628 citations · 5.8k across the 122 of their papers we have counts for
124 papers
A Simple Pendulum in Schwarzschild Spacetime
Andrzej Czarnecki, Andrew Czezowski
We determine the small-oscillation period of a simple pendulum in Schwarzschild spacetime. After transients decay, the displaced rope coincides with a geodesic of the induced spati…
Energy-momentum tensor of a hydrogen atom: stability, D-term, and the Lamb shift
Andrzej Czarnecki, Yizhuang Liu, Syed Navid Reza
We clarify two issues related to the so-called -term in matrix elements of the energy-momentum tensor. First, we show that in a stable system, the -term can have either sign,…
Positronium hydride decay into proton, electron, and one or zero photons
M. Jamil Aslam, Wen Chen, Andrzej Czarnecki +2
Decay rates of the positronium hydride PsH, a bound state of a proton, a positron, and two electrons, are determined for two rare channels, PsH and PsH $\to p^+ e^-…
Negative energy effects in processes involving bound particles: finite nuclear size effects
Andrzej Czarnecki
Probability of finding negative energy states in a hydrogen atom is decreased when the nucleus is extended. Reduced electron Compton wavelength is the characteristic size of the re…
Basis for time crystal phenomena in ultra-cold atoms bouncing on an oscillating mirror
Weronika Golletz, Andrzej Czarnecki, Krzysztof Sacha +1
We consider classical dynamics of a 1D system of particles bouncing on an oscillating mirror in the presence of gravitational field. The particles behave like hard balls and th…
Negative energy states in pionic hydrogen
Andrzej Czarnecki
Probabilities of finding an antiparticle in an atom or ion containing a particle of spin 1/2 or spin 0 are determined. The spin 1/2 case was previously solved by Hans Bethe and his…