activity
20072026
most citedFundamental Solutions for the Klein-Gordon Equation in de Sitter Spacetime

74 citations · 200 across the 25 of their papers we have counts for

collaborators

29 papers

gr-qc2026

Propagation of Dirac spherical waves in the expanding universe

Karen Yagdjian

The explicit formulas for the spherical solutions of the Dirac equation in the expanding universe are given. The initial value of the solution can be, in particular, a wave functio…

math.AP2025

Spherical solutions to the Klein-Gordon equation in the expanding universe

Karen Yagdjian

We produce an explicit formula for the wave function of the spherically symmetric fields emitted to the FLRW universe with the scale factor generated by the de~Sitter universe. As…

math.AP2024

Semilinear Klein-Gordon equation in space-time of black hole, which is gaining mass in the universe with accelerating expansion

Karen Yagdjian, Anahit Galstian

In this paper, we consider the propagation of waves in the space-time of a single black hole with a static Schwarzschild radius in the expanding universe, namely, the solutions of…

math.AP2023★ 2 cited

Waves in cosmological background with static Schwarzschild radius in the expanding universe

Karen Yagdjian

In this paper, we prove the existence of global in time small data solutions of semilinear Klein-Gordon equations in space-time with a static Schwarzschild radius in the expanding…

math.AP2021

The self-interacting Dirac fields in FLRW spacetime

Anahit Galstian, Karen Yagdjian

We prove the existence of global in time solution with the small initial data for the semilinear equation of the spin-1/2 particles in the Friedmann-Lemaitre-Robertson-Walker space…

gr-qc2021

Huygens' principle for the spin-1/2 particle in spacetime of non-constant curvature

Karen Yagdjian

In this article we give sufficient and necessary conditions for the validity of the Huygens' principle for the Dirac operator in the non-constant curvature spacetime of the Friedma…