Good tachyons, bad bradyons: Role reversal in Einstein-nonlinear-electrodynamics models
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 Maxw...
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| Format: | Article |
| Language: | English |
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Elsevier
2025-07-01
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| Series: | Physics Letters B |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0370269325002746 |
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| author | Marco A.A. de Paula Haroldo C.D. Lima Junior Pedro V.P. Cunha Carlos A.R. Herdeiro Luís C.B. Crispino |
| author_facet | Marco A.A. de Paula Haroldo C.D. Lima Junior Pedro V.P. Cunha Carlos A.R. Herdeiro Luís C.B. Crispino |
| author_sort | Marco A.A. de Paula |
| collection | DOAJ |
| description | 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. |
| format | Article |
| id | doaj-art-1594334f877941eeb5bcd384f2789231 |
| institution | DOAJ |
| issn | 0370-2693 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Physics Letters B |
| spelling | doaj-art-1594334f877941eeb5bcd384f27892312025-08-20T02:55:33ZengElsevierPhysics Letters B0370-26932025-07-0186613951310.1016/j.physletb.2025.139513Good tachyons, bad bradyons: Role reversal in Einstein-nonlinear-electrodynamics modelsMarco A.A. de Paula0Haroldo C.D. Lima Junior1Pedro V.P. Cunha2Carlos A.R. Herdeiro3Luís C.B. Crispino4Programa de Pós-Graduação em Física, Universidade Federal do Pará, 66075-110, Belém, Pará, Brazil; Corresponding author.Departamento de Física, Universidade Federal do Maranhão, Campus Universitário do Bacanga, 65080-805, São Luís, Maranhão, BrazilDepartamento de Matemática da Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA), Campus de Santiago, 3810-193, Aveiro, PortugalDepartamento de Matemática da Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA), Campus de Santiago, 3810-193, Aveiro, PortugalPrograma de Pós-Graduação em Física, Universidade Federal do Pará, 66075-110, Belém, Pará, BrazilIn 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.http://www.sciencedirect.com/science/article/pii/S0370269325002746 |
| spellingShingle | Marco A.A. de Paula Haroldo C.D. Lima Junior Pedro V.P. Cunha Carlos A.R. Herdeiro Luís C.B. Crispino Good tachyons, bad bradyons: Role reversal in Einstein-nonlinear-electrodynamics models Physics Letters B |
| title | Good tachyons, bad bradyons: Role reversal in Einstein-nonlinear-electrodynamics models |
| title_full | Good tachyons, bad bradyons: Role reversal in Einstein-nonlinear-electrodynamics models |
| title_fullStr | Good tachyons, bad bradyons: Role reversal in Einstein-nonlinear-electrodynamics models |
| title_full_unstemmed | Good tachyons, bad bradyons: Role reversal in Einstein-nonlinear-electrodynamics models |
| title_short | Good tachyons, bad bradyons: Role reversal in Einstein-nonlinear-electrodynamics models |
| title_sort | good tachyons bad bradyons role reversal in einstein nonlinear electrodynamics models |
| url | http://www.sciencedirect.com/science/article/pii/S0370269325002746 |
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