Single field models of inflation capable of producing primordial black holes usually require a significant departure from the standard, perturbative slow-roll regime. In fact, in many of these scenarios, the size of the slow-roll parameter $|\eta |$ becomes larger than one during a short phase of inflationary evolution. In order to develop an analytical control on these systems, we explore the limit of $|\eta |$ large, and promote $1/|\eta |$ to a small quantity to be used for perturbative expansions. Formulas simplify, and we obtain analytic expressions for the two and three point functions of curvature fluctuations, which share some of the features found in realistic inflationary models generating primordial black holes. We study one-loop corrections in this framework: we discuss criteria for adsorbing ultraviolet divergences into the available parameters, leaving log-enhanced infrared contributions of controllable size.

We study the cross-correlation between the stochastic gravitational-wave background (SGWB) generated by binary black hole mergers across the Universe and the distribution of galaxies across the sky. We use the anisotropic SGWB measurement obtained using data from the third observing run (O3) of Advanced LIGO detectors and galaxy overdensity obtained from the Sloan Digital Sky Survey spectroscopic catalog. We compute, for the first time, the angular power spectrum of their cross-correlation. Instead of integrating the SGWB across frequencies, we analyze the cross-correlation in 10-Hz-wide SGWB frequency bands to study the frequency dependence of the cross-correlation angular power spectrum. Finally, we compare the observed cross-correlation to the spectra predicted by astrophysical models. We apply a Bayesian formalism to explore the parameter space of the theoretical models, and we set constraints on a set of (effective) astrophysical parameters describing the galactic process of gravitational-wave (GW) emission. Parametrizing with a Gaussian function the astrophysical kernel describing the local process of GW emission at galactic scales, we find the 95% upper limit on kernel amplitude to be $2.88\times {10}^{-32}\mathrm{erg}{\mathrm{cm}}^{-3}{\mathrm{s}}^{-1/3}$ when ignoring the shot noise in the GW emission process and $2.52\times {10}^{-32}\mathrm{erg}{\mathrm{cm}}^{-3}{\mathrm{s}}^{-1/3}$ when the shot noise is included in the analysis. As the sensitivity of the LIGO-Virgo-KAGRA network improves, we expect to be able to set more stringent bounds on this kernel function and constrain its parameters.

We present a convolutional neural network, designed in the autoencoder configuration that can detect and denoise astrophysical gravitational waves from merging black hole binaries, orders of magnitude faster than the conventional matched-filtering based detection that is currently employed at advanced LIGO (aLIGO). The neural-net architecture is such that it learns from the sparse representation of data in the time-frequency domain and constructs a nonlinear mapping function that maps this representation into two separate masks for signal and noise, facilitating the separation of the two, from raw data. This approach is the first of its kind to apply machine learning based detection/denoising of gravitational waves from binary black holes in the 2D representation of gravitational wave data. We applied our formalism to the first gravitational wave event detected, GW150914, successfully recovering the signal at all three phases of coalescence at both detectors. This method is further tested on the gravitational wave data from the second observing run ($O2$) of aLIGO, reproducing all binary black hole mergers detected in $O2$ at both the aLIGO detectors. This method can also interpolate and extrapolate between modeled templates and explore gravitational waves that are not present in the template bank of signals used in the matched-filtering detection pipelines. Faster and efficient detection schemes, such as this method, will be instrumental as ground based detectors reach their design sensitivity, likely to result in several hundreds of potential detections in a few months of observing runs.

If “dark quarks” from a confining hidden sector are produced at the LHC, they will shower and hadronize to dark sector hadrons, which may decay back to Standard Model particles within the detector, possibly resulting in a collimated spray of particles resembling a QCD jet. In this work we address scenarios in which dark hadrons decay with a measurable small displacement, such that the relevant background is dominated by heavy-flavor jets. Since dark sector parameters are largely unconstrained, and the precise properties of a dark QCD-like theory are difficult to compute or simulate reliably in any case, model-independent, data-based searches for such scenarios are desirable. We explore a search strategy employing weakly supervised machine learning to search for anomalous jets with displaced vertices. The method is tested on several toy signals, demonstrating the feasibility of such a search. Our approach has potential to outperform simple cut-based methods in some cases and has the advantage of being more model independent.

We demonstrate that ionization of ${\mathrm{H}}_2$ by dark matter in dense molecular clouds can provide strong constraints on the scattering strength of dark matter with electrons. Molecular clouds have high UV-optical attenuation, shielding them from ultraviolet and x-ray photons. Their chemical and thermal evolution are governed by low-energy cosmic rays. Dark matter with mass $\gtrsim 4\mathrm{MeV}$ can ionize ${\mathrm{H}}_2$, contributing to the observed ionization rate. We require that the dark matter-induced ionization rate of ${\mathrm{H}}_2$ not exceed the observed cosmic-ray ionization rate ${\zeta }^{{\mathrm{H}}_2}$, in diffuse molecular clouds as well as dense molecular clouds such as L1551 in the Taurus cloud complex. This allows us to place strong constraints on the dark matter-electron cross section ${\overline{\sigma }}_e$ that complement existing astrophysical constraints and probe the strongly interacting parameter space where terrestrial and underground direct-detection experiments lose sensitivity. We show that constraints from molecular clouds combined with planned balloon and satellite-based experiments would strongly constrain the fractional abundance of dark matter that interacts strongly with electrons. We comment on future modeling and observational efforts that may improve our bounds.

We assess the capabilities of the CMS and LHCb searches for low-$p_T$ displaced dimuon pairs to discover hidden valley models. To do so, we develop a new benchmark model featuring a light dark photon with dark flavor-violating couplings, which realizes a range of dimuon vertex topologies. We show that the data scouting techniques used in these searches provide unique sensitivity and we make some additional suggestions to further extend the scope of future experimental searches.

We examine the parameter space region of the inverse seesaw model that is consistent with neutrino oscillation data. We focus on the correlation between the current limits from the search of the $\mu \to e\gamma$ lepton flavor violating decay and the nonstandard effects associated with the presence of new heavy neutrino states. Unlike what we would expect from an inverse seesaw model, we present a structure for the neutrinos mass matrices in which the rates of charged lepton flavor-violating processes are negligible. Additionally, we provide a model based on symmetries for such a scenario.

The proposed work is an extension of the Standard Model, where we have introduced two gauge symmetries, i.e., $U(1{)}_{B-L}$ and $U(1{)}_{L_e-L_{\mu }}$ to study neutrino phenomenology, muon, and electron ($g-2$) as well as leptogenesis using the inverse seesaw mechanism. For this purpose, we have included three right-handed neutrinos $N_{R_i}$, three neutral fermions $S_{L_i}$ ($i=1$, 2, 3), and two scalar singlet bosons (${\chi }_1$ and ${\chi }_2$). We get a definite structure for the neutrino mass matrix due to the aforementioned gauge symmetries. Thus, our model is able to predict the neutrino oscillation results, which are in accordance with the experimental data and is inclined towards normal ordering. The outcomes comprise the active neutrino masses, mixing angles, mass-squared differences, $CP$-violating phase, etc. Moreover, since the extended gauge symmetries are local, there are corresponding gauge bosons, denoted as $Z_{B-L}$ and $Z_{e\mu }$. Of these, mass of $Z_{B-L}$ is $\mathcal{O}(\mathrm{TeV})$ range to satisfy the collider constraint, while the mass of $Z_{e\mu }$ is in the MeV range, making it feasible to account for current electron and muon ($g-2$) results via neutral current interactions. Furthermore, our model is able to account for leptogenesis, which can demonstrate the matter-antimatter asymmetry of the Universe. Additionally, we have carried out the prospect of probing our model in the context of upcoming long-baseline experiments; DUNE, T2HK, and T2HKK, at a confidence level of $5\sigma$. From the result it is clear that, our model can be tested in its $3\sigma$ CL with $5\sigma$ allowed region of DUNE, T2HK, and T2HKK.

In this study, we extend the HAL QCD method to a case where a total momentum of a two-particle system is nonzero and apply it to the $I=2$ S-wave $\pi \pi$ scattering in order to confirm its validity. We derive a fundamental relation of an energy-independent nonlocal potential defined in the center of mass frame with Nambu-Bethe-Salpeter wave functions in a laboratory frame. Based on the relation, we propose the time-dependent method to extract potentials, often used in practice for the HALQCD method in the center of mass frame. For numerical simulations in the $I=2$ $\pi \pi$ system, we employ ($2+1$)-flavor gauge configurations on a ${32}^3\times 64$ lattice at the lattice spacing $a\approx 0.0907\mathrm{fm}$ and $m_{\pi }\approx 700\mathrm{MeV}$. Both effective leading order (LO) potentials and corresponding phase shifts obtained in laboratory frames agree with those obtained in the center-of-mass frame by the conventional HAL QCD method within somewhat larger statistical errors. In addition, we observe a consistency in scattering phase shifts between ours and results by the finite-volume method as well. The HAL QCD method with nonzero total momenta, established in this study, brings more flexibility to the HAL QCD method, which enables us to handle systems having the same quantum numbers with a vacuum or to access energy regions prohibited in the center of mass frame.

We analyze the two purely isospin-violating decays ${\mathrm{\Lambda }}_b\to {\mathrm{\Sigma }}^0\varphi$ and ${\mathrm{\Lambda }}_b\to {\mathrm{\Sigma }}^{0}J/\psi$, proceeding merely via the exchange topologies, in the framework of the perturbative QCD approach. Assuming ${\mathrm{\Sigma }}^0$ baryon belongs to the idealized isospin triplet with quark components of $usd$, the branching ratios of the two decay modes are predicted to be tiny, of the order ${10}^{-8}-{10}^{-9}$, leading to difficulty in observing them. We then extend our study to include the $\mathrm{\Sigma }-\mathrm{\Lambda }$ mixing. It is found that the mixing has significant effect on the ${\mathrm{\Lambda }}_b\to \mathrm{\Sigma }$ decays, especially it can greatly increase the rate of the $J/\psi$ process, by as much as two orders of magnitude, yield ${10}^{-7}$, which should be searchable in the future. We also estimate a set of asymmetry observables with and without the mixing effect, which will be tested in coming experiments.

A measurement is presented for the electroweak production of a $W$ boson, a photon ($\gamma$), and two jets (j) in proton-proton collisions. The leptonic decay of the $W$ boson is selected by requiring one identified electron or muon and large missing transverse momentum. The two jets are required to have large invariant dijet mass and large separation in pseudorapidity. The measurement is performed with the data collected by the CMS detector at a center-of-mass energy of $13\mathrm{TeV}$, corresponding to an integrated luminosity of $138{\mathrm{fb}}^{-1}$. The cross section for the electroweak $W\gamma \mathrm{jj}$ production is ${23.5}_{-4.7}^{+4.9}\mathrm{fb}$, whereas the total cross section for $W\gamma \mathrm{jj}$ production is $113\pm 13\mathrm{fb}$. Differential cross sections are also measured with the distributions unfolded to the particle level. All results are in agreement with the standard model expectations. Constraints are placed on anomalous quartic gauge couplings (aQGCs) in terms of dimension-8 effective field theory operators. These are the most stringent limits to date on the aQGCs parameters $f_{\mathrm{M},2–5}/{\mathrm{\Lambda }}^4$ and $f_{\mathrm{T},6–7}/{\mathrm{\Lambda }}^4$.

Topological duality defects arise as codimension one generalized symmetry operators in quantum field theories (QFTs) with a duality symmetry. Recent investigations have shown that in the case of 4D $\mathcal{N}=4$ Super Yang-Mills (SYM) theory, an appropriate choice of (complexified) gauge coupling and global form of the gauge group can lead to a rather rich fusion algebra for the associated defects, leading to examples of noninvertible symmetries. In this work we present a top down construction of these duality defects which generalizes to QFTs with lower supersymmetry, where other 0-form symmetries are often present. We realize the QFTs of interest via D3-branes probing $X$ a Calabi-Yau threefold cone with an isolated singularity at the tip of the cone. The IIB duality group descends to dualities of the 4D worldvolume theory. Nontrivial codimension one topological interfaces arise from configurations of 7-branes “at infinity” which implement a suitable $SL(2,\mathbb{Z})$ transformation when they are crossed. Reduction on the boundary topology $\partial X$ results in a 5D symmetry topological field theory. Different realizations of duality defects, such as the gauging of 1-form symmetries with certain mixed anomalies and half-space gauging constructions, simply amount to distinct choices of where to place the branch cuts in the 5D bulk.

In this work we investigate the anisotropic conformal structure of the gravitational field incorporating dark gravity in a generalized Lagrange geometric framework on the Lorentz tangent bundle and we present two applications: the anisotropic conformal Minkowski spacetime and the anisotropic conformal Friedmann–Lemaître–Robertson–Walker cosmology. In the first application, the conformal factor induces an anisotropic conformal de-Sitter-like space with extra curvature which causes extra gravity and allows for Sasaki-type Finsler-like structures which could potentially describe certain gravitational phenomena in a more extended form. The cosmological properties of the model are also studied using a Friedmann–Lemaître–Robertson–Walker metric structure for the underlying base manifold in the second application, where we derive generalized Friedmann-like equations for the horizontal subspace of the Lorentz tangent bundle spacetime that reduce under certain conditions to those given by Triantafyllopoulos and Stavrinos [Classical Quantum Gravity 35, 085011 (2018)] as well as those of general relativity.

Being arguably the most massive binary black hole merger event observed to date, GW190521 deserves special attention. The exceptionally loud ringdown of this merger makes it an ideal candidate to search for gravitational wave echoes, a proposed smoking gun for the quantum structure of black hole horizons. We perform a multipronged search for echoes via two well-established and independent pipelines; a template-based search for stimulated emission of Hawking radiation, or Boltzmann echoes, and the model-agnostic coherent WaveBurst (cwb) search. Stimulated Hawking radiation from the merger is proposed to lead to postmerger echoes at horizon mode frequency of $\sim 50\mathrm{Hz}$ (for quadrupolar gravitational radiation), repeating at intervals of $\sim 1$ second, due to partial reflection off Planckian quantum structure of the horizon. An analysis using dynamic nested sampling yields a Bayesian evidence of $8_{-2}^{+4}$ (90% confidence level) for this signal following GW190521, carrying an excess of $6_{-5}^{+10}\%$ in gravitational wave energy, relative to the main event (consistent with the predicted amplitude of Boltzmann echoes). The “look-elsewhere” effect is estimated by using general relativity (plus Boltzmann echoes) injections in real data, before and after the event, giving a false (true) positive detection probability for higher Bayes factors of ${1.5}_{-0.9}^{+1.2}\%$ ($35\pm 7\%$). Similarly, the reconstructed waveform of the first echo in cwb carries an energy excess of ${13}_{-7}^{+16}\%$. While the current evidence for stimulated Hawking radiation does not reach the gold standard of $5\sigma$ (or p-value $<3\times {10}^{-7}$), our findings are in line with predictions for stimulated Hawking radiation at current detector sensitivities. The next generation of gravitational wave observatories can thus draw a definitive conclusion on the quantum nature of black hole horizons.

We discuss the equilibrium conditions of the gravitational collapse of a spherically symmetric matter cloud. We analyze the spinor structure of a general collapsing spacetime and redefine the equilibrium conditions by using Cartan scalars. We qualitatively investigate the equilibrium configuration of a two-fluid system consisting of a dustlike fluid and a fluid with a negative equation of state. We use our results to investigate certain cosmological scenarios where dark energy can cluster inside the overdense regions of dark matter and together reaches a stable configuration. We compare the outcomes of our work with existing work where the virialization technique is used to stabilize the two-fluid system.

We analyze the restricted phase-space thermodynamics (RPST) of Kerr-Sen-AdS black holes with the central charge $C$ and its conjugate chemical potential $\mu$ but exclude the familiar $PdV$ term in the first law of black hole thermodynamics. That gives rise to a new perspective on the thermodynamics of black holes. Using the scaling properties, we investigate the first law and the corresponding Euler formula. Such formalism has its beauty; for example, the mass is considered to be a homogeneous function of the extensive variables in the first order. In contrast, the intensive variables are of zeroth order. Because of the complicated expressions of the metric, we numerically calculate the critical values of the thermodynamic quantities. We find the phase-transition behavior of the free energy and other thermodynamic conjugate variables that appear in the first law. The RPST of the Kerr-Sen-AdS black holes is like that of the Reissner-Nordström-AdS and the Kerr-AdS black holes. Such notions of the phase transition behavior show that there should be some underlying universality in the RPST formalism.

We construct and explore the physical properties of scalaroca stars: spherically symmetric solitonic solutions made of a complex scalar field $\mathrm{\Phi }$ and a complex Proca field $A^{\mu }$. We restrict our attention to configurations in which both fields are in the fundamental state and possess an equal mass, focusing on the cases when (i) the scalar and Proca fields are (nonlinearly) superimposed and do not interact with each other; and (ii) the scalar and Proca fields interact through the term $\alpha |\mathrm{\Phi }{|}^2{A}^{\mu }{A}_{\mu }$. The solutions are found numerically for the noninteracting case ($\alpha =0$) as well as for both signs of the interaction coupling constant $\alpha$. While pure (i.e., single–field) Proca/scalar boson stars are the most/least massive for weakly interacting fields, one can obtain more massive solutions for a sufficiently strong interaction. Besides, in the latter case, solutions can be either in a synchronized state—in which both fields have the same frequency—or in a nonsynchronized state. In addition, we observe that the coupling between the two fields allows solitonic solutions with a real scalar field. We further comment on the possibility of spontaneous scalarization and vectorization of the interacting solitonic solution.

The lack of a well-established solution for the gravitational energy problem might be one of the reasons why a clear road to quantum gravity does not exist. In this paper, the gravitational energy is studied in detail with the help of the teleparallel approach that is equivalent to general relativity. This approach is applied to the solutions of the Einstein-Maxwell equations known as $pp$-wave spacetimes. The quantization of the electromagnetic energy is assumed and it is shown that the proper area measured by an observer must satisfy an equation for consistency. The meaning of this equation is discussed and it is argued that the spacetime geometry should become discrete once all matter fields are quantized, including the constituents of the frame; it is shown that for a harmonic oscillation with wavelength ${\lambda }_0$, the area and the volume take the form $A=4(N+1/2)l_p^2/n$ and $V=2(N+1/2)l_p^2{\lambda }_0$, where $N$ is the number of photons, $l_p$ the Planck length, and $n$ is a natural number associated with the length along the $z$-axis of a box with cross-sectional area $A$. The localization of the gravitational energy problem is also discussed. The stress-energy tensors for the gravitational and electromagnetic fields are decomposed into energy density, pressures, and heat flow. The resultant expressions are consistent with the properties of the fields, thus indicating that one can have a well-defined energy density for the gravitational field regardless of the principle of equivalence.

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.