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New measurements on cross sections in $e^+e^-\to J/\psi\pi^+\pi^-$, $h_c\pi^+\pi^-$, $D^0D^{*-}\pi^++c.c.$, $\psi(2S)\pi^+\pi^-$, $\omega\chi_{c0}$ and $J/\psi\eta$ channels have been carried out by BESIII, Belle and BABAR collaborations, and also in the $D_s^*\bar D_s^*$ channel. We perform extensive numerical analyses by combining all these data available, together with those in $D\bar D^*$ and $D^*\bar D^*$ channels. Though the latter show no evident peak around $\sqrt{s}=4.230$ GeV, the missing $X(4260)$ is explained as that it is concealed by the interference effects of the well established charmonia $\psi(4040)$, $\psi(4160)$ and $\psi(4415)$. Our analyses reveal that the leptonic decay width of $X(4260)$ ranges from $O(10^2)$ eV to $O(1)$ keV, and hence may be explained in the conventional quark model picture. That is, the $X(4260)$ may well be interpreted as a mixture of $4^3S_1$ and $3^3D_1$ states., Comment: two small mistakes are fixed, figures redrawn, major physical outputs remain unchanged. Version published in EPJC

In this letter, we have demonstrated the possibility to efficiently relay the radiative heat flux between two nanoparticles by opening a smooth channel for heat transfer. By coating the nanoparticles with a silica shell and modifying the substrate with multilayered graphene sheets respectively, the localized phonon polaritons excited near the nanoparticles can couple with the multiple surface plasmon polaritons near the substrate to realize the heat relay in the long distance. The heat transfer can be enhanced by more than six orders of magnitude and the relay distance can be as high as 35 times in the far-field regime. The work may provide a way to realize the energy modulation or thermal communications especially in long distance., Comment: 10 pages, 4 figures

This paper presents a comprehensive theoretical study of the magnetic-tunable near-field radiative heat transfer (NFRHT) between two twisted graphene gratings. As a result of the quantum Hall regime of magneto-optical graphene and the grating effect, three types of graphene surface plasmon polaritons (SPPs) modes are observed in the system: near-zero modes, high-frequency hyperbolic modes, and elliptic modes. The elliptic SPPs modes, which are caused by the combined effect of magnetic field and grating, are observed in the graphene grating system for the first time. In addition, the near-zero modes can be greatly enhanced by the combined effect grating and magnetic field, rendering graphene devices promising for thermal communication at ultra-low frequency. In particular, the near-zero modes result in a unique enhancement region of heat transfer, no matter for any twisted angle between gratings. The combined effect of grating and magnetic field is investigated simultaneously. By changing the strength of magnetic field, the positions and intensities of the modes can be modulated, and hence the NFRHT can be tuned accordingly, no matter for parallel or twisted graphene gratings. The magnetic field endows the grating action (graphene filling factors and twisted angles) with a higher modulation ability to modulate the NFRHT compared with zero-field. Moreover, the modulation ability of twist can be tuned by the magnetic field at different twisted angles. In sum, the combined effect of magnetic field and grating provides a tunable way to realize the energy modulation or multi-frequency thermal communications related to graphene devices., Comment: 15 pages,10 figures. International Journal of Heat and Mass Transfer, 2020

We propose a cosmological scenario which describes the evolution history of the universe based on the particle creation and holographic equipartition. The model attempts to solve the inflation of the early universe and the accelerated expansion of the present universe without introducing the dark energy from the perspective of thermodynamics. Throughout the evolution of the universe, we assume that the universe always creates particles in some way and holographic equipartition is always satisfied. Further, we choose that the creation rate of particles is proportional to $H^{2}$ in the early universe and to $H$ in the present and late universe, where $H$ is the Hubble parameter. Then we obtain the solutions $a(t)\propto e^{\alpha t/3}$ and $a(t)\propto t^{1/2}$ for the early universe and the solutions $a(t)\propto t^{\delta}$ and $a(t)\propto e^{Ht}$ for the present and late universe, where $\alpha$ and $\delta$ are the parameters. Finally, we obtain and analyze two important thermodynamic properties for the present model., Comment: 11 pages

The observation of binary neutron star merger GW170817, along with its optical counterpart, provided the first constraint on the Hubble constant $H_0$ using gravitational wave standard sirens. When no counterpart is identified, a galaxy catalog can be used to provide the necessary redshift information. However, the true host might not be contained in a catalog which is not complete out to the limit of gravitational-wave detectability. These electromagnetic and gravitational-wave selection effects must be accounted for. We describe and implement a method to estimate $H_0$ using both the counterpart and the galaxy catalog standard siren methods. We perform a series of mock data analyses using binary neutron star mergers to confirm our ability to recover an unbiased estimate of $H_0$. Our simulations used a simplified universe with no redshift uncertainties or galaxy clustering, but with different magnitude-limited catalogs and assumed host galaxy properties, to test our treatment of both selection effects. We explore how the incompleteness of catalogs affects the final measurement of $H_0$, as well as the effect of weighting each galaxy's likelihood of being a host by its luminosity. In our most realistic simulation, where the simulated catalog is about three times denser than the density of galaxies in the local universe, we find that a 4.4\% measurement precision can be reached using galaxy catalogs with 50\% completeness and $\sim 250$ binary neutron star detections with sensitivity similar to that of Advanced LIGO's second observing run., Comment: 19 pages, 8 figures

A careful reanalysis is made on $e^+e^-\to X(4660)\to (\Lambda_c\bar{\Lambda}_c)/(\psi'\pi\pi)$ processes, aiming at resolving the apparent conflicts between Belle and BESIII data above $\Lambda_c\bar{\Lambda}_c$ threshold. We use a model containing a Breit-Wigner resonance and $\Lambda_c\bar{\Lambda}_c$ four-point contact interactions, with which the enhancement right above the $\Lambda_c\bar{\Lambda}_c$ threshold is well explained by a virtual pole generated by $\Lambda_c\bar{\Lambda}_c$ attractive final state interaction, located at $M_V=4.566\pm0.007$ GeV. Meanwhile, $X(4660)$ remains to be a typical Breit-Wigner resonance, and is hence of confinement nature. Our analysis strongly suggests the existence of the virtual pole with statistical significance of $4.2$ standard deviation ($\sigma$). Nevertheless, the conclusion crucially depends on the line-shape of cross sections which are of limited statistics, hence we urge new experimental analyses from Belle II, BESIII, and LHCb to settle the issue., Comment: 7 pages, 7 figures