Scattering amplitudes encode the essential physical information of microscopic interactions and serve as the bridge between theoretical framework and experimental data in quantum field theories (QFTs). Feynman diagrams provide a standard method for calculating scattering amplitudes, and the calculation of one-loop Feynman diagrams is usually significant or even indispensable. Passarino-Veltman Reduction (PVR) can systematically and efficiently reduce the calculation of one-loop Feynman diagrams in relativistic QFTs, and is suitable for large-scale calculations of physical processes related to one-loop Feynman diagrams. The application prerequisite of PVR is that the system respects Lorentz symmetry, which requires not only relativistic energy-momentum relations but also zero temperature and zero density. In many practical problems, physical quantities depend on finite temperature and/or finite density, and finite temperature or finite density specifies a special inertial reference frame for measuring temperature or density, thereby destroying Lorentz symmetry and making PVR no longer applicable. In this talk, I will introduce generalized PVR that can reduce one-loop Feynman diagrams in relativistic QFTs at finite temperature and/or finite density. This reduction method can be applied to the study of physical properties in hot dense quark matter/nuclear matter.

Biography

Hao-Ran Chang, is an associate professor of physics at Sichuan Normal University. He joined the Department of Physics at Sichuan Normal University after receiving his Ph.D. from the University of Science and Technology of China in 2012. He visited the Department of Physics at McGill University from 2017 to 2018. His research interests include the reduction of one-loop Feynman diagrams in finite-temperature field theory, and Higgs decays in particle physics, and collective excitations, optical conductivity, and magnetic interactions in condensed matter physics as well.

Inviter

Gang Yang