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.

Studies on limiting factors relating to the cryopreservation of fish embryos

A thesis submitted to the University of Luton in accordance with the requirements for the degree of Doctor of PhilosophyCryopreservation of fish embryos has proven to be a difficult problem in cryobiology. Three main difficulties have been identified or suspected: 1) embryo membrane permeability barriers to cryoprotectants and water; 2) high chilling sensitivity of the embryos; and 3) the twocompartment nature of the embryos with a large yolk. Using the zebrafish embryo as a model system, these limiting factors and possible approaches to overcoming them were investigated with a view to developing an effective procedure for fish embryo cryopreservation. Compared to previous studies, vitrification of zebrafish embryos on gold electron microscope grids using methanol as the cryoprotectant resulted in improved morphological survival, being -50% for early stage (I-cell and 64-cell) and ~ 80% for late stage (50%epiboly, 6-somite and prim-6) embryos, but no embryo showed viability. Poor cryoprotectant permeation and embryo dehydration, and consequently intraembryonic ice formation, remained as the main problem for vitrification. Embryo chilling sensitivity studies suggested that later stage zebrafish embryos were sensitive to cold shock injury arising from rapid cooling followed by being held for an extended exposure period (1 h) at 0 or -5°C. Studies on embryo developmental arrest by anoxia showed that chilling injury in zebrafish embryos was probably not associated with their high development rate. However, the chilling sensitivity of zebrafish embryos was found to be related to the amount of yolk present. Yolk-reduced embryos at prim-6 and high-pec stages became less sensitive to chilling at O°C. Differential scanning calorimetry studies on the depression of intraembyonic nucleation temperatures by cryoprotectants revealed that multi-punctured embryos at 6-somite and prim-6 stages became significantly more permeable to methanol and propylene glycol when compared with their nonpunctured controls. Puncturing of the yolk-sac of fish embryos to reduce yolk content, and the increased permeability to cryoprotectants that this promotes, may offer a new approach to surmounting the difficulties confronting the cryopreservation of fish embryos

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.