Black hole solutions in the braneworld scenario are predicted to possess a tidal charge parameter, leaving imprints in the quasinormal spectrum. We conduct an extensive computation of such a spectrum, and use it to construct a waveform model for the ringdown relaxation regime of binary black hole mergers observed by LIGO and Virgo. Applying a Bayesian time-domain analysis formalism, we analyze a selected dataset from the GWTC-3 LIGO-Virgo-Kagra catalog of binary coalescences, bounding the value of the tidal charge. With our analysis we obtain the first robust constraints on such charges, highlighting the importance of accounting for the previously ignored correlations with the other black hole intrinsic parameters.

The $\sim 5\sigma$ mismatch between the value of the Hubble parameter measured by SH0ES and the one inferred from the inverse distance ladder (IDL) constitutes the biggest tension afflicting the standard model of cosmology, which could be pointing to the need of physics beyond $\mathrm{\Lambda }\mathrm{CDM}$. In this paper, we study the background history required to solve the $H_0$ tension if we consider standard prerecombination physics, paying special attention to the role played by the data on baryon acoustic oscillations (BAO) employed to build the IDL. We show that the anisotropic BAO data favor an ultra-late-time (phantomlike) enhancement of $H(z)$ at $z\lesssim 0.2$, accompanied by a transition in the absolute magnitude of supernovae of type Ia $M(z)$ in the same redshift range. This agrees with previous findings in the literature. The effective dark energy (DE) density must be smaller than in the standard model at higher redshifts. Instead, when angular BAO data (claimed to be less subject to model dependencies) is employed in the analysis, we find that the increase of $H(z)$ starts at much higher redshifts, typically in the range $z\sim 0.5–0.8$. In this case, $M(z)$ could experience also a transition (although much smoother), and the effective DE density becomes negative at $z\gtrsim 2$. Both scenarios require a violation of the weak energy condition (WEC) but leave an imprint on completely different redshift ranges and might also have a different impact on the perturbed observables. They allow for the effective crossing of the phantom divide. Finally, we employ two alternative methods to show that current data from cosmic chronometers do not exclude the violation of the WEC but neither do they add any strong evidence in its favor. Our work puts the accent on the utmost importance of the choice of the BAO data set in the study of the possible solutions to the $H_0$ tension.

As a potential candidate for the late-time accelerating expansion of the Universe, the Chaplygin gas and its generalized models have significant implications to modern cosmology. In this work we investigate the effects of dark energy on the internal structure of a neutron star composed of two phases, which leads us to wonder: Do stable neutron stars have a dark-energy core? To address this question, we focus on the radial stability of stellar configurations composed by a dark-energy core—described by a Chaplygin-type equation of state (EOS)—and an ordinary-matter external layer which is described by a polytropic EOS. We examine the impact of the rate of energy densities at the phase-splitting surface, defined as $\alpha ={\rho }_{\mathrm{dis}}^{-}/{\rho }_{\mathrm{dis}}^{+}$, on the radius, total gravitational mass, and oscillation spectrum. The resulting mass-radius diagrams are notably different from dark-energy stars without a common-matter crust. Specifically, it is found that both the mass and the radius of the maximum-mass configuration decrease as $\alpha$ becomes smaller. Furthermore, our theoretical predictions for mass-radius relations consistently describe the observational measurements of different massive millisecond pulsars as well as the central compact object within the supernova remnant HESS $\mathrm{J}1731-347$. The analysis of the normal oscillation modes reveals that there are two regions of instability on the $M({\rho }_c)$ curve when $\alpha$ is small enough, indicating that the usual stability criterion $dM/d{\rho }_c>0$ still holds for rapid phase transitions. However, this is no longer true for the case of slow transitions.

We present a signal-foreground separation algorithm for filtering observational data to extract spectral distortions of the cosmic microwave background (CMB). Our linear method, called the least response method (LRM), is based on the idea of simultaneously minimizing the response to all possible foregrounds with poorly defined spectral shapes and random noise while maintaining a constant response to the signal of interest. This idea was introduced in detail in our previous paper. Here, we have expanded our analysis by taking into consideration all the main foregrounds. We draw a detailed comparison between our approach and the moment internal linear combination method, which is a modification of the internal linear combination technique previously used for CMB anisotropy maps. We demonstrate advantages of LRM and evaluate the prospects for measuring various types of spectral distortions. Besides, we show that LRM suggests the possibility of its improvements if we use an iterative approach with sequential separation and partial subtraction of foreground components from the observed signal. In addition, we estimate the optimal temperature that the telescope’s optical system should have in order to detect the chemical type $\mu$ distortions. We present a design of an instrument where, according to our estimates, the optimal contrast between its thermal emission and the CMB allows us to measure such distortions.

The most conservative interpretation of the nHz stochastic gravitational wave background (SGWB) discovered by NANOGrav and other pulsar timing array (PTA) collaborations is astrophysical, namely that it originates from supermassive black hole (SMBH) binaries. However, alternative cosmological models have been proposed, including cosmic strings, phase transitions, domain walls, primordial fluctuations, and “audible” axions. We perform a multimodel analysis (MMA) to compare how well these different hypotheses fit the NANOGrav data, both in isolation and in combination with SMBH binaries, and address the questions: Which interpretations fit the data best, and which are disfavored? We also discuss experimental signatures that can help discriminate between different sources of the PTA GW signal, including fluctuations in the signal strength between frequency bins, individual sources, and how the PTA signal extends to higher frequencies.

The positron excess in cosmic rays has stimulated a lot of interest in the last decade. The dark matter origin of the extra positrons has attracted great attention. However, the $\gamma$-ray search set very stringent constraints on the dark matter annihilation/decay rate, which leads to great disfavor of the dark matter scenario. In this work, we incorporate the recent progress in cosmic ray propagation and reexamine the dark matter scenario accounting for the positron excess. Recent observations indicate that cosmic ray propagation in the Milky Way may be not uniform and diffusion in the Galactic disk should be slower than that in the halo. In the spatially dependent propagation model, the positrons/electrons are more concentrated in the disk and lead to smaller dark matter annihilation/decay rates to account for the positron excess and also a smaller deficit in the background positron flux. Especially for the ${\mu }^{+}{\mu }^{-}$ channel the positron spectrum fits the AMS-02 latest data perfectly and the annihilation rate satisfies all the present constraints from $\gamma$-ray and cosmic microwave background observations.

We investigate the different decompositions of the angular momentum in QCD for a relativistic spin $1/2$ composite state, namely a quark dressed with a gluon. We use light-front Hamiltonian perturbation theory, and in the light-front gauge, use the two-component framework by eliminating the constrained degrees of freedom. We also investigate the different decompositions of the angular momentum at the level of two-dimensional densities in the front form, including the effect of the so-called potential term. In this work, we consider the contribution coming from the quark part of the energy-momentum tensor. We contrast the different decompositions and also compare with other calculations in the literature. We also present the gravitational form factor related to the antisymmetric part of the energy-momentum tensor.

In this study, we explore the phenomenological signatures associated with a light fermiophobic Higgs boson, $h_{\mathrm{f}}$, within the type-I two-Higgs-doublet model at the HL-LHC. Our meticulous parameter scan illuminates an intriguing mass range for $m_{h_{\mathrm{f}}}$, spanning $[1,10]\mathrm{GeV}$. This mass range owes its viability to substantial parameter points, largely due to the inherent challenges of detecting the soft decay products of $h_{\mathrm{f}}$ at contemporary high-energy colliders. Given that this light $h_{\mathrm{f}}$ ensures $\mathrm{Br}(h_{\mathrm{f}}\to \gamma \gamma )\simeq 1$, $\mathrm{Br}(H^{\pm }\to h_{\mathrm{f}}{W}^{\pm })\simeq 1$, and $M_{H^{\pm }}\lesssim 330\mathrm{GeV}$, we propose a golden discovery channel: $pp\to h_{\mathrm{f}}{H}^{\pm }\to \gamma \gamma \gamma \gamma {\ell }^{\pm }\nu$, where ${\ell }^{\pm }$ includes $e^{\pm }$ and ${\mu }^{\pm }$. However, a significant obstacle arises as the two photons from the $h_{\mathrm{f}}$ decay mostly merge into a single jet due to their proximity within $\mathrm{\Delta }R<0.4$. This results in a final state characterized by two jets, rather than four isolated photons, thus intensifying the QCD backgrounds. To tackle this, we devise a strategy within delphes to identify jets with two leading subparticles as photons, termed diphoton jets. Our thorough detector-level simulations across 18 benchmark points predominantly show signal significances exceeding the $5\sigma$ threshold at an integrated luminosity of $3{\mathrm{ab}}^{-1}$. Furthermore, our approach facilitates accurate mass reconstructions for both $m_{h_{\mathrm{f}}}$ and $M_{H^{\pm }}$. Notably, in the intricate scenarios with heavy charged Higgs bosons, our application of machine learning techniques provides a significant boost in significance.

We discuss the analytic continuation of scaling function in the three-dimensional $Z(2)$, $O(2)$ and $O(4)$ universality classes using the Schofield representation of the magnetic equation of state. We show that a determination of the location of Lee-Yang edge singularities and, in the case of $Z(2)$, also the Langer edge singularity yields stable results. Results for the former are in good agreement with functional renormalization group calculations. We also present results for the location of the Langer edge singularity in the $3d$, $Z(2)$ universality class. We find that in terms of the complex scaling variable $z$ the distance of the Langer edge singularity to the critical point agrees within errors with that of the Lee-Yang edge singularity. Furthermore the magnitude of the discontinuity along the Langer branch cut is an order of magnitude smaller than that along the Lee-Yang branch cut.

Recent BESIII data on radiative $J/\psi$ decays from $\sim {10}^{10}$ $J/\psi$ samples should significantly advance our understanding of the controversial nature of $\eta (1405/1475)$. This motivates us to develop a three-body unitary coupled-channel model for radiative $J/\psi$ decays to three-meson final states of any partial wave ($J^{PC}$). Basic building blocks of the model are bare resonance states such as $\eta (1405/1475)$ and $f_1(1420)$, and $\pi K$, $K\overline{K}$, and $\pi \eta$ two-body interactions that generate resonances such as $K^{*}(892)$, $K_0^{*}(700)$, and $a_0(980)$. This model reasonably fits $K_S{K}_S{\pi }^0$ Dalitz plot pseudodata generated from the BESIII’s $J^{PC}=0^{-+}$ amplitude for $J/\psi \to \gamma K_S{K}_S{\pi }^0$. The experimental branching ratios of $\eta (1405/1475)\to \eta \pi \pi$ and $\eta (1405/1475)\to \gamma \rho$ relative to that of $\eta (1405/1475)\to K\overline{K}\pi$ are simultaneously fitted. Our $0^{-+}$ amplitude is analytically continued to find three poles, two of which correspond to $\eta (1405)$ on different Riemann sheets of the $K^{*}\overline{K}$ channel, and the third one for $\eta (1475)$. This is the first pole determination of $\eta (1405/1475)$ and, furthermore, the first-ever pole determination from analyzing experimental Dalitz plot distributions with a manifestly three-body unitary coupled-channel framework. Process-dependent $\eta \pi \pi$, $\gamma {\pi }^{+}{\pi }^{-}$, and $\pi \pi \pi$ lineshapes of $J/\psi \to \gamma (0^{-+})\to \gamma (\eta \pi \pi )$, $\gamma (\gamma \rho )$, and $\gamma (\pi \pi \pi )$ are predicted, and are in reasonable agreement with data. A triangle singularity is shown to play a crucial role to cause the large isospin violation of $J/\psi \to \gamma (\pi \pi \pi )$.

It has been recently proposed that at each infinite distance limit in the moduli space of quantum gravity a perturbative description emerges with fundamental degrees of freedom given by those infinite towers of states whose typical mass scale is parametrically not larger than the ultraviolet cutoff, identified with the species scale. This proposal is applied to the familiar ten-dimensional type IIA and IIB superstring theories, when considering the limit of infinite string coupling. For type IIB, the light towers of states are given by excitations of the $D1$-brane, as expected from self-duality. Instead, for type IIA at strong coupling, which is dual to M-theory on $S^1$, we make the observation that the emergent degrees of freedom are bound states of transversal $M2$- and $M5$-branes with Kaluza-Klein momentum along the circle. We speculate on the interpretation of the necessity of including all these states for a putative quantum formulation of M-theory.

GW190521 is a remarkable gravitational-wave signal on multiple fronts: its source is the most massive black hole binary identified to date and could have spins misaligned with its orbit, leading to spin-induced precession; an astrophysically consequential property linked to the binary’s origin. However, due to its large mass, GW190521 was only observed during its final 3–4 cycles, making precession constraints puzzling and giving rise to alternative interpretations, such as eccentricity. Motivated by these complications, we trace the observational imprints of precession on GW190521 by dissecting the data with a novel time domain technique, allowing us to explore the morphology and interplay of the few observed cycles. We find that precession inference hinges on a quiet portion of the pre-merger data that is suppressed relative to the merger ringdown. Neither premerger nor postmerger data alone are the sole driver of inference, but rather their combination; in the quasicircular scenario, precession emerges as a mechanism to accommodate the lack of a stronger premerger signal in light of the observed postmerger. In terms of source dynamics, the premerger suppression arises from a tilting of the binary with respect to the observer. Establishing such a consistent picture between the source dynamics and the observed data is crucial for characterizing the growing number of massive binary observations and bolstering the robustness of ensuing astrophysical claims.

We compare the dark matter (DM) production processes and its parameters space in the background of reheating obtained from two chief systems in the early Universe: the inflaton $\varphi$ and the primordial black holes (PBHs). We concentrated on the mechanism where DMs are universally produced only from the PBH decay and the generation of the standard model plasma from both inflaton and PBHs. Whereas the distribution of primordial black holes behaves like dust, the inflaton phenomenology depends strongly on its equation of state after the inflationary phase, which in turn is conditioned by the nature of the potential $V(\varphi )$. Depending upon the initial mass and population of PBHs, a large range of DM mass is shown to be viable if reheating is controlled by PBHs itself. Inflaton-dominated reheating is observed to further widen such possibilities depending on the initial population of black holes and its mass as well as the coupling of the inflaton to the standard model sector.

We investigate the capture rate of the cosmic neutrino background on tritium within the Standard Model, extended to incorporate three right-handed singlet neutrinos with explicit lepton-number violation. We consider a scenario where the $6\times 6$ neutrino mixing matrix factorizes into three independent $2\times 2$ pairs and analyze the states produced from weak interactions just before neutrino decoupling. Taking into account the unrestricted Majorana mass scale associated with lepton number violation, spanning from the grand unification scale to Planck-suppressed values, we observe a gradual transition in the capture rate from a purely Majorana neutrino to a purely (pseudo) Dirac neutrino. We demonstrate that the capture rate is modified if the lightest active neutrino is relativistic, and this can be used to constrain the tiniest value of mass-squared difference $\sim {10}^{-35}{\mathrm{eV}}^2$, between the active-sterile pair, probed so far. Consequently, the cosmic neutrino capture rate could become a promising probe for discerning the underlying mechanism responsible for generating neutrino masses.

We investigate how our baryon-loss limits from anomalous binary-pulsar period lengthening can be interpreted microscopically to yield specific constraints on the particle physics of baryon number violation within a neutron star. We focus on the possibility of anomalous baryon disappearance via dark baryon processes and on scenarios in which the produced dark-sector particles do not survive to influence the response of the star to baryon-number-violating effects. We flesh out the conditions for which this may occur, as well as other key assumptions. We then turn to the analysis of particle processes in the dense nuclear medium found at the core of a neutron star, employing the techniques of relativistic mean-field theory. Using our study of in-medium effects and limits on macroscopic baryon number violation, we extract limits on in-vacuum baryon-number-violating processes, and we determine them for various equations of state. We conclude by noting the implications of our results for models of dark-sector-enabled baryogenesis.

Gravitational-wave searches for cosmic strings are currently hindered by the presence of detector glitches, some classes of which strongly resemble cosmic string signals. This confusion greatly reduces the efficiency of searches. A deep-learning model is proposed for the task of distinguishing between gravitational-wave signals from cosmic string cusps and simulated blip glitches in design sensitivity data from the future Einstein Telescope. The model is an ensemble consisting of three convolutional neural networks, achieving an accuracy of 79%, a true positive rate of 76%, and a false positive rate of 18%. This marks the first time convolutional neural networks have been trained on a realistic population of Einstein Telescope glitches. On a dataset consisting of signals and glitches, the model is shown to outperform matched filtering, specifically being better at rejecting glitches. The behaviour of the model is interpreted through the application of several methods, including a novel technique called waveform surgery, used to quantify the importance of waveform sections to a classification model. In addition, a method to visualize convolutional neural network activations for one-dimensional time series is proposed and used. These analyses help further the understanding of the morphological differences between cosmic string cusp signals and blip glitches. Because of its classification speed in the order of magnitude of milliseconds, the deep-learning model is suitable for future use as part of a real-time detection pipeline. The deep-learning model is transverse and can therefore potentially be applied to other transient searches.

We theoretically investigate the propagation of light in the presence of a homogeneous gravitational field. To model this, we derive the solutions of the wave equation in Rindler spacetime, which account for gravitational redshift and light deflection. The developed theoretical framework is used to explore the propagation of plane light waves in a horizontal Fabry-Pérot cavity. We pay particular attention to the cavity output power. It is shown that this power depends not only on the input frequency but also on the vertical position of a detector. We state that the height-dependent detector signal arising from the cavity internal light deflection effect also opens a new alternative way to frequency stabilization in Earth-based laser experiments and to study gravitational light deflection at laboratory scales.

We explore the properties of neutral mesons within the context of a chirally imbalanced medium, employing the two-flavor Nambu–Jona-Lasinio model. The temperature dependence of the constituent quark mass at finite values of the chiral chemical potential (CCP) demonstrates the well-established phenomena of chiral catalysis at lower temperatures and inverse chiral catalysis at higher temperatures. The polarization functions in both the scalar ($\sigma$) and pseudoscalar (${\pi }^0$) channels have been evaluated using the real-time formalism of thermal field theory. These have been used to determine the masses and spectral functions of $\sigma$ and $\pi$ mesons. Detailed investigation of the analytic structure of the imaginary part of the polarization function for $\sigma$ and $\pi$ mesons results in the emergence of nontrivial Landau-cut contributions due to the presence of chiral imbalance. The multiple solutions for the mass of the $\pi$ meson for specific values of CCP have been analyzed on the basis of their residue at the pole. Furthermore, we have observed abrupt changes in the masses of both scalar and pseudoscalar mesons at finite CCP values, particularly at higher temperatures. A decreasing trend in the Mott transition temperature is seen with the increase in CCP.

Among the vast variety of proposals put forward by the community to resolve tree-level unitarity violations in Higgs inflation models, there exists the concept of self-healing. It heals the theory from supposed tree-level violations for elastic scattering processes by summing over successive vacuum polarization loop corrections. In this work, we examine this technique to check whether unitarity is indeed restored and find that there exist underlying constraints in self-healing unitarity that pose the same perturbative unitarity bounds that it was expected to heal.