6,371 research outputs found
Monster Anatomy
We investigate the two-dimensional conformal field theories (CFTs) of
, and `dual' to the critical Ising
model, the three state Potts model and the tensor product of two Ising models,
respectively. We argue that these CFTs exhibit moonshines for the double
covering of the baby Monster group, , the triple covering of
the largest Fischer group, and multiple-covering of
the second largest Conway group, . Various
twined characters are shown to satisfy generalized bilinear relations involving
Mckay-Thompson series. We also rediscover that the `self-dual' two-dimensional
bosonic conformal field theory of has the Conway group
as an automorphism group.Comment: 23 pages, revised according to suggestions from JHEP refere
Modular Constraints on Superconformal Field Theories
We constrain the spectrum of and
superconformal field theories in two-dimensions by requiring the NS-NS sector
partition function to be invariant under the congruence
subgroup of the full modular group . We employ semi-definite
programming to find constraints on the allowed spectrum of operators with or
without charges. Especially, the upper bounds on the twist gap for the
non-current primaries exhibit interesting peaks, kinks, and plateau. We
identify a number of candidate rational (S)CFTs realized at the numerical
boundaries and find that they are realized as the solutions to modular
differential equations associated to . Some of the candidate
theories have been discussed by H\"ohn in the context of self-dual extremal
vertex operator (super)algebra. We also obtain bounds for the charged operators
and study their implications to the weak gravity conjecture in AdS.Comment: 50 pages, 16 figure
Modular Constraints on Conformal Field Theories with Currents
We study constraints coming from the modular invariance of the partition
function of two-dimensional conformal field theories. We constrain the spectrum
of CFTs in the presence of holomorphic and anti-holomorphic currents using the
semi-definite programming. In particular, we find the bounds on the twist gap
for the non-current primaries depend dramatically on the presence of
holomorphic currents, showing numerous kinks and peaks. Various rational CFTs
are realized at the numerical boundary of the twist gap, saturating the upper
limits on the degeneracies. Such theories include Wess-Zumino-Witten models for
the Deligne's exceptional series, the Monster CFT and the Baby Monster CFT. We
also study modular constraints imposed by -algebras of various
type and observe that the bounds on the gap depend on the choice of
-algebra in the small central charge region.Comment: 49 pages, 23 figure
Trilinear Fourier multipliers on Hardy spaces
In this paper, we obtain the
boundedness for trilinear Fourier multiplier operators, which is a trilinear
analogue of the multiplier theorem of Calder\'on and Torchinsky (Adv. Math. 24
: 101-171, 1977). Our result improves the trilinear estimate in the very recent
work of the authors, Lee, Heo, Hong, Park, and Yang (Math. Ann., to appear ) by
additionally assuming an appropriate vanishing moment condition, which is
natural in the boundedness into the Hardy space for
Taste symmetry breaking with HYP-smeared staggered fermions
We study the impact of hypercubic (HYP) smearing on the size of taste
breaking for staggered fermions, comparing to unimproved and to asqtad-improved
staggered fermions. As in previous studies, we find a substantial reduction in
taste-breaking compared to unimproved staggered fermions (by a factor of 4-7 on
lattices with spacing fm). In addition, we observe that
discretization effects of next-to-leading order in the chiral expansion () are markedly reduced by HYP smearing. Compared to asqtad valence
fermions, we find that taste-breaking in the pion spectrum is reduced by a
factor of 2.5-3, down to a level comparable to the expected size of generic
effects. Our results suggest that, once one reaches a lattice
spacing of fm, taste-breaking will be small enough after HYP
smearing that one can use a modified power counting in which , simplify fitting to phenomenologically interesting quantities.Comment: 14 pages, 13 figures, references updated, minor change
Magnetically charged AdS5 black holes from class S theories on hyperbolic 3-manifolds
We study the twisted index of 4d = 2 class S theories on a
closed hyperbolic 3-manifold . Via 6d picture, the index can be written in
terms of topological invariants called analytic torsions twisted by irreducible
flat connections on the 3-manifold. Using the topological expression, we
determine the full perturbative 1/N expansion of the twisted index. The leading
part nicely matches the Bekestein-Hawking entropy of a magnetically charged
black hole in the holographic dual with near-horizon.Comment: 10 pages, v2: minor corrections and references adde
Evolution of 2D Truss Structures using Topology Optimization Technique with Meshless Method
p. 1058-1065Particle Swarm Optimization (PSO) is a new paradigm of Swarm Intelligence which is
inspired by concepts from 'Social Psychology' and 'Artificial Life'. Essentially, PSO
proposes that the co-operation of individuals promotes the evolution of the swarm. In terms of optimization, the hope would be to enhance the swarm's ability to search on a global scale so as to determine the global optimum in a fitness landscape. It has been empirically shown to perform well with regard to many different kinds of optimization problems. PSO is particularly a preferable candidate to solve highly nonlinear, non-convex and even discontinuous problems. In this paper, one enhanced version of PSO: Modified Lbest based PSO (LPSO) is proposed and applied to one of the most challenging fields of optimization -- truss topological optimization. Through a benchmark test and a spatial structural example, LPSO exhibited competitive performance due to improved global searching ability.Bae, J.; Lee, S.; Lee, C. (2009). Evolution of 2D Truss Structures using Topology Optimization Technique with Meshless Method. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/676
Development of a miniature Twin Rotary Compressor
In this paper, we will introduce the miniature compressor, which is designed for various applications. Twin rotary compressor structure was adopted to reduced in size and minimize vibration. The weight of the miniature rotary compressor is about 20% that of the reciprocating compressor which has equivalent cooling capacity. To minimize the noise and vibration, the muffler and the cylinder are optimized and torque control algorithm is used for the compressor controller. For a variety of applications, developed compressor is designed for both HBP and LBP condition. Considering the mass-productivity and reliability, IPM type motor is designed
Fermionic Rational Conformal Field Theories and Modular Linear Differential Equations
We define Modular Linear Differential Equations (MLDE) for the level-two
congruence subgroups , and of
. Each subgroup corresponds to one of the spin
structures on the torus. The pole structures of the fermionic MLDEs are
investigated by exploiting the valence formula for the level-two congruence
subgroups. We focus on the first and second order holomorphic MLDEs without
poles and use them to find a large class of `Fermionic Rational Conformal Field
Theories', which have non-negative integer coefficients in the -series
expansion of their characters. We study the detailed properties of these
fermionic RCFTs, some of which are supersymmetric. This work also provides a
starting point for the classification of the fermionic Modular Tensor Category.Comment: 63 pages, 4 figures, 19 tables, references added, minor correction
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