Using data samples with a total integrated luminosity of approximately $18{\mathrm{fb}}^{-1}$ collected by the BESIII detector operating at the Beijing Electron-Positron Collider II, the process $e^{+}{e}^{-}\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}\eta$ is studied at center-of-mass energies between 3.5106 and 4.6988 GeV. The Born cross section for the process $e^{+}{e}^{-}\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}\eta$ is measured. No significant structure is observed in the Born cross section line shape. An enhancement near the $\mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ mass threshold is observed for the first time in the process. The structure can be described by an $S$-wave Breit-Wigner function. Neglecting contribution of excited $\mathrm{\Lambda }$ states and potential interferences, the mass and width are determined to be $(2356\pm 7\pm 15)\mathrm{MeV}/c^2$ and $(304\pm 28\pm 54)\mathrm{MeV}$, respectively, where the first uncertainties are statistical and the second are systematic.

In this paper, we determine, at weak coupling, the nonrelativistic $n$-body Schrödinger equation that describes the low-lying color singlet bound states of two-dimensional adjoint quantum chromodynamics with heavy quarks. In the case of three adjoint quarks, we show that the three-body equation reduces equivalently to the Schrödinger equation that describes a point electric dipole in an electric field in a plane angular sector. We conjecture that the three-body problem is exactly solvable. We show that the eigenstates are given in terms of the triconfluent Heun functions. Equivalently, our conjecture also implies a bound state of three adjoint quarks is described by a particle in two dimensions confined in a Cornell potential. We expect the $n$-parton problem also to be solvable in a similar approach. We also comment on the Hamiltonian that describes the associated classical $n$-parton system.

The two-point string amplitude at tree level in flat spacetime reproduces the expected expression for free particles. This has been proven by Erbin et al. in [J. High Energy Phys. 07 (2019) 139.] by two methods. Here, we provide an alternative proof of this result. Our method consists in considering a timelike Liouville direction as a regularization parameter, which suffices to break time translation invariance and, at the same time, to stabilize the residual conformal symmetry in the worldsheet. This allows taking a limit and restoring Poincaré symmetry in a controlled way, thus reproducing the correct expression of the two-point amplitude.

Recent work has shown that it may be possible to detect gravitationally induced entanglement in tabletop experiments in the not-too-distant future. However, there are at present no thoroughly developed models for this type of experiment where the entangled particles are treated more fundamentally as excitations of a relativistic quantum field, and with the measurements modeled using expectation values of field observables. Here we propose a thought experiment where two particles are initially prepared in a superposition of coherent states within a common three-dimensional (3D) harmonic trap. The particles then develop entanglement through their mutual gravitational interaction, which can be probed through particle position detection probabilities. The present work gives a nonrelativistic quantum mechanical analysis of the gravitationally induced entanglement of this system, which we term the “gravitational harmonium” due to its similarity to the harmonium model of approximate electron interactions in a helium atom; the entanglement is operationally determined through the matter wave interference visibility. The present work serves as the basis for a subsequent investigation, which models this system using quantum field theory, providing further insights into the quantum nature of gravitationally induced entanglement through relativistic corrections, together with an operational procedure to quantify the entanglement.

The coincidence limits of the massless, minimally coupled scalar propagator and its first two derivatives have great relevance for the project of summing up the leading logarithms induced by loops of inflationary gravitons. We use dimensional regularization to derive good analytic approximations for the three quantities on a general cosmological background geometry which underwent inflation.

In this paper, we discuss the quantization of an interesting model of Carlip that appeared recently. It shows a way to associate boundary degrees of freedom with the stretched horizon of a stationary nonextremal black hole, as has been done in Jackiw-Teitelboim (JT) gravity for near-extremal black holes. The path integral now contains an integral over the boundary degrees of freedom, which are time reparametrizations of the stretched horizon keeping its length fixed. These boundary degrees of freedom can be viewed as elements of $\text{Diff}(S^1)/S^1$, which is the coadjoint orbit of an ordinary coadjoint vector under the action of the Virasoro group. From the symplectic form on this manifold, we obtain the measure in the boundary path integral. Doing a one-loop computation about the classical solution, we find that the one-loop answer is not finite, signaling that either the classical solution is unstable or there is an indefiniteness problem with this action, similar to the conformal mode problem in quantum gravity. Upon analytically continuing the field, the boundary partition function we get is independent of the inverse temperature and does not contribute to the thermodynamics at least at one-loop. This is in contrast to the study of near-extremal black holes in JT gravity, where the entire contribution to thermodynamics is from boundary degrees of freedom.

We consider the issue of stability at the linearized level for static, spherically symmetric wormhole solutions within a subclass of scalar-tensor theories of beyond Horndeski type. In this class of theories we derive a set of stability conditions ensuring the absence of ghosts and both radial and angular gradient instabilities about a static, spherically symmetric background. This set of constraints extends the existing one and completes the stability analysis for high energy modes in both parity odd and parity even sectors, while “slow” tachyonic instabilities remain unconstrained. We give an example of beyond Horndeski Lagrangian admitting a wormhole solution which complies with all stability constraints for the high energy modes.

The geodesics of the Ellis-Bronnikov wormhole with two parameters are studied. The asymmetric wormhole has only one light ring and one innermost stable circular orbit located on one side of the wormhole throat. Consequently, certain light rays can be reflected back by the wormhole. Additionally, the same wormhole can have different appearances on both sides of the throat. We present novel images of the wormhole with a light ring behind the throat in a scenario with an accretion disk as the light source and in a backlit wormhole scenario, which are distinct from the images of other compact objects and have the potential to be observed.

Compensated isocurvature perturbations (CIPs) are perturbations to the primordial baryon density that are accompanied by dark-matter-density perturbations so that the total matter density is unperturbed. Such CIPs, which may arise in some multifield inflationary models, can be long-lived and only weakly constrained by current cosmological measurements. Here we show that the CIP-induced modulation of the electron number density interacts with the electron-temperature fluctuation associated with primordial adiabatic perturbations to produce, via the Biermann-battery mechanism, a magnetic field in the post-recombinaton Universe. Assuming the CIP amplitude saturates the current BBN bounds, this magnetic field can be stronger than ${10}^{-15}\mathrm{nG}$ at $z\simeq 20$ and stronger by an order of magnitude than that (produced at second order in the adiabatic-perturbation amplitude) in the standard cosmological model, and thus can serve as a possible seed for galactic dynamos.

General classical arguments on the time evolution of the phase-space density can be used to derive constraints on the mass of particle candidates for the cosmological dark matter (DM). The resulting Tremaine-Gunn limit is extremely useful in constraining particle DM models. In certain models, however, the DM particle mass varies appreciably over time. In this work, we generalize the phase-space limits on possible DM particle masses to these scenarios. We then examine the ensuing cosmological implications on the effective DM equation of state and indirect DM detection.

We present a novel $n\mathrm{EPT}$ ($n$th-order Eulerian perturbation theory) scheme to model the nonlinear density field by the summation up to $n$th-order density fields in perturbation theory. The obtained analytical power spectrum shows excellent agreement with the results from all 20 Dark-Quest suites of $N$-body simulations spreading over a broad range of cosmologies. The agreement is much better than the conventional two-loop standard perturbation theory and would reach out to $k_{\max }\simeq 0.4h/\mathrm{Mpc}$ at $z=3$ for the best-fitting Planck cosmology, without any free parameters. We find that the $n\mathrm{EPT}$ results, particularly for $n>4$, depend sensitively on the grid size, but that can be removed by employing an effective field theory-type fitting function. The method can accelerate the forward modeling of the nonlinear cosmological density field, an indispensable probe of cosmic mysteries such as inflation, dark energy, and dark matter.

In light of the recent muon $g-2$ experiment data from Fermilab, we investigate the implications of a gauged $L_{\mu }-L_{\tau }$ model for high energy neutrino telescopes. It has been suggested that a new gauge boson at the MeV scale can both account for the muon $g-2$ data and alleviate the tension in the Hubble parameter measurements. It also strikes signals at IceCube from the predicted resonance scattering between high-energy neutrinos and the cosmic neutrino background. We revisit this model based on the latest IceCube shower data, and perform a four-parameter fit to find a preferred region. We do not find evidence for secret interactions. The best-fit points of $m_{Z^{\prime }}$ and $g_{\mu \tau }$ are $\sim 10\mathrm{MeV}$ and $\sim 0.1$, respectively, depending on assumptions regarding the absolute neutrino masses, and the secret interaction parameter space allowed by the observed IceCube data overlaps with the regions of the parameter space that can explain the muon $g-2$ anomaly and Hubble tension as well. We demonstrate that future neutrino telescopes such as IceCube-Gen2 can probe this unique parameter space, and point out that successful measurements would infer the neutrino mass with $0.06\mathrm{eV}\lesssim \mathrm{\Sigma }{m}_{\nu }\lesssim 0.3\mathrm{eV}$.

Recent gravitational wave observations of neutron-star-neutron-star and neutron-star-black-hole binaries appear to indicate that massive neutron stars may not be too uncommon in merging systems. These discoveries have led to an increased interest in the simulation of merging compact binaries involving massive stars. In this paper, we present a first set of evolution of massive neutron star binaries using Monte Carlo radiation transport for the evolution of neutrinos. We study a range of systems, from nearly symmetric binaries that collapse to a black hole before forming a disk or ejecting material, to more asymmetric binaries in which tidal disruption of the lower mass star leads to the production of more interesting postmerger remnants. For the latter type of systems, we additionally study the impact of viscosity on the properties of the outflows, and compare our results to two recent simulations of identical binaries performed with the whiskythc code. We find agreement on the black hole properties, disk mass, and mass and velocity of the outflows within expected numerical uncertainties, and some minor but noticeable differences in the evolution of the electron fraction when using a subgrid viscosity model, with viscosity playing a more minor role in our simulations. The method used to account for r-process heating in the determination of the outflow properties appears to have a larger impact on our result than those differences between numerical codes. We also use the simulation with the most ejected material to verify that our newly implemented Lagrangian tracers provide a reasonable sampling of the matter outflows as they leave the computational grid. We note that, given the lack of production of hot outflows in these mergers, the main role of neutrinos in these systems is to set the composition of the postmerger remnant. One of the main potential uses of our simulations is, thus, as improved initial conditions for longer evolutions of such remnants.

A large collection of equations of state (EOSs) built within the covariant density functional theory of hadronic matter and allowing for density dependent couplings is employed to study polar $f$- and $p$-oscillations of cold and hot compact stars. Correlations between oscillation frequencies of cold purely nucleonic neutron stars (NSs), their global parameters as well as properties of nuclear matter (NM) are investigated by considering a set of models from Beznogov and Raduta, [Phys. Rev. C 107, 045803 (2023)], where a number of constraints on the saturation properties of NM, pure neutron matter and the lower bound of the maximal NS mass were imposed within a Bayesian framework. The roles of finite temperature and exotic particle degrees of freedom, e.g., hyperons, $\mathrm{\Delta }$-resonances, antikaon condensates or a hadron to quark phase transition, are addressed by employing a family of models publicly available on compose and assuming idealized profiles of temperature or entropy per baryon and charge fraction. We find that finite temperature effects reduce the oscillation frequencies of nucleonic stars while the opposite effect is obtained for stars with exotic particle degrees of freedom. When the $\mathrm{\Gamma }$-law is employed to build finite temperature EOSs, errors in estimating oscillation modes frequencies are of the order of 10% to 30%, depending on the mass. Throughout this work the Cowling approximation is used.

Some recent, long-term numerical simulations of binary neutron star mergers have shown that the long-lived remnants produced in such mergers might be affected by convective instabilities. Those would trigger the excitation of inertial modes, providing a potential method to improve our understanding of the rotational and thermal properties of neutron stars through the analysis of the modes’ imprint in the late postmerger gravitational-wave signal. In this paper, we assess the detectability of those modes by injecting numerically generated postmerger waveforms into colored Gaussian noise of second-generation and future detectors. Signals are recovered using BayesWave, a Bayesian data-analysis algorithm that reconstructs them through a morphology-independent approach using series of sine-Gaussian wavelets. Our study reveals that current interferometers (i.e., the Hanford-Livingston-Virgo network) recover the peak frequency of inertial modes only if the merger occurs at distances of up to 1 Mpc. For future detectors such as the Einstein Telescope, the range of detection increases by about a factor 10.

Resonant anomaly detection is a promising framework for model-independent searches for new particles. Weakly supervised resonant anomaly detection methods compare data with a potential signal against a template of the Standard Model (SM) background inferred from sideband regions. We propose a means to generate this background template that uses a flow-based model to create a mapping between high-fidelity SM simulations and the data. The flow is trained in sideband regions with the signal region blinded, and the flow is conditioned on the resonant feature (mass) such that it can be interpolated into the signal region. To illustrate this approach, we use simulated collisions from the Large Hadron Collider (LHC) Olympics dataset. We find that our flow-constructed background method has competitive sensitivity with other recent proposals and can therefore provide complementary information to improve future searches.

We discuss the production of dark matter with mass of order 10–100 TeV and $\mathcal{O}(1)$ couplings to the standard model, a scenario we refer to as the “mesotuned WIMP.” Given the lack of new physics observed at the LHC, indicating we live in a world with some degree of fine-tuning, this scale is a natural scale to expect new particles to appear. However, dark matter with mass in this range and large couplings is difficult to produce with the observed relic abundance via the usual mechanisms. Here we discuss the nonthermal production of dark matter and show that this mechanism can produce the observed dark matter in this mass range, but requires a specific relationship between the dark matter mass and the reheat temperature. It is shown that the avoided deconfinement model removes the dependence on the reheat temperature and predicts a dark matter candidate that can be tested at the Cherenkov Telescope Array and direct detection experiments, offering a natural setting for mesotuned WIMP dark matter.

We present a comprehensive analysis of the SU(3) octet and decuplet baryon masses and $\sigma$ terms using high-precision lattice QCD data and chiral SU(3) effective theory with finite range regularization. The effects of various systematic uncertainties, including from the scale setting of the lattice data and the regularization prescriptions, are quantified. We find the pion-nucleon and strange nucleon $\sigma$ terms to be ${\sigma }_{\pi N}=44(3)(3)\mathrm{MeV}$ and ${\sigma }_{Ns}=50(6)(1)\mathrm{MeV}$, respectively. The results provide constraints on the energy-momentum tensor mass decompositions of the SU(3) octet and decuplet baryons, where we find that the trace anomaly and quark-gluon energies decrease for strange baryons due to their larger strange $\sigma$ terms.

We analyze the magnetic field of electroweak dumbbells. While the magnetic field of the untwisted dumbbell is given by the usual dipole formula and falls off as $1/r^3$, dumbbells with twist have a novel twisted magnetic field that only falls off as $\cos \theta /r^2$ (in spherical coordinates). We comment on the relevance of twisted electroweak dumbbells for understanding the coherence of the magnetic field generated at the electroweak phase transition.