Dear Colleagues,

This Special Issue of Symmetry, devoted to quantum field theory, elementary particle theory, nuclear physics, statistical mechanics, fluid mechanics, and astrophysics, is dedicated to Prof. Dr. Zhengdao Li's 95^th birthday. 

In 1948, Zhengdao Li, working as a student of Enrico Fermi in Chicago and as a colleague of J. Steinberger, was looking for interactions similar to beta decays. He proposed, in collaboration with M.N. Rosenbluth and Z. Yang, the existence of intermediate heavy bosons in weak interactions.

In 1956, in collaboration with Z. Yang, Li was encouraged by Wú Jiànxióng and colleagues to carry out an experiment which would demonstrate the parity violation in weak decays, for which they were awarded the Nobel Prize in Physics in 1957.

Li proposed to Jack Steinberger that he reanalyze his data on hyperon decays, which was actually the first parity violation experiment in weak interactions. The experiment on parity violation, performed in 1956 and published before his theoretical work with Z. Yang, lacked sufficient statistical significance. 

In those years, Li also carried out extensive analyses of other C.P.T symmetries in weak interactions.

Li collaborated extensively with Yang during the 1950s, leading to other important results in statistical mechanics, such as the Li–Yang theorem.

During the 1960s, his studies on massless particles were vital. It was these studies, in collaboration with Nauenberg and, independently, Kinoshita that led to the KLN theorem.

In the 1970s, his studies on matter at high densities influenced relativistic heavy ions collisions physics (RHIC).

Many other fields of physics, including statistical mechanics, astrophysics and hydrodynamics, have been covered by Zhengdao Li during his long career.

In this Special Issue, we want to invite contributions on the subjects developed by Prof. Dr. Zhengdao Li. Personal recollections by people close to him are also welcomed. 

As is apparent, Li’s work covered all the primary areas of active work at present on Particle Physics and High Energy Physics. Therefore, we welcome contributions relating to gravity, cosmology, particle physics phenomenology and experiment, supersymmetry, and relativistic heavy ion collision physics (phenomenology and experiment).

This is the year of Li’s 95th birthday; therefore, we hope to commemorate one of the most important physicists of our time and provide perspectives on the future of fundamental physics as seen by different contributors.

Prof. Dr. Tomohiro Inagaki
Prof. Dr. Alberto Ruiz Jimeno
Dr. Olga Kodolova
Guest Editors

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