentation functions.

We investigate the possibility that the recently reported GW231123 event, with component masses $M_1=137_{-17}^{+22}{M}_{\odot }$ and $M_2=103_{-52}^{+20}{M}_{\odot }$ and a local merger rate $R_{\text{local}}=0.08_{-0.07}^{+0.19}{\mathrm{Gpc}}^{-3}{\mathrm{yr}}^{-1}$, originates from primordial black holes (PBHs) formed during an early matter-dominated era. We compute the PBH mass function, abundance, spin distribution, and merger rate density and find a set of choices for the parameters to reproduce the key properties of GW231123. While PBHs formed in such a scenario can acquire large spins through sustained tidal torques, the spin distribution remains uncertain, and additional accretion might lead to extreme spin values inferred in GW231123. We also show that the resulting PBH abundance $f_{\mathrm{pbh}}=1.64_{-1.59}^{+5.00}\times {10}^{-1}$ lies close to the exclusion bounds from cosmic microwave background accretion limits and other probes, highlighting a potential tension with current constraints. Finally, we estimate the scalar-induced gravitational waves that are inevitably generated during PBH formation. PBHs that interpret GW231123 are accompanied by negligible scalar-induced gravitational waves in the nanohertz band, indicating no conflict with current pulsar timing array data.

We employ a model of nuclear structure that takes into account the quark substructure of the baryons to understand the behavior of static two-point correlation functions of meson fields in dense nuclear matter. We show that these correlation functions display “moat” regimes, where the inverse static correlation function is nonmonotonic in momentum space. This can have interesting consequences for the nature of nuclear matter, and it strengthens the possibility of a liquid-crystal phase for high densities.

Motivated by the potential experimental relevance of magnetically affected heavy-quark diffusion, we consider here a five-dimensional nonlinear Einstein-Born-Infeld-dilaton model to not only holographically model the QCD thermodynamics in a magnetic background but also to probe the charged inner structure of a heavy quarkonium. The dual model’s gravitational equations of motion can be solved in analytical form via the potential reconstruction method. Using a variety of tools—spectral functions, hydrodynamic expansions, or hanging strings—we study the anisotropic diffusion constants and heavy-quark number susceptibility, each time reporting closed form expressions.

We investigate the thermodynamics of a charged dilaton black hole arising from Einstein–Maxwell–dilaton theory, where the dilaton couples exponentially to the Maxwell field via a dimensionless parameter $a$. Treating $a$ as a continuous solution parameter, we extend the black hole first law to include a term ${\mathrm{\Psi }}^{A}da$, where ${\mathrm{\Psi }}^A$ is the thermodynamic potential conjugate to $a$. We derive ${\mathrm{\Psi }}^A$ explicitly through a differential analysis of the mass, charge, and entropy and confirm its form via an independent Hamiltonian calculation. Additionally, by promoting $a$ to a spacetime-dependent scalar and introducing auxiliary gauge fields, we provide a geometric interpretation of ${\mathrm{\Psi }}^A$ as a conserved Noether charge. We further analyze the implications of treating $a$ as a thermodynamic variable within the extended phase space. Despite the modification to the first law, we demonstrate that the Smarr relation remains unaffected due to the dimensionless nature of $a$, highlighting the distinction between variational and scaling symmetries. Our analysis supports the thermodynamic relevance of coupling constants and enriches the framework of extended black hole thermodynamics.

We present a detailed Hamiltonian treatment of an inhomogeneous fermionic perturbation propagating on a closed Friedmann-Lemaître-Robertson-Walker spacetime quantized via loop quantum cosmology. Expanding the fermion in spinor harmonics on a spatial three-sphere and truncating at quadratic order, we derive a decoupled, mode-by-mode Hamiltonian, where each mode behaves as a time-dependent Fermi oscillator. This framework naturally facilitates a Schrödinger-picture evolution for fermionic perturbations on a quantum-corrected background. Under the test-field approximation, each massive mode sees its own “dressed metric,” akin to bosonic perturbations, but with distinctive Planck-scale modifications in both temporal and spatial components. Massless modes, by contrast, experience only an equivalent class of conformally invariant backgrounds: quantum corrections drop out of the spatial sector, while the temporal component alone is dressed by quantum gravity corrections. Extending beyond the test-field regime via a Born-Oppenheimer approximation, we incorporate fermionic backreaction self-consistently. Each mode’s energy (depending on the either vacuum or pair states they occupied) sources a mode-dependent shift of the background Hamiltonian, resulting in a “rainbow metric.” In the deep Planck regime, vacuum occupation yields a positive fermionic perturbation term in the Hamiltonian, raising the effective minisuperspace potential and delaying the bounce to higher density in the contracting branch. Excited occupation flips the perturbation sign, lowering the barrier and advancing the bounce to lower density and larger volume. At large volumes, massive fermion backreaction settles into a constant energy density—an emergent cosmological constant—capable of driving late-time acceleration, whereas massless modes remain dynamically inert postbounce. These effects break the exact time-reversal symmetry of the quantum bounce, modify the critical density condition, and generate asymmetric pre- and postbounce trajectories. Our results highlight the crucial role that fermionic degrees of freedom—through both their two-state spectrum and quantum gravity couplings—play in shaping Planck-era and subsequent cosmological dynamics.

The violation of the Bell-Clauser-Horne-Shimony-Holt inequality in a relativistic scalar quantum field theory is analyzed by means of a set of bounded Hermitian operators constructed out of the unitary Weyl operators. These operators allow for both analytic and numerical approaches. While the former relies on the modular theory of Tomita-Takesaki, the latter is devised through an explicit construction of the test functions needed for the localization of the aforementioned operators. The case of causal tangent diamonds in $1+1$ Minkowski spacetime is scrutinized.

Gravitational waves (GWs) have enabled direct detections of compact binary coalescences (CBCs). However, their poor sky localisation and the typical lack of observable electromagnetic (EM) counterparts make it difficult to confidently identify their hosts and study the environments that nurture their evolution. In this work, we show that detailed information of the host environment (e.g., the mass and steepness of the host potential) can be directly inferred by measuring the kinematic parameters (acceleration and its time derivatives) of the binary’s center of mass using GWs alone, without requiring an EM counterpart. We consider CBCs in various realistic environments such as globular clusters, nuclear star clusters, and active galactic nuclei disks to demonstrate how orbit and environment parameters can be extracted for CBCs detectable by ground- and space-based observatories, including the LIGO detector at $\mathrm{A}+$ sensitivity, Einstein Telescope of the XG network, LISA, and DECIGO, on a single-event basis. These constraints on host stellar environments promise to shed light on our understanding of how CBCs form, evolve, and merge.

The Hamiltoinian analysis of the vector-tensor theory of gravity is performed. The resulting geometrical dynamics is reformulated into the connection dynamics, with the real SU(2) connection serving as one of the configuration variables. This formulation allows us to extend the loop quantization scheme of general relativity to the vector-tensor theory, thereby rigorously constructing its quantum kinematical framework. The scalar constraint is promoted to a well-defined operator in the vertex Hilbert space, to represent quantum dynamics. Moreover, the spherically symmetric model of the vector-tensor theory is obtained by the symmetric reduction. Following the general deparametrization strategy for theories with diffeomorphism invariance, the spherically symmetric model can be fully deparametrized in terms of the degrees of freedom of the vector field. The corresponding reduced phase space quantization is carried out. The physical Hamiltonian generating relative evolution is promoted to a well-defined operator on the physical Hilbert space.

We present Bayesian inference results from an extensive injection-recovery campaign to test the validity of three state of the art quasicircular gravitational waveform models: SEOBNRv5PHM, imrphenomtphm, imrphenomxphm, the latter with the SpinTaylorT4 implementation for its precession dynamics. We analyze 35 strongly precessing binary black hole numerical relativity simulations with all available harmonic content. Ten simulations have a mass ratio of $4:1$ and five, mass ratio of $8:1$. Overall, we find that SEOBNRv5PHM is the most consistent model to numerical relativity, with the majority of true source properties lying within the inferred 90% credible interval. However, we find that none of the models can reliably infer the true source properties for binaries with mass ratio $8:1$ systems. We additionally conduct inspiral-merger-ringdown (IMR) consistency tests to determine if our chosen state of the art waveform models infer consistent properties when analysing only the inspiral (low frequency) and ringdown (high frequency) portions of the signal. For the simulations considered in this work, we find that the IMR consistency test depends on the frequency that separates the inspiral and ringdown regimes. For two sensible choices of the cutoff frequency, we report that imrphenomxphm can produce false GR deviations. Meanwhile, we find that imrphenomtphm is the most reliable model under the IMR consistency test. Finally, we reanalyze the same 35 simulations, but this time we incorporate model accuracy into our Bayesian inference. Consistent with the work in Hoy et al. Incorporating model accuracy into gravitational-wave Bayesian inference, Nat. Astron. 9, 1256 (2025)., we find that this approach generally yields more accurate inferred properties for binary black holes with less biases compared to methods that combine model-dependent posterior distributions based on their evidence, or with equal weight.

We investigate black hole solutions in a modified gravity theory inspired by a phenomenological approach to quantum gravity based on spacetime thermodynamics developed by Alonso-Serrano and Liška. The field equations are traceless, similar to unimodular gravity, and include quadratic curvature corrections. We find that static, spherically symmetric, vacuum spacetimes in this theory split into two branches. The first branch is indistinguishable from corresponding solutions in unimodular gravity and describes Schwarzschild–(anti) de Sitter black holes. The second branch instead describes horizonless solutions and is characterized by large values of the spatial curvature. We analyze the dynamics of first-order metric perturbations on both branches, showing that there are no deviations from unimodular gravity at this level.

We investigate static, spherically symmetric solutions in Einstein-scalar-Gauss-Bonnet gravity nonminimally coupled to a massless real scalar field, both in vacuum and in the presence of fermionic matter. Focusing on a specific quadratic scalar–Gauss–Bonnet coupling, we identify two distinct classes of compact objects: one with a regular scalar field at the origin—connected to general relativity in an appropriate limit—and another one with a divergent scalar field at the origin but a regular geometry. We analyze both purely scalar and matter-supported (hybrid) configurations, showing that the former can describe a broad class of compact objects, while the latter can reproduce neutron starlike masses even when modeled with a simple polytropic equation of state. Furthermore, we highlight distinctive phenomenological signatures, including the ability of these stars to exceed known compactness limits and their potential to act as gravitational wave superemitters. We also examined the motion of test particles nonminimally coupled to the scalar field and showed the existence of stable circular orbits within the Schwarzschild’s ISCO and static configurations at finite radii for particles with zero angular momentum.

Recently, the baryon acoustic oscillations (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) Collaboration survey have suggested hints of dynamical dark energy, challenging the standard $\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) model. In this work, we adopt an improved inverse distance ladder approach based on the latest cosmological data to provide a model-independent perspective, employing a global parametrization based on cosmic age (PAge). Our analysis incorporates DESI DR2 BAO measurements, cosmic chronometer (CC) data, and type Ia supernovae observations from either the DESY5 or PantheonPlus datasets. For the $\mathrm{DESY}5+\mathrm{DESI}\mathrm{DR}2+\mathrm{CC}$ datasets, we obtain $H_0=67.91\pm 2.33\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$. This value is consistent with the Planck 2018 result, while showing $2.0\sigma$ tension with the SH0ES measurement. Furthermore, by mapping specific cosmological models into PAge approximation parameter space $(p_{\mathrm{age}},\eta )$, our model-independent analysis reveals a notable deviation from the $\mathrm{\Lambda }\mathrm{CDM}$ model, as indicated by the DESY5 and DESI DR2 datasets. Finally, $\mathrm{DESY}5+\mathrm{DESI}$ $\mathrm{DR}2+\mathrm{CC}$ datasets provide nearly decisive evidence favoring the PAge model over the standard $\mathrm{\Lambda }\mathrm{CDM}$ model. These findings highlight the need for further investigation into the expansion history to better understand the deviations from the $\mathrm{\Lambda }\mathrm{CDM}$ model.

We present a fast and accurate formulation for computing the nonlinear matter power spectrum at one-loop order based on unified Lagrangian perturbation theory (ULPT). ULPT decomposes the density field into the Jacobian deviation, capturing intrinsic nonlinear growth, and the displacement-mapping factor, accounting for large-scale distortions due to bulk flows. This structural separation leads to a natural division of the power spectrum into a source term and a displacement-mapping factor, ensuring infrared (IR) safety by construction. We implement an efficient numerical algorithm using fftlog and fast-pt, achieving approximately two-second evaluations on a standard laptop. The results are validated against simulation-based emulators, including the Dark Emulator and Euclid Emulator 2. Across 100 sampled cosmologies, ULPT agrees with emulator predictions at the 2%–3% level up to $k\simeq 0.4h{\mathrm{Mpc}}^{-1}$ for $z\ge 0.5$, without any nuisance parameters. Similar agreement is found in configuration space, where the two-point correlation function remains accurate down to $r\simeq 10h^{-1}\mathrm{Mpc}$. Compared to standard perturbation theory, which fails at small scales due to series expansion of the displacement factor, ULPT maintains convergence by preserving its full exponential form. We also clarify the mechanism of baryon acoustic oscillation (BAO) damping: exponential suppression by displacement and peak sharpening by nonlinear growth. The combination accurately reproduces BAO features seen in simulations. ULPT thus offers a robust, IR-safe, and computationally efficient framework for modeling large-scale structure in galaxy surveys. The numerical implementation developed in this work is publicly released as the open-source python package ulptkit.

We theoretically analyze the dipole anisotropy observed in the quasar distribution from the CatWISE2020 catalog. The catalog data shows a peak around $z\approx 1$, suggesting the presence of a large-scale dipole component. We explore the possibility that this dipole could be driven by primordial density fluctuations from modes that were superhorizon at the time of cosmic microwave background (CMB) decoupling but have since entered the horizon and become subhorizon. In particular, we consider the impact of adiabatic modes with wave numbers $k$ in the range $({10}^{-4}-4\times {10}^{-3}){\mathrm{Mpc}}^{-1}$, corresponding to wavelength scales of several Gpc. Such modes can create large-scale density variations, likely causing anisotropies in the distribution of matter and, as a result, affecting the number density of observed quasars. We find that these can lead to a significant contribution to the dipole for sources up to redshifts of about 1, but are unable to explain the observed dipole. We also demonstrate that a superhorizon curvature perturbations mode, with a comoving wave number $k\lesssim 0.3H_0$ can lead to a significant enhancement in the locally inferred Hubble constant. This effect offers a viable explanation for the observed discrepancy between local and CMB inferred measurements of $H_0$.

Primordial non-Gaussianity (PNG) is a signature of fundamental physics in the early Universe that is probed by cosmological observations. It is well known that the local type of PNG generates a strong signal in the two-point function of large-scale structure tracers, such as galaxies. This signal, often termed “scale-dependent bias” is a generic feature of modulation of gravitational structure formation by a large-scale mode. It is less well appreciated that the coefficient controlling this signal, $b_{\varphi }$, is closely connected to the time evolution of the tracer number density. This correspondence between time evolution and local PNG can be simply explained for a universal tracer whose mass function only depends on peak height and, more generally, for nonuniversal tracers in the separate universe picture, which we validate in simulations. We also describe how to recover the bias of tracers subject to a survey selection function and perform a simple demonstration on simulated galaxies. Since the local PNG amplitude in $n$-point statistics ($f_{\mathrm{NL}}$) is largely degenerate with the coefficient $b_{\varphi }$, this proof of concept study demonstrates that Galaxy survey data can allow for more optimal and robust extraction of local PNG information from upcoming surveys.