The line shape of the radiative open-charm decay of Y(4140) and Y(3930)

In this work, we study the radiative open-charm decays $Y(4140)\to {D}_s^{\ast+} D_s^- \gamma$ and $Y(3930)\to{D}^{\ast+} D^-\gamma$ under the assignments of $D_{s}^*\bar{D}_s^*$ and $D^*\bar{D}^*$ as molecular states for Y(4140) and Y(3930) respectively. Based on our numerical result, we propose the experimental measurement of the photon spectrum of $Y(4140)\to {D}_s^{\ast+} D_s^- \gamma, D_{s}^+D_{s}^{*-}\gamma$ and $Y(3930)\to D^{*0}\bar{D}^0\gamma, D^{0}\bar{D}^{*0}\gamma, D^{*+}D^-\gamma, D^+D^{*-}\gamma$ can further test the molecular assignment for Y(4140) and Y(3930).Comment: 4 pages, 4 figures. More references and discussions added, typos corrected. Accepted by Phys. Rev.

Spatiotemporal variation in precipitation during rainy season in Beibu Gulf, South China, from 1961 to 2016

The spatiotemporal variation in precipitation is an important part of water cycle change, which is directly associatedwith the atmospheric environment and climate change. The high-resolution spatiotemporal change of precipitation is still unknown inmany areas despite its importance. This study analyzed the spatiotemporal variation in precipitation in Beibu Gulf, South China, during the rainy season (fromApril to September) in the period of 1961–2016. The precipitation datawere collected from 12 national standard rain-gauge observation stations. The spatiotemporal variation in precipitation was evaluated with incidence rate and contribution rate of precipitation. The tendency of variations was analyzed using the Mann–Kendall method. The precipitation in the rainy season contributed 80% to the total annual precipitation. In general, there was an exponential decreasing tendency between the precipitation incidence rate and increased precipitation durations. The corresponding contribution rate showed a downward trend after an initial increase. The precipitation incidence rate decreased with the rising precipitation grades, with a gradual increase in contribution rate. The precipitation incidence rate and contribution rate of 7–9 d durations showed the significant downward trends that passed the 95% level of significance test. The results provide a new understanding of precipitation change in the last five decades, which is valuable for predicting future climate change and extreme weather prevention and mitigation

Review of computer vision in intelligent environment design

This paper discusses and compares the use of vision based and non-vision based technologies in developing intelligent environments. By reviewing the related projects that use vision based techniques in intelligent environment design, the achieved functions, technical issues and drawbacks of those projects are discussed and summarized, and the potential solutions for future improvement are proposed, which leads to the prospective direction of my PhD research

Re-Study on the wave functions of Υ(nS)\Upsilon(nS) states in LFQM and the radiative decays of Υ(nS)→ηb+γ\Upsilon(nS)\to \eta_b+\gamma

The Light-front quark model (LFQM) has been applied to calculate the transition matrix elements of heavy hadron decays. However, it is noted that using the traditional wave functions of the LFQM given in literature, the theoretically determined decay constants of the $\Upsilon(nS)$ obviously contradict to the data. It implies that the wave functions must be modified. Keeping the orthogonality among the $nS$ states and fitting their decay constants we obtain a series of the wave functions for $\Upsilon(nS)$. Based on these wave functions and by analogy to the hydrogen atom, we suggest a modified analytical form for the $\Upsilon(nS)$ wave functions. By use of the modified wave functions, the obtained decay constants are close to the experimental data. Then we calculate the rates of radiative decays of $\Upsilon(nS)\to \eta_b+\gamma$. Our predictions are consistent with the experimental data on decays $\Upsilon(3S)\to \eta_b+\gamma$ within the theoretical and experimental errors.Comment: 10 pages, 2 figures, 1 table. Typos corrected and more discussions added. accepted for publication in Physical Review

Exploring open-charm decay mode ΛcΛˉc\Lambda_c\bar{\Lambda}_c of charmonium-like state Y(4630)Y(4630)

The newly observed $X, Y, Z$ exotic states are definitely not in the standard $Q\bar Q'$ structures, thus their existence composes a challenge to our understanding on the fundamental principles of hadron physics. Therefore the studies on their decay patterns which are determined by the non-perturbative QCD will definitely shed light on the concerned physics. Generally the four-quark states might be in a molecular state or tetraquark or their mixture. In this work, we adopt the suggestion that $Y(4630)$ is a charmonium-like tetraquark made of a diquark and an anti-diquark. If it is true, its favorable decay mode should be $Y(4630)$ decaying into an open-charm baryon pair, since such a transition occurs via strong interaction and is super-OZI-allowed. In this work, we calculate the decay width of $Y(4630)\to\Lambda_c\bar{\Lambda}_c$ in the framework of the quark pair creation (QPC) model. Our numerical results on the partial width computed in the tetraquark configuration coincide with the Belle data within a certain error tolerance.Comment: 8 pages, 4 figures, 1 table. Accepted by Eur. Phys. J.