118431275
IDV observations & study of the quasar 0917+624
We carried out intra-day variability (IDV) observations from August 2005 to January 2010 with the Urumqi 25 m radio telescope for a dozen IDV sources including the quasar 0917+624. This target exhibited pronounced centimeter-band, intra-day variability during the 1980s–1990s, but its strong IDV phase ceased in 2000. The source showed no IDV in the majority of the Urumqi observing sessions, although weak IDV activity was detected in some. Multifrequency UMRAO data for 0917+624 show that the spectral index is steeper during the weak and non-IDV phases than during the strong IDV phase, supporting the idea that the size of the scintillating component may be enlarged in the weak/non IDV phases.
7519824
Seven-frequency VLBI Observations of the GHz-Peaked-Spectrum Source OQ 208
We present quasi-simultaneous VLBI images of the GHz-Peaked-Spectrum radio source OQ 208 obtained with the Very Long Baseline Array at 1.4, 1.7, 2.3, 5.0, 8.4, 15.4 GHz and the European VLBI Network at 6.7 GHz. The low frequency (1.4, 1.7 and 2.3 GHz) observations reveal a weak and extended steep-spectrum component at about 30mas away at position angle -110 degrees, which may be a remnant emission. The radio structure of OQ 208 consists of two mini-lobes at 5.0, 6.7, 8.4 and 15.4 GHz. Our spectral analysis further confirms that the southwest lobe undergoes free-free absorption and finds that the free-free absorption is stronger in the inner region. By fitting the 8.4 GHz images from 1994 to 2005, we obtain a separation speed of 0.031+/-0.006 mas yr(-1) between the two mini-lobes. This indicates a jet proper motion of 0.105+/-0.020 c and a kinematic age of 219+/-42 yr for the radio source.
119249008
Does the enhancement observed in $\gamma\gamma\to D\bar{D}$ contain two P-wave higher charmonia?
We solve a new puzzle raised by the observation of an enhancement structure Z(3930) in $\gamma\gamma\to D\bar{D}$. If categorizing Z(3930) as χc2(2P), as suggested by Belle and BaBar, we must explain why χc0(2P) dominantly decaying into $D\bar{D}$ is missing in the $D\bar{D}$ invariant mass spectrum. In this work, we propose that the Z(3930) enhancement structure may contain two P-wave higher charmonia χc0(2P) and χc2(2P). We show that this assumption is supported by our analysis of the $D\bar{D}$ invariant mass spectrum and cosθ∗ distribution of $\gamma\gamma\to D\bar{D}$. This observation would not only provide valuable information of two P-wave higher charmonia χc0(2P) and χc2(2P), but also serve as the crucial test of our novel proposal to the observed enhancement structure Z(3930), especially at the forthcoming BelleII and the approved SuperB.
118381949
Pseudotensor meson family
The pseudoscalar tensor states, π 2 , η 2 , and K 2 , are systematically studied through the Okubo-Zweig-Iizuka- allowed two-body strong decays, including both the observed states reported by the Particle Data Group and the predicted states. Phenomenological analysis combined with the experimental data not only can test the assignments to these discussed states, but it can also predict more abundant information on their partial decay widths, which is helpful in the experimental study of these observed and predicted pseudotensor states.
117830965
A Novel explanation of charmonium-like structure in $e^+e^-\to \psi(2S)\pi^+\pi^-$
We first present a non-resonant description to charmonium-like structure $Y(4360)$ in the $\psi(2S)\pi^+\pi^-$ invariant mass spectrum of the $e^+e^-\to \psi(2S)\pi^+\pi^-$ process. The $Y(4360)$ structure is depicted well by the interference effect of the production amplitudes of $e^{+} e^{-} \to \psi(2S) \pi^+ \pi^-$ via the intermediate charmonia $\psi(4160)/\psi(4415)$ and direct $e^+e^-$ annihilation into $\psi(2S)\pi^+ \pi^-$. This fact shows that $Y(4360)$ is not a genuine resonance, which naturally explains why $Y(4360)$ was only reported in its hidden-charm decay channel $\psi(2S)\pi^+\pi^-$ and was not observed in the exclusive open-charm decay channel or $R$-value scan.
118566497
The LEGUE input catalog for dark night observing in the LAMOST pilot survey
We outline the design of the dark nights portion of the LAMOST Pilot Survey, which began observations in 2011 October. In particular, we focus on Milky Way stellar candidates that are targeted for the LEGUE (LAMOST Experiment for Galactic Understanding and Exploration) survey. We discuss the regions of sky in which spectroscopic candidates were selected, and the motivations for selecting each of these sky areas. Some limitations due to the unique design of the telescope are discussed, including the requirement that a bright (V < 8) star be placed at the center of each plate for wavefront sensing and active optics corrections. The target selection categories and scientific goals motivating them are briefly discussed, followed by a detailed overview of how these selection functions were implemented. We illustrate the difference between the overall input catalog - Sloan Digital Sky Survey (SDSS) photometry and the final targets selected for LAMOST observations.
118457798
New structure around 3250 MeV in the baryonic B decay and the $D^{*}_{0}(2400)N$ molecular hadron
In this work, we first propose the isovector $nD^{*}_{0}(2400)^{0}$ molecular state to explain the enhancement structure around 3250 MeV (Xc(3250)0) in the $\varSigma_{c}^{++}\pi^{-}\pi^{-}$ invariant mass spectrum newly observed by the BaBar Collaboration. Under this molecular state configuration, both the analysis of the mass spectrum and the study of its dominant decay channel can well shed light on its resonance parameters measured by BaBar. Our investigation also shows that the isovector $nD^{*}_{0}(2400)^{0}$ molecular state can decay into $\varSigma_{c}^{++}\pi^{-}\pi^{-}$, which is consistent with experimental observation. These studies provide direct support to the isovector $nD^{*}_{0}(2400)^{0}$ molecular state assignment to Xc(3250)0.