We use the hemisphere comparison method to test the isotropy of the SnIa absolute magnitudes of the $\mathrm{Pantheon}+$ and SH0ES samples in various redshift/distance bins. We compare the identified levels of anisotropy in each bin with Monte Carlo simulations of corresponding isotropized data to estimate the frequency of such levels of anisotropy in the context of an underlying isotropic cosmological model. We find that the identified levels of anisotropy in all bins are consistent with the Monte Carlo isotropic simulated samples. However, in the real samples for both the $\mathrm{Pantheon}+$ and the SH0ES cases, we find sharp changes of the level of anisotropy occurring at distances less than 40 Mpc. For the $\mathrm{Pantheon}+$ sample, we find that the redshift bin [0.005, 0.01] is significantly more anisotropic than the other five redshift bins considered. For the SH0ES sample, we find a sharp drop of the anisotropy level at distances larger than about 30 Mpc. These anisotropy transitions are relatively rare in the Monte Carlo isotropic simulated data and occur in 2% of the SH0ES simulated data and at about 7% of the $\mathrm{Pantheon}+$ isotropic simulated samples. This effect is consistent with the experience of an off-center observer in a 30 Mpc bubble of distinct physics or systematics.

Convolutional neural networks (CNNs) have seen extensive applications in scientific data analysis, including in neutrino telescopes. However, the data from these experiments present numerous challenges to CNNs, such as nonregular geometry, sparsity, and high dimensionality. Consequently, CNNs are highly inefficient on neutrino telescope data, and require significant preprocessing that results in information loss. We propose sparse submanifold convolutions (SSCNNs) as a solution to these issues and show that the SSCNN event reconstruction performance is comparable to or better than traditional and machine learning algorithms. Additionally, our SSCNN runs approximately 16 times faster than a traditional CNN on a GPU. As a result of this speedup, it is expected to be capable of handling the trigger-level event rate of IceCube-scale neutrino telescopes. These networks could be used to improve the first estimation of the neutrino energy and direction to seed more advanced reconstructions, or to provide this information to an alert-sending system to quickly follow-up interesting events.

Methods for parameter estimation of gravitational-wave data assume that detector noise is stationary and Gaussian. Real data deviate from these assumptions, which causes bias in the inferred parameters and incorrect estimates of the errors. We develop a sensitive test of non-Gaussianity for real gravitational-wave data that measures meaningful parameters that can be used to characterize these effects. As a test case, we investigate the quality of data cleaning performed by the LIGO-Virgo-KAGRA Collaboration around GW200129, a binary black hole signal that overlapped with the noise produced by the radio frequency modulation. We demonstrate that a significant portion of the non-Gaussian noise is removed below 50 Hz, yet some of the noise still remains after the cleaning; at frequencies above $\sim 85\mathrm{Hz}$, there is no excess noise removed. We also show that this method can quantify the amount of non-Gaussian noise in continuous data, which is useful for general detector noise investigations. To do that, we estimate the difference in non-Gaussian noise in the presence and absence of light scattering noise.

We perform a comprehensive study of a model in which the Higgs sector is extended to contain two Higgs doublet fields, with the four types of possibilities to couple to standard fermions, as well as an additional light pseudoscalar Higgs boson which mixes with the one of the two doublets. This two-Higgs-doublet-plus-pseudoscalar model includes also a stable isosinglet massive fermion that has the correct thermal relic abundance to account for the dark matter in the Universe. We summarize the theoretical constraints to which the model is subject and then perform a detailed study of the phenomenological constraints. In particular, we discuss the bounds from the LHC in the search for light and heavy scalar resonances and invisible states and those from high-precision measurements in the Higgs, electroweak, and flavor sectors, addressing the possibility of explaining the deviation from the standard expectation of the anomalous magnetic moment of the muon and the $W$-boson mass recently observed at Fermilab. We also summarize the astrophysical constraints from direct and indirect detection dark matter experiments. We finally conduct a thorough analysis of the cosmic phase transitions and the gravitational wave spectrum that are implied by the model and identify the parameter space in which the electroweak vacuum is reached after single and multiple phase transitions. We then discuss the prospects for observing the signal of such gravitational waves in near-future experiments such as the Laser Interferometer Space Antenna, Big Bang Observer, or Deci-hertz Interferometer Gravitational wave Observatory.

By combining relativistic mean field models and equivparticle models with density-dependent quark masses, we construct explicitly “a quark Fermi sea” and “a baryonic Fermi surface” to model the quarkyonic phase, where baryons with momentums ranging from zero to Fermi momentums are included. The properties of nuclear matter, quark matter, and quarkyonic matter are then investigated in a unified manner, where quarkyonic matter is more stable and energy minimization is still applicable to obtain the microscopic properties of dense matter. Three different covariant density functionals TW99, PKDD, and DD-ME2 are adopted in our work, where TW99 gives satisfactory predictions for the properties of nuclear matter in both neutron stars and heavy-ion collisions and quarkyonic transition is unfavorable. Nevertheless, if PKDD with larger slope of symmetry energy $L$ or DD-ME2 with larger skewness coefficient $J$ are adopted, the corresponding equations of state (EOSs) are too stiff according to both experimental and astrophysical constraints. The situation is improved if quarkyonic transition takes place, where the EOSs become softer and can accommodate various experimental and astrophysical constraints.

We present theoretical predictions for top-quark total cross sections and for differential distributions in top-quark transverse momentum and rapidity. Third-order soft gluon corrections are added to the complete NNLO quantities to provide approximate ${\mathrm{N}}^3\mathrm{LO}$ ($\mathrm{a}{\mathrm{N}}^3\mathrm{LO}$) results, and electroweak corrections at NLO are also included. We calculate the theoretical uncertainties from scale dependence and from parton distribution functions in the proton, and estimate their impact on the total and differential cross sections. The higher-order corrections are large, and they reduce the scale uncertainties. The results presented in this work include the best current theoretical input and are in good agreement with recent data from the LHC.

An optical quantum sensor (OQS) based on lasers and alkali-metal atoms is a sensitive ambient-temperature magnetometer that can be used in axion dark matter search with an inductor-capacitor (LC) circuit at kHz and MHz frequencies. We have previously investigated the sensitivity of an LC circuit-OQS axion detector to ultralight axion dark matter that could be achieved using a fT-noise OQS constructed in our lab. In this paper, we investigate the sensitivity that could be potentially reached by an OQS performing close to the fundamental quantum noise levels of $10\mathrm{aT}/\sqrt{\mathrm{Hz}}$. To take advantage of the quantum-limited OQS, the LC circuit has to be made of a superconductor and cooled to low temperature of a few K. After considering the intrinsic noise of the advanced axion detector and characterizing possible background noises, we estimate that such an experiment could probe benchmark QCD axion models in an unexplored mass range near 10 neV. Reaching such a high sensitivity is a difficult task, so we have conducted some preliminary experiments with a large-bore magnet and a prototype axion detector consisting of a room-temperature LC circuit and a commercial OQS unit. This paper describes the prototype experiment and its projected sensitivity to axions in detail.

We consider three-dimensional quantum electrodynamics in the presence of a Chern-Simons term at level $k$ and $N_f$ flavors, in the limit of large $N_f$ and $k$ with $k/N_f$ fixed. We consider either bosonic or fermionic matter fields, with and without quartic terms at criticality: the resulting theories are critical and tricritical bosonic ${\mathrm{QED}}_3$, Gross-Neveu, and fermionic ${\mathrm{QED}}_3$. For all such theories we compute the effective potentials and the $\beta$ functions of classically marginal couplings, at the leading order in the large $N_f$ limit and to all orders in $k/N_f$ and in the couplings. We determine the renormalization group fixed points and discuss the quantum stability of the corresponding vacua. While critical bosonic and fermionic ${\mathrm{QED}}_3$ are always stable conformal field theories, we find that tricritical bosonic and Gross-Neveu ${\mathrm{QED}}_3$ exist as stable conformal field theories only for specific values of $k/N_f$. Finally, we discuss the phase diagrams of these theories as a function of their relevant deformations.

The last three decades have witnessed the surge of quantum gravity phenomenology in the ultraviolet regime as exemplified by the Planck-scale accuracy of time-delay measurements from highly energetic astrophysical events. Yet, recent advances in precision measurements and control over quantum phenomena may usher in a new era of low-energy quantum gravity phenomenology. In this study, we investigate relativistic modified dispersion relations (MDRs) in curved spacetime and derive the corresponding nonrelativistic Schrödinger equation using two complementary approaches. First, we take the nonrelativistic limit and canonically quantize the result. Second, we apply a WKB-like expansion to an MDR-inspired deformed relativistic wave equation. Both approaches imply equivalent results for single-particle quantum mechanics. Based on a map between our approach and the generalized uncertainty principle (GUP), we recognize in the latter the MDR, which is least amenable to low-energy experiments. Consequently, importing data from time-delay measurements, we constrain the linear GUP up to the Planck scale and improve on current bounds to the quadratic one by 17 orders of magnitude. MDRs with larger implications in the infrared, however, can be tightly constrained in the nonrelativistic regime, from which we use the ensuing deviation from the equivalence principle to bound some MDRs to up to 1 order of magnitude below the Planck scale, while constraining those customarily associated with the bicrossproduct basis of the $\kappa$-Poincaré algebra to energy scales beyond ${10}^{15}\mathrm{GeV}$.

Using gauge/gravity duality, we first study the string breaking and melting of doubly heavy baryon at a finite chemical potential and temperature in this paper. The decay mode $\mathrm{QQq}\to \mathrm{Qqq}+\mathrm{Q}\overline{\mathrm{q}}$ is investigated with the presence of temperature and chemical potential in this paper. With the increase of temperature and chemical potential, string breaking takes place at a smaller potential energy, and the string-breaking distance will increase slightly. It is also found that the QQq melts at a small separate distance with the increase of temperature and chemical potential. Then, we compare the screening distance of QQq with $\mathrm{Q}\overline{\mathrm{Q}}$ under the same conditions. Finally, we draw the melting diagram of QQq and $\mathrm{Q}\overline{\mathrm{Q}}$ in the $T-\mu$ plane.

Very compact stars seem to be forbidden in general relativity. While Buchdahl’s theorem sets an upper bound on compactness, further no-go results rely on the existence of two light rings, the inner of which has been associated to gravitational instabilities. However, little is known about the role of quantum fields in these strong gravity regimes. Here, we consider the particularly simple model of a constant density star and we work in the probe approximation where the backreaction is ignored. We show that the trapping of modes inside the star leads the renormalized stress tensor of conformal field theories to diverge faster than the classical source in the Buchdahl limit. This leads to the violation of the null energy condition around the inner light ring. The backreaction of quantum fields in this regime therefore cannot be ignored. This happens as the star’s surface approaches the Buchdahl radius $9GM/4$ rather than the Schwarzschild radius. The results are independent of the details of the interactions, but contain an ambiguity associated to the renormalization scheme.

We study fermionic modes localized on the static spherically symmetric self-gravitating non-Abelian monopole in the $SU(2)$ Einstein-Dirac-Yang-Mills-Higgs theory. We consider dependence of the spectral flow on the effective gravitational coupling constant and show that, in the limiting case of transition to the Reissner-Nordström black hole, the fermion modes are fully absorbed into the interior of the black hole.

The line of sight velocity dispersion of the ultradiffuse galaxies (UDGs) NGC1052-DF2 and NGC1052-DF4 have been reasonably explained only with the baryonic matter, without requiring any dark matter contribution. The comparable ratio between the baryonic and halo mass also ascertain the above claim for the two dark matter deficit galaxies. This paves the way for analyzing alternative gravity theories such as the $f(R)$ gravity and the renormalization group correction to general relativity (RGGR). The analysis of the line of sight velocity dispersion shows that the choice of $f(R)$ gravity models such as Taylor expanded $f(R)$ about $R=0$ or a simple power law model of choice $R^n$ is consistent with the observational data. Similar statistical analysis is done for the RGGR and is also found to be a viable explanation for the observed velocity dispersion. We perform a global fit of the model parameters together with both the UDGs. The coupling parameters of the theories are considered as the global ones, and local variables such as the scale parameters are considered to be dependent on the individual galaxy.

When gravitational waves (GWs) pass by a massive object on its way to Earth, a strong gravitational lensing effect will happen. Thus, the GW signal will be amplified, deflected, and delayed in time. Through analyzing the lensed GW waveform, physical properties of the lens can be inferred. On the other hand, neglecting lensing effects in the analysis of GW data may induce systematic errors in the estimating of source parameters. As a space-borne GW detector, TianQin will be launched in the 2030s. It is expected to detect dozens of mergers of massive black hole binaries (MBHBs) as far as $z=15$ and thus will have high probability to detect at least one lensed event during the mission lifetime. In this article, we discuss the capability of TianQin to detect lensed MBHB signals. Three lens models are considered in this work: the point mass model, the singular isothermal sphere (SIS) model, and the Navarro-Frenk-White (NFW) model. The sensitive frequency band for space-borne GW detectors is around millihertz, and the corresponding GW wavelength could be comparable to the lens gravitational length scale, which requires us to account for wave diffraction effects. In calculating lensed waveforms, we adopt the approximation of geometric optics at high frequencies to accelerate computation, while precisely evaluating the diffraction integral at low frequencies. Through a Fisher analysis, we analyze the accuracy to estimate the lens parameters. We find that the accuracy can reach to the level of ${10}^{-3}$ for the mass of point mass and SIS lens and to the level of ${10}^{-5}$ for the density of the NFW lens. We also assess the impact on the accuracy of estimating the source parameters and find that the improvement of the accuracy is dominated by the increasing of signal-to-noise ratio.

Gravitational wave echoes may appear following a compact binary coalescence if the remnant is an “exotic compact object.” Exotic compact objects are proposed alternatives to the black holes of Einstein’s general relativity theory and are predicted to possess reflective boundaries. This work reports a search for gravitational wave transients (GWTs) of generic morphology occurring shortly after ($\lesssim 1\mathrm{s}$) binary black hole (BBH) mergers, therefore targeting all gravitational wave echo models. We investigated the times after the ringdown for the higher signal-to-noise ratio BBHs within the public catalog GWTC-3 by the LIGO-Virgo-KAGRA collaboration. Our search is based on the coherent WaveBurst pipeline, widely used in generic searches for GWTs by the LIGO-Virgo-KAGRA collaboration, and deploys new methods to enhance its detection performances at low signal-to-noise ratios. We employ Monte Carlo simulations for estimating the detection efficiency of the search and determining the statistical significance of candidates. We find no evidence of previously undetected GWTs and our loudest candidates are morphologically consistent with known instrumental noise disturbances. Finally, we set upper limits on the amplitude of GW echoes for single BBH mergers.

According to general relativity, an isolated black hole in vacuum shall be described by the Kerr metric, whose geodesic equations are integrable. The violation of integrability leads to chaos for particles moving around the black hole. This chaotic dynamics could leave imprints on the associated gravitational waveform and could be tested with upcoming observations. In this paper, we investigate the chaotic orbital dynamics induced by the violation of a certain spacetime symmetry, the circularity. Specifically, we focus on the resonant orbits of a particular noncircular spacetime as an example and find that they form chains of Birkhoff islands on Poincaré surfaces of section. We compare the island structures with those generated in typical nonintegrable but circular spacetimes. The islands of stability induced by noncircularity appear asymmetric on the most common Poincaré surface of section at the equatorial plane. The asymmetric patterns of islands vary discontinuously when the spacetime parameters transit through integrable regions. The origin of such features is explained in the context of perturbation analysis by considering the orbits associated with stable fixed points on the section. Possible observational implications about testing circularity through gravitational wave detection are discussed.

Motivated by current status of dark matter (DM) search, a new type of DM production mechanism is proposed based on the dynamical process of a strong first-order phase transition in the early Universe, namely, the filtered DM mechanism. We study the hydrodynamic effects on the DM relic density. By detailed calculations, we demonstrate that the hydrodynamic modes with the corresponding hydrodynamic heating effects play essential roles in determining the DM relic density. The corresponding phase transition gravitational wave could help to probe this new mechanism.

In quantum theory, the concept of time rests on shaky ground. One way to address this problem is to remove the usual background time parameter as a primitive entity and explain its emergence via correlations between physical systems. This approach was adopted by Page and Wootters [Phys. Rev. D 27, 2885 (1983)], who showed how time can emerge in a stationary quantum universe from the correlations between two of its subsystems, one of them acting as a clock for the other. In this work, I study the robustness of the Page-Wootters construction across different pictures, states of the universe, and clock interactions, clarifying the role and the nature of the correlations between the subsystems of the universe. I start by showing how to formulate the Page-Wootters construction in the Heisenberg picture via a unitary change of basis. I consider both pure and mixed states of the universe and extend the analysis to include interactions between the clock and the other subsystem of the universe. The study reveals what kind of correlations are necessary for the construction to work. Interestingly, entanglement is not required as long as there are no interactions with the clock. The study also shows that these interactions can lead to a nonunitary evolution for some mixed states of the universe. In a simple two-level system, this aspect becomes relevant at scales where one would expect strong relativistic effects. At these scales, I also observe an inversion in the system’s direction of time.

Weakly interacting massive particles, as a major candidate of dark matter (DM), may directly annihilate or decay into high-energy photons, producing monochromatic spectral lines in the gamma-ray band. These spectral lines, if detected, are smoking-gun signatures for the existence of new physics. Using the 5 years of Dark Matter Particle Explorer (DAMPE) data and 13 years of Fermi Large Area Telescope (Fermi-LAT) data, we search for linelike signals in the energy range of 3 GeV–1 TeV from the Galactic Halo. Different regions of interest are considered to accommodate different DM density profiles. We do not find any significant line structure, and the previously reported linelike feature at $\sim 133\mathrm{GeV}$ is also not detected in our analysis. Adopting a local DM density of ${\rho }_{\text{local}}=0.4\mathrm{GeV}{\mathrm{cm}}^{-3}$, we derive 95% confidence level constraints on the velocity-averaged cross section of $⟨\sigma v{⟩}_{\gamma \gamma }\lesssim 4\times {10}^{-28}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ and the decay lifetime of ${\tau }_{\gamma \nu }\gtrsim 5\times {10}^{29}\mathrm{s}$ at 100 GeV, achieving the strongest constraints to date for the line energies of 6–660 GeV. The improvement stems from the longer Fermi-LAT dataset used and the inclusion of DAMPE data in the analysis. The simultaneous use of two independent datasets could also reduce the systematic uncertainty of the search.