We propose a dual primordial black hole (PBH) formation scenario realized in two-stage inflation separated by a noninflationary break. A single comoving scale re-enters the horizon twice, leading to the formation of two PBH populations at different epochs: ultralight PBHs during the break stage and heavier PBHs after inflation. The former evaporate before big bang nucleosynthesis and can reheat the Universe, while the latter may account for all dark matter today. We show that the required hierarchy in PBH abundances arises naturally from the suppression of curvature perturbations during the break. This scenario predicts a distinctive bipeak stochastic gravitational wave signal, originating from PBH evaporation and enhanced curvature perturbations, which lies within the sensitivity of future observatories such as LISA and DECIGO.

Boson stars have been extensively studied in classical gravity, but their quantum properties remain comparatively unexplored. In this paper, we compute the quantum scalar fields and stress tensor in boson star spacetimes within the framework of semiclassical gravity. Divergences are regularized using Pauli-Villars fields, and accurate numerical results are obtained through spectral methods. Employing coherent states enables a direct comparison between the classical part of the stress tensor and the quantum fluctuation. Our results indicate that strong spacetime curvature is the primary source of large quantum effects. The renormalized quantum energy density is mostly positive but the radial pressure is negative, suggesting that classical boson star solutions require modification once quantum effects are included. Moreover, in regimes of large curvature, the quantum fluctuations can constitute a significant fraction of the total stress tensor. The methods developed here can be generalized to other compact objects and used to study their response to quantum corrections.

We investigate the gravitational wave (GW) signals emitted by planetary-mass primordial black holes (PBHs) passing nearby or traversing neutron stars (NSs). While previous studies mainly focused on the detailed waveforms of the signals, we estimate the rate of PBH-NS gravitational-wave events originating from the Galactic Center and compute the probability of detecting a signal over 10 years of LIGO-Virgo-KAGRA observations. We examine in detail the case of PBHs bound to NSs, focusing on eccentric orbits that give rise to repeated GW bursts emitted in correlated series, each burst corresponding to a periastron passage. Despite the enhancement from the large number of bursts produced by a single PBH-NS pair, the total number of signals produced in this way remains subdominant to those due to random unbound encounters of PBHs with NSs. We also find that both types of signals have a very small probability $P\lesssim {10}^{-8}$ to be detected in a 10 year period.

An important next step for pulsar timing arrays (PTAs) is to measure anisotropies in the gravitational wave background (GWB) at $\sim$ nanohertz frequencies. We calculate the expected GWB anisotropies using empirically calibrated models for the merger rates of supermassive black hole binaries (SMBHBs). The anisotropies reflect both shot noise in the discrete SMBHB populations while also tracing, in part, the large-scale structure (LSS) of the universe. The shot-noise term is sensitive to the high-mass end of the merging SMBH mass function, depends somewhat on the low-redshift tail of the merger distribution, and is a strong function of observing frequency. The precise frequency dependence provides a test of SMBHB residence times. In our models, the mean shot-noise anisotropy typically lies close to or above the broad frequency-band NANOGrav upper limits. Consequently, near-future PTA data, and potentially, reanalyses of existing measurements using frequency-dependent shot-noise anisotropy templates, should be capable of detecting this signal or placing meaningful constraints on SMBHB merger models. A full interpretation, however, will require modeling the probability distribution of shot-noise amplitudes rather than relying solely on ensemble-averaged predictions. The LSS-induced anisotropies are at least 2 to 3 orders of magnitude smaller. Although the LSS contribution contains valuable information regarding the redshift distribution and clustering bias of the merging SMBHBs, detecting this component will be challenging.

Long-term observations indicate that the relative intensity of cosmic-ray anisotropy remains below 0.1% for energies less than $\sim 1\mathrm{PeV}$. Measuring such faint signals poses a significant challenge in data analysis, requiring careful removal of instrumental and atmospheric artifacts. The all-distance equizenith angle method is widely employed to extract cosmic-ray anisotropies, as it effectively suppresses the instantaneous variations arising from the instrument and atmosphere. However, instability in the detector efficiency makes precise measurements of anisotropy challenging with this method. In this work, we present an enhanced all-distance equizenith angle method for cosmic-ray anisotropy measurement. Unlike previous implementations, our improved approach enables the simultaneous measurement of anisotropies over multiple time frames and allows the detection efficiency to be determined directly from the data. This feature makes the method especially suitable for applications where the detector array does not operate with long-term stabilit, and thus allows for the measurement of anisotropy with high precision. Moreover, our enhanced method is also feasible when the data do not span complete tropical years.

We analyze hadronic final states of $e^{+}{e}^{-}$ annihilation through event shape observables, Thrust and C-parameter, and inclusive hadron spectra at the planned center-of-mass (c.m.) energies of the Future Circular Electron-Positron Collider (FCC-ee). Collision data is produced using Monte Carlo event generation in PYTHIA at 91.2, 160, 240, and 365 GeV. Distortions of event shapes due to initial-state photon radiation and background decays of Z pairs, W pairs, top-quark pairs, and Higgs bosons are investigated. An extraction of the strong coupling ${\alpha }_{\mathrm{s}}$ is performed by fitting event shape distributions to perturbative quantum chromodynamics (QCD) predictions at next-to-next-to-leading-order (NNLO) accuracy, and the sources of systematic uncertainties at high c.m. energies are discussed. Soft gluon dynamics is examined through charged particle multiplicities and momentum distributions, and energy evolution of mean values is compared with prior experimental results. The inferences from this phenomenological study provide a reference to QCD studies at future high-energy $e^{+}{e}^{-}$ colliders.

The increasingly stringent bounds on the Higgs-portal coupling, arising from dark matter (DM) direct-detection searches, confront the minimal renormalizable complex scalar DM scenario with thermal production, where freeze-out occurs in the standard radiation-dominated era. This limitation can be alleviated by introducing a dimension-five Higgs-portal operator in the minimal renormalizable complex scalar DM model and/or by modifying the standard cosmological history of the Universe. In this article, we analyze complex scalar DM production in both the reheating and radiation-dominated epochs within an effective field theory (EFT) framework. While both scenarios exhibit sizable regions of parameter space consistent with existing constraints, freeze-out during reheating opens up additional viable regions that are otherwise ruled out by DM overabundance in the radiation-dominated scenario. Notably, the renormalizable Higgs-portal coupling is constrained by relic density and direct- and indirect-detection limits. In contrast, the EFT coupling associated with the dimension-five operator is constrained by relic density and indirect-detection bounds arising from DM semiannihilation. We further study the production cross section of complex scalar DM at hadron and lepton colliders.

We consider ${\varphi }^4$ theory with $\varphi (x)\in \mathbb{R}$ in two Euclidean dimensions. We determine for a variety of self-couplings $\widehat{\lambda }$ the (negative) critical bare mass ${\widehat{\mu }}_{0\mathrm{c}}^2(\widehat{\lambda })$ where the lattice-regularized system changes from the symmetric to the broken phase. Based on these data, the transition to infinite volume and a universal scheme with the renormalized parameter ${\widehat{\mu }}_{\mathrm{c}}^2(\widehat{\lambda })$ is made. Finally, $f_{\mathrm{c}}={\lim }_{\widehat{\lambda }\to 0}\widehat{\lambda }/{\widehat{\mu }}_{\mathrm{c}}^2(\widehat{\lambda })$ is determined, with a judicious choice of the parametrizations considered. Our final result reads $f_{\mathrm{c}}=11.1097(20{)}_{\mathrm{stat}}(09{)}_{\mathrm{sys}}=11.1097(22{)}_{\mathrm{tot}}$.

We examine the Lüscher quantization condition to high order for the scattering of a spinless particle and a spin-$1/2$ particle in a periodic box. First, we derive the quantization conditions in a nonrelativistic framework up to total angular momentum $J=11/2$ in both cubic and elongated geometries, and for both rest and moving frames. Then, we introduce a method to transparently cross-check their convergence, using both quantized energy levels in the box and infinite-volume phase shifts for the same potential. We clarify how to incorporate spin-orbit coupling into the formalism and show in detail how the quantization conditions converge order by order in the various irreducible representations. In all, we validated 19 quantization conditions (12 in cubic box, 7 in elongated box). This is a necessary step in applying the method in precision studies of systems in finite volume with half-integer spin, such as meson-baryon scattering.

Ultralong range angular correlations have been recently reported by the ALICE collaboration in pp collisions at $\sqrt{s}=13\mathrm{TeV}$ below $\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta =7$. The measurements have been performed as a function of the charged-particle multiplicity at midrapidity ($N_{\mathrm{ch}}$ in $|\eta |<0.8$), which is known to be strongly sensitive to local multiplicity fluctuations. The present work investigates the impact of the event-activity estimator on ultralong range angular correlations. The study is conducted in the framework of pythia8 with the string shoving mechanism since it gives a nonzero elliptic flow coefficient, $V_{2\mathrm{\Delta }}$. Such collectivelike effects arise from repulsive interactions between overlapping color strings, without invoking hydrodynamic collectivity. The analysis is conducted as a function of $N_{\mathrm{ch}}$, the number of parton-parton scatterings ($N_{\mathrm{mpi}}$) and flattenicity. Surprisingly, for ultralong range correlations, pp collisions with $N_{\mathrm{mpi}}=1$ (dijets) seem to be the most sensitive to string shoving. The effect diminishes with increasing $N_{\mathrm{mpi}}$. While in data, within uncertainties, $V_{2\mathrm{\Delta }}$ exhibits a weak multiplicity dependence; the string shoving mechanism gives a $V_{2\mathrm{\Delta }}$ that decreases with the increase in $N_{\mathrm{ch}}$. The present work therefore supports the picture stating that mechanisms such as string shoving might explain the low multiplicity limit, whereas, hydro becomes relevant in high-multiplicity pp collisions. This work also suggests that flattenicity might be more effective than $N_{\mathrm{ch}}$ to better handle collectivelike effects.

Motivated by the recent $3.9\sigma$ evidence for $CP$ violation from the LHCb collaboration in decays of an antitriplet beauty baryon to a charmonium, an octet baryon, and a pseudoscalar meson, we perform, for the first time, a systematic analysis of this class of decays within the framework of flavor $SU(3)$ symmetry. Several predictions for branching ratios and $CP$ violating relations that can be tested in future experiments are found, in particular $\mathrm{\Delta }{A}_{CP}=A_{CP}({\mathrm{\Lambda }}_b^0\to p{\pi }^{-}J/\psi )-A_{CP}({\mathrm{\Lambda }}_b^0\to p{K}^{-}J/\psi )=A_{CP}({\mathrm{\Lambda }}_b^0\to n{\pi }^{0}J/\psi )-A_{CP}({\mathrm{\Lambda }}_b^0\to (n{K}_S,n{K}_L)J/\psi )$. Our results provide guidance to test the availability of $SU(3)$ symmetry and search for possible $CP$ violation effects in this class of decays.

Exclusive semileptonic and nonleptonic $J/\psi$ decays are investigated in the framework of the relativistic quark model based on the quasipotential approach and quantum chromodynamics. The form factors parametrizing the hadronic matrix element of the weak current are calculated with the complete account of the relativistic effects. These form factors are expressed as the overlap integrals of the meson wave functions and are determined in the whole accessible kinematic range. On this basis the semileptonic decay branching fractions are evaluated for decays involving both electrons and muons. The nonleptonic decays are considered in the factorization approximation in the limit for the number of colors $N_c\to \infty$. The obtain branching fractions are found to be of the order ${10}^{-9}–{10}^{-12}$. They are compared with the previous theoretical predictions and available experimental upper bounds.

There is a significant uncertainty in the prediction of atmospheric muon neutrino and antineutrino flux ratio using different flux models, especially at higher energies. We study the prospects of experimentally measuring this flux ratio as a function of energy with the ATLAS detector at the LHC. To this end, we compute the contained-vertex and external upward going charged current event rates induced by atmospheric muon (anti)neutrinos through deep inelastic scattering at the 4 kiloton hadron calorimeter (HCAL) component of ATLAS. We illustrate the event selection criteria necessary to eliminate the cosmic ray muon background for the above event classes. While the contained vertex events have a striking topology with a muon being created inside the HCAL and then traveling to the muon chamber possibly through the tracker, for muons with energy larger than 3 GeV, nearly 10 times more events are obtained for the external upward going muons created in the rock column below the detector. Our estimates show that the energy dependence of the ratio of negative and positively charged muons induced by atmospheric muon neutrino and antineutrino fluxes can be measured by ATLAS up to a muon energy of 100 GeV, with 1000-live days of neutrino physics exposure over a period of several years, considering only the period with the LHC beams not in circulation, but the detector and magnetic fields of ATLAS in operation. With this exposure, we expect to obtain $60{\mu }^{-}$ and $30{\mu }^{+}$ contained vertex events, and $599{\mu }^{-}$ and $292{\mu }^{+}$ external upward-going events, after imposing the necessary selection criteria. For the latter class of events, this corresponds to an expected ratio of negative to positive charged muon events averaged over all energies, $R_{{\mu }^{-}/{\mu }^{+}}=2.05_{-0.14}^{+0.15}$, at 68% CL. The CMS detector at the LHC can also be used with comparable reach for studying the external upward-going rock muon events.

A quantum object is extended by virtue of uncertainty. When subjected to gravity, different parts of its wave function experience distinct local relativistic effects, leading to tidal and interference phenomena absent in the classical limit. These effects can be incorporated into a geometric extension of classical spacetime. For states quantum correlated in at least two directions, a complete description of motion requires a non-Riemannian geometry whose form is controlled by the state’s entropy and purity and affects a broad range of phenomena from laboratory measurements to Hawking radiation. A specific implication of this framework is the appearance of quantum parameters in the time-dilation law in addition to the usual dependence on velocity and gravitational potential. The quantum-corrected time-dilation law is universal: the corrections depend solely on the external degrees of freedom and are independent of internal details of the clock mechanism.

We propose an exceptional-point (EP) framework for black-hole ringdown beyond the standard quasinormal-mode (QNM) paradigm. It provides a first-principles characterization of the resonance associated with avoided crossings near EPs, an effect that conventional QNM analysis cannot fully capture. Employing a phenomenological environmental black-hole model with the hyperboloidal framework, we identify near-coalescence of both QNM eigenvalues and eigenfunctions, and directly demonstrate that the resonance produces enhanced mode contributions in the time domain, resulting in characteristic departures from exponentially damped oscillations. Our formulation further reveals that the EP frequency, given by the average of the resonant modes, emerges as the physically relevant observable in the near-EP regime, and offers a robust foundation for modeling and extracting resonant ringdown signals.

Numerical relativity (NR) provides the most accurate waveforms for comparable-mass binary black holes but becomes prohibitively expensive for increasingly asymmetric mass ratios. Point-particle black hole perturbation theory (ppBHPT), which expands the Einstein equations in the small-mass-ratio limit, offers a computationally efficient alternative but is expected to break down in the comparable-mass regime because it neglects nonlinear effects. Nonetheless, several recent studies have shown that ppBHPT can model nonspinning binaries with high accuracy when supplemented by simple calibrations or a first postadiabatic (PA) correction. Here we assess the applicability of ppBHPT to quasicircular binaries with a nonprecessing primary and a nonspinning secondary by comparing waveform amplitudes, orbital frequencies, and phases. We find that spin effects in ppBHPT waveforms (without additional spin information beyond adiabatic order) agree surprisingly well with NR (outperforming some post-Newtonian models) over the last $\approx 20$ orbital cycles. This suggests that, after incorporating higher-order nonspinning corrections into ppBHPT—via second-order self-force results or semianalytical fits—only modest spin-dependent adjustments may be required to achieve NR-faithful waveforms. We also show that combining nonspinning NR information with adiabatic ppBHPT yields reasonably accurate inspiral waveforms for spins $\chi \lesssim 0.5$ and mass ratios $q\gtrsim 5$.

Cavity optomechanical systems have recently been proposed as detectors for ultralight dark matter, leveraging their ability to cool and probe mechanical oscillators at the quantum limit. Here we present a resonant search for ultralight dark matter using a cavity optomechanical accelerometer. The detector consists of a cryogenic ${\text{Si}}_3{\mathrm{N}}_4$-membrane cavity mounted to a 4 K copper plate, with photothermal tuning used to scan its 39 kHz mechanical resonance. Shot-noise-limited displacement readout and radiation-pressure feedback cooling yield an acceleration sensitivity of $10\mathrm{n}{g}_0/\sqrt{\mathrm{Hz}}$ over 30 Hz near resonance. The detector’s material inhomogeneity gives access to direct vector coupling to the dark-matter field. We conduct a resonant search based on matched-filter statistics, yielding upper bounds consistent with thermal noise and above those set by equivalence principle tests. No signal is observed, but the experiment demonstrates stable, quantum-limited operation and validates a scalable approach to resonant detection. With optimized test masses, lower temperature, and multiplexed arrays, the platform offers a path toward competitive constraints on vector-mediated dark-matter interactions.

We calculate the large-$N$ expansion of the sphere free energy $F=-\log Z_{S^d}$ of the $\mathrm{O}(N){\varphi }^4$ and the Gross-Neveu $(\overline{\psi }\psi {)}^2$ conformal field theories (CFTs) to order $1/N$. Analytic regularization of these theories requires consistently shifting the UV scaling dimension of the auxiliary field: this can only be done by modifying its kinetic term. This modification combines with the counterterms to give the result that matches the $\epsilon$ expansion, resolving a puzzle raised by Tarnopolsky. These $F$’s can be written compactly in terms of the anomalous dimensions, for both the short- and long-range versions of these CFTs. We also provide various technical results including a computation of the counterterms on the sphere and a neat derivation of the sphere free energy of a free conformal field. Finally, we observe that the long-range CFT becomes the short-range CFT at exactly the point where its $\tilde{F}=-\sin \frac{\pi d}{2}F$ is maximized as a function of the vector’s scaling dimension.

The symmetry reduction of dynamical systems that are invariant under changes of global scale is well understood for classical theories of particles and fields. The excision of the superfluous degree of freedom generating such rescalings leads to a dynamically equivalent theory, which is frictional in nature. In this article, we extend the formalism to physical models, of both particles and fields, described by singular Lagrangians. In order to work with a finite-dimensional (velocity) phase space, our construction requires that we treat classical field theories within the De-Donder Weyl formalism, in which a multisymplectic structure is introduced on the first jets of the bundle of fields. The results obtained are subsequently applied to a number of physically motivated examples, as well as a discussion presented on the implications of our work for classical general relativity.