728 research outputs found
Exceptional Indices
Recently a prescription to compute the superconformal index for all theories
of class S was proposed. In this paper we discuss some of the physical
information which can be extracted from this index. We derive a simple
criterion for the given theory of class S to have a decoupled free component
and for it to have enhanced flavor symmetry. Furthermore, we establish a
criterion for the "good", the "bad", and the "ugly" trichotomy of the theories.
After interpreting the prescription to compute the index with non-maximal
flavor symmetry as a residue calculus we address the computation of the index
of the bad theories. In particular we suggest explicit expressions for the
superconformal index of higher rank theories with E_n flavor symmetry, i.e. for
the Hilbert series of the multi-instanton moduli space of E_n.Comment: 33 pages, 11 figures, v2: minor correction
On a modular property of N=2 superconformal theories in four dimensions
In this note we discuss several properties of the Schur index of N=2
superconformal theories in four dimensions. In particular, we study modular
properties of this index under SL(2,Z) transformations of its parameters.Comment: 23 page, 2 figure
Gauge Theories and Macdonald Polynomials
We study the N=2 four-dimensional superconformal index in various interesting
limits, such that only states annihilated by more than one supercharge
contribute. Extrapolating from the SU(2) generalized quivers, which have a
Lagrangian description, we conjecture explicit formulae for all A-type quivers
of class S, which in general do not have one. We test our proposals against
several expected dualities. The index can always be interpreted as a correlator
in a two-dimensional topological theory, which we identify in each limit as a
certain deformation of two-dimensional Yang-Mills theory. The structure
constants of the topological algebra are diagonal in the basis of Macdonald
polynomials of the holonomies.Comment: 57 pages, 6 figures; v2: references added and minor improvements; v3:
typos correcte
Towards structured sharing of raw and derived neuroimaging data across existing resources
Data sharing efforts increasingly contribute to the acceleration of
scientific discovery. Neuroimaging data is accumulating in distributed
domain-specific databases and there is currently no integrated access mechanism
nor an accepted format for the critically important meta-data that is necessary
for making use of the combined, available neuroimaging data. In this
manuscript, we present work from the Derived Data Working Group, an open-access
group sponsored by the Biomedical Informatics Research Network (BIRN) and the
International Neuroimaging Coordinating Facility (INCF) focused on practical
tools for distributed access to neuroimaging data. The working group develops
models and tools facilitating the structured interchange of neuroimaging
meta-data and is making progress towards a unified set of tools for such data
and meta-data exchange. We report on the key components required for integrated
access to raw and derived neuroimaging data as well as associated meta-data and
provenance across neuroimaging resources. The components include (1) a
structured terminology that provides semantic context to data, (2) a formal
data model for neuroimaging with robust tracking of data provenance, (3) a web
service-based application programming interface (API) that provides a
consistent mechanism to access and query the data model, and (4) a provenance
library that can be used for the extraction of provenance data by image
analysts and imaging software developers. We believe that the framework and set
of tools outlined in this manuscript have great potential for solving many of
the issues the neuroimaging community faces when sharing raw and derived
neuroimaging data across the various existing database systems for the purpose
of accelerating scientific discovery
Superconformal indices of three-dimensional theories related by mirror symmetry
Recently, Kim and Imamura and Yokoyama derived an exact formula for
superconformal indices in three-dimensional field theories. Using their
results, we prove analytically the equality of superconformal indices in some
U(1)-gauge group theories related by the mirror symmetry. The proofs are based
on the well known identities of the theory of -special functions. We also
suggest the general index formula taking into account the global
symmetry present for abelian theories.Comment: 17 pages; minor change
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