Spontaneously broken spacetime symmetries and the role of inessential Goldstones

Klein, Remko; Roest, Diederik; Stefanyszyn, David

doi:10.1007/jhep10(2017)051

Cited by 22 publications

(36 citation statements)

References 47 publications

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“…The absence of a WZ term in this case is easy to see via the coset construction [22][23][24] (see e.g. [25,26] for reviews) with symmetry breaking pattern…”

Section: Strong Coupling and The Goldstone Equivalence Theoremmentioning

confidence: 99%

UV constraints on massive spinning particles: lessons from the gravitino

Melville

Roest

Stefanyszyn

2020

J. High Energ. Phys.

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Self-interacting massive particles with spin ≥ 1 unavoidably violate unitarity; the question is at what scale. For spin-1 the strong coupling scale (at which perturbative unitarity is lost) cannot be raised by any finite tuning of the interactions, while for spin-2 there exists a special tuning of the Wilson coefficients which can raise this scale (and enjoys numerous special properties such as ghost-freedom). Here, we fill in the missing piece by describing how the self-interactions of a massive spin-3/2 field, or "massive gravitino", become strongly coupled at high energies. We show that while several different structures appear in the leading order potential, the strong coupling scale cannot be raised (in the absence of additional fields). At the level of the off-shell Lagrangian, it is always the non-linear symmetries of the longitudinal Stückelberg mode that dictate the strong coupling, and we show that in general it is only possible to parametrically raise the strong coupling scale if Wess-Zumino structures exist for these symmetries. We complement this off-shell approach with a first analysis of positivity bounds for a massive spin-3/2 particle, showing that any potential self-interaction which contributes to an on-shell 2-to-2 elastic process at tree level must vanish if this low-energy theory is to have a standard UV completion. We identify the mixing between the longitudinal mode and the transverse modes as the main obstacle to positivity, and clarify how the non-Abelian nature of non-linear (dRGT) massive gravity allows it to satisfy positivity where all known spin ≥ 3/2 Abelian theories fail. Our results imply that a massive gravitino cannot appear alone in a controlled EFT-it must be accompanied by other particles, e.g. as part of a supermultiplet. Together with the spin-1 and spin-2 cases, we suggest features which will persist in even higher spin massive theories.In this paper we fill in the gap between spin-1 and spin-2 by studying the EFT of a massive, self-interacting spin-3/2 field [6], which we shall refer to as a "massive gravitino" (although we are not considering supermultiplets). Such particles appear in many areas of physics-e.g. as QCD resonances, in supergravity and string theoryhowever a detailed study of their possible self-interactions is, until now, absent from the literature. We will approach the massive gravitino EFT from two complementary perspectives: an off-shell analysis of the strong coupling scales appearing in the Lagrangian (signalling when new physics must become important), and an on-shell analysis of the positivity properties of scattering amplitudes (revealing whether this new physics can be consistent with standard QFT axioms), drawing various parallels with the spin-1 and spin-2 cases as we proceed. By completing the catalogue of massive fields with spins ≤ 2, we will draw some general conclusions/conjectures for arbitrary spin.On the strong coupling side, if we assume a simple EFT power counting (naive dimensional analysis, or NDA [7,8]) in which the gauge invariant...

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“…The absence of a WZ term in this case is easy to see via the coset construction [22][23][24] (see e.g. [25,26] for reviews) with symmetry breaking pattern…”

Section: Strong Coupling and The Goldstone Equivalence Theoremmentioning

confidence: 99%

UV constraints on massive spinning particles: lessons from the gravitino

Melville

Roest

Stefanyszyn

2020

J. High Energ. Phys.

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“…We refer the reader to [30] for a discussion on the most important aspects of the coset construction for spontaneous breaking of internal and space-time symmetries, and for an introduction to inverse Higgs constraints.…”

Section: Kinetic Sector Symmetriesmentioning

confidence: 99%

“…For the Minkowski coset space, the broken generators are translations P i and Lorentz transformations M µi where i is an SO(n) index and µ is a 4-dimensional space-time index. Given the intricate link between the coset parametrisation and one's ability to impose inverse Higgs constraints [30], we parametrise the coset element as…”

Section: Space-time Symmetriesmentioning

confidence: 99%

“…The AdS basis is useful since the resulting kinetic sector matches the one from embedding Minkowski 3-branes in (4 + n)-dimensional anti-de Sitter space. 5 Again given the discussion in [30], we parametrise the coset element as…”

Section: Jhep06(2018)006mentioning

confidence: 99%

“…4 Note that we have set the AdS radius L = 1/ √ 2 but will reintroduce it later on. 5 We refer the reader to [30,35] for discussions on the physical equivalence of the resulting non-linear realisations with the conformal group defined in these two different bases.…”

Section: )mentioning

confidence: 99%

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Symmetry breaking patterns for inflation

Klein

Roest

Stefanyszyn

2018

J. High Energ. Phys.

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Abstract:We study inflationary models where the kinetic sector of the theory has a nonlinearly realised symmetry which is broken by the inflationary potential. We distinguish between kinetic symmetries which non-linearly realise an internal or space-time group, and which yield a flat or curved scalar manifold. This classification leads to well-known inflationary models such as monomial inflation and α-attractors, as well as a new model based on fixed couplings between a dilaton and many axions which non-linearly realises higher-dimensional conformal symmetries. In this model, inflation can be realised along the dilatonic direction, leading to a tensor-to-scalar ratio r ∼ 0.01 and a spectral index n s ∼ 0.975. We refer to the new model as ambient inflation since inflation proceeds along an isometry of an anti-de Sitter ambient space-time, which fully determines the kinetic sector.

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Nonlinear Realization of Spacetime Symmetry

Brauner

2024

Lecture Notes in Physics

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Spontaneously broken spacetime symmetries and the role of inessential Goldstones

Cited by 22 publications

References 47 publications

UV constraints on massive spinning particles: lessons from the gravitino

UV constraints on massive spinning particles: lessons from the gravitino

Symmetry breaking patterns for inflation

Nonlinear Realization of Spacetime Symmetry

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