Particles with masses much larger than the inflationary Hubble scale, $H_I$, can be pair-produced nonadiabatically during inflation. Due to their large masses, the produced particles modify the curvature perturbation around their locations. These localized perturbations eventually give rise to localized signatures on the cosmic microwave background (CMB), in particular, pairwise hotspots (PHSs). In this work, we show that convolutional neural networks (CNNs) provide a powerful tool for identifying PHSs on the CMB. While for a given hotspot profile a traditional matched filter analysis is known to be optimal, a neural network learns to effectively detect the large variety of shapes that can arise in realistic models of particle production. Considering an idealized situation where the dominant background to the PHS signal comes from the standard CMB fluctuations, we show that a CNN can isolate the PHSs with $\mathcal{O}(10)\%$ efficiency even if the hotspot temperature is $\mathcal{O}(10)$ times smaller than the average CMB fluctuations. Overall, the CNN search is sensitive to heavy particle masses $M_0/H_I=\mathcal{O}(200)$, and constitutes one of the unique probes of very high energy particle physics.

A discrete space-time structure lying at about the Planck scale may become manifest in the form of very small violations of the conservation of the matter energy-momentum tensor. In order to include such kind of violations, forbidden within the general relativity framework, the theory of unimodular gravity seems as the simplest option to describe the gravitational interaction. In the cosmological context, a direct consequence of such violation of energy conservation might be heuristically viewed a “diffusion process of matter (both dark and ordinary)” into an effective dark energy term in Einstein’s equations, which leads under natural assumptions to an adequate estimate for the value of the cosmological constant. Previous works have also indicated that these kinds of models might offer a natural scenario to alleviate the Hubble tension. In this work, we consider a simple model for the cosmological history including a late time occurrence of such energy violation and study the modifications of the predictions for the anisotropy and polarization of the cosmic microwave background (CMB). We compare the model’s predictions with recent data from the CMB, supernovae type Ia, cosmic chronometers and baryon acoustic oscillations. The results show the potential of this type of model to alleviate the Hubble tension.

Gravitational-wave observations have the capability to strongly differentiate between different assumptions for how binary compact objects form. The agreement of observations to different models of the evolution of massive stellar binaries leading to the formation of compact binaries can be characterized by a Bayesian marginal likelihood. In this work, we show how to carefully interpolate this marginal likelihood between choices of binary evolution model parameters, enabling the analysis of their posterior distributions between expensive binary evolution simulations. Using the startrack binary evolution code, we compare one- and four-dimensional binary evolution models to the compact binary mergers reported in recent gravitational-wave observing runs, considering merger detection rates and mass distributions. We demonstrate that the predicted detection rates and mass distribution of simulated binaries can be effective in constraining binary evolution formation. We first consider a one-dimensional model, studying the effect of supernova (SN) kick velocity (drawn from a Maxwellian with dispersion ${\sigma }_{\mathrm{eff}}$) on the simulated population of compact binary mergers, and find support for substantial SN recoil kicks. We follow this up with a four-dimensional study of ${\sigma }_{\mathrm{eff}}$, mass transfer efficiency ($f_a$), the efficiency of angular momentum depletion from ejected material ($\beta$) during Roche-lobe accretion, and an observation-driven reduction in the mass-loss rate estimated from stellar wind models ($f_{\mathrm{wind}1}$). Of those four formation parameters we investigated, we find that three of them (${\sigma }_{\mathrm{eff}}$, $f_a$, and $f_{\mathrm{wind}1}$) can be efficiently limited by these observational comparisons. After initially sampling from a uniform prior in the space of these parameters, we refined our sampling by iteratively estimating a Bayesian likelihood for each simulation, fitting that likelihood to a parametric model (a truncated Gaussian) in the four-dimensional formation parameter space, and sampling directly from that Gaussian in order to propose new simulations in a way that is informed by previous simulations. Our maximum likelihood simulation (K0559) has parameters ${\sigma }_{\mathrm{eff}}=108.3\mathrm{km}/\mathrm{s}$ (indicating substantial SN recoil kicks), $f_a=0.922$ (indicating efficient mass transfer), and $f_{\mathrm{wind}1}=0.328$ (indicating support for reduced wind-driven mass loss). Note that our estimates are only valid within one particular model of compact binary formation through isolated binary evolution and do not yet take into account the impact of other uncertain pieces of stellar physics and binary evolution.

The flavor composition of high-energy neutrinos carries important information about their birth. However, the two most common production scenarios, $pp$ (hadronuclear) and $p\gamma$ (photohadronic) collisions, lead to the same flavor ratios when neutrinos and antineutrinos cannot be distinguished. The Glashow resonant interaction ${\overline{\nu }}_e+e^{-}\to W^{-}$ becomes a window to differentiate the antineutrino contribution from the total diffuse neutrino flux, thus lifting this degeneracy. We examine the power of Glashow resonant events in measuring the fraction of the ${\overline{\nu }}_e$ flux with current IceCube data, and produce projected sensitivities based on the combined exposure of planned Cherenkov neutrino telescopes around the globe. We find that $pp$ and $p\gamma$ can be distinguished at a $2\sigma$ significance level in the next decades, in both an event-wise analysis and a more conservative statistical analysis, even with pessimistic assumptions on the spectral index of the astrophysical flux. Finally, we consider the sensitivity of future experiments to mixed production mechanisms.

We study a novel six-dimensional gauge theory compactified on the $T^2/{\mathbb{Z}}_3$ orbifold utilizing the diagonal embedding method. The bulk gauge group is $G\times G\times G$, and the diagonal part $G^{\mathrm{diag}}$ remains manifest in the effective four-dimensional theory. Further spontaneous breaking of the gauge symmetry occurs through the dynamics of the zero modes of the extradimensional components of the gauge field. We apply this setup to the $SU(5)$ grand unified theory and examine the vacuum structure determined by the dynamics of the zero modes. We find bulk matter contents that radiatively induce spontaneous breakings of the unified symmetry $G^{\mathrm{diag}}\cong SU(5)$ down to $SU(3)\times SU(2)\times U(1)$ at the global minima of the one-loop effective potential for the zero modes. This spontaneous breaking provides notable features such as a realization of the doublet-triplet splitting without a fine tuning and a prediction of light adjoint fields.

We explore the pair production of third-generation scalar leptoquark at the Large Hadron Collider to next-to-leading order accuracy in QCD, matched to parton shower for a precise probing of the stemming model. We propose to tag two boosted toplike fatjets produced from the decay of heavy leptoquarks in association with notably large missing transverse momentum and consider them as the potential signal. Such a signal demonstrates the capability of a robust discovery prospect in the multivariate analysis with different high-level observables, including jet substructure variables. Various scalar leptoquark models predict different chirality of the top quark appearing from the decay of the leptoquark carrying the same electromagnetic charge. We make use of the polarization variables sensitive to the top-quark polarization in order to identify the underlying theory.

Finite-volume pionless effective field theory (${\mathrm{FVEFT}}_{\cancel{\pi }}$) at next-to-leading order (NLO) is used to analyze the two-nucleon lattice QCD spectrum of Ref. [S. Amarasinghe et al., Phys. Rev. D 107, 094508 (2023)], performed at quark masses corresponding to a pion mass of approximately 800 MeV. Specifically, the effective theory is formulated in finite volume, and variational sets of wave functions are optimized using differential programming. Using these wave functions projected to the appropriate finite-volume symmetry group, variational bounds from ${\mathrm{FVEFT}}_{\cancel{\pi }}$ are obtained for the ground state, as well as excited states. By comparison with the lattice QCD GEVP spectrum, different low energy constants (LECs) are constrained. Relativistic corrections are incorporated, allowing for the extractions of NLO LECs, as well as the leading $s-d$-wave mixing term in the deuteron channel.

We present measurements of the cross section for antineutrino charged-current quasielasticlike scattering on hydrocarbon using the medium energy NuMI wide-band neutrino beam peaking at antineutrino energy $⟨E_{\overline{\nu }}⟩\sim 6\mathrm{GeV}$. The measurements are presented as a function of the longitudinal momentum ($p_{||}$) and transverse momentum ($p_T$) of the final state muon. This work complements our previously reported high statistics measurement in the neutrino channel and extends the previous antineutrino measurement made in a low energy beam at $⟨E_{\overline{\nu }}⟩\sim 3.5\mathrm{GeV}$ out to $p_T$ of $2.5\mathrm{GeV}/\mathrm{c}$. Current theoretical models do not completely describe the data in this previously unexplored high $p_T$ region. The single differential cross section as a function of four-momentum transfer ($Q_{QE}^2$) now extends to $4{\mathrm{GeV}}^2$ with high statistics. The cross section as a function of $Q_{QE}^2$ shows that the tuned simulations developed by the MINERvA Collaboration that agreed well with the low energy beam measurements do not agree as well with the medium energy beam measurements. Newer neutrino interaction models such as the GENIE v3 tunes are better able to simulate the high $Q_{QE}^2$ region.

In the present paper we study the singularity structure of the exterior field of neutron stars with the aid of the four-parameter exact solution of the Einstein-Maxwell equations. The complete analysis of this problem in the generic case becomes possible due to the implementation of the novel analytical approach to the resolution of the singularity condition, and it shows the absence of the ring singularities off the symmetry axis in the positive mass case, as well as the possibility of the removal of the ring singularity by a strong magnetic field in the negative mass case. The solution takes an extraordinarily simple form in the equatorial plane, very similar to that of the Kerr solution, which makes it most suitable for astrophysical applications as the simplest model of a rotating magnetized deformed mass and hence of the exterior of a neutron star. It also provides a nontrivial example confirming a recent claim that the $\phi$ component of the electromagnetic four-potential has features inconsistent with the intrinsic properties of the electrovac metric, while the magnetic field is represented correctly by the $t$ component of the dual electromagnetic four-potential.

This work provides gravitational-wave energy and angular momentum asymptotic fluxes from a spinning body moving on generic orbits in a Kerr spacetime up to the linear-in-spin approximation. To achieve this, we have developed a new frequency-domain Teukolsky equation solver that calculates asymptotic amplitudes from generic orbits of spinning bodies with their spin aligned with the total orbital angular momentum. However, the energy and angular momentum fluxes from these orbits in the linear-in-spin approximation are appropriate for adiabatic models of extreme-mass-ratio inspirals even for spins nonaligned to the orbital angular momentum. To check the newly obtained fluxes, they are compared with already known frequency-domain results for equatorial orbits and with results from a time-domain Teukolsky equation solver called Teukode for off-equatorial orbits. The spinning-body framework of our work is based on the Mathisson-Papapetrou-Dixon equations under the Tulczyjew-Dixon spin supplementary condition.

A simple procedure is given to construct curved, non-self-dual (complexified) Kähler metrics on space-time in terms of deformations of holomorphic quadric surfaces in flat twistor space, as a variation of Penrose’s original twistor construction. Imposing Lorentzian reality conditions, astrophysically relevant space-times such as the standard (non-self-dual) Schwarzschild, Kerr, and Plebański-Demiański metrics, among others, are derived as examples of the construction, and an interpretation of the associated space-time singularities is provided.

We calculate the high-order post-Newtonian (PN) expansion of the energy and angular momentum fluxes onto the horizon of a nonspinning black hole primary in eccentric-orbit extreme-mass-ratio inspirals. The first-order black hole perturbation theory calculation uses Mathematica and makes an analytic expansion of the Regge-Wheeler-Zerilli functions using the Mano-Suzuki-Takasugi formalism. The horizon absorption, or tidal heating and torquing, is calculated to 18PN relative to the leading horizon flux (i.e., 22PN order relative to the leading quadrupole flux at infinity). Each PN term is a function of eccentricity $e$ and is calculated as a series to $e^{10}$. A second expansion, to 10PN horizon-relative order (or 14PN relative to the flux at infinity), is computed deeper in eccentricity to $e^{20}$. A number of resummed closed-form functions are found for the low PN terms in the series. Using a separate Teukolsky perturbation code, numerical comparisons are made to test how accurate the PN expansion is when extended to a close $p=10$ orbit. We find that the horizon absorption expansion is not as convergent as a previously computed infinity-side flux expansion. However, given that the horizon absorption is suppressed by 4PN, useful results can be obtained even with an orbit as tight as this for $e\lesssim 1/2$. Combining the present results with our earlier expansion of the fluxes to infinity makes the knowledge of the total dissipation known to 19PN for eccentric-orbit nonspinning extreme-mass-ratio inspirals.

The evaporation of primordial black holes provides a promising dark matter production mechanism without relying on any nongravitational interactions between the dark sector and the Standard Model. In theories of “large” extra dimensions (LEDs), the true scale of quantum gravity, $M_{*}$, could be well below the Planck scale, thus allowing for energetic particle collisions to produce microscopic black holes in the primordial plasma at temperatures as low as $T\gtrsim 100\mathrm{GeV}$. Additionally, LEDs modify the relationship between black hole mass, radius, and temperature, allowing microscopic black holes to grow to macroscopic sizes in the early Universe. In this work we study three scenarios for the production of dark matter via LED black holes: (1) delayed evaporating black holes (DEBHs) which grow to macroscopic sizes before ultimately evaporating, (2) instantly evaporating black holes (IEBHs) which immediately evaporate, and (3) stable black hole relics with a mass $M_{*}$ known as Planckeons. For a given reheating temperature, $T_{\mathrm{RH}}$, we show that DEBHs produce significantly less dark matter than both IEBHs and Planckeons. IEBHs are able to produce the observed relic abundance of dark matter so long as the reheating scale is in the range ${10}^{-2}\le T_{\mathrm{RH}}/M_{*}\le {10}^{-1}$. We calculate the average speed for the resulting dark matter and show that it would be sufficiently cold for all dark matter masses $m_{dm}\gtrsim {10}^{-4}\mathrm{GeV}$. This mechanism is viable for any scale of quantum gravity in the range ${10}^4\mathrm{GeV}\le M_{*}\le M_{\mathrm{Pl}}$ and for any number of LEDs.

We construct a numerical model of steady-state, general relativistic (GR) super-Eddington accretion flows in an optically thick, advection-dominated regime, motivated by tidal disruption events wherein super-Eddington accretion assumes a pivotal role. Our model takes into account the loss of angular momentum due to radiation and the scale-height derivative in the basic equations of the GR slim disk. For comparison purposes, we also provide a new analytical solution for a radiation-pressure-dominant GR slim disk, which neglects the angular momentum loss due to radiation and the scale-height derivative. We find that the radiation pressure enhances by incorporating the scale-height derivative into the basic equations. As a result, the surface density near the disk’s inner edge decreases, whereas the disk temperature and scale-height increase, brightening the disk spectrum in the soft x-ray wave band. Notably, an extremely high-mass accretion rate significantly enhances the effect of the scale-height derivative, affecting the entire disk. In contrast, the inclusion of the radiation-driven angular momentum loss only slightly influences the disk surface density and temperature compared with the case of the scale-height derivative inclusion. The x-ray luminosity increases significantly due to scale-height derivative for $\dot{M}/{\dot{M}}_{\mathrm{Edd}}\gtrsim 2$, where ${\dot{M}}_{\text{Edd}}$ is the Eddington accretion rate with 0.1 energy conversion efficiency. In addition, the increment is higher for the nonspinning black hole than the spinning black hole case, resulting in a one order of magnitude difference for $\dot{M}/{\dot{M}}_{\mathrm{Edd}}\gtrsim 100$. We conclude that incorporating the scale-height derivative into a GR slim-disk model is crucial as it impacts the disk structure and its resultant spectrum, particularly on a soft x-ray wave band.

We study the blackbody properties and the thermodynamic equilibrium quantities of a photon gas in the framework of nonlinear electrodynamics. In this vein, we take into account the photon propagation in a uniform external magnetic field in the weak field approximation, where an angular anisotropic energy density distribution appears in the frequency spectrum. The special case when the photon propagates perpendicular to the background magnetic field is also discussed, which allows us to probe the strong field regime. We then derive a modified blackbody spectral distribution and the Stefan-Boltzmann law in this situation. Considerations about Wien’s displacement law and the Rayleigh-Jeans formula are contemplated as well. Deviations from the thermodynamic quantities at thermal equilibrium such as energy, pressure, entropy, and heat capacity densities are obtained from the Helmholtz free energy. As an application, we study three nonlinear electrodynamics, namely, the Euler-Heisenberg, the generalized Born-Infeld, and the logarithmic electrodynamics. Possible implications on stellar systems with strong magnetic fields such as magnetars are discussed.

Gravitational-wave black-hole spectroscopy provides a unique opportunity to test the strong-field regime of gravity and the nature of the final object formed in the aftermath of a merger. Here we investigate the prospects for black-hole spectroscopy with third-generation gravitational-wave detectors, in particular the Einstein Telescope in different configurations, possibly in combination with Cosmic Explorer. Using a state-of-the-art population model for stellar-origin binary black holes informed by LIGO-Virgo-KAGRA data, we compute the average number of expected events for precision black-hole spectroscopy using a Fisher-matrix analysis. We perform our analysis on the dominant mode (2, 2, 0) and a set of subdominant modes $[(3,3,0),(2,1,0),(4,4,0)]$ using amplitude and phase fits corresponding to the aligned spin configurations. We find that the Einstein Telescope will measure two independent quasinormal modes within $\mathcal{O}(1)\%$ (resp $\mathcal{O}(10)\%$) relative uncertainty for at least $\mathcal{O}(1)$ [resp $\mathcal{O}(500)$] events per year, with similar performances in the case of a single triangular configuration or two L-shaped detectors with same arm length. A 15-km arm-length configuration would improve rates by roughly a factor of two relative to a 10-km arm-length configuration. When operating in synergy with Cosmic Explorer the rates will improve significantly, reaching few-percent accuracy for $\mathcal{O}(100)$ events per year.

We construct an efficient frequency domain waveform for generic circular compact object binaries that include neutron stars. The orbital precession is solved on the radiation reaction timescale (and then transformed to the frequency domain), which is used to map the nonprecessional waveform from the source frame of the binary to the lab frame. The treatment of orbital precession is different from that for precessional binary black holes, as ${\chi }_{\mathrm{eff}}$ is no longer conserved due to the spin-induced quadrupole moments of neutron stars. We show that the new waveform achieves $\le {10}^{-4}$ difference in terms of the one minus the overlap compared with waveforms generated by numerically evolved precession for neutron star-black hole systems for $\ge 90\%$ configurations with component mass/spin magnitude assumed in the analysis and randomized initial spin directions. We expect this waveform to be useful to test the nature of the mass-gap objects similar to the one discovered in GW 190814 by measuring their spin-induced quadrupole moments, as it is possible that these mass-gap objects are rapidly spinning. It is also applicable for the tests of black hole mimickers in precessional binary black hole events, if the black hole mimicker candidates have nontrivial spin-induced quadrupole moments.

We derive and investigate several hydrodynamic formalisms that emerge from a system of classical, ultrarelativistic scalar particles self-interacting via a quartic potential. The specific form of the total cross-section enables the analytical computation of all transport coefficients that appear in Navier-Stokes (NS), Bemfica-Disconzi-Noronha-Kovtun (BDNK), and second-order transient hydrodynamic theories. We solve all these formalisms in a Bjorken flow scenario and show that NS and BDNK theories display unphysical features when gradients become sufficiently large. This implies that these hydrodynamic approaches may not be suitable to describe the early stages of heavy ion collisions.

We study the deeply virtual Compton scattering process $e^{-}N\to e^{-}\gamma \pi N$ involving the transition between a nucleon and a nucleon resonance in the $\pi N$ system, within the framework of generalized parton distributions (GPDs). For the four lowest-lying nucleon resonances, $\mathrm{\Delta }(1232)$, $P_{11}(1440)$, $D_{13}(1520)$, and $S_{11}(1535)$, we express the deeply virtual Compton scattering amplitude in the Bjorken limit in terms of corresponding nucleon-to-resonance GPDs. Building upon the knowledge of the well studied electromagnetic nucleon-to-resonance transition form factors, which map the quark charge densities in transverse position space, the corresponding GPDs will open the prospect to also access the longitudinal momentum distributions of quarks in the transition. We provide estimates for cross sections and beam-spin asymmetries in the first and second $\pi N$ resonance regions in the kinematics of forthcoming CLAS12 data from Jefferson Lab.