Motivated by the remarkable sensitivity levels of the Lorentz-symmetry tests at some presentlyrunning and (further improved) forthcoming experiments, I attempt a general analysis of the fate of Lorentz symmetry in quantum spacetime. In particular, I analyze the deformation of Lorentz symmetry that holds in certain noncommutative spacetimes and the way in which Lorentz symmetry is broken in othe...

In this paper we continue our study of the Kelvin-Helmholtz (KH) instability in relativistic planar jets following the long-term evolution of the numerical simulations which were introduced in Paper I. The models have been classified into four classes (I to IV) with regard to their evolution in the nonlinear phase, characterized by the process of jet/ambient mixing and momentum transfer. Models...

The full spectrum of two-dimensional fermion states in a scalar soliton trap with a Lorentz breaking background is investigated in the context of the novel 2D materials, where the Lorentz symmetry should not be strictly valid. The field theoretical model with Lorentz breaking terms represents Dirac electrons in one valley and in a scalar field background. The Lorentz violation comes from the di...

Theories that spontaneously break Lorentz invariance also violate diffeomorphism symmetries, implying the existence of extra degrees of freedom and modifications of gravity. In the minimal model (“ghost condensation”) with only a single extra degree of freedom at low energies, the scale of Lorentz violation cannot be larger than about M ∼ 100 GeV due to an infrared instability in the gravity se...

Lorentz symmetry is algebraic foundation of the theory of special relativity. Nearly one hundred years the theory of special relativity keeps the status as a cornerstone of modern physics and has been supported by numerous high energy physics experiments and astrophysical observation. However, physics is a science born out of experimental observation. With the availability of higher precision e...

Among the symmetries in physics, the rotation symmetry is most familiar to us. It is known that the spherical harmonics serve useful purposes when the world is rotated. Squeeze transformations are also becoming more prominent in physics, particularly in optical sciences and in high-energy physics. As can be seen from Dirac’s light-cone coordinate system, Lorentz boosts are squeeze transformatio...

Among the symmetries in physics, the rotation symmetry is most familiar to us. It is known that the spherical harmonics serve useful purposes when the world is rotated. Squeeze transformations are also becoming more prominent in physics, particularly in optical sciences and in high-energy physics. As can be seen from Dirac’s light-cone coordinate system, Lorentz boosts are squeeze transformatio...

Let Nn+p p be an (n + p)-dimensional connected semi-Riemannian manifold of index p. It is called a semi-definite space of index p. When we refer to index p, we mean that there are only p negative eigenvalues of semi-Riemannian metric of Nn+p p and the other eigenvalues are positive. In particular, Nn+1 1 is called a Lorentz space when p = 1. When the Lorentz space Nn+1 1 is of constant curvatur...

The approximate equivalence relation equating the frequency dispersion of the Lorentz model alone with that modified by the Lorentz-Lorenz formula is shown to also equate the branch points appearing in each of these two descriptions.