154 research outputs found
Higgs branch RG-flows via Decay and Fission
Magnetic quivers have been an instrumental technique for advancing our
understanding of Higgs branches of supersymmetric theories with 8 supercharges.
In this work, we present the decay and fission algorithm for unitary magnetic
quivers. It enables the derivation of the complete phase (Hasse) diagram and is
characterised by the following key attributes: First and foremost, the
algorithm is inherently simple; just relying on convex linear algebra. Second,
any magnetic quiver can only undergo decay or fission processes; these reflect
the possible Higgs branch RG-flows (Higgsings), and the quivers thereby
generated are the magnetic quivers of the new RG fixed points. Third, the
geometry of the decay or fission transition (i.e. the transverse slice) is
simply read off. As a consequence, the algorithm does not rely on a complete
list of minimal transitions, but rather outputs the transverse slice geometry
automatically. As a proof of concept, its efficacy is showcased across various
scenarios, encompassing SCFTs from dimensions 3 to 6, instanton moduli spaces,
and little string theories.Comment: 55 pages; v.2 added clarifications for sec 3.
Algebraic Structure of Combined Traces
Traces and their extension called combined traces (comtraces) are two formal
models used in the analysis and verification of concurrent systems. Both models
are based on concepts originating in the theory of formal languages, and they
are able to capture the notions of causality and simultaneity of atomic actions
which take place during the process of a system's operation. The aim of this
paper is a transfer to the domain of comtraces and developing of some
fundamental notions, which proved to be successful in the theory of traces. In
particular, we introduce and then apply the notion of indivisible steps, the
lexicographical canonical form of comtraces, as well as the representation of a
comtrace utilising its linear projections to binary action subalphabets. We
also provide two algorithms related to the new notions. Using them, one can
solve, in an efficient way, the problem of step sequence equivalence in the
context of comtraces. One may view our results as a first step towards the
development of infinite combined traces, as well as recognisable languages of
combined traces.Comment: Short variant of this paper, with no proofs, appeared in Proceedings
of CONCUR 2012 conferenc
Taphonomy or signal sensitivity in palaeoecological investigations of Norse landnám in Vatnahverfi, southern Greenland?
Acknowledgements. We thank The Leverhulme Trust for financial support, Gordon Cook for the provision of radiocarbon dates and Andy McMullen for botanical identifications and assistance in the field. Jane Bunting, Jan A. Piotrowski and an anonymous reviewer provided helpful comments that improved the manuscriptPeer reviewedPostprin
Illusions, transformations, and iterations : storytelling as fiction, image, artefact : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Fine Arts, College of Creative Arts, Massey University, Wellington, Aotearoa New Zealand
Listed in the 2020 Dean's List of Exceptional ThesesThis creative practice research project proposes that books may act as performative artefacts, and simultaneously discovers the narrative potential of fragmented fictional texts. The hybrid processes used during this research incorporate artistic practice and fiction writing. Throughout the duration of this project, there have been presentations of work across different modes – print publication, live art/performance, conference presentations, articles/essays, workshops, installations and readings. The most significant outcomes of the project are a small collection of physically transformed books, which stand as hybrid art/fiction artefacts. The reader/viewer is encouraged to performatively engage with the books by exploring what is visible, partially visible, and concealed. To spend time touching and reading words, whispers, silence
Bogoliubov Quasiparticle on the Gossamer Fermi Surface in Electron-Doped Cuprates
In contrast to hole-doped cuprates, electron-doped cuprates consistently
exhibit strong antiferromagnetic correlations with a commensurate ({\pi},
{\pi}) ordering wave vector, leading to the prevalent belief that
antiferromagnetic spin fluctuations mediate Cooper pairing in these
unconventional superconductors. However, early investigations produced two
paradoxical findings: while antiferromagnetic spin fluctuations create the
largest pseudogap at "hot spots" in momentum space, Raman scattering and
angle-resolved photoemission spectroscopy measurements using the leading-edge
method seem to suggest the superconducting gap is also maximized at these
locations. This presented a dilemma for spin-fluctuation-mediated pairing:
Cooper pairing is strongest at momenta where normal state low energy spectral
weight is most suppressed. Here we investigate this dilemma in Nd2-xCexCuO4
using angle-resolved photoemission spectroscopy under significantly improved
experimental conditions. The unprecedented signal-to-noise ratio and resolution
allow us to directly observe the Bogoliubov quasiparticles, demonstrating the
existence and importance of two sectors of states: 1. The reconstructed main
band and the states gapped by the antiferromagnetic pseudogap around the hot
spots. 2. The gossamer Fermi surface states with distinct dispersion inside the
pseudogap, from which Bogoliubov quasiparticle coherence peaks emerge below Tc.
Supported by numerical results, we propose that the non-zero modulus of the
antiferromagnetic order parameter causes the former, while fluctuations in the
antiferromagnetic order parameter orientation are responsible for the latter.
Our revelations of the gossamer Fermi surface reconcile the paradoxical
observations, deepening our understanding of superconductivity in
electron-doped cuprates in particular, and unconventional superconductivity in
general.Comment: Submitted version 30 pages, 4 main figures, 8 extended data figures.
Accepted version in press at Nature Physic
- …