Using a data sample of $(1310.6\pm 7.0)\times {10}^{6}J/\psi$ events collected with the BESIII detector operating at the BEPCII collider, we perform the first experimental search for invisible decays of a light vector meson ($V=\omega$, $\varphi$) via $J/\psi \to V\eta$ decays. The decay of $\eta \to {\pi }^{+}{\pi }^{-}{\pi }^0$ is utilized to tag the $V$ meson decaying into the invisible final state. No evidence for a significant invisible signal is observed, and the upper limits on the ratio of branching fractions at the 90% confidence level are determined to be $\frac{\mathcal{B}(\omega \to \text{invisible})}{\mathcal{B}(\omega \to {\pi }^{+}{\pi }^{-}{\pi }^0)}<8.1\times {10}^{-5}$ and $\frac{\mathcal{B}(\varphi \to \text{invisible})}{\mathcal{B}(\varphi \to K^{+}{K}^{-})}<3.4\times {10}^{-4}$. By using the world average values of $\mathcal{B}(\omega \to {\pi }^{+}{\pi }^{-}{\pi }^0)$ and $\mathcal{B}(\varphi \to K^{+}{K}^{-})$, the upper limits on the decay branching fractions at the 90% confidence level are set as $\mathcal{B}(\omega \to \text{invisible})<7.3\times {10}^{-5}$ and $\mathcal{B}(\varphi \to \text{invisible})<1.7\times {10}^{-4}$, respectively.

We consider a procedure for directly constructing general tree-level four-particle scattering amplitudes of massive spinning particles that are consistent with the usual requirements of Lorentz invariance, unitarity, crossing symmetry, and locality. There are infinitely many such amplitudes, but we can isolate interesting theories by bounding the high-energy growth of the tree amplitudes within the effective field theory. This allows us to set model-independent lower bounds on the growth of tree-level amplitudes in any effective field theory with a given particle content and any interaction terms with an arbitrary but finite number of derivatives. In certain common cases this corresponds to finding the highest possible strong coupling scale. When applied to spin 2, we show that the only amplitudes that saturate this bound are generated by the known ghost-free theories of a massive spin-2 particle, namely de Rham, Gabadadze and Tolley massive gravity and the pseudolinear theory. We also make a conjecture for the allowed growth of tree amplitudes in a theory with a single massive particle of any integer spin.

This work is the first in a series of studies aimed at understanding the dynamics of highly eccentric binary neutron stars, and constructing an appropriate gravitational-waveform model for detection. Such binaries are possible sources for ground-based gravitational wave detectors, and are expected to form through dynamical scattering and multibody interactions in globular clusters and galactic nuclei. In contrast to black holes, oscillations of neutron stars are generically excited by tidal effects after close pericenter passage. Depending on the equation of state, this can enhance the loss of orbital energy by up to tens of percent over that radiated away by gravitational waves during an orbit. Under the same interaction mechanism, part of the orbital angular momentum is also transferred to the star. We calculate the impact of the neutron star oscillations on the orbital evolution of such systems, and compare these results to full numerical simulations. Utilizing a post-Newtonian flux description we propose a preliminary model to predict the timing of different pericenter passages. A refined version of this model (taking into account post-Newtonian corrections to the tidal coupling and the oscillations of the stars) may serve as a waveform model for such highly eccentric systems.

The collisional Penrose process of charged spinning particles (charged tops) near the black hole/white hole horizon (black hole and white hole horizon) for the metric of an extreme Kerr-Newman black hole is studied. We have explicitly written the equation of motion together with the energy gain of the collisional process for the massive particles. We have also investigated the effects of spin and charge hold by the particles as well as that of the angular momentum and charge possessed by the black hole/white hole on the energy extraction.

We study a quintessential black hole solution in three dimensions, with mass and quintessence charge. By exploring the Carter-Penrose diagram, we show the presence of spacelike and lightlike singularities in the metric, given different values for the quintessence parameter, as well as an AdS-like spatial infinity and event horizon encapsulating the singularity. We also study the propagation of scalar and Dirac (Weyl) fields around the black hole solutions with different quintessence charges, obtaining the quasinormal spectra for both fields using two different numerical methods with good agreement between the data. In both cases, the presence of quintessence increases the imaginary part of the quasinormal mode, since this is related to the event horizon of the solution, preserving the interpretation of this quantity as relaxation time in the corresponding CFT. We also investigate the behavior of high-temperature scalar field modes, demonstrating the presence of the so-called hydrodynamical limit, different from the BTZ black hole, for which no such modes exist.

Scalar-tensor theories are one of the most natural and well-constrained alternative theories of gravity, while still allowing for significant deviations from general relativity. We present the equations of motion of nonspinning compact binary systems at the third post-Newtonian (PN) order in massless scalar-tensor theories. We adapt the Fokker action of point particles in harmonic coordinates in general relativity to the specificities of scalar-tensor theories. We use dimensional regularization to treat both the infrared and ultraviolet divergences, and we consistently include the tail effects that contribute by a nonlocal term to the dynamics. This work is crucial in order to later compute the scalar gravitational waveform and the energy flux at 2PN order.

To discuss the possible contribution of parafermions to the dark matter abundance, we extend the Boltzmann equation for fermionic dark matter to include parafermions. Parafermions can accommodate $r$ particles per quantum state $(2\le r<\infty )$, in which the parafermion of order $r=1$ is identical to the ordinary fermion. It is found that the parafermionic dark matter can be more abundant than the fermionic dark matter in the present Universe.

Cosmological data can be used to search for—and characterize—light particles in the standard model, if these populate our Universe. In addition to the well-known effect of these light relics in the background cosmology, usually parametrized through a change in the effective number $N_{\mathrm{eff}}$ of neutrino species, these particles can become nonrelativistic at later times, affecting the growth of matter fluctuations due to their thermal velocities. An extensively studied example is that of massive neutrinos, which are known to produce a suppression in the matter power spectrum due to their free streaming. Galaxies, as biased traces of matter fluctuations, can therefore provide us with a wealth of information about both known and unknown degrees of freedom in the standard model. To harness this information, however, the galaxy bias has to be determined in the presence of massive relics, which is expected to vary with scale. Here, we present the code RelicFast, which efficiently computes the scale-dependent bias induced by relics of different masses, spins, and temperatures, through spherical collapse and the peak-background split. Using this code, we find that, in general, the bias induced by light relics partially compensates for the suppression of power and should be accounted for in any search for relics with galaxy data. In particular, for the case of neutrinos, we find that both the normal and inverted hierarchies present a percent-level step in the Lagrangian bias, with a size scaling linearly with the neutrino-mass sum, in agreement with recent simulations. This effect persists at the subpercent level even if one defines the Eulerian bias with respect to dark matter only, suggesting that it has to be properly included in cosmological searches for the neutrino mass. RelicFast can compute halo bias in under a second, allowing for this effect to be properly included for different cosmologies, and light relics, at little computational cost.

Dark gauge sectors and axions are well motivated in string theory. We demonstrate that if a confining gauge sector gives rise to dark glueballs that are a fraction of the dark matter, and the associated axion has a decay constant near the string scale, then this axion is ultralight and naturally realizes the fuzzy dark matter scenario with a modest tuning of a temperature ratio. Astrophysical observations constrain the size of the glueball component relative to the axionic component, while electric dipole moments constrain mixing with the QCD axion.

Recent simulation studies indicate that right-handed neutrinos may be discovered at future high luminosity LHC runs as long as a new neutral gauge boson, $Z^{\prime }$, have been discovered first. In this case, when $Z^{\prime }$ is resonantly produced at the LHC it, subsequently, decays into a pair of right-handed neutrinos with mass up to TeV scale. Then the decay of these neutrinos leave as signature trilepton final states and/or same-sign dimuon and a boost diboson. The prospect of discovering right-handed neutrinos through this mechanism has been developed within Abelian gauge extension of the standard model. In this work we study the processes involved in this discovery mechanism within the framework of a 3-3-1 model.

A possible density spike of dark matter (DM) in the subparsec region near the supermassive black hole at the Galactic center could have a significant effect on indirect signals of dark matter annihilation. Here we explore the impacts of the modeling of the dark matter distribution in the inner Galaxy on gamma-ray signals of dark matter annihilation. We consider a range of values for relevant astrophysical parameters that describe the dark matter profile, including a possible spike, and quantify the dependence of the gamma-ray flux on these choices. We consider both an idealized case where no depletion of the spike has occurred since its formation, as well as a case where the spike is significantly depleted over time due, e.g., to gravitational interactions with baryons. We also consider a range of power-law descriptions of the dark matter profile outside of the spike region. Taking Fermi-$LAT$ data for the gamma-ray flux from the point source 3FGL J1745.6-2859c (Sgr A*), we calculate the resulting constraints on generic models of DM, allowing for the possibility of a non-negligible velocity-dependent component of the annihilation cross section. We find that for very depleted spikes, the spike itself would contribute insignificantly to a dark matter annihilation signal, though constraints on dark matter models are still possible depending on the power law behavior of the dark matter profile on larger scales. For idealized spikes, we quantify the influence of the spike, as well as the larger-scale dark matter profile, on the gamma-ray flux from dark matter annihilations and on the constraints on the properties of particle dark matter from observations of the Galactic center point source.

Relativistic light-front bound-state equations for double-heavy mesons, baryons and tetraquarks are constructed in the framework of supersymmetric light front holographic QCD. Although heavy quark masses strongly break conformal symmetry, supersymmetry and the holographic embedding of semiclassical light-front dynamics still holds. The theory, derived from five-dimensional anti–de Sitter space, predicts that the form of the confining potential in the light-front Hamiltonian is harmonic even for heavy quarks. Therefore, the basic underlying supersymmetric mechanism, which transforms meson-baryon and baryon-tetraquark wave functions into each other, can also be applied to the double-heavy sector; one can then successfully relate the masses of the double-heavy mesons to double-heavy baryons and tetraquarks. The dependence of the confining potential on the hadron mass scale agrees completely with the one derived in heavy light systems from heavy quark symmetry. We also make predictions for higher excitations of the charmonium and bottomonium states. In particular, the remarkable equality of the Regge slopes in the orbital angular momentum, $L$, and the principal quantum number, $n$, is predicted to remain valid.

We decompose the tribaryon configuration in terms of SU(3) flavor and spin state and analyze their color-spin-flavor wave function following the Pauli principle. By comparing the color-color and color-spin interactions of compact tribaryon configuration against the lowest three nucleon threshold within a constituent quark model, we show that the three nucleon configurations have to be repulsive at short distance for all possible quantum numbers and all values of the SU(3) symmetry breaking parameter. Our work identifies the origin of the repulsive nuclear three body forces including the hyperons at short distance that are called for from phenomenological considerations starting from nuclear matter to the maximum mass of a neutron star.

An experimental test of quantum effects in gravity has recently been proposed, where the gravitational field’s ability to entangle two masses is used as a witness of its quantum nature. Here, we discuss what existing models for coupled matter and gravity predict for this experiment. Collapse-type models, and also quantum field theory in curved spacetime, as well as various induced gravities, do not predict entanglement generation; they would, therefore, be ruled out as fundamental descriptions of gravity if entanglement were observed. Instead, local linearized quantum gravity models predict that the masses can become entangled. We analyze the mechanism by which entanglement is established in such models, modeling a gravity-assisted two-qubit gate.

We determine central charges, critical exponents and appropriate gradient flow relations for nonsupersymmetric vector-like and chiral Gauge-Yukawa theories that are fundamental according to Wilson and that feature calculable UV or IR interacting fixed points. We further uncover relations and identities among the various local and global conformal data. This information is used to provide the first extensive characterization of general classes of free and safe quantum field theories of either chiral or vector-like nature via their conformal data. Using large $N_f$ techniques we also provide examples in which the safe fixed point is nonperturbative but for which conformal perturbation theory can be used to determine the global variation of the $a$ central charge.

We demonstrate the extension to parity-time ($\mathcal{PT}$)-symmetric field theories of the Goldstone theorem, confirming that the spontaneous appearance of a field vacuum expectation value via minimization of the effective potential in a non-Hermitian model is accompanied by a massless scalar boson. Laying a basis for our analysis, we first show how the conventional quantization of the path-integral formulation of quantum field theory can be extended consistently to a non-Hermitian model by considering $\mathcal{PT}$ conjugation instead of Hermitian conjugation. The extension of the Goldstone theorem to a $\mathcal{PT}$-symmetric field theory is made possible by the existence of a conserved current that does not, however, correspond to a symmetry of the non-Hermitian Lagrangian. In addition to extending the proof of the Goldstone theorem to a $\mathcal{PT}$-symmetric theory, we exhibit a specific example in which we verify the existence of a massless boson at the tree and one-loop levels.

Observations have revealed that nearly all galaxies contain supermassive black holes (SMBHs) at their centers. When galaxies merge, these SMBHs form SMBH binaries (SMBHBs) that emit low-frequency gravitational waves (GWs). The incoherent superposition of these sources produce a stochastic GW background (GWB) that can be observed by pulsar timing arrays. The optimal statistic is a frequentist estimator of the amplitude of the GWB that specifically looks for the spatial correlations between pulsars induced by the GWB. In this paper, we introduce an improved method for computing the optimal statistic that marginalizes over the red noise in individual pulsars. We use simulations to demonstrate that this method more accurately determines the strength of the GWB, and we use the noise-marginalized optimal statistic to compare the significance of monopole, dipole, and Hellings-Downs (HD) spatial correlations and perform sky scrambles.

We analyze the asymptotic behavior of small perturbations of Minkowski space caused by the presence of ensembles of massive and massless particles in spherical symmetries. The perturbations we consider are compactly supported in space and momenta.

Considering the unexpected similarity between the thermodynamic features of charged AdS black holes and that of the van der Waals fluid system, we calculate the number densities of black hole micromolecules and derive the thermodynamic scalar curvature for the small and large black holes on the coexistence curve based on the so-called Ruppeiner thermodynamic geometry. We reveal that the microscopic feature of the small black hole perfectly matches that of the ideal anyon gas and that the microscopic feature of the large black hole matches that of the ideal Bose gas. More importantly, we investigate the issue of molecular potential among micromolecules of charged AdS black holes and point out explicitly that the well-known experiential Lennard-Jones potential is a feasible candidate to describe interactions among black hole micromolecules completely from a thermodynamic point of view. The behavior of the interaction force induced by the Lennard-Jones potential coincides with that of the thermodynamic scalar curvature. Both the Lennard-Jones potential and the thermodynamic scalar curvature offer a clear and reliable picture of microscopic structures for the small and large black holes on the coexistence curve for charged AdS black holes.