Abstract:
We derive the spectral representations of QED 3-point functions and then explicitly calculate the 3-point spectral densities in hard thermal loop approximation within the real time formalism. The Ward identities obeyed by the retarded and advanced 2- and 3-point functions are discussed. We compare our results with those for hot QCD .

Abstract:
By considering the Debye screening and damping rate of gluons, the viscosity coefficient of the quark-gluon plasma was evaluated via real-time finite temperature QCD in the relaxation time approximation at finite temperature and chemical potential . The results show that both the damping rate and the chemical potential cause considerable enhancements to the viscosity coefficient of hot dense quark-gluon plasma.

Abstract:
We derive a set of relations among the thermal components of the 3-point function and its spectral representations at finite temperature in the real-time formalism. We then use these to explicitly calculate the 3-point spectral densities for $\phi^3_6$ theory and relate the result to the case of hot QCD.

Abstract:
The aim of this study was to determine the effect of the combined application of a urease inhibitor (thiophosphric triamide, NBPT) and a nitrification inhibitor (dicyandiamide, DCD) on yield and quality of wheat. By applying labeled urea into an aquic brown soil, a pot experiment with spring wheat as test crop was conducted in the Shenyang Experimental Station of Ecology (CAS). The results showed that 15N-U+NBPT and 15N-U+DCD, the combination of urea with NBPT and DCD (15N-U+NBPT+DCD) could retard the hydrolysis of urea, increase 15N uptake by wheat, reduce the loss of urea-N in soil-wheat system; the yield of wheat in 15N-U+NBPT+DCD treatment increased 27.77%, and the content of protein increased 10.19% in comparison with CK.

Abstract:
In this paper, we compare the dispersion relations of hard thermal loop and complete one loop. It is shown that in the dynamical screening regime, the completely one-loop calculation presents a prominent threshold frequency, below which no pure imaginary mode survives. This phenomenon is responsible for the oscillatory static in-medium potential and ultimately results in a damping oscillation of the radial distribution function. We consider this typical shape is the footprint of liquid QGP.

Abstract:
We investigate the in-medium interparticle potential of hot gauge system with bound states by employing the QED and scalar QED coupling. At finite temperature an oscillatory behavior of the potential has been found as well as its variation in terms of different free parameters. We expect the competition among the parameters will lead to an appropriate interparticle potential which could be extended to discuss the fluid properties of QGP with scalar bound states.

Abstract:
The quarkonium states in a quark-gluon plasma is examined with the heavy quark potential implied by the holographic principle. Both the vanila AdS-Schwarzschild metric and the one with an infrared cutoff are considered. The dissociation temperature is calculated by solving the Schr\"o dinger equation of the potential model. In the case of the AdS-Schwarzschild metric with a IR cutoff, the dissociation temperatures for $J/\psi$ and $\Upsilon$ with the U-ansatz of the potential are found to agree with the lattice results within a factor of two.

Abstract:
We study $n$-point functions at finite temperature in the closed time path formalism. With the help of two basic column vectors and their dual partners we derive a compact decomposition of the time-ordered $n$-point functions with $2^n$ components in terms of $2^{n-1} -1$ independent retarded/advanced $n$-point functions. This representation greatly simplifies calculations in the real-time formalism.

Abstract:
We calculate the relaxation time self-consistently to study the damping of collective color modes and the color conductivity in a QGP by deriving self-consistent equations for the damping rates of gluons and quarks to leading order QCD by TFD including a chemical potential for quarks. We show that the damping rates are not sensitive to the chemical potential whereas color conductivity is enhanced considerably.

Abstract:
We study shear viscosity in weakly coupled hot $\phi^4$ theory using the CTP formalism . We show that the viscosity can be obtained as the integral of a three-point function. Non-perturbative corrections to the bare one-loop result can be obtained by solving a decoupled Schwinger-Dyson type integral equation for this vertex. This integral equation represents the resummation of an infinite series of ladder diagrams which contribute to the leading order result. It can be shown that this integral equation has exactly the same form as the Boltzmann equation. We show that the integral equation for the viscosity can be reexpressed by writing the vertex as a combination of polarization tensors. An expression for this polarization tensor can be obtained by solving another Schwinger-Dyson type integral equation. This procedure results in an expression for the viscosity that represents a non-perturbative resummation of contributions to the viscosity which includes certain non-ladder graphs, as well as the usual ladders. We discuss the motivation for this resummation. We show that these resummations can also be obtained by writing the viscosity as an integral equation involving a single four-point function. Finally, we show that when the viscosity is expressed in terms of a four-point function, it is possible to further extend the set of graphs included in the resummation by treating vertex and propagator corrections self-consistently. We discuss the significance of such a self-consistent resummation and show that the integral equation contains cancellations between vertex and propagator corrections.