5,175 research outputs found
AdS/CFT for Unprotected Operators
We consider the four-point function of the lowest scalar in the stress-energy
tensor multiplet in ABJ(M) theory \cite{Aharony:2008ug,
Aharony:2008gk}. At large central charge , this correlator is
given by the corresponding holographic correlation function in 11d supergravity
on . We use Mellin space techniques to compute the leading
correction to anomalous dimensions and OPE coefficients of operators
that appear in this holographic correlator. For half and quarter-BPS operators,
we find exact agreement with previously computed localization results. For the
other BPS and non-BPS operators, our results match the
numerical bootstrap for ABJ(M) at large , which provides a precise check
of unprotected observables in AdS/CFT.Comment: 22 pages, 1 figure, v4, fixed typo
A comparison of the physical and chemical composition of UK waste streams based on hypothetical compound structure
The suitability and effectiveness of a waste treatment process or strategy depends upon a waste
stream’s physical and chemical composition. Chemical properties of UK waste streams,
particularly MSW, are limited while physical properties are better documented. Consequently
this presents a degree of uncertainty with the waste’s properties, manifesting itself as financial
risk in the investment of new treatment or disposal plant. To mitigate this uncertainty, a number
of UK waste surveys have been reviewed to determine if there is significant difference in the
calorific value between waste streams. Ultimate and proximate analysis data from a number of
sources have been collected and used to approximate the chemical composition of each waste
fraction. To facilitate the comparison of each waste stream, a hypothetical compound of the form
C6HaOb has been determined for each. Based on this analysis, all UK waste streams share the
hypothetical formula C6H10O3, indicating that on a dry basis, the composition of waste in the UK
is fairly consistent. Monte Carlo analysis of the hypothetical compound structure revealed that
for both household and civic amenity waste streams, the hydrogen and oxygen content only
deviate slightly from the mean values. Since MSW is predominantly comprised of household and
civic amenity waste, the hypothetical compound C6H10O3 can be used to approximate UK MSW
M-Theory Reconstruction from (2,0) CFT and the Chiral Algebra Conjecture
We study various aspects of the M-theory uplift of the series of
CFTs in 6d, which describe the worldvolume theory of M5 branes in
flat space. We show how knowledge of OPE coefficients and scaling dimensions
for this CFT can be directly translated into features of the momentum expansion
of M-theory. In particular, we develop the expansion of the four-graviton
S-matrix in M-theory via the flat space limit of four-point Mellin amplitudes.
This includes correctly reproducing the known contribution of the term
from 6d CFT data. Central to the calculation are the OPE coefficients for
half-BPS operators not in the stress tensor multiplet, which we obtain for
finite via the previously conjectured relation [arXiv:1404.1079] between
the quantum algebra and the CFT. We further
explain how the expansion of structure constants exhibits
the structure of protected vertices in the M-theory action. Conversely, our
results provide strong evidence for the chiral algebra conjecture.Comment: 30+18 pages. v2: added refs, fixed typos/notatio
Towards Bootstrapping QED
We initiate the conformal bootstrap study of Quantum Electrodynamics in
space-time dimensions (QED) with flavors of charged fermions by
focusing on the 4-point function of four monopole operators with the lowest
unit of topological charge. We obtain upper bounds on the scaling dimension of
the doubly-charged monopole operator, with and without assuming other gaps in
the operator spectrum. Intriguingly, we find a (gap-dependent) kink in these
bounds that comes reasonably close to the large extrapolation of the
scaling dimensions of the singly-charged and doubly-charged monopole operators
down to and .Comment: 29 pages plus an appendix, 5 figures, v2 minor improvements, refs
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Urban heat stress vulnerability in the U.S. Southwest: The role of sociotechnical systems
Heat vulnerability of urban populations is becoming a major issue of concern with climate change, particularly in the cities of the Southwest United States. In this article we discuss the importance of understanding coupled social and technical systems, how they constitute one another, and how they form the conditions and circumstances in which people experience heat. We discuss the particular situation of Los Angeles and Maricopa Counties, their urban form and the electric grid. We show how vulnerable populations are created by virtue of the age and construction of buildings, the morphology of roads and distribution of buildings on the landscape. Further, the regulatory infrastructure of electricity generation and distribution also contributes to creating differential vulnerability. We contribute to a better understanding of the importance of sociotechnical systems. Social infrastructure includes codes, conventions, rules and regulations; technical systems are the hard systems of pipes, wires, buildings, roads, and power plants. These interact to create lock-in that is an obstacle to addressing issues such as urban heat stress in a novel and equitable manner
Heat pipe cooling of power processing magnetics
A heat pipe cooled transformer and input filter were developed for the 2.4 kW beam supply of a 30 cm ion thruster system. This development yielded a mass reduction of 40% (1.76 kg) and lower mean winding temperature (20 C lower). While these improvements are significant, preliminary designs predict even greater benefits to be realized at higher power. The design details are presented along with the results of thermal vacuum operation and the component performance in a 3 kW breadboard power processor
Bootstrapping Vector Models in
We use the conformal bootstrap to study conformal field theories with
global symmetry in and spacetime dimensions that have a scalar
operator transforming as an vector. The crossing symmetry of
the four-point function of this vector operator, along with unitarity
assumptions, determine constraints on the scaling dimensions of conformal
primary operators in the OPE. Imposing a lower bound on
the second smallest scaling dimension of such an -singlet conformal
primary, and varying the scaling dimension of the lowest one, we obtain an
allowed region that exhibits a kink located very close to the interacting
-symmetric CFT conjectured to exist recently by Fei, Giombi, and
Klebanov. Under reasonable assumptions on the dimension of the second lowest
singlet in the OPE, we observe that this kink
disappears in for small enough , suggesting that in this case an
interacting CFT may cease to exist for below a certain critical
value.Comment: 24 pages, 5 figures; v2 minor improvement
Solving M-theory with the Conformal Bootstrap
We use the conformal bootstrap to perform a precision study of 3d maximally
supersymmetric () SCFTs that describe the IR physics on
coincident M2-branes placed either in flat space or at a \C^4/\Z_2
singularity. First, using the explicit Lagrangians of ABJ(M)
\cite{Aharony:2008ug,Aharony:2008gk} and recent supersymmetric localization
results, we calculate certain half and quarter-BPS OPE coefficients, both
exactly at small , and approximately in a large expansion that we
perform to all orders in . Comparing these values with the numerical
bootstrap bounds leads us to conjecture that some of these theories obey an OPE
coefficient minimization principle. We then use this conjecture as well as the
extremal functional method to reconstruct the first few low-lying scaling
dimensions and OPE coefficients for both protected and unprotected multiplets
that appear in the OPE of two stress tensor multiplets for all values of .
We also calculate the half and quarter-BPS operator OPE coefficients in the
BLG theory for all values of the Chern-Simons
coupling , and show that generically they do not obey the same OPE
coefficient minimization principle.Comment: 30 pages, 5 figures, v2 submitted for publicatio
A New Duality Between Superconformal Field Theories in Three Dimensions
We propose a new duality between two 3d superconformal
Chern-Simons-matter theories: the ABJM theory and a
theory consisting of the product between the BLG theory and a free theory of
eight real scalars and eight Majorana fermions. As evidence supporting this
duality, we show that the moduli spaces, superconformal indices,
partition functions, and certain OPE coefficients of BPS operators in the two
theories agree.Comment: 29 pages, 2 figure
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