Good tachyons, bad bradyons: role reversal in Einstein-nonlinear-electrodynamics models

Autor:	de Paula, Marco A. A., Junior, Haroldo C. D. Lima, Cunha, Pedro V. P., Herdeiro, Carlos A. R., Crispino, Luís C. B.
Rok vydání:	2024
Předmět:	General Relativity and Quantum Cosmology
Druh dokumentu:	Working Paper
Popis:	In relativistic mechanics, the 4-velocity and the 4-momentum need not be parallel. This allows their norm to have a different sign. This possibility occurs in nonlinear electrodynamics (NED) models minimally coupled to Einstein's theory. Surprisingly, for a large class of NED models with a Maxwell limit, for weak fields, the causal (acausal) photons, as determined by their 4-velocity, have a spacelike (timelike) 4-momentum, leading to good tachyons and bad bradyons. Departing from weak fields, this possibility is determined solely by the concavity of the NED Lagrangian, which is consistent with the Dominant Energy Condition analysis. As a corollary, some popular regular black hole solutions sourced by NED, such as the Bardeen and Hayward solutions, are acausal. Comment: 6 pages, 1 figure, 1 table
Databáze:	arXiv
Externí odkaz:	http://arxiv.org/abs/2412.18659 Zobrazit plný text záznamu View this record from Arxiv