Vedad Pasic

pp-waves with torsion and metric-affine gravity

A classical pp-wave is a four-dimensional Lorentzian spacetime which admits a nonvanishing parallel spinor field; here the connection is assumed to be Levi-Civita. We generalize this definition to metric compatible spacetimes with torsion and describe basic properties of such spacetimes. We use our generalized pp-waves for constructing new explicit vacuum solutions of quadratic metric-affine gravity.

Torsion Wave Solutions in Yang-Mielke Theory of Gravity

The approach of metric-affine gravity initially distinguishes it from Einstein’s general relativity. Using an independent affine connection produces a theory with 10

PP-waves with Torsion - a Metric-affine Model for the Massless Neutrino

In this paper we deal with quadratic metric-affine gravity, which we briefly introduce, explain and give historical and physical reasons for using this particular theory of gravity. We then introduce a generalisation of well known spacetimes, namely pp-waves. A classical pp-wave is a 4-dimensional Lorentzian spacetime which admits a nonvanishing parallel spinor field; here the connection is assumed to be Levi-Civita. This definition was generalised in our previous work to metric compatible spacetimes with torsion and used to construct new explicit vacuum solutions of quadratic metric-affine gravity, namely generalised pp-waves of parallel Ricci curvature. The physical interpretation of these solutions we propose in this article is that they represent a conformally invariant metric-affine model for a massless elementary particle. We give a comparison with the classical model describing the interaction of gravitational and massless neutrino fields, namely Einstein–Weyl theory and construct pp-wave type solutions of this theory. We point out that generalised pp-waves of parallel Ricci curvature are very similar to pp-wave type solutions of the Einstein–Weyl model and therefore propose that our generalised pp-waves of parallel Ricci curvature represent a metric-affine model for the massless neutrino.

Construction of a global solution for the one dimensional singularly-perturbed boundary value problem

We consider an approximate solution for the one-dimensional semilinear singularly-perturbed boundary value problem, using the previously obtained numerical values of the boundary value problem in the mesh points and the representation of the exact solution using Greens function. We present an

Axial torsion waves in metric-affine gravity

\varepsilon

Physical Interpretation of PP-waves With Axial Torsion

-uniform convergence of such gained the approximate solutions, in the maximum norm of the order

New vacuum solutions for quadratic metric–affine gravity

\mathcal{O}\left(N^{-1}\right)

Analyzing the spectral (a)symmetry of the massless Dirac operator on the 3-torus

on the observed domain. After that, the constructed approximate solution is repaired and we obtain a solution, which also has

A New Representation of the Field Equations of Quadratic Metric-Affine Gravity

\varepsilon

Continuity of modulus of noncompact convexity for minimalizable measures of noncompactness

--uniform convergence, but now of order