arXiv subjects
Publications and source records attributed to Chongshou Gao.
Based on the hadron transport frames, detailed simulations are carried out to discuss $ϕ$, $Ω$ productions and the significant enhancements in the very low $p_T$ region for some of the soft spectra in RHIC. Elastic interactions are introduced in the simulations. The elastic cross sections vary from different hadrons and energy scales, which can qualitatively explain the different collective motions of various hadrons.
A transport model is developed to describe hadron emission from a strongly coupled quark-gluon plasma formed in relativistic heavy ion collisions. The quark-gluon plasma is controlled by ideal hydrodynamics, and the hadron motion is characterized by a transport equation with loss and gain terms. The two sets of equations are coupled to each other, and the hadronization hypersurface is determined by both the hydrodynamic evolution and the hadron emission. The model is applied to calculate the transverse momentum distributions of mesons and baryons, and most of the results agree well with the experimental data at RHIC.
Bound states, such as $qq$ and $q\bar{q}$, may exist in the Quark Gluon Plasma. As the system is at high density, the volume of the bound states may evoke a reduction to the phase space. We introduce an extended bag model to investigate qualitatively the volume effect on the properties of the system. We find a limit temperature where the bound states start to be completely melted.
Assuming that axial-vector and scalar diquarks exist in the Quark-Gluon Plasma near the critical temporature $T_c$, baryons can be produced from quark-diquark interactions. In RHIC conditions ($\sqrt{s_{NN}} = 130GeV$ and $200GeV$), the ratio $\barΩ^+/Ω^-$ may be larger than 1, based on the concept that QGP with diquarks would exist. This unusual result might be a helpful evidence for QGP existing in RHIC.
Assuming that vector and scalar diquarks exist in the Quark-Gluon Plasma near the critical temporature $T_c$, baryons can be produced through the processes of quarks and diquarks forming $({1/2})^+$ baryon states. Ratios of different baryons can be estimated through this method, if such kind of QGP with diquarks can exists.
Sijie Gao has recently investigated Hawking radiation from spherically symmetrical gravitational collapse to an extremal R-N black hole for a real scalar field. Especially he estimated the upper bound for the expected number of particles in any wave packet belonging to $\mathcal{H}_{out}$ spontaneously produced from the state $|0>_{in}$, which confirms the traditional belief that extremal black holes do not radiate particles. Making some modifications, we demonstrate that the analysis can go through for a charged scalar field.
Evolution process could be calculated from the relativistic hydrodynamic equation with certain estimated initial conditions about a single spherical fireball here. So one could estimate a kind of initial condition qualitatively with a possible energy density about $ε_0\approx 1.9$ $GeV/fm^3$, based on this process to fit the experimental data at thermal freeze-out. The evolution from a cylindrical fireball will be discussed simply in a later chapter.
We introduce an anomalous top quark coupling (right-handed current) into Standard Model Lagrangian. Based on this, a more complete calculation of $b \to sγ$ decay including leading log QCD corrections from $m_{top}$ to $M_W$ in addition to corrections from $M_{W}$ to $m_b$ is given. The inclusive decay rate is found to be suppressed comparing with the case without QCD running from $m_t$ to $M_W$ except at the time of small values of $|f_R^{tb}|$. e.g. when $f_R^{tb}=-0.08$, it is only $1/10$ of the value given before. As $|f_R^{tb}|$ goes smaller, this contribution is an enhancement like standard model case. From the newly experiment of CLEO Collaboration, strict restrictions to parameters of this top-bottom quark coupling are found.