We revisit the Keplerian-like parametrization of the two-body problem in Yukawa gravity studied in the literature. Some inconsistencies, which spoil Bertrand’s theorem, observed in the $\eta$ parametrization of the true anomaly $\theta$ and in the formulae for the pericenter’s advance are resolved. Moreover, inspired in this kind of study, we couple the Buckingham potential, a variation of the Lennard-Jones intermolecular potential, with the gravitational Newtonian potential and find a Keplerian-like parametrization for the solution of the two-body problem in this sort of gravity. The outcomes for the advance of the pericenter in both types of gravity are corroborated by using the Landau and Lifshitz’s method. We also tested the expressions thus obtained against Solar System and S2 star data. The result for both models is that while some deviation from general relativity (GR) is allowed, GR cannot be discarded by the current analysis.

Cosmic shear, galaxy clustering, and the abundance of massive halos each probe the large-scale structure of the Universe in complementary ways. We present cosmological constraints from the joint analysis of the three probes, building on the latest analyses of the lensing-informed abundance of clusters identified by the South Pole Telescope (SPT) and of the auto- and cross-correlation of galaxy position and weak lensing measurements ($3\times 2\mathrm{pt}$) in the Dark Energy Survey (DES). We consider the cosmological correlation between the different tracers and we account for the systematic uncertainties that are shared between the large-scale lensing correlation functions and the small-scale lensing-based cluster mass calibration. Marginalized over the remaining $\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) parameters (including the sum of neutrino masses) and 52 astrophysical modeling parameters, we measure ${\mathrm{\Omega }}_{\mathrm{m}}=0.300\pm 0.017$ and ${\sigma }_8=0.797\pm 0.026$. Compared to constraints from Planck primary cosmic microwave background (CMB) anisotropies, our constraints are only 15% wider with a probability to exceed of 0.22 ($1.2\sigma$) for the two-parameter difference. We further obtain $S_8\equiv {\sigma }_8({\mathrm{\Omega }}_{\mathrm{m}}/0.3{)}^{0.5}=0.796\pm 0.013$ which is lower than the Planck measurement at the $1.6\sigma$ level. The combined SPT cluster, DES $3\times 2\mathrm{pt}$, and Planck datasets mildly prefer a nonzero positive neutrino mass, with a 95% upper limit $\sum m_{\nu }<0.25\mathrm{eV}$ on the sum of neutrino masses. Assuming a $w\mathrm{CDM}$ model, we constrain the dark energy equation of state parameter $w=-1.15_{-0.17}^{+0.23}$ and when combining with Planck primary CMB anisotropies, we recover $w=-1.20_{-0.09}^{+0.15}$, a $1.7\sigma$ difference with a cosmological constant. The precision of our results highlights the benefits of multiwavelength multiprobe cosmology and our analysis paves the way for upcoming joint analyses of next-generation datasets.

We report on a study of axion string networks using fixed-grid simulations of up to 16384 points per side. The length of string can be characterized in terms of standard dimensionless parameters ${\zeta }_{\mathrm{w}}$ and ${\zeta }_{\mathrm{r}}$, the length density measured in the cosmic rest frame and the string rest frame, scaled with the cosmic time $t$. The motion of the string can be characterized by the root-mean-square (RMS) velocity of the string. Starting from a range of initial length densities and velocities, we analyze the string network in the standard scaling framework and find evolution toward a fixed point with estimated values ${\widehat{\zeta }}_{\mathrm{w},*}=1.220(57)$ and ${\widehat{\zeta }}_{\mathrm{r},*}=1.491(93)$. The two measures are related by the RMS velocity, which we estimate to be ${\widehat{v}}_{*}=0.5705(93)$. The length density is consistent with previous measurements, while the velocity is about 5% lower. For simulations starting from low enough density, the length density parameters ${\zeta }_{\mathrm{w}}$ and ${\zeta }_{\mathrm{r}}$ remain below their fixed point values throughout, while growing slowly, giving rise to an impression of approximately logarithmic increase with time. This has been proposed as the true long-term behavior. We find that the growth tends to slow down as the values of ${\zeta }_{\mathrm{w}}$ and ${\zeta }_{\mathrm{r}}$ identified as fixed points are approached. In the case of ${\zeta }_{\mathrm{r}}$, the growth stops for simulations that started close to the fixed point length density. The difference between ${\zeta }_{\mathrm{w}}$ and ${\zeta }_{\mathrm{r}}$ can be understood to result from the continuing velocity evolution. Our results indicate that the growth of ${\zeta }_{\mathrm{w}}$ is a transient appearing at low densities and while the velocity is converging. This highlights the importance of studying the string density and the velocity together, and the preparation of initial conditions.

A previous calculation of the one-loop photon contribution to the graviton self-energy on the de Sitter background is considered. We first show that there is no local obstacle to conservation, unlike the contribution from a loop of massless, minimally coupled scalars. This is correlated to the absence of an Eddington ($R^2$) counterterm and to the vanishing of the stress tensor when the photon is integrated out in the presence of a constant graviton field. We also show that there is a secularly growing one-loop contribution to the electric components of the Weyl tensor for plane wave gravitons. Its coefficient agrees with that of the secular one-loop correction to the Newtonian potential, and both can be resummed using a variant of the renormalization group.

We study the decay of a homogeneous condensate of a massive scalar field of mass $m$ into massless fields in thermal equilibrium in a radiation dominated cosmology. The model is a proxy for the nonequilibrium dynamics of a misaligned axion condensate decaying into radiation. After consistent field quantization in the cosmological background, we obtain the linearized causal equations of motion for a homogeneous condensate including the finite temperature self-energy corrections up to one loop. The dynamical renormalization group is implemented to obtain the time dependent relaxation rate that describes the decay dynamics of the condensate amplitude from stimulated emission and recombination of massless quanta in the medium. It is explicitly shown that a simple friction term in the equation of motion does not describe correctly the decay of the condensate. During the super-Hubble regime, relevant for ultralight dark matter, the condensate amplitude decays as $e^{-\frac{g^2}{10}{t}^2\ln (1/mt)}$. In the sub-Hubble regime the amplitude decays as $e^{-\gamma (t;T(t))/2}$ with $T(t)=T_0/a(t)$; therefore, the finite temperature contribution to the decay rate vanishes fast during the expansion. A main conclusion is that a phenomenological friction term is inadequate to describe the decay in the super-Hubble regime, and the decay function $\gamma (t)$ is always smaller than that from a local friction term as a consequence of the cosmological expansion. For ultralight dark matter, the timescale, during which transient dynamics is sensitive to cosmological expansion and a local friction term is inadequate, is much longer. A friction term always underestimates the timescale of decay in the sub-Hubble case.

The existence of a strange quark star (QS) predicted in the Bodmer-Witten hypothesis has been a matter of debate. The combustion from a neutron star to a strange QS in its accreted process in a low-mass X-ray binary is proposed to be a scenario that generates gamma-ray bursts (GRBs); the baryon contamination of the outflow is very low and mainly from the masses of crusts ($M_{\text{crust}}$) of QSs. A special subset of GRBs detected in the past 16 years is collected and used to estimate $M_{\text{crust}}$ under this assumption of QSs as central engines. Correspondingly, $M_{\text{crust}}$ is calculated in the frameworks of several models for cold dense quark matter (MIT bag model and Nambu-Jona-Lasino model with or without the impacts from the formation of color superconducting condensates being considered) for comparison with the observation. In conclusion, we find that the GRB samples have so far failed to provide positive support for this hypothesis, and the Nambu-Jona-Lasino model in which the existence of hybrid stars is allowed might be more consistent with the observation.

We perform fully relativistic simulations of the head-on collisions between intermediate-mass black holes and very massive stars. Such collisions are expected to occur in dense stellar clusters and may play an important role in growing the mass of the seed black hole. For the cases considered here, for which the masses of the black holes and stars are comparable, the vast majority of the stellar material is accreted onto the black hole within a stellar dynamical timescale, as expected from analytical estimates, and leads to a rapid growth of the black hole. A small amount of mass, which is shock-heated in the wake of the black hole, is ejected from the collision and will contribute to the interstellar material in the cluster.

In environments with prodigious numbers of neutrinos, such as core-collapse supernovae, neutron star mergers, or the early Universe, neutrino-neutrino interactions are dynamically significant. They can dominate neutrino flavor evolution and force it to be nonlinear, causing collective neutrino oscillations. Such collective oscillations have been studied numerically, for systems with up to millions of neutrinos, using mean-field or one-particle effective approximations. However, such a system of interacting neutrinos is a quantum many-body system, wherein quantum correlations could play a significant role in the flavor evolution—thereby motivating the exploration of many-body treatments that follow the time evolution of these correlations. In many-body flavor evolution calculations with two neutrino flavors, the emergence of spectral splits in the neutrino energy distributions has been found to be correlated with the degree of quantum entanglement across the spectrum. In this work, for the first time, we investigate the emergence of spectral splits in the three-flavor many-body collective neutrino oscillations. We find that the emergence of spectral splits resembles the number and location found in the mean-field approximation but not in the width. Moreover, unlike in the two-flavor many-body calculations, we find that additional degrees of freedom make it more difficult to establish a correlation between the location of the spectral splits and the degree of quantum entanglement across the neutrino energy spectrum. The observation from the two-flavor case, that neutrinos nearest to the spectral split frequency exhibit the highest level of entanglement, is more difficult to ascertain in the three-flavor case because of the presence of multiple spectral splits across different pairwise combinations of flavor and/or mass states.

The mergers of massive black hole binaries could generate rich electromagnetic emissions, which allow us to probe the environments surrounding these massive black holes and gain deeper insights into the high energy astrophysics. However, due to the short timescale of binary mergers, it is crucial to predict the time of the merger in advance to devise detailed observational plans. The overwhelming noise and slow accumulation of the signal-to-noise ratio in the inspiral phase make this task particularly challenging. To address this issue, we propose a novel deep neural denoising network in this study, capable of denoising a 30-day inspiral phase signal. Following the denoising process, we perform the detection and merger time prediction based on the denoised signals. Our results demonstrate that, for a 30-day inspiral phase data with a signal-to-noise ratio between 10 and 50 occurring no more than 10 days before the merger, our absolute prediction error for the merger time is generally within 24 h.

Recent studies point out that quantum effects, referred to as “memory burden,” may slow down the evaporation of black holes. As a result, a population of light primordial black holes could potentially survive to the present day, thus contributing to the energy density of dark matter. In this work, we focus on light primordial black holes with masses $M_{\mathrm{PBH}}\lesssim {10}^9\mathrm{g}$ that, due to the memory burden effect, are currently evaporating, emitting high-energy particles, among which neutrinos, in the local Universe. Analyzing the latest IceCube data, we place novel constraints on the combined parameter space of primordial black holes and the memory burden effect. We also study the projected reach of future neutrino telescopes such as IceCube-Gen2 and GRAND. We find that the neutrino observations are crucial to probe scenarios with highly suppressed evaporation and light masses for primordial black holes.

We introduce form factors that relate the amplitude of a quantum electrodynamics (QED) process in vacuum to its corresponding background-field process. The latter is characterized by a reduced S-matrix element where one or more photon field operators are replaced by classical background fields. In the associated Feynman diagram, external photon lines are supplanted with lines representing the c-number field. This modifies the cross section by factors proportional to powers of the Fourier amplitude of the classical field (and its complex conjugate). We demonstrate this explicitly by comparing different reaction channels of low-energy photon-photon scattering in a classical background. We find that background field cross sections typically undergo coherent enhancement and for some reaction channels display a more favorable scaling with center-of-mass energy compared to the vacuum process. Similar coherent enhancement may be found for leading-order pair annihilation to one photon, but this competes with kinematic suppression. This suppression can be minimized by using an x-ray free electron laser as the classical background.

The dynamically assisted Schwinger effect, the generation of fermion-antifermion pairs in vacuum under a strong, slow-varying field and a weak, high-frequency field, has become a promising avenue to probe the vacuum structure and the nonlinear dynamics of QED. However, the role of axial fields in this phenomenon has remained underexplored. This study aims at analyzing how spatial axial fields influence particle production in the dynamically assisted Schwinger effect. Employing the high-frequency effective theory based on the Floquet-Magnus expansion, we demonstrate that a spatial axial field can occur as the effective field of a circular polarized high-frequency plane wave and significantly increase the number of fermions produced across different timescales. This enhancement offers both theoretical insights and useful tools for the experimental implementation of the Schwinger effect.

Three-loop electronic vacuum-polarization corrections due to irreducible diagrams are evaluated for two-body muonic ions with nuclear charge numbers $1\le Z\le 6$. The corrections are of order ${\alpha }^3(Z\alpha {)}^2{m}_r$, where $\alpha$ is the fine-structure constant and $m_r$ is the reduced mass. Numerically, the energy corrections are found to be of the same order of magnitude as the largest of the order ${\alpha }^2(Z\alpha {)}^6{m}_r$ corrections, and are thus phenomenologically interesting. Our method of calculation eliminates numerical uncertainty encountered in other approaches.

Parametrization of cascading hadronic reactions is a central tool in hadron spectroscopy for modeling matrix elements and extracting parameters of hadronic states. Implementing the helicity formalism consistently presents challenges, particularly for particles with spin, due to the need to match spin states of final-state particles, an operation known as the Wigner rotation. This paper discusses these challenges in detail and offers solutions, including a practical method for implementation. Equipped with a general algorithm for computing Wigner rotations, we extend the studies to alternative amplitude formulations, the minus-phi and canonical conventions.

We study the generation of baryon asymmetry as well as dark matter (DM) in an extended reheating period after the end of slow-roll inflation. Within the regime of perturbative reheating, we consider different monomial potential of the inflaton field during reheating era. The inflaton condensate reheats the Universe by decaying into the Standard Model (SM) bath either via fermionic or bosonic decay modes. Assuming the leptogenesis route to baryogenesis in a canonical seesaw framework with three right handed neutrinos (RHN), we consider both the radiation bath and perturbative inflaton decay to produce such RHNs during the period of reheating when the maximum temperature of the SM bath is well above the reheating temperature. The DM, assumed to be a SM gauge singlet field, also gets produced from the bath during the reheating period via UV freeze-in. In addition to obtaining different parameter space for such nonthermal leptogenesis and DM for both bosonic and fermionic reheating modes and the type of monomial potential, we discuss the possibility of probing such scenarios via spectral shape of primordial gravitational waves.

In this paper, we do three things. First, we outline the conditions under which the interaction rate of inelastic processes that change the internal state of a system of $N$ targets scales as $N^2$. This is an effect distinct from coherent elastic scattering but with the same scaling. Second, we compute example rates for such processes for various weakly interacting particles. Finally, we point to potential quantum observables for these processes that go beyond traditional energy exchange. Maximal coherence in inelastic processes is achieved when the targets are placed in an equal superposition of the ground and excited states. These coherent inelastic processes are analogous to Dicke superradiance, where cooperative effects reinforce the emission of radiation from matter, and we thus refer to them as superradiant interactions. We compute the superradiant interaction rates for the cosmic neutrino background ($\mathrm{C}\nu \mathrm{B}$), dark matter scattering and absorption, and late-universe particles, such as reactor neutrinos, when the two-level system is realized by nuclear or electron spins in a magnetic field. The rates we find can be quite sizable on macroscopic yet small targets. For example, the $\mathrm{C}\nu \mathrm{B}$ interacts with a rate of $\mathcal{O}(\mathrm{Hz})$ when scattering off a 10 cm liquid or solid-state density spin-polarized sphere, a $\mathcal{O}({10}^{21})$ enhancement compared to the incoherent inelastic contribution. For QCD axion dark matter, similar rates can be achieved with much smaller samples, $N\sim \mathcal{O}({10}^{15}){(\frac{m}{2\times {10}^{-8}\mathrm{eV}})}^{-1/2}$, where $m$ is the axion mass. Using the Lindblad formalism for open quantum systems, we show that these superradiant interactions can manifest as a source of noise on the system. This noise is tunable however and can serve as a signature of new physics, as the energy splitting controls the momentum transfer and hence, the amount of macroscopic coherence. These considerations point to new observables that go beyond traditional net energy exchange. These observables are sensitive to the sum of the excitation and deexcitation rates—instead of the net energy exchange rate which can be very suppressed—and can be viewed as introducing diffusion and decoherence to the system. While we postpone to upcoming work proposing a concrete protocol that extracts these effects from a macroscopic ensemble of atoms, the effects presented in this paper may point to a new class of ultra-low threshold detectors.

We study complex Langevin simulations of a toy model as well as QCD, supplemented with a dynamical stabilization (DS) term, which was proposed to regularize the complexified process at lower temperatures. We compare the results to reweighting from zero chemical potential to measure the bias that the inclusion of the stabilization term causes, depending on its strength. At high temperatures the stabilization term is not needed. At low temperatures (below deconfinement transition) the DS term has a beneficial stabilizing effect, but too strong a DS term causes phase quenching on the system. We observed that the bias of the dynamical stabilization can, with good accuracy, be removed by extrapolating to zero dynamical stabilization force using a sigmoid fit.

We use antistatic-antistatic potentials computed with lattice quantum chromodynamics (QCD) and a coupled-channel Born-Oppenheimer approach to explore the existence of a $\overline{b}\overline{b}ud$ tetraquark resonance with quantum numbers $I(J^P)=0(1^{-})$. A pole in the $\mathrm{T}$ matrix signals a resonance with mass $m=2m_B+{94.0}_{-5.4}^{+1.3}\mathrm{MeV}$ and decay width $\mathrm{\Gamma }=140_{-66}^{+86}\mathrm{MeV}$, i.e., very close to the $B^{*}{B}^{*}$ threshold. We also compute branching ratios, which clearly indicate that this resonance is mainly composed of a $B^{*}{B}^{*}$ meson pair with a significantly smaller $BB$ contribution. By varying the potential matrix responsible for the coupling of the $BB$ and the $B^{*}{B}^{*}$ channel as well as the $b$ quark mass, we provide additional insights and understanding concerning the formation and existence of the resonance. We also comment on the importance of our findings and the main takeaways for a possible future full lattice QCD investigation of this $I(J^P)=0(1^{-})$ $\overline{b}\overline{b}ud$ tetraquark resonance.

There are three scalar nonets in the Particle Data Group, one of which includes [$a_0(980),K_0^{*}(700)$], another includes [$a_0(1450),K_0^{*}(1430)$], and the third includes [$a_0(1710),K_0^{*}(1950)$]. Motivated by [D. Black et al., Phys. Rev. D 61, 074001 (2000).], we examine an alternative mixing mechanism that could potentially explain the small mass difference between the $a_0(1450)$ and $K_0^{*}(1430)$. According to the tetraquark mixing model, two types, distinguished by their color-spin structures, are necessary to describe the tetraquark structure of the two nonets containing [$a_0(980),K_0^{*}(700)$] and [$a_0(1450),K_0^{*}(1430)$]. Considering the color-spin structures, we argue that the mixing mechanism generating $a_0(1450)$ and $K_0^{*}(1430)$ on the one hand, and $a_0(1710)$ and $K_0^{*}(1950)$ on the other hand might be relevant for resolving the small mass difference. We also discuss the limitations of other mixing mechanisms that generate the two nonets involving [$a_0(980),K_0^{*}(700)$] and [$a_0(1450)$, $K_0^{*}(1430)$] or [$a_0(980),K_0^{*}(700)$] and [$a_0(1710)$, $K_0^{*}(1950)$].

Machine learning has become an essential tool in jet physics. Due to their complex, high-dimensional nature, jets can be explored holistically by neural networks in ways that are not possible manually. However, innovations in all areas of jet physics are proceeding in parallel. We show that specially constructed machine learning models trained for a specific jet classification task can improve the accuracy, precision, or speed of all other jet physics tasks. This is demonstrated by training on a particular multiclass generation and classification task and then using the learned representation for different generation and classification tasks, for datasets with a different (full) detector simulation, for jets from a different collision system ($pp$ versus $ep$), for generative models, for likelihood ratio estimation, and for anomaly detection. We consider our omnilearn approach thus as a jet-physics foundation model. It is made publicly available for use in any area where state-of-the-art precision is required for analyses involving jets and their substructure.