1,074 research outputs found
An Algebraic Classification of Exceptional EFTs Part II: Supersymmetry
We present a novel approach to classify supersymmetric effective field
theories (EFTs) whose scattering amplitudes exhibit enhanced soft limits. These
enhancements arise due to non-linearly realised symmetries on the Goldstone
modes of such EFTs and we classify the algebras that these symmetries can form.
Our main focus is on so-called exceptional algebras which lead to
field-dependent transformation rules and EFTs with the maximum possible soft
enhancement at a given derivative power counting. We adapt existing techniques
for Poincar\'{e} invariant theories to the supersymmetric case, and introduce
superspace inverse Higgs constraints as a method of reducing the number of
Goldstone modes while maintaining all symmetries.
Restricting to the case of a single Goldstone supermultiplet in four
dimensions, we classify the exceptional algebras and EFTs for a chiral, Maxwell
or real linear supermultiplet. Moreover, we show how our algebraic approach
allows one to read off the soft weights of the different component fields from
superspace inverse Higgs trees, which are the algebraic cousin of the on-shell
soft data one provides to soft bootstrap EFTs using on-shell recursion. Our
Lie-superalgebraic approach extends the results of on-shell methods and
provides a complementary perspective on non-linear realisations
An Algebraic Classification of Exceptional EFTs
We classify four-dimensional effective field theories (EFTs) with enhanced
soft limits, which arise due to non-linearly realised symmetries on the
Goldstone modes of such theories. We present an algorithm for deriving all
possible algebras that can be non-linearly realised on a set of Goldstone modes
with canonical propagators, linearly realised Poincar\'{e} symmetries and
interactions at weak coupling. We then perform a full classification of the
cases with multiple scalars or multiple spin- fermions as the Goldstone
modes. In each case there are only a small number of algebras consistent with
field-dependent transformation rules, leading to the class of exceptional EFTs
including the scalar sector of Dirac-Born-Infeld, Special Galileon and
Volkov-Akulov theories. We also discuss the coupling of a gauge vector
to the exceptional scalar theories, showing that there is a Special Galileon
version of the full Dirac-Born-Infeld theory. This paper is part I in a series
of two papers, with the second providing an algebraic classification of
supersymmetric theories
Internal Supersymmetry and Small-field Goldstini
The dynamics of the Goldstino mode of spontaneously broken supersymmetry is
universal, being fully determined by the non-linearly realized symmetry. We
investigate the small-field limit of this theory. This model non-linearly
realizes an alternative supersymmetry algebra with vanishing anti-commutators
between the fermionic generators, much like an internal supersymmetry. This
Goldstino theory is akin to the Galilean scalar field theory that arises as the
small-field limit of Dirac-Born-Infeld theory and non-linearly realizes the
Galilean symmetry. Indeed, the small-field Goldstino is the partner of a
complex Galilean scalar field under conventional supersymmetry. We close with
the generalization to extended internal supersymmetry and a discussion of its
higher-dimensional origin.Comment: 12 pages, v2: references added, typos corrected, discussion about a
fermionic invariant improve
Moduli Backreaction on Inflationary Attractors
We investigate the interplay between moduli dynamics and inflation, focusing
on the KKLT-scenario and cosmological -attractors. General couplings
between these sectors can induce a significant backreaction and potentially
destroy the inflationary regime; however, we demonstrate that this generically
does not happen for -attractors. Depending on the details of the
superpotential, the volume modulus can either be stable during the entire
inflationary trajectory, or become tachyonic at some point and act as a
waterfall field, resulting in a sudden end of inflation. In the latter case
there is a universal supersymmetric minimum where the scalars end up,
preventing the decompactification scenario. The gravitino mass is independent
from the inflationary scale with no fine-tuning of the parameters. The
observational predictions conform to the universal value of attractors, fully
compatible with the Planck data, with possibly a capped number of e-folds due
to the interplay with moduli.Comment: 23 pages, 13 figures. v2: minor clarifications and refs added. PRD
versio
Commercialisation of precision agriculture technologies in the macadamia industry
A prototype vision-based yield monitor has been developed for the macadamia industry. The system estimates yield for individual trees by detecting nuts and their harvested location. The technology was developed by the National Centre for Engineering in Agriculture, University of Southern Queensland for the purpose of reducing labour and costs in varietal assessment trials where yield for individual trees are required to be measured to indicate tree performance. The project was commissioned by Horticulture Australia Limited
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