The quartic effective action for the heterotic string

Gross, David J.; Sloan, J.

doi:10.1016/0550-3213(87)90465-2

Cited by 1,044 publications

(1,255 citation statements)

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“…The coupling of a scalar field with a quadratic expression of the curvature invariants emerges naturally in the context of string theory. In particular, as was shown in [46] by Gross and Sloan, in the low-energy effective action the dilaton is coupled to a Gauss-Bonnet term. It is well known that such a term, expanded about a Minkowski vacuum, ensures that the theory is ghost-free (see [47]).…”

Section: The Physical Degrees Of Freedommentioning

confidence: 81%

Ghosts, instabilities, and superluminal propagation in modified gravity models

Felice

Hindmarsh

Trodden

2006

J. Cosmol. Astropart. Phys.

162

167

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We consider Modified Gravity models involving inverse powers of fourth-order curvature invariants.Using these models' equivalence to the theory of a scalar field coupled to a linear combination of the invariants, we investigate the properties of the propagating modes. Even in the case for which the fourth derivative terms in the field equations vanish, we find that the second derivative terms can give rise to ghosts, instabilities, and superluminal propagation speeds. We establish the conditions which the theories must satisfy in order to avoid these problems in Friedmann backgrounds, and show that the late-time attractor solutions generically exhibit superluminally propagating tensor or scalar modes. * a. de-felice@sussex.ac.uk

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Section: The Physical Degrees Of Freedommentioning

confidence: 81%

Ghosts, instabilities, and superluminal propagation in modified gravity models

Felice

Hindmarsh

Trodden

2006

J. Cosmol. Astropart. Phys.

162

167

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“…It can be shown [25,26] that the field strength H µνρ plays a rôle analogous to a totally antisymmetric torsion [27,28], entering through a generalised Christoffel connection Γ ρ µν Γ ρ νµ :…”

Section: Lorentz and Cpt Violating Geometries (With Torsion) In The Strmentioning

confidence: 99%

Proceedings of the 12th International Conference on Low Energy Antiproton Physics (LEAP2016)

Hiyama¹,

Kanai²,

Ulmer

et al. 2017

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I review briefly string-inspired models of the Early Universe in which the Robertson-Walker geometry is extended to involve appropriate torsion fields that are constant in the frame of a cosmological observer. Fermion fields in such geometries are described by Lagrangians that fall in the simplest Lorentz-and CPT-violating extensions of the Standard Model (SME), in which the fermions couple to a constant axial vector background b µ γ 5 , with the b µ "axion-like" field associated to torsion. In the talk I also review mechanisms to suppress the torsion in the current era, compatible with the existing stringent upper bounds, which are of relevance to searches for CPT violation of interest to this conference. KEYWORDS:Early Universe, Torsion, Strings, Standard Model Extension, CPT Violation Theoretical motivations for Lorentz and CPT ViolationBaryogenesis/Leptogenesis, that is processes in the early Universe that lead to the observed matter-antimatter asymmetry in the Cosmos, represent a long-standing unresolved issue in cosmology [1]. Many approaches to the problem proposed in the literature [2] but no consensus has emerged on the potential mechanisms. Many of them predict lepton number violation, and in particular some of them entail [3] a µ → e − γ interaction with predictions on the corresponding branching ratio which may be falsified at the next generation experiments, but others are more difficult to falsify.A standard measure of the abundance of baryons over that of antibaryons is defined by the ratiowhere n B is the number density of baryons, nB is the number density of antibaryons and n γ is the density of photons (proportional to the entropy density s). This number was determined with accurate measurements of the CMB radiation by the experiments WMAP [5] and Planck [6]. However, there is no experimental evidence for primordial antimatter in the visible universe. Similarly, the generation of an asymmetry between leptons and antileptons is known as leptogenesis. This is expected to be of the same order of magnitude as Y ∆B . If B, the net baryon number, is conserved in Nature, the matter asymmetry can only originate from an asymmetric initial condition B 0. However, such an asymmetry would rapidly diminish during inflation, and extreme fine tuning of the initial condition would become necessary. This is highly unsatisfactory from a theoretical point of view. Consequently a mechanism for the dynamical generation of a baryon asymmetry is required. In the seminal paper [7], Sakharov identified three sufficient conditions that must be satisfied in order to produce a net baryon number.(1) The theory must allow for interactions that violate B conservation. These interactions must become effective at high energy scales in order to guarantee the stability of the proton. (2) Both discrete symmetries C (charge conjugation) and CP (where P denotes parity) are violated.In fact C violation is not enough, as correlations between the spins of particles and antiparticles 1

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“…4 ] under the local supersymmetry. In order to execute this, it is convenient to use the variation of the Riemann tensor,…”

Section: δL[er 4 ] Termsmentioning

confidence: 99%

“…In a similar way, it is basically possible to vary the ansatz L[eR 4 ] under the local supersymmetry. Since this operation is systematic, we employ the computer programming by the mathematica to calculate the variations.…”

Section: Now Let Us Consider the Variation Of The Ansatz L[ermentioning

confidence: 99%

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Higher derivative corrections to eleven dimensional supergravity via local supersymmetry

Hyakutake

Ogushi

2006

J. High Energy Phys.

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In this paper we derive higher derivative corrections to the eleven dimensional supergravity by applying the Noether method with respect to the N = 1 local supersymmetry. An ansatz for the higher derivative effective action, which includes quartic terms of the Riemann tensor, is parametrized by 132 parameters. Then we show that by the requirement of the local supersymmetry, the higher derivative effective action is essentially described by two parameters. The bosonic parts of these two superinvariants completely match with the known results obtained by the perturbative calculations in the type IIA superstring theory.Since the calculations are long and systematic, we build the computer programming to check the cancellation of the variations under the local supersymmetry. This is an extended version of our previous paper[1

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The quartic effective action for the heterotic string

Cited by 1,044 publications

References 32 publications

Ghosts, instabilities, and superluminal propagation in modified gravity models

Ghosts, instabilities, and superluminal propagation in modified gravity models

Proceedings of the 12th International Conference on Low Energy Antiproton Physics (LEAP2016)

Higher derivative corrections to eleven dimensional supergravity via local supersymmetry

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