We investigate E1 radiative transitions within charmonium in a relativistic approach based on light-front QCD. In quantum field theory, two sets of processes are pure E1: ${\chi }_{c0}\to J/\psi \gamma$ ($\psi \to {\chi }_{c0}\gamma$) and $h_c\to {\eta }_c\gamma$ (${\eta }_c^{\prime }\to h_c\gamma$), both involving the $P$-wave charmonia. We compute the E1 radiative decay widths as well as the corresponding transition form factors of various processes including those involving $2P$ states. These observables provide an access to the microscopic structures of the $P$-wave charmonium. We show that our parameter-free predictions are in excellent agreement with the experimental measurements as well as lattice simulations whenever available.

We demonstrate that triangle singularity (TS) and box singularity (BS) mechanisms can produce unique narrow enhancements at the ${\mathrm{\Lambda }}_c\overline{D}$ and ${\mathrm{\Lambda }}_c{\overline{D}}^{*}$ thresholds in the invariant mass spectra of $J/\psi p$ and $J/\psi p\pi$, respectively. Taking into account that such mechanisms only depend on the initial ${\mathrm{\Sigma }}_c^{(*)}{\overline{D}}^{(*)}$ interactions near threshold within the TS or BS kinematic regimes, the ${\mathrm{\Lambda }}_c\overline{D}$ and ${\mathrm{\Lambda }}_c{\overline{D}}^{*}$ threshold enhancements can also acquire contributions from both the heavier pentaquark decays and the ${\mathrm{\Sigma }}_c^{(*)}{\overline{D}}^{(*)}$ scatterings of the continuum as a feed-down phenomenon. A search for these structures in the $J/\psi p$ and $J/\psi p\pi$ spectra in both exclusive and semi-inclusive processes will provide a crucial evidence for the hadronic molecule nature of these observed pentaquarks and clarify the role played by the TS and BS in the near-threshold dynamics.

In this paper we investigate some general aspects of fluctuation and dissipation in the holographic scenario at zero and finite density. We model this situation with a probe string in a diagonal metric representing a black brane. The string stretches from the black brane to a probe brane, thus simulating a stochastic driven particle. In this scenario, we compute the admittance, the diffusion coefficient, the correlation functions, and the regularized mean square displacement, for bosons and fermions, all from the metric components. We check these calculations with the fluctuation-dissipation theorem. Further, we show that at finite temperature and density, the mean square displacement in the limit of short times reproduces the usual quadratic (ballistic) behavior, for bosons and fermions. For large times, we find ultraslow diffusive processes in various cases, except for bosons at the zero chemical potential. We apply this general analysis in two different models: hyperscaling violation at finite temperature and a charged dilatonic anti–de Sitter black hole, both for bosons and fermions. This is important because we found the fermionic diffusion in systems that allow the appearance of Fermi surfaces and Fermi liquids.

Mermin’s inequalities are investigated in a quantum field theory framework by using von Neumann algebras built with Weyl operators. We devise a general construction based on the Tomita-Takesaki modular theory and use it to compute the vacuum expectation value of the Mermin operator, analyzing the parameter space and explicitly exhibiting a violation of Mermin’s inequalities. Therefore, relying on the power of modular operators, we are able to demonstrate that Mermin’s inequalities are violated when examined within the vacuum state of a scalar field theory.

Higher-form symmetries are a valuable tool for classifying topological phases of matter. However, emergent higher-form symmetries in interacting many-body systems are typically not exact due to the presence of topological defects. In this paper, we develop a systematic framework for building effective theories with approximate higher-form symmetries. We focus on a continuous U(1) $q$-form symmetry and study phases with various patterns of spontaneous and explicit symmetry breaking. We uncover a web of dualities between such phases and highlight their role in describing the presence of dynamical higher-form topological defects. In order to study the out-of-equilibrium dynamics of these phases of matter, we formulate respective hydrodynamic theories and study the spectra of excitations exhibiting higher-form charge relaxation and Goldstone relaxation effects. We show that our framework is able to describe various phase transitions due to proliferation of vortices or defects. This includes the melting transition in smectic crystals, the plasma phase transition from polarized gases to magnetohydrodynamics, the spin-ice transition, the superfluid to neutral fluid transition, and the Meissner effect in superconductors, among many others.

Generic models in Galileons or Horndeski theory do not have cosmological solutions that are free of instabilities and singularities in the entire time of evolution. We extend this no-go theorem to a spacetime with torsion. On this more general geometry the no-go argument now holds provided the additional hypothesis that the graviton is also subluminal throughout the entire evolution. Thus, critically different for Galileons’ stability on a torsionful spacetime, an arguably unphysical although arbitrarily short (deep UV) phase occurring at an arbitrary time, when the speed of gravity $(c_g)$ is slightly higher than luminal ($c$), and by at least an amount $c_g\ge \sqrt{2}c$, can lead to an all-time linearly stable and nonsingular cosmology. As a proof of principle we build a stable model for a cosmological bounce that is almost always subluminal, where the short-lived superluminal phase occurs before the bounce, and that transits to general relativity in the asymptotic past and future.

We present a novel approach, metric perturbations with spectral methods (METRICS), to calculate the gravitational metric perturbations and the quasinormal-mode frequencies of rotating black holes of any spin without decoupling the linearized field equations. We demonstrate the method by applying it to perturbations of Kerr black holes of any spin, simultaneously solving all ten linearized Einstein equations in the Regge-Wheeler gauge through purely algebraic methods and computing the fundamental (corotating) quadrupole mode frequency at various spins. We moreover show that the METRICS approach is accurate and precise, yielding (i) quasinormal mode frequencies that agree with Leaver’s, continuous-fraction solution with a relative fractional error smaller than ${10}^{-5}$ for all dimensionless spins below up to 0.95, and (ii) metric perturbations that lead to Teukolsky functions that also agree with Leaver’s solution with mismatches below 1% for all spins below 0.9. By not requiring the decoupling or the angular separation of the linearized field equations, the METRICS approach has the potential to be straightforwardly adapted for the computation of the quasinormal-mode frequencies of rotating black holes of any spin beyond general relativity or in the presence of matter.

We propose a novel method to probe the global 21-cm background. This background experiences the integrated Sachs-Wolfe effect (ISW) as the cosmic microwave background does. The 21-cm ISW is modulated by the spectral shape of the global 21-cm signal, and thus the measure of the 21-cm ISW will be a probe of the evolution of the global signal. This strategy naturally mitigates the impact of the Milky Way foreground, which is a common and most significant challenge in conventional 21-cm background probes. With the phase-1 SKA telescope, probing the global 21-cm background would be feasible with a few 1000 hours of observation, enabling consistency checks with existing measures of the global 21-cm signal by EDGES and SARAS that are conflicting with each other.

The origin of interstellar and intergalactic magnetic fields remains largely unknown. One possibility is that they are related to the primordial magnetic fields (PMFs) produced by, for instance, the phase transitions of the early Universe. In this paper, the PMF-induced turbulence generated at around the QCD phase transition epoch—the characteristic magnetic field strength $B_{\mathrm{ch}}^{*}\sim \mathcal{O}(1)\mathrm{\mu }\mathrm{G}$ and coherent length scale ${\ell }_{\mathrm{ch}}^{*}\sim \mathcal{O}(1)\mathrm{pc}$—can naturally accommodate nanohertz gravitational waves reported by pulsar timing array (PTA) collaborations. Moreover, the evolution of the PMFs to the recombination era with the form of $B_{\mathrm{ch}}\sim {\ell }_{\mathrm{ch}}^{-\alpha }$ can induce baryon density inhomogeneities, alter the recombination history, and alleviate the tension of the Hubble parameter $H_0$ and the matter clumpiness parameter $S_8$ between early- and late-time measurements for $0.88\le \alpha \le 1.17$ (approximate 95% credible region based on three PTA likelihoods). This allowed range of $\alpha$ is for the first time obtained by data-driven approach. The further evolved PMFs may account for the $\sim \mathcal{O}({10}^{-16})$ Gauss extragalactic magnetic field inferred with GRB 221009A.

Primordial black holes (PBHs) in the mass range $\sim {10}^{17}–{10}^{23}\mathrm{g}$ are currently unconstrained, and can constitute the full dark matter (DM) density of the universe. Motivated by this, in the current work, we aim to relate the existence of PBHs in the said mass range to the production of observable gravitational waves (GWs) in the upcoming GW detectors. We follow a relatively model-independent approach assuming that the PBHs took birth in a radiation dominated era from enhanced primordial curvature perturbation at small scales produced by inflation. We show that the constraints from cosmic microwave background and BAO data allow for the possibility of PBHs being the whole of DM density of the universe. Finally, we derive the GW spectrum induced by the enhanced curvature perturbations and show that they are detectable in the future GW detectors like eLISA, LISA, BBO, and DECIGO.

In this paper, we elaborate and extend our proposal [1] of the cosmological bouncing model in which a chiral condensate violates the null energy condition and induces a bounce. The condensate formation is caused by the gravitational effects that arise in the effective action when the curvature of space-time is nonzero. As the chiral condensation is a vacuum effect, the symmetries of the Friedmann-Robertson-Walker space-time are not violated. We explicitly calculate the spinor effective action in the presence of a background gravitational field up to second order in curvature and with derivative corrections and also derive the initial conditions of the condensate. In addition, a new interaction term between the condensate and the scalar field is introduced that might be relevant for producing the adiabatic perturbations during the contraction phase. The curvature/energy density stays far from Planckian values throughout this evolution.

The equation of state for dense matter is studied with color molecular dynamics, in which hadron matter and quark matter are automatically distinguished only from quark color state. The quark-quark interactions are optimized to be consistent with saturation properties: symmetric energy, $L$-parameter, and incompressibility around nuclear density. In the calculations, the degrees of freedom of colors are solved at each numerical step, although the flavors are fixed as up or down quarks. The resultant mass-radius relations also satisfy the observational constraints such as the gravitational wave observations, NICER, and “the two-solar mass observations” of neutron stars. In this model with the allowed parameter range, deconfined quark matter appears in the core of neutron stars via crossover. Although the current constraints from the observations are not enough to conclude whether quark matter appears at high-density region and also our study is still in a qualitative level, our method would help to understand high-density material properties inside neutron stars in the future.

We study the prospects for detection of solar, atmospheric neutrino, and diffuse supernova neutrino background (DSNB) fluxes at future large-scale dark matter detectors through both electron and nuclear recoils. We specifically examine how the detection prospects change for several prospective detector locations [Sanford Underground Research Facility (SURF), SNOlab, Gran Sasso, China Jinping Underground Laboratory (CJPL), and Kamioka] and improve upon the statistical methodologies used in previous studies. Because of its ability to measure lower neutrino energies than other locations, we find that the best prospects for the atmospheric neutrino flux are at the SURF location, while the prospects are weakest at CJPL because it is restricted to higher neutrino energies. On the contrary, the prospects for the DSNB are best at CJPL, due largely to the reduced atmospheric neutrino background at this location. Including full detector resolution and efficiency models, the CNO component of the solar flux is detectable via the electron recoil channel with exposures of $\sim {10}^3$ ton-yr for all locations. These results highlight the benefits for employing two detector locations, one at high and one at low latitude.

In this work, we perform a comparative analysis between the density-dependent quark model and the vector MIT bag model using Bayesian analysis. We use the equations of state generated by these two models to describe quark stars. We impose four recent observational astrophysical constraints on both models to determine their model-dependent parameters in an optimized manner assuming that the compact objects observed are composed entirely of self-bound quarks. The restrictions are aimed at producing stars with maximum masses $2-2.35M_{\odot }$ and a mass-radii diagram compatible with the observed pulsars PSR $\mathrm{J}0740+6620$, PSR J0952-0607, and PSR $\mathrm{J}0030+0451$ and the compact object XMMU J173203.3-344518. With this analysis, the parameter dependence of the nuclear equation of state of both models is restricted.

The next generation gravitational wave (GW) detectors—Einstein Telescope (ET) and Cosmic Explorer (CE)—will have distance horizons up to $\mathcal{O}(10)\mathrm{Gpc}$ for detecting binary neutron star (BNS) mergers. This will make them ideal for triggering high-energy neutrino searches from BNS mergers at the next generation neutrino detectors, such as IceCube-Gen2. We calculate the distance limits as a function of the time window of neutrino analysis, up to which meaningful triggers from the GW detectors can be used to minimize backgrounds and collect a good sample of high-energy neutrino events at the neutrino detectors, using the sky localization capabilities of the GW detectors. We then discuss the prospects of the next generation detectors to work in synergy to facilitate coincident neutrino detections or to constrain the parameter space in the case of nondetection of neutrinos. We show that good localization of GW events, which can be achieved by multiple third generation GW detectors, is necessary to detect a GW-associated neutrino event or put a meaningful constraint ($\sim 3\sigma$ confidence level) on neutrino emission models. Such an analysis can also help constrain physical models and hence provide insights into neutrino production mechanisms in binary neutron star mergers.

The maximal gravitational mass of nonrotating neutron stars ($M_{\mathrm{TOV}}$) is one of the key parameters of compact objects and only loose bounds can be set based on the first principle. With reliable measurements of the masses and/or radii of the neutron stars, $M_{\mathrm{TOV}}$ can be robustly inferred from either the mass distribution of these objects or the reconstruction of the equation of state of the very dense matter. For the first time we take the advantages of both two approaches to have a precise inference of $M_{\mathrm{TOV}}=2.25_{-0.07}^{+0.08}{M}_{\odot }$ (68.3% credibility), with the updated neutron star mass measurement sample, the mass-tidal deformability data of GW170817, the mass-radius data of PSR $\mathrm{J}0030+0451$ and PSR $\mathrm{J}0740+6620$, as well as the theoretical information from the chiral effective theory and perturbative quantum chromodynamics (pQCD) at low- and very high-energy densities, respectively. This narrow credible range is benefited from the suppression of the high $M_{\mathrm{TOV}}$ by the pQCD constraint and the exclusion of the low $M_{\mathrm{TOV}}$ by the mass function. Three different EoS reconstruction methods are adopted separately, and the resulting $M_{\mathrm{TOV}}$ and $R_{\mathrm{TOV}}$ are found to be almost identical, where $R_{\mathrm{TOV}}=11.90_{-0.60}^{+0.63}\mathrm{km}$ is the radius of the most massive nonrotating neutron star. This precisely evaluated $M_{\mathrm{TOV}}$ suggests that the EoS of neutron star matter is just moderately stiff and the $\sim 2.5–3M_{\odot }$ compact objects detected by the second-generation gravitational wave detectors are most likely the lightest black holes.

We introduce an effective field theory to study indirect mixing of two fields induced by their couplings to a common decay channel in a medium. The extension of the method of Lee, Oehme, and Yang, the cornerstone of analysis of $CP$ violation in flavored mesons, to include the mixing of particles with different masses provides a guide to and benchmark for the effective field theory. The analysis reveals subtle caveats in the description of mixing in terms of the widely used non-Hermitian effective Hamiltonian, more acute in the nondegenerate case. The effective field theory describes the dynamics of field mixing where the common intermediate states populate a bath in thermal equilibrium, as an open quantum system. We obtain the effective action up to second order in the couplings, where indirect mixing is a consequence of off-diagonal self-energy components. We find that if only one of the mixing fields features an initial expectation value, indirect mixing induces an expectation value of the other field. The equal time two point correlation functions exhibit an asymptotic approach to a stationary thermal state, and the emergence of long-lived bath-induced coherence which displays quantum beats as a consequence of interference of quasinormal modes in the medium. The amplitudes of the quantum beats are resonantly enhanced in the nearly degenerate case with potential observational consequences.

We develop an improved method to explore the ${\mathrm{\Xi }}_c-{\mathrm{\Xi }}_c^{\prime }$ mixing, which arises from the flavor SU(3) and heavy quark symmetry breaking. In this method, the flavor eigenstates under the SU(3) symmetry are at first constructed, and the corresponding masses can be nonperturbatively determined. Matrix elements of the mass operators, which break the flavor SU(3) symmetry sandwiched by the flavor eigenstates, are then calculated. Diagonalizing the corresponding matrix of Hamiltonian gives the mass eigenstates of the full Hamiltonian and determines the mixing. Following the previous lattice QCD calculation of ${\mathrm{\Xi }}_c$ and ${\mathrm{\Xi }}_c^{\prime }$, and estimating an off diagonal matrix element, we extract the mixing angle between the ${\mathrm{\Xi }}_c$ and ${\mathrm{\Xi }}_c^{\prime }$. Preliminary numerical results for the mixing angle confirm the previous observation that such mixing is incapable to explain the large SU(3) symmetry breaking in semileptonic decays of charmed baryons.

Renormalization group analysis with the present measurements of the top quark mass $m_t=172.69\pm 0.30\mathrm{GeV}$ [1] indicates that the Standard Model (SM) Higgs potential becomes unstable at energy scales $\sim {10}^{10}\mathrm{GeV}$. This may be interpreted as hinting at new particles at high energy. The minimal extension of the SM that can avoid this instability while leaving the SM Higgs as the sole scalar particle of the theory is obtained by adding suitable fermions to the SM. These fermions are good dark matter candidates and the model is known as the minimal dark matter model. We revisit the inflationary scenario based on the minimal dark matter model, taking into account updated parameter constraints and recent understanding of reheating dynamics. We explore the model with different values of the right-handed neutrino mass and find that the cosmological prediction is insensitive to such details. We obtained a spectral index of the cosmic microwave background $n_s=0.9672$ and a tensor-to-scalar ratio $r=0.0031$ as a robust prediction of this scenario.

Restricted Boltzmann machines (RBMs) are well-known tools used in machine learning to learn probability distribution functions from data. We analyze RBMs with scalar fields on the nodes from the perspective of lattice field theory. Starting with the simplest case of Gaussian fields, we show that the RBM acts as an ultraviolet regulator, with the cutoff determined by either the number of hidden nodes or a model mass parameter. We verify these ideas in the scalar field case, where the target distribution is known, and explore implications for cases where it is not known using the MNIST dataset. We also demonstrate that infrared modes are learnt quickest.