1,803 research outputs found
Effective action of three-dimensional extended supersymmetric matter on gauge superfield background
We study the low-energy effective actions for gauge superfields induced by
quantum N=2 and N=4 supersymmetric matter fields in three-dimensional Minkowski
space. Analyzing the superconformal invariants in the N=2 superspace we propose
a general form of the N=2 gauge invariant and superconformal effective action.
The leading terms in this action are fixed by the symmetry up to the
coefficients while the higher order terms with respect to the Maxwell field
strength are found up to one arbitrary function of quasi-primary N=2
superfields constructed from the superfield strength and its covariant spinor
derivatives. Then we find this function and the coefficients by direct quantum
computations in the N=2 superspace. The effective action of N=4 gauge multiplet
is obtained by generalizing the N=2 effective action.Comment: 1+27 pages; v2: minor corrections, references adde
U(N|M) quantum mechanics on Kaehler manifolds
We study the extended supersymmetric quantum mechanics, with supercharges
transforming in the fundamental representation of U(N|M), as realized in
certain one-dimensional nonlinear sigma models with Kaehler manifolds as target
space. We discuss the symmetry algebra characterizing these models and, using
operatorial methods, compute the heat kernel in the limit of short propagation
time. These models are relevant for studying the quantum properties of a
certain class of higher spin field equations in first quantization.Comment: 21 pages, a reference adde
Increased Adiposity, Dysregulated Glucose Metabolism and Systemic Inflammation in Galectin-3 KO Mice
PMCID: PMC3579848This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
D3-instantons, Mock Theta Series and Twistors
The D-instanton corrected hypermultiplet moduli space of type II string
theory compactified on a Calabi-Yau threefold is known in the type IIA picture
to be determined in terms of the generalized Donaldson-Thomas invariants,
through a twistorial construction. At the same time, in the mirror type IIB
picture, and in the limit where only D3-D1-D(-1)-instanton corrections are
retained, it should carry an isometric action of the S-duality group SL(2,Z).
We prove that this is the case in the one-instanton approximation, by
constructing a holomorphic action of SL(2,Z) on the linearized twistor space.
Using the modular invariance of the D4-D2-D0 black hole partition function, we
show that the standard Darboux coordinates in twistor space have modular
anomalies controlled by period integrals of a Siegel-Narain theta series, which
can be canceled by a contact transformation generated by a holomorphic mock
theta series.Comment: 42 pages; discussion of isometries is amended; misprints correcte
Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures
This is the author accepted manuscript. The final version is available from Nature Research via the DOI in this recordData availability
The climate model output data are available for analysis and download at https://www.paleo.bristol.ac.uk/ummodel/scripts/papers/Bradshaw_et_al_2021.html. It is possible to reproduce the information in Figs. 2, 3, 5 and 6 via this interface as well as download the data itself and the ancillary information (palaeogeography and ice-sheet configuration).Oxygen isotopes from ocean sediments (δ O) used to reconstruct past continental ice volumes additionally record deep water temperatures (DWTs). Traditionally, these are assumed to be coupled (ice-volume changes cause DWT changes). However, δ O records during peak Middle Miocene warmth (~16–15 million years ago) document large rapid fluctuations (~1–1.5‰) difficult to explain as huge Antarctic ice sheet (AIS) volume changes. Here, using climate modelling and data comparisons, we show DWTs are coupled to AIS spatial extent, not volume, because Antarctic albedo changes modify the hydrological cycle, affecting Antarctic deep water production regions. We suggest the Middle Miocene AIS had retreated substantially from previous Oligocene maxima. The residual ice sheet varied spatially more rapidly on orbital timescales than previously thought, enabling large DWT swings (up to 4 °C). When Middle Miocene warmth terminated (~13 million years ago) and a continent-scale AIS had stabilized, further ice-volume changes were predominantly in height rather than extent, with little impact on DWT. Our findings imply a shift in ocean sensitivity to ice-sheet changes occurs when AIS retreat exposes previously ice-covered land; associated feedbacks could reduce the Earth system’s ability to maintain a large AIS. This demonstrates ice-sheet changes should be characterized not only by ice volume but also by spatial extent. 18 18Natural Environment Research CouncilNatural Environment Research CouncilSwedish Research Counci
Nonlinear Supersymmetry as a Hidden Symmetry
Ver abstrac
S-duality in Twistor Space
In type IIB string compactifications on a Calabi-Yau threefold, the
hypermultiplet moduli space must carry an isometric action of the modular
group SL(2,Z), inherited from the S-duality symmetry of type IIB string theory
in ten dimensions. We investigate how this modular symmetry is realized at the
level of the twistor space of , and construct a general class of
SL(2,Z)-invariant quaternion-Kahler metrics with two commuting isometries,
parametrized by a suitably covariant family of holomorphic transition
functions. This family should include corrected by D3-D1-D(-1)-instantons
(with fivebrane corrections ignored) and, after taking a suitable rigid limit,
the Coulomb branch of five-dimensional N=2 gauge theories compactified on a
torus, including monopole string instantons. These results allow us to
considerably simplify the derivation of the mirror map between type IIA and IIB
fields in the sector where only D1-D(-1)-instantons are retained.Comment: 29 pages, 1 figur
The Rotterdam Scan Study: design and update up to 2012
Neuroimaging plays an important role in etiologic research on neurological diseases in the elderly. The Rotterdam Scan Study was initiated as part of the ongoing Rotterdam Study with the aim to unravel causes of neurological disease by performing neuroimaging in a population-based longitudinal setting. In 1995 and 1999 random subsets of the Rotterdam Study underwent neuroimaging, whereas from 2005 onwards MRI has been implemented into the core protocol of the Rotterdam Study. In this paper, we discuss the background and rationale of the Rotterdam Scan Study. We also describe the imaging protocol and post-processing techniques, and highlight the main findings to date. Finally, we make recommendations for future research, which will also be the main focus of investigation in the Rotterdam Scan Study
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