Exclusion of ccˉc\bar c Interpretation for X(3940)X(3940)

Partial decay widths of the $X(3940)$ are evaluated in the $^3P_0$ quark model, assuming a charmonium scenario for its structure. In the study all model parameters are predetermined by other reactions. The work reveals that it is difficult to accommodate the $X(3940)$ with any $c\bar c$ meson state in the picture of the potential quark model plus the $^3P_0$ quark dynamics.Comment: 8 pages, 1 figure, title changed, reference adde

"High-field" pulsars torqued by accretion disk?

The nature of AXPs/SGRs (anomalous X-ray pulsars/soft $\gamma$-ray repeaters) and high field radio pulsars is still unclear even in the magnetar and/or accretion models. The detection of radio emission from AXP XTE J1810$-$197 and the discovery of a debris disk around AXP 4U 0142+61 might shed light on the problem. We propose that AXPs/SGRs could be pulsars that have magnetic field $B\lesssim 10^{13} \mathrm{G}$ as normal pulsars, but in accretion environments. We investigate these issues under the accretion model and find that two of the AXPs/SGRs might be low mass quark stars if all AXPs and SGRs are likely grouped together.Comment: 6 pages, 1 figures, submitted to "Advances in Space Research" (Proceedings of COSPAR 2006

An Intense γ\gamma-ray Beam Line of 10 MeV Order Based on Compton Backscattering

Shanghai Laser Electron Gamma Source, a $\gamma$-ray beam line of 10MeV order was proposed recently. The beam line is expected to generate $\gamma$-ray with maximum energy of 22MeV by backward Compton scattering between CO$_2$ laser and electron in the 3.5GeV storage ring of future Shanghai Synchrotron Radiation Facility. The flux of non-collimated $\gamma$-ray can be 10$^9$ $\sim$ 10$^{10}$s$^{-1}$ if a commercial CO$_2$ laser of 100W order output power is employed and injected with optimized settings.Comment: 7 pages, 9 figure

The Proto Type of Shanghai Laser Electron Gamma Source at 100 MeV LINAC

The design for the proto type of the Shanghai Laser Electron Gamma Source (SLEGS) at the Shanghai Synchrotron Radiation Facility (SSRF) is introduced. Some detailed descriptions for design of related instruments are provided. The proto type can produce X-ray with energy of 10 keV order. A description of the kinematics of Compton backscattering mechanism and the related simulation results are presented and discussed. The backgrounds from dipole magnet and bremsstrahlung are estimated and the signal-noise ratio is also given.Comment: 7 pages, 9 figure

A P\'olya criterion for (strict) positive definiteness on the sphere

Positive definite functions are very important in both theory and applications of approximation theory, probability and statistics. In particular, identifying strictly positive definite kernels is of great interest as interpolation problems corresponding to these kernels are guaranteed to be poised. A Bochner type result of Schoenberg characterises continuous positive definite zonal functions, $f(\cos \cdot)$, on the sphere \Sdmone, as those with nonnegative Gegenbauer coefficients. More recent results characterise strictly positive definite functions on \Sdmone by stronger conditions on the signs of the Gegenbauer coefficients. Unfortunately, given a function $f$, checking the signs of all the Gegenbauer coefficients can be an onerous, or impossible, task. Therefore, it is natural to seek simpler sufficient conditions which guarantee (strict) positive definiteness. We state a conjecture which leads to a P\'olya type criterion for functions to be (strictly) positive definite on the sphere \Sdmone. In analogy to the case of the Euclidean space, the conjecture claims positivity of a certain integral involving Gegenbauer polynomials. We provide a proof of the conjecture for $d$ from 3 to 8.Comment: 21 page

SDSS J090152.05+624342.6: A New "Overlapping-Trough" FeLoBAL Quasar At Z∼2\sim2

We here report an identification of SDSS J090152.04+624342.6 as a new "overlapping-trough" iron low-ionization broad absorption line quasar at redshift of $z\sim2.1$. No strong variation of the broad absorption lines can be revealed through the two spectra taken by the Sloan Digital Sky Survey with a time interval of $\sim6$yr. Further optical and infrared spectroscopic study on this object is suggested.Comment: 6 pages, 2 figures, proceedings of the conference "QUASARS at all cosmic epochs", accepted for publication on Frontiers in Astronomy and Space Scienc

Proposed method for direct measurement of non-Markovian character of the qubits coupled to bosonic reservoirs

The non-Markovianity is a recently proposed characterization of the non-Markovian behavior in an open quantum system, based on which we first present a practical idea for directly measuring the non-Markovian character of a single qubit coupled to a zero-temperature bosonic reservoir, and then extend to investigate the dynamics of two noninteracting qubits subject to two reservoirs respectively with a lower bound of non-Markovianity. Our scheme, with no need of optimization procedures and quantum state tomography, is helpful for experimental implementation.Comment: 5 pages, 2 figures; revised version accepted for publication in Phys. Rev.

A Study of Outflows in Luminous Quasars at Redshift ∼0.4−0.8\sim0.4-0.8

We perform a systematic study of outflow in the narrow-line region (NLR) of active galactic nuclei (AGNs) at $z\sim0.4-0.8$ basing upon a large sample of $\sim900$ quasars at $z\sim 0.4-0.8$. The sample is extracted from the Sloan Digital Sky Survey by mainly requiring 1) the g-band magnitude is brighter than 19 magnitude; and 2) the [OIII]$\lambda5007$ emission line has a signal-to-noise ration larger than 30. Profiles of multiple emission lines are modeled by a sum of several Gaussian functions. The spectral analysis allows us to identify 1) a prevalence of both [OIII]$\lambda5007$ line blue asymmetry and bulk velocity blueshift of both [NeIII]$\lambda3869$ and [NeV]$\lambda3426$ lines, when the [\ion{O}{2}]$\lambda3727$ line is used as a reference. The velocity offset of [\ion{O}{3}]$\lambda5007$ line is, however, distributed around zero value, except for a few outliers. 2) not only the significant [OIII]$\lambda5007$ line asymmetry, but also the large bulk velocity offsets of [NeIII]$\lambda3869$ and [NeV]$\lambda3426$ emission lines tend to occur in the objects with high $L/L_{\mathrm{Edd}}$, which is considerably consistent with the conclusions based on local AGNs. With three $M_{\mathrm{BH}}$ estimation methods, the significance level of the trend is found to be better than $2.9\sigma$, $3.2\sigma$ and $1.8\sigma$ for [OIII], [NeIII] and [NeV], respectively. \rm After excluding the role of radio jets, the revealed dependence of NLR gas outflow on $L/L_{\mathrm{Edd}}$ allows us to argue that the pressure caused by the wind/radiation launched/emitted from central supermassive black hole is the most likely origin of the outflow in these distant quasars, which implies that the outflow in luminous AGNs up to $z\sim1$ have the same origin.Comment: 17 pages, 8 figures, and 2 tables. To be published in ApJ. arXiv admin note: text overlap with arXiv:1512.0192

Universal quantum computation with quantum-dot cellular automata in dephasing-free subspace

We investigate the possibility to have electron-pairs in dephasing-free subspace (DFS), by means of the quantum-dot cellular automata (QCA) and single-spin rotations, to carry out a high-fidelity and deterministic universal quantum computation. We show that our QCA device with electrons tunneling two dimensionally is very suitable for DFS encoding, and argue that our design favors a scalable quantum computation robust to collective dephasing errors.Comment: 10 pages, 3 figure

Merging Strangeon Stars

The state of supranuclear matter in compact star remains puzzling, and it is argued that pulsars could be strangeon stars. What if binary strangeon stars merge? This kind of merger could result in the formation of a hyper-massive strangeon star, accompanied by bursts of gravitational waves and electromagnetic radiation (and even strangeon kilonova explained in the paper). The tidal polarizability of binary strangeon stars is different from that of binary neutron stars, because a strangeon star is self-bound on surface by fundamental strong force while a neutron star by the gravity, and their equations of state are different. Our calculation shows that the tidal polarizability of merging binary strangeon stars is favored by GW170817. Three kinds of kilonovae (i.e., of neutron, quark and strangeon) are discussed, and the light curve of the kilonova AT 2017gfo following GW170817 could be explained by considering the decaying strangeon nuggets and remnant star spin-down. Additionally, the energy ejected to the fireball around the nascent remnant strangeon star, being manifested as a Gamma-ray burst (GRB), is calculated. It is found that, after a promote burst, an X-ray plateau could follow in a timescale of $10^{2-3}$ s. Certainly, the results could be tested also by further observational synergies between gravitational wave detectors (e.g., aLIGO) and X-ray telescopes (e.g., Chinese HXMT and eXTP), and especially if the detected gravitational wave form is checked by peculiar equation of state provided by the numerical relativistical simulation.Comment: Research in Astronomy and Astrophysics, 18, 24 (2018