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Full-Text Articles in Physical Sciences and Mathematics
New Tests Of General Relativity, Quentin Bailey
New Tests Of General Relativity, Quentin Bailey
Quentin Bailey
The last decade has seen a rapid increase in the number of precision tests of relativity. This research has been motivated by the intriguing possibility that tiny deviations from relativity might arise in the underlying theory that is widely believed to successfully mesh General Relativity (GR) with quantum physics. Many of these tests have been analyzed within an effective field theory framework which generically describes possible deviations from exact relativity and contains some traditional test frameworks as limiting cases. One part of the activity has been a resurgence of interest in tests of relativity in the Minkowski-spacetime context, where Lorentz …
The Hyperspherical Four-Fermion Problem, Seth Rittenhouse, J Stecher, J D'Incao, Nirav Mehta, Chris Greene
The Hyperspherical Four-Fermion Problem, Seth Rittenhouse, J Stecher, J D'Incao, Nirav Mehta, Chris Greene
Nirav P Mehta
The problem of a few interacting fermions in quantum physics has sparked intense interest, particularly in recent years owing to connections with the behaviour of superconductors, fermionic superfluids and finite nuclei. This review addresses recent developments in the theoretical description of four fermions having finite-range interactions, stressing insights that have emerged from a hyperspherical coordinate perspective. The subject is complicated, so we have included many detailed formulae that will hopefully make these methods accessible to others interested in using them. The universality regime, where the dominant length scale in the problem is the two-body scattering length, is particularly stressed, including …
Static And Dynamic Casimir Effect Instabilities, Y. N. Srivastava, A. Widom, S. Sivasubramanian, M. Pradeep Ganesh
Static And Dynamic Casimir Effect Instabilities, Y. N. Srivastava, A. Widom, S. Sivasubramanian, M. Pradeep Ganesh
Allan Widom
The static Casimir effect concerns quantum electrodynamic induced Lamb shifts in the mode frequencies and thermal free energies of condensed matter systems. Sometimes, the condensed matter constitutes the boundaries of a vacuum region. The static frequency shift effects have been calculated in the one photon loop perturbation theory approximation. The dynamic Casimir effect concerns two photon radiation processes arising from time dependent frequency modulations again computed in the one photon loop approximation. Under certain conditions the one photon loop computation may become unstable and higher order terms must be invoked to achieve stable solutions. This stability calculation is discussed for …
Acuasal Behavior In Quantum Electrodynamics, A. Widom, Y. N. Srivastava, E. Sassaroli
Acuasal Behavior In Quantum Electrodynamics, A. Widom, Y. N. Srivastava, E. Sassaroli
Allan Widom
Acausal features of quantum electrodynamic processes are discussed. While these processes are not present for the classical electrodynamic theory, in the quantum electrodynamic theory, acausal processes are well known to exist. For example, any Feynman diagram with a "loop" in space-time describes a "particle" which may move forward in time or backward in time or in space-like directions. The engineering problems involved in experimentally testing such causality violations on a macroscopic scale are explored.
Causality And Electromagnetic Transmissions Through Materials, V. Kidambi, A. Widom
Causality And Electromagnetic Transmissions Through Materials, V. Kidambi, A. Widom
Allan Widom
There have been several experiments which hint at evidence for superluminal transport of electromagnetic energy through a material slab. On the theoretical side, it has appeared evident that acausal signals are indeed possible in quantum electrodynamics. However, it is unlikely that superluminal signals can be understood on the basis of a purely classical electrodynamic signals passing through a material. The classical and quantum theories represent quite different views, and it is the quantum view which may lead to violations of Einstein causality.