It was recently conjectured that the ratio of the shear viscosity to entropy density eta/s for any fluid always exceeds [formula: see text]. A theoretical counterexample to this bound can be constructed from a nonrelativistic gas by increasing the number of species in the fluid while keeping the dynamics essentially independent of the species type. The question of whether the underlying structu...

This book is an attempt to build a consistent relativistic quantum theory of interacting particles. In the first part of the book “Quantum electrodynamics” we present traditional views on theoretical foundations of particle physics. Our discussion proceeds systematically from the principle of relativity and postulates of measurements to the renormalization in quantum electrodynamics. In the sec...

Quantum field theory reconciles quantum mechanics and special relativity, and plays a central role in many areas of physics. We developed a quantum algorithm to compute relativistic scattering probabilities in a massive quantum field theory with quartic self-interactions (φ(4) theory) in spacetime of four and fewer dimensions. Its run time is polynomial in the number of particles, their energy,...

The formulation of relativistic two-body bound state wave equations and their relationship to quantum field theory began with the work by Eddington and Gaunt in 1928 [1]. However, the large variety of approaches attempted in recent years shows that this problem still has no generally agreed-upon solution. Perhaps for this reason, most recent field theory books have skirted this topic. In his re...

Any local relativistic quantum field theory of Dirac-Weyl fermions conserves CPT . Here we examine whether a simple nonlocal field theory can violate CPT . We construct a new relativistic field theory of fermions, which we call “homeotic”, which is nonlocal but causal and Lorentz invariant. The free homeotic theory is in fact equivalent to free Dirac theory. We show that a homeotic theory with ...