Screened Perturbation Theory to Three Loops
نویسندگان
چکیده
The thermal physics of a massless scalar field with a φ interaction is studied within screened perturbation theory (SPT). In this method the perturbative expansion is reorganized by adding and subtracting a mass term in the lagrangian. We consider several different mass prescriptions that generalize the one-loop gap equation to two-loop order. We calculate the pressure and entropy to three-loop order and the screening mass to two-loop order. In contrast to the weak-coupling expansion, the SPT-improved approximations appear to converge even for rather large values of the coupling constant.
منابع مشابه
ar X iv : h ep - p h / 02 10 19 5 v 1 1 3 O ct 2 00 2 1 Hard Thermal Loops and QCD
The conventional weak-coupling expansion for thermodynamic quantities in hot field theories shows poor convergence unless the coupling constant is tiny. I discuss screened perturbation theory (SPT) which is a way of reorganizing the perturbative expansion for scalar theories and hard-thermal-loop perturbation theory (HTLPT), which is its generalization to gauge theories. I present results for t...
متن کاملScreened perturbation theory at four loops
We study the thermodynamics of massless φ-theory using screened perturbation theory, which is a way to systematically reorganise the perturbative series. The free energy and pressure are calculated through four loops in a double expansion in powers of g and m/T , where m is a thermal mass of order gT . The result is truncated at order g. We find that the convergence properties are significantly...
متن کاملTopics in Cusped/Lightcone Wilson Loops
I review several old/new approaches to the string/gauge correspondence for the cusped/lightcone Wilson loops. The main attention is payed to SYM perturbation theory calculations at two loops and beyond and to the cusped loop equation. These three introductory lectures were given at the 48 Cracow School of Theoretical Physics: “Aspects of Duality”, June 13-22, 2008, Zakopane, Poland.
متن کاملSymbolic Summation and Higher Orders in Perturbation Theory
Higher orders in perturbation theory require the calculation of Feynman integrals at multiple loops. We report on an approach to systematically solve Feynman integrals by means of symbolic summation and discuss the underlying algorithms. Examples such as the non-planar vertex at two loops, or integrals from the recent calculation of the three-loop QCD corrections to structure functions in deep-...
متن کاملDesign and Dynamic Modeling of Planar Parallel Micro-Positioning Platform Mechanism with Flexible Links Based on Euler Bernoulli Beam Theory
This paper presents the dynamic modeling and design of micro motion compliant parallel mechanism with flexible intermediate links and rigid moving platform. Modeling of mechanism is described with closed kinematic loops and the dynamic equations are derived using Lagrange multipliers and Kane’s methods. Euler-Bernoulli beam theory is considered for modeling the intermediate flexible link. Based...
متن کامل