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Hard-thermal-loop QED thermodynamics

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Chinese Physics C 2010年第9期34卷 1527-1529页

作者：苏楠 Jens O.Andersen Michael Strickland Frankfurt Institute for Advanced Studies Department of Physics Norwegian University of Science and Technology Department of Physics Gettysburg College

The weak-coupling expansion for thermodynamic quantities in thermal field theories is poorly convergent unless the coupling constant is *** discuss the calculation of the free energy for a hot gas of electrons and photons to three-loop order using hard-thermal-loop perturbation theory （HTLpt）.We show that the hard-thermal-loop perturbation reorganization improves the convergence of the successive approximations to the QED free energy at large coupling,e ～ *** reorganization is gauge invariant by construction,and due to the cancellations among various contributions,we obtain a completely analytic result for the resummed thermodynamic potential at three loops.

关键词： resummation hard-thermal-loop thermal field theory QED free Energy

A Brief Overview of Hard-Thermal-Loop Perturbation Theory

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Communications in Theoretical Physics 2012年第3期57卷 409-421页

作者：苏楠 Fakultt fr Physik Universitt BielefeldD-33615 BielefeldGermany

The poor convergence of quantum field theory at finite temperature has been one of the main obstacles in the practical applications of thermal QCD for *** we briefly review the progress of hard-thermal-loop perturbation theory (HTLpt) in reorganizing the perturbative expansion in order to improve the *** quantum mechanical anharmonic oscillator is used as a simple example to show the breakdown of weak-coupling expansion,and variational perturbation theory is introduced as an effective resummation scheme for divergent weak-coupling *** discuss HTLpt thermodynamic calculations for QED,pure-glue QCD,and QCD with N f=3 up to three-loop *** results suggest that HTLpt provides a systematic framework that can be used to calculate both static and dynamic quantities for temperatures relevant at LHC.

关键词： thermal field theory resummation hard thermal loops

Invariant-mass distribution of top-quark pairs and top-quark mass determination

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Chinese Physics C 2020年第9期44卷 1-6页

作者： Wan-Li Ju Guoxing Wang Xing Wang Xiaofeng Xu Yongqi Xu Li Lin Yang School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking UniversityBeijing 100871China Institute for Particle Physics Phenomenology Durham UniversityDurham DH13LEUK PRISMA+Cluster of Excellence&Mainz Institute for Theoretical Physics Johannes Gutenberg University55099 MainzGermany Institut für Theoretische Physik Universität BernSidlerstrasse 5CH-3012 BernSwitzerland Zhejiang Institute of Modern Physics Department of PhysicsZhejiang UniversityHangzhou 310027China

In this study,we investigate the invariant-mass distribution of top-quark pairs near the 2mt threshold,which strongly influences the determination of the top-quark mass ***-order non-relativistic corrections lead to large contributions,which are not included in the state-of-the-art theoretical predictions.A factorization formula is derived to resum such corrections to all orders in the strong-coupling,and necessary ingredients are calculated to perform the resummation at next-to-leading *** combine the resummation with fixed-order results and present phenomenologically relevant numerical *** resummation effect significantly increases the differential cross-section in the threshold region and makes the theoretical prediction more compatible with experimental *** estimate that using our prediction in the determination of mt will lead to a value closer to the direct measurement result.

关键词： top quark QCD resummation

Improved calculation of effective potential and symmetry-restored transition in Higgs model

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Chinese Science Bulletin 1995年第1期40卷 15-19页

作者：侯德富王恩科李家荣刘连寿 Institute of Particle Physics Huazhong Normal University Wuhan 430070 China

Early in the 1970s, some authors suggested that the electroweak gauge symmetry should be restored at high enough temperature and density. Recently the electroweak phase transition has attracted much attention, because it is of crucial importance for the baryon asymmetry of the universe. So it is required to discuss the electroweak phase transition in detail. The basical tool for studying the phase transition is effective potential, and naive calculation of the effective potential has two difficulties. Here we will propose a self-consistent calculation of the effecitve potential by the resummation of hard thermal loops, and use this improved method to discuss the symmetry-restored transition in the Higgs model.

关键词： effective potential resummation symmetry-restored transition.