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Causality constraints on nonlinear supersymmetry

It is well-known that gravitino propagation in standard supergravities is free of any causality problems. However, two issues related to gravitino propagation were recently uncovered in specific supergravities with nonlinear supersymmetry. One of them concerns potential acausality/superluminality, w...

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Detalles Bibliográficos
Autores principales: Bonnefoy, Quentin, Casagrande, Gabriele, Dudas, Emilian
Lenguaje:eng
Publicado: 2022
Materias:
Acceso en línea:https://dx.doi.org/10.1007/JHEP11(2022)113
http://cds.cern.ch/record/2813957
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author Bonnefoy, Quentin
Casagrande, Gabriele
Dudas, Emilian
author_facet Bonnefoy, Quentin
Casagrande, Gabriele
Dudas, Emilian
author_sort Bonnefoy, Quentin
collection CERN
description It is well-known that gravitino propagation in standard supergravities is free of any causality problems. However, two issues related to gravitino propagation were recently uncovered in specific supergravities with nonlinear supersymmetry. One of them concerns potential acausality/superluminality, whereas the second one arises from the vanishing of the sound speed at specific points during inflation. The former is famously related to positivity constraints on specific EFT operators, derived from dispersion relations on the energy-growing part of scattering amplitudes, and indeed we show that subluminality constraints for the gravitino are related via the equivalence theorem to positivity bounds in low-energy goldstino actions. However, the former are stronger, in the sense that they apply to functions of the scalar fields not only in the ground state, but for any field values such as those scanned by time-dependent solutions, unlike bounds derived from 2 → 2 scattering amplitudes in the vacuum. We also argue that nontrivial causality constraints arise only in the case where nonlinear supersymmetry in the matter sector is encoded into superfield constraints which do not seem to arise from microscopic two-derivative lagrangians, in particular for the orthogonal constraint used to build minimal models of inflation in supergravity. This allows us to propose simple alternatives which maintain the minimality of the spectra and are causal in all points of the theory parameter space. We also discuss minimal supergravity models of inflation along these lines.
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spelling cern-28139572023-10-19T02:23:36Zdoi:10.1007/JHEP11(2022)113http://cds.cern.ch/record/2813957engBonnefoy, QuentinCasagrande, GabrieleDudas, EmilianCausality constraints on nonlinear supersymmetryParticle Physics - PhenomenologyAstrophysics and AstronomyParticle Physics - TheoryIt is well-known that gravitino propagation in standard supergravities is free of any causality problems. However, two issues related to gravitino propagation were recently uncovered in specific supergravities with nonlinear supersymmetry. One of them concerns potential acausality/superluminality, whereas the second one arises from the vanishing of the sound speed at specific points during inflation. The former is famously related to positivity constraints on specific EFT operators, derived from dispersion relations on the energy-growing part of scattering amplitudes, and indeed we show that subluminality constraints for the gravitino are related via the equivalence theorem to positivity bounds in low-energy goldstino actions. However, the former are stronger, in the sense that they apply to functions of the scalar fields not only in the ground state, but for any field values such as those scanned by time-dependent solutions, unlike bounds derived from 2 → 2 scattering amplitudes in the vacuum. We also argue that nontrivial causality constraints arise only in the case where nonlinear supersymmetry in the matter sector is encoded into superfield constraints which do not seem to arise from microscopic two-derivative lagrangians, in particular for the orthogonal constraint used to build minimal models of inflation in supergravity. This allows us to propose simple alternatives which maintain the minimality of the spectra and are causal in all points of the theory parameter space. We also discuss minimal supergravity models of inflation along these lines.It is well-known that gravitino propagation in standard supergravities is free of any causality problems. However, two issues related to gravitino propagation were recently uncovered in specific supergravities with nonlinear supersymmetry. One of them concerns potential acausality/superluminality, whereas the second one arises from the vanishing of the sound speed at specific points during inflation. The former is famously related to positivity constraints on specific EFT operators, derived from dispersion relations on the energy-growing part of scattering amplitudes, and indeed we show that subluminality constraints for the gravitino are related via the equivalence theorem to positivity bounds in low-energy goldstino actions. However, the former are stronger, in the sense that they apply to functions of the scalar fields not only in the ground state, but for any field values such as those scanned by time-dependent solutions, unlike bounds derived from $2\to 2$ scattering amplitudes in the vacuum. We also argue that nontrivial causality constraints arise only in the case where nonlinear supersymmetry in the matter sector is encoded into superfield constraints which do not seem to arise from microscopic two-derivative lagrangians, in particular for the orthogonal constraint used to build minimal models of inflation in supergravity. This allows us to propose simple alternatives which maintain the minimality of the spectra and are causal in all points of the theory parameter space. We also discuss minimal supergravity models of inflation along these lines.arXiv:2206.13451DESY-22-103CPHT-RR040.062022CERN-TH-2022-096oai:cds.cern.ch:28139572022-06-27
spellingShingle Particle Physics - Phenomenology
Astrophysics and Astronomy
Particle Physics - Theory
Bonnefoy, Quentin
Casagrande, Gabriele
Dudas, Emilian
Causality constraints on nonlinear supersymmetry
title Causality constraints on nonlinear supersymmetry
title_full Causality constraints on nonlinear supersymmetry
title_fullStr Causality constraints on nonlinear supersymmetry
title_full_unstemmed Causality constraints on nonlinear supersymmetry
title_short Causality constraints on nonlinear supersymmetry
title_sort causality constraints on nonlinear supersymmetry
topic Particle Physics - Phenomenology
Astrophysics and Astronomy
Particle Physics - Theory
url https://dx.doi.org/10.1007/JHEP11(2022)113
http://cds.cern.ch/record/2813957
work_keys_str_mv AT bonnefoyquentin causalityconstraintsonnonlinearsupersymmetry
AT casagrandegabriele causalityconstraintsonnonlinearsupersymmetry
AT dudasemilian causalityconstraintsonnonlinearsupersymmetry