Temperature effects on the nuclear symmetry energy and symmetry free energy with an isospin and momentum dependent interaction

Within a self-consistent thermal model using an isospin and momentum dependent interaction (MDI) constrained by the isospin diffusion data in heavy-ion collisions, we investigate the temperature dependence of the symmetry energy $E_{sym}(\rho, T)$ and symmetry free energy $F_{sym}(\rho, T)$ for hot, isospin asymmetric nuclear matter. It is shown that the symmetry energy $E_{sym}(\rho, T)$ generally decreases with increasing temperature while the symmetry free energy $F_{sym}(\rho, T)$ exhibits opposite temperature dependence. The decrement of the symmetry energy with temperature is essentially due to the decrement of the potential energy part of the symmetry energy with temperature. The difference between the symmetry energy and symmetry free energy is found to be quite small around the saturation density of nuclear matter. While at very low densities, they differ significantly from each other. In comparison with the experimental data of temperature dependent symmetry energy extracted from the isotopic scaling analysis of intermediate mass fragments (IMF's) in heavy-ion collisions, the resulting density and temperature dependent symmetry energy $E_{sym}(\rho, T)$ is then used to estimate the average freeze-out density of the IMF's.used to estimate the average freeze-out density of the IMF's.Comment: 9 pages, 7 figures, 1 figure added to show the temperature dependence of the potential and kinetic parts of the symmetry energy. Revised version to appear in PR

Probing WL′WHW^\prime_L WH and WR′WHW^\prime_R W H Interaction at LHC

Many new physics models predict the existence of TeV-scale charged gauge boson $W^\prime$ together with Higgs boson(s). We study the $W^\prime WH$ interaction and explore the angular distribution of charged lepton to distinguish $W_R^\prime WH$ from $W_L^\prime WH$ in $pp\to HW\to b \bar b l \nu$ process at the LHC. It is found that a new type forward-backward asymmetry($A_{FB}$) relating to the angle between the direction of the charged lepton in $W$ rest frame and that of the reconstructed $W^\prime$ in laboratory frame is useful to investigate the properties of $W^\prime W H$ interaction. We analyze the Standard Model backgrounds and develop a set of cuts to highlight the signal and suppress the backgrounds at LHC. We find that $A_{FB}$ can reach 0.03(-0.07) for $W_R^\prime$($W_L^\prime$) production at $\sqrt{S}=14$ TeV

Investigating the NCQ scaling of elliptic flow at LHC with a multiphase transport model

The number of constituent quark (NCQ) scaling behavior of elliptic flow has been systematically studied at the LHC energy within the framework of a multiphase transport model (AMPT) in this work. We find that the parameters used to generate the initial states and the collision centrality are important for the existence of NCQ scaling even when hadronic rescattering contribution is off in Pb-Pb collisions of $\sqrt{s_{NN}}=2.76$ TeV. By turning on the hadron rescattering process, the hadronic evolution impacts are also found to be significant. Extending the analysis to Pb-Pb collsions of $\sqrt{s_{NN}}=5.02$ TeV, one would observe similar qualitative features

Dynamic modelling and control for fully-steerable large reflector antenna considering rigid-flexible coupling

As the size of reflector antenna increases, the influence of flexible deformation to the system dynamics is much more significant. The coupling between the flexible deformation and the rigid displacement needs to be considered. However, the traditional dynamic modelling and control method for large reflector antenna ignores this coupling. To overcome this problem, this paper proposes a dynamic method based on Lagrange Principle, and the corresponding control strategy is discussed. Finally, we take a 110 m diameter fully-steerable antenna as an example to carry out this method. All the results show that the method is stable and with high precision. It will also lay a solid foundation for the high-precision pointing of large reflector antenna

Color Constant Descriptors Combining Image Derivative Structures

Color constant image description is a fundamental problem in many computer vision applications. In this paper, the diagonal-offset model is adopted as reflectance model to get color constant image descriptors. This model makes the descriptors much more robust, and also fits the real world images very well. By introducing 3D moment invariants, this paper contributes to give an illumination independent descriptor generation framework. In detail, 0-, 1- and even higher order color constant descriptors can be generated from such framework. These descriptors can characterize n-order derivative image information. Furthermore, the combination thereof can characterize not only original image but also n-order edge image color information. The experiments on real image databases show that all these descriptors are robust to illumination variation and affine transformation, and perform very well for object recognition under various situations

Study Majorana Neutrino Contribution to B-meson Semi-leptonic Rare Decays

B meson semi-leptonic rare decays are sensitive to new physics beyond standard model. We study the $B^{-}\to \pi^{-}\mu^{+}\mu^{-}$ process and investigate the Majorana neutrino contribution to its decay width. The constraints on the Majorana neutrino mass and mixing parameter are obtained from this decay channel with the latest LHCb data. Utilizing the best fit for the parameters, we study the lepton number violating decay $B^{-}\to \pi^{+}\mu^{-}\mu^{-}$, and find its branching ratio is about $6.4\times10^{-10}$, which is consistent with the LHCb data reported recently.Comment: 10 pages, 3 figure