The de Sitter (dS) Group and Its Representations

Introduction.- As a preliminary: 1 + 1-dimensional dS (dS2) geometry and relativity.- 1+3-dimensional dS (dS4) geometry and relativity (classical and quantum mechanics).- 1+3-dimensional dS (dS4) geometry and relativity (QFT).- Notion of mass in (A)dS4 relativity.

Mohammad Enayati, Ph.D., is a Resident Researcher at Razi University where he received his Ph.D. in theoretical physics in 2017. He has also been a visiting researcher at Azad University and Zhejiang University of Technology. His research interests include group-theoretical methods in physics, with an emphasis on de Sitter (spacetime) symmetry considerations on both classical and quantum levels.

Jean-Pierre Gazeau, Ph.D., is an Emeritus Professor at the University Paris Cité.  He was chairman of the Standing Committee of the International Colloquium on Group Theoretical Methods in Physics from 2006 to 2014.  He obtained his academic degrees from Sorbonne University and Pierre-and-Marie Curie University.  He has authored more than 252 scientific publications, including three books, in theoretical and mathematical physics, mostly devoted to group theoretical methods in physics, coherent states, quantization methods, number theory for aperiodic systems, and foundations of quantum physics.

Hamed Pejhan, Ph.D., is a Senior Postdoctoral Researcher at the Institute of Mathematics and Informatics, Bulgarian Academy of Sciences. Dr. Pejhan previously served as a Postdoctoral Fellow at Zhejiang University of Technology. He has authored more than 20 scientific publications in theoretical and mathematical physics, primarily focusing on the application of group theoretical methods in physics. His research pays particular attention to developing a consistent formulation of quantum elementary systems in (anti-) de Sitter spacetime.

Anzhong Wang, PhD, is a Professor from Physics Department, Baylor University.  His research interests include classical and quantum theories of gravity, their applications to cosmology and black hole physics; gravitational wave astronomy, and the nature and origins of dark matter and dark energy.  He has published more than 290 articles and received