We study three-dimensional quantum field theories on the interval with symmetry-preserving boundary conditions. The physics and symmetries of the effective 2D theory in the IR are the main subjects of this note. We focus on the (super-)Yang-Mills-Chern-Simons (YM-CS) theories with the Dirichlet boundary conditions on both ends. We warm up with the $\mathcal{N}=0$ and $\mathcal{N}=1$ cases flowing to the bosonic and $\mathcal{N}=(0,1)$ WZW models in 2D. Then we study the 3D $\mathcal{N}=2$ YM-CS on the interval with the $\mathcal{N}=(0,2)$ Dirichlet boundaries. It flows to a noncompact version of the $\mathcal{N}=(0,2)$ WZW. We compute its perturbatively exact two-derivative effective action (i.e., the metric and the B-field), and speculate on the possibility of novel nonperturbative effects. We also construct the 2D Landau-Ginzburg models flowing to the similar sigma models.

Stabilization of the moduli in any higher-dimensional model is essential to obtain the lower-dimensional effective theories where the stable values of the moduli appear as parameters that in turn determine various observables in the present-day Universe. In this work, we obtain a new warped solution for a five-dimensional $f(R)$ higher-curvature gravity in an anti–de Sitter bulk. The higher-curvature term appears as a natural generalization in the bulk-gravity action and is shown to modify the usual warped metric. The novel feature of this modification leads to a geometric stabilization of the modulus/radion field in the underlying effective theory on the visible 3-brane without the need for any external stabilizing field. It is further shown that the stabilized value of the modulus resolves the well-known gauge hierarchy problem without any unnatural fine-tuning of the model parameters. This new solution along with the stabilized modulus opens up the possibilities of new observable signatures in the effective lower-dimensional theory where the stabilized value of the modulus not only appears as a parameter in the lower-dimensional brane but also decides the dynamics of the modulus i.e., the radion.

In this paper, we revisit the problem of using gravitational wave data to test the Einstein-dilation-Gauss-Bonnet theory by using nine selected gravitational wave events from the third Gravitational-Wave Transient Catalog. Compared with existing work, we take into account the higher harmonics more properly and we also study the contribution of the merger-ringdown data. Using the inspiral data alone, we find that the best result is from GW200115, giving $\sqrt{|\alpha |}<1.1\mathrm{km}$, which is about 17% tighter than the previous best result. Several combinations of the selected events give $\sqrt{|\alpha |}\le 1.0\mathrm{km}$. The result is further improved when the merger-ringdown data are also included, using two phenomenological schemes, giving $\sqrt{|\alpha |}<0.87\mathrm{km}$ for GW200115 in the best case scenario. We also notice the possible existence of a simple unexpected relation among the constraints from different events, and it is important to have more large mass ratio events that can help clarify if there is indeed such a trend.

We perform a comprehensive numerical study of gravitational waves from stellar core collapse in the massive scalar-tensor theory with the cubic and quartic self-interactions of the scalar field. We investigate the dependence of gravitational waves on the self-interaction as well as the mass of the scalar field and the conformal factor. We find that gravitational-wave spectra show a systematic difference between the cubic and quartic self-interactions. We also find that this systematic difference is insensitive to the mass of the scalar field and the conformal factor. Our results indicate that the type of the self-interaction could be constrained by observations of gravitational waves using the future-planned detectors.

Spacetimes representing expanding impulsive gravitational waves propagating on a flat background are studied. The impulses are generated by various configurations of snapped cosmic strings. Employing the previous results [J. Podolský et al., The global uniqueness and $C^1$-regularity of geodesics in expanding impulsive gravitational waves, Classical Quantum Gravity 33, 195010 (2016)], analyzing the geodesic motion in generic expanding impulses, we investigate geometric properties of more intricate stringlike wave sources than the standard case of a single snapped string. Such solutions representing pairs of snapping strings were technically derived in Podolský and Griffiths [The collision and snapping of cosmic strings generating spherical impulsive gravitational waves, Classical Quantum Gravity 17, 1401 (2000)], however, the corresponding physical analysis requires to introduce their generalizations to point out various subtleties in the construction. As the main tool, we thus use the close connection between the spacetime structure and the motion of free test particles crossing the impulse. Within our contribution, the explicit models of a boosted snapped cosmic string and boosted perpendicular or parallel configurations of string pairs are discussed in detail.

The frozen star model provides a classical description of a regularized black hole and is based upon the idea that regularizing the singularity requires deviations from the Schwarzschild geometry which extend over horizon-sized scales, as well as maximally negative radial pressure as an equation of state. The frozen star has also been shown to be ultrastable against perturbations, a feature that can be attributed to the equation of state and corresponds to this model mimicking a black hole in the limit $\hslash \to 0$ or, equivalently, the limit of an infinite Newton’s constant. Here, we “defrost” the frozen star by allowing its radial pressure to be perturbatively less negative than maximal. This modification to the equation of state is implemented by appropriately deforming the background metric so as to allow the frozen star to mimic a quantum black hole at finite $\hslash$ and Newton’s constant. As a consequence, the defrosted star acquires a nontrivial spectrum of oscillatory perturbations. To show this, we first use the Cowling approximation to obtain generic equations for the energy density and pressure perturbations of a static, spherically symmetric background with an anisotropic fluid. The particular setting of a deformed frozen star is then considered, for which the dispersion relation is obtained to leading order in terms of the deviation from maximal pressure. The current results compare favorably with those obtained earlier for the collapsed polymer model, whose strongly nonclassical interior is argued to provide a microscopic description of the frozen and defrosted star geometries.

The present study focuses on analyzing the generalized free energy function of $D$-dimensional charged Gauss-Bonnet-AdS black holes. We examine fluctuating black holes that are in contact with thermal baths at an arbitrary ensemble temperature, resulting in the corresponding Euclidean geometry with a conical singularity at the event horizon. By properly regularizing the conical singularity, we have derived the generalized free energy of fluctuating black holes in the canonical ensemble using the Euclidean gravitational path integral approach. We demonstrate that the derived generalized free energy is consistent with the definition from a thermodynamic perspective. Then we explore the free energy landscapes of charged Gauss-Bonnet black holes in diverse spacetime dimensions and examine the corresponding thermodynamics of the black hole phase transition. Finally, we discuss the generalized free energy landscape of fluctuating black holes in the grand canonical ensemble.

The decrease of both the rolling speed of the inflaton and the sound speed of the curvature perturbations can amplify the curvature perturbations during inflation so as to generate a sizable amount of primordial black holes. In the ultraslow-roll inflation scenario, it has been found that the power spectrum of curvature perturbations has a $k^4$ growth. In this paper, we find that when the speed of sound decreases suddenly, the curvature perturbations becomes scale dependent in the infrared limit and the power spectrum of the curvature perturbation only has a $k^2$ growth. Furthermore, by studying the evolution of the power spectrum in the inflation model, in which both the sound speed of the curvature perturbations and the rolling speed of the inflaton are reduced, we find that the power spectrum is nearly scale invariant at the large scales to satisfy the constraint from the cosmic microwave background radiation observations, and at the same time can be enhanced at the small scales to result in an abundant formation of primordial black holes. In the cases of the simultaneous changes of the sound speed and the slow-roll parameter $\eta$ and the change of the sound speed preceding that of the slow-roll parameter $\eta$, the power spectrum can possess a $k^6$ growth under certain conditions, which is the steepest growth of the power spectrum reported so far.

The 21-cm power spectrum of reionization is a promising probe for cosmology and fundamental physics. Exploiting this new observable, however, requires fast predictors capable of efficiently scanning the very large parameter space of cosmological and astrophysical uncertainties. In this paper, we introduce the halo model of reionization (HMreio), a new analytical tool that combines the halo model of the cosmic dawn with the excursion-set bubble model for reionization, assuming an empirical correction factor to deal with overlapping ionization bubbles. First, HMreio is validated against results from the well-known seminumerical code 21 cmfast, showing a good overall agreement for wave-modes of $k\lesssim 1\mathrm{h}/\mathrm{Mpc}$. Based on this result, we perform a Monte-Carlo Markov-Chain (MCMC) forecast analysis assuming mock data from 1000-hour observations with the low-frequency part of the Square Kilometre Array (SKA) observatory. We simultaneously vary the six standard cosmological parameters together with seven astrophysical parameters quantifying the abundance and spectral properties of sources. Depending on the assumed theory error, we find very competitive constraints on cosmological parameters. In particular, it will be possible to conclusively test current cosmological tensions related to the Hubble parameter ($H_0$-tension) and the matter clustering amplitude ($S_8$-tension). Furthermore, the sum of the neutrino masses can be strongly constrained, making it possible to determine the neutrino mass hierarchy at the $\sim 90$ percent confidence level. However, these goals can only be achieved if the current modeling uncertainties are substantially reduced to below $\sim 3$ percent.

Axionlike particles (ALPs) can be produced in the Sun and are considered viable candidates for the cosmological dark matter (DM). It can decay into two photons or interact with matter. We identify new inelastic channels of inverse Primakoff processes due to atomic excitation and ionization. Their cross sections are derived by incorporating full electromagnetic fields of atomic charge and current densities, and computed by well-benchmarked atomic many-body methods. Complementing data from the underground XENONnT and surface TEXONO experiments are analyzed. Event rates and sensitivity reaches are evaluated with respect to solar- and DM-ALPs. New parameter space in ALP couplings with the photons versus ALP masses in (1 eV–10 keV) not previously accessible to laboratory experiments are probed and excluded with solar-ALPs. However, at regions where DM-ALPs have already decayed, there would be no ALP-flux and hence, no interactions at the detectors in direct search experiments. No physics constraints can be derived. Future projects would be able to evade the stability bound and open new observable windows in (100 eV–1 MeV) for DM-ALPs.

The present work analyzes various aspects of M31 gamma-ray halo emission in its relation to annihilating dark matter (DM). The main aspect is the predicted effect of asymmetry of the intensity of emission due to inverse Compton scattering (ICS) of a possible population of relativistic electrons and positrons ($e^{\pm }$) in the galactic halo on starlight photons. This asymmetry is expected to exist around the major galactic axis, and arises due to anisotropy of the interstellar radiation field and the inclination of M31. ICS emission and its asymmetry were modeled by galprop code for the trial case of $e^{\pm }$ generated by annihilating weakly interacting massive particles (WIMPs) with various properties. The asymmetry was obtained to appear at photon energies above $\sim 0.1\mathrm{MeV}$. Morphological and spectral properties of the asymmetry were studied in detail. Potential observational detection of the asymmetry may allow to infer the leptonic fraction in the emission generation mechanism, thus providing valuable inferences for understanding the nature of M31 gamma-ray halo emission. Specific asymmetry predictions were made for the recently claimed DM interpretation of the outer halo emission. The paper also studied the role of secondary—ICS and bremsstrahlung—emissions due to DM annihilation for that interpretation. And, finally, the latter was shown to be somewhat restricted by the recently derived WIMP constraints from radio data on M31.

A new generation of terrestrial gravitational wave detectors is currently being planned for the next decade, and it is expected to detect most of the coalescences of compact objects in the Universe with masses up to a thousand times the solar mass. Among the several possible applications of current and future detections, we focus on the impact to the measure of the luminosity distance of the sources, which is an invaluable tool for constraining the cosmic expansion history of the Universe. We study two specific detector topologies, triangular and $L$-shaped, by investigating how the topology and relative orientation of up to three detectors can minimize the uncertainty measure of the luminosity distance. While the precision of the distance measurement is correlated with several geometric angles determining the source position and orientation, focusing on the bright standard sirens and assuming a redshift to be measured with high accuracy, we obtain analytic and numerical results for its uncertainty, depending on the type and number of detectors composing a network, as well as on the inclination angle of the binary plane with respect to the wave propagation direction. We also analyze the best relative location and orientation of two third generation detectors to minimize the luminosity distance uncertainty, showing that prior knowledge of the inclination angle distribution plays an important role in the precision recovery of luminosity distance and that a suitably arranged network of detectors can drastically reduce the uncertainty measure, approaching the limit imposed by lensing effects intervening between source and detector at a redshift $z\gtrsim 0.7$.

The current and upcoming generations of gravitational wave experiments represent an exciting step forward in terms of detector sensitivity and performance. For example, key upgrades at the LIGO, Virgo and KAGRA facilities will see the next observing run (O4) probe a spatial volume around four times larger than the previous run (O3), and design implementations for, e.g., the Einstein Telescope, Cosmic Explorer, and LISA experiments are taking shape to explore a wider frequency range and probe cosmic distances. In this context, however, a number of very real data analysis problems face the gravitational wave community. For example, it will be critical to develop tools and strategies to analyze (among other scenarios) signals that arrive coincidentally in detectors, longer signals that are in the presence of nonstationary noise or other shorter transients, as well as noisy, potentially correlated, coherent stochastic backgrounds. With these challenges in mind, we develop peregrine, a new sequential simulation-based inference approach designed to study broad classes of gravitational wave signal. In this work, we describe the method and implementation, before demonstrating its accuracy and robustness through direct comparison with established likelihood-based methods. Specifically, we show that we are able to fully reconstruct the posterior distributions for every parameter of a spinning, precessing compact binary coalescence using one of the most physically detailed and computationally expensive waveform approximants (SEOBNRv4PHM). Crucially, we are able to do this using only 2% of the waveform evaluations that are required in, e.g., nested sampling approaches. Finally, we provide some outlook as to how this level of simulation efficiency and flexibility in the statistical analysis could allow peregrine to tackle these current and future gravitational wave data analysis problems.

Present and upcoming neutrino experiments can have considerable sensitivity to dark sectors that interact feebly with the Standard Model (SM). We consider dark sectors interacting with the SM through irrelevant portals that are motivated on general principles. We derive bounds on such scenarios by considering decays of dark sector excitations inside the neutrino detector, placed downstream from the target. Our approach is model agnostic and applies to a wide range of dark sector models, both strongly and weakly coupled. In this approach, the dark sector is characterized by two scales; ${\mathrm{\Lambda }}_{\mathrm{UV}}$ (mass of mediators generating the portals) and ${\mathrm{\Lambda }}_{\mathrm{IR}}$ (mass gap of the dark sector). At intermediate energies, far away from these scales, the theory is approximately scale invariant. This allows the calculation of production rates independent of the threshold corrections, although some mild model-dependent assumptions are needed. We look at various dark sector production processes relevant at neutrino experiments such as meson decays, direct partonic production, and dark bremsstrahlung. We consider representative experiments from past (CHARM), present (ICARUS, NOvA, MicroBooNE), and upcoming future (DUNE-MPD), and compare their reach to existing bounds from high-energy experiments (LHC and LEP) and dedicated future LLP experiments (SHiP). We find that the upcoming DUNE-MPD can probe ${\mathrm{\Lambda }}_{\mathrm{UV}}$ in the TeV range, and ${\mathrm{\Lambda }}_{\mathrm{IR}}$ in the 0.1–1 GeV range, covering parts of parameter space currently inaccessible in high-energy experiments and fixed-target/beam dump experiments, and is comparable to future LLP experiments. In general, future neutrino experiments can be an efficient probe of dark sectors, providing complementary as well as a new reach in parameter space.

Particulate dark matter (DM), completely isolated from the Standard Model particle sector, can be produced in the early Universe from primordial black hole (PBH) evaporation. However, big bang nucleosynthesis (BBN) observations put an upper bound on the initial mass of PBH requiring the PBH to evaporate completely before the advent of BBN. DM particles in the mass range $\sim (1–{10}^9)\mathrm{GeV}$ cannot explain the observed relic abundance for an early matter dominated universe due to this BBN constraint. However, this assumes the presence of only one monochromatic PBH mass distribution in the early Universe. In this work, we explore the simple possibility of achieving the observed relic with DM masses from the above mentioned range for an early matter dominated era with two monochromatic evaporating PBH mass distributions and demonstrate that the fermionic DM masses consistent with BBN change slightly.

In this paper, we place new bounds on $CPT$ violation in the solar neutrino sector analyzing the results from solar experiments and KamLAND. We also discuss the sensitivity of the next-generation experiments DUNE and Hyper-Kamiokande, which will provide accurate measurements of the solar neutrino oscillation parameters. The joint analysis of both experiments will further improve the precision due to cancellations in the systematic uncertainties regarding the solar neutrino flux. In combination with the next-generation reactor experiment JUNO, the bound on $CPT$ violation in the solar sector could be improved by 1 order of magnitude in comparison with current constraints. The distinguishability among $CPT$-violating neutrino oscillations and neutrino nonstandard interactions in the solar sector is also addressed.

In the presence of QCD axion dark matter, atoms acquire time-dependent electric dipole moments. This effect gives rise to an oscillating current in a nuclear spin-polarized dielectric, which can resonantly excite an electromagnetic mode of a microwave cavity. We show that with existing technology such a “polarization haloscope” can explore orders of magnitude of new parameter space for QCD-coupled axions. If any cavity haloscope detects a signal from the axion-photon coupling, an upgraded polarization haloscope has the unique ability to test whether it arises from the QCD axion.

We apply a previously developed scheme to consistently include the improved saturation model for the unintegrated gluon distribution (UGD) in order to evaluate, in the framework of $k_t$ factorization, at small $x$ at the next-to-leading order in ${\alpha }_s$. We start the unintegrated gluon distribution with a parametrization of the deep inelastic structure function for electromagnetic scattering with protons, and then extract the color dipole cross section, which preserves its behavior success in a wide range of $k_t^2$ in comparison with the UGD models (M. Hentschinski, A. Sabio Vera, and C. Salas; I. P. Ivanov and N. N. Nikolaev; and G. Watt, A. D. Martin, and M. G. Ryskin). These results show that the geometric scaling holds for the improved saturation model in a wide kinematic region $r{Q}_s$, and is comparable with the Golec-Biernat-Wüsthof model. The unintegrated gluon distribution at low and high momentum transfer in a wide range of $x$ is considered.

Transition generalized parton distributions have emerged as a novel tool for studying the quantum chromodynamics (QCD) structure of resonances. They provide an integrated picture of the transition form factors and the transition parton distribution functions. In this study, we delve into the angular momentum (AM) properties for the $N\to \mathrm{\Delta }$ transition and its decomposition into the orbital angular momentum and the intrinsic spin in the context of the quark distribution functions. First, we explore the spin-flavor structures within the framework of both the overlap representations of the three-quark light-cone wave functions and the large $N_c$ limit of QCD. We then estimate the AM quark distribution functions for the $N\to \mathrm{\Delta }$ transition. Our analysis reveals a substantial flavor asymmetry present in both the orbital angular momentum and intrinsic spin components.