4,303 research outputs found
Flavor-symmetry Breaking with Charged Probes
We discuss the recombination of brane/anti-brane pairs carrying brane
charge in . These configurations are dual to co-dimension one
defects in the super-Yang-Mills description. Due to their
charge, these defects are actually domain walls in the dual gauge theory,
interpolating between vacua of different gauge symmetry. A pair of unjoined
defects each carry localized dimensional fermions and possess a global
flavor symmetry while the recombined brane/anti-brane pairs
exhibit only a diagonal U(N). We study the thermodynamics of this
flavor-symmetry breaking under the influence of external magnetic field.Comment: 21 pages, 10 figure
Faster subsequence recognition in compressed strings
Computation on compressed strings is one of the key approaches to processing
massive data sets. We consider local subsequence recognition problems on
strings compressed by straight-line programs (SLP), which is closely related to
Lempel--Ziv compression. For an SLP-compressed text of length , and an
uncompressed pattern of length , C{\'e}gielski et al. gave an algorithm for
local subsequence recognition running in time . We improve
the running time to . Our algorithm can also be used to
compute the longest common subsequence between a compressed text and an
uncompressed pattern in time ; the same problem with a
compressed pattern is known to be NP-hard
Bekenstein entropy bound for weakly-coupled field theories on a 3-sphere
We calculate the high temperature partition functions for SU(Nc) or U(Nc)
gauge theories in the deconfined phase on S^1 x S^3, with scalars, vectors,
and/or fermions in an arbitrary representation, at zero 't Hooft coupling and
large Nc, using analytical methods. We compare these with numerical results
which are also valid in the low temperature limit and show that the Bekenstein
entropy bound resulting from the partition functions for theories with any
amount of massless scalar, fermionic, and/or vector matter is always satisfied
when the zero-point contribution is included, while the theory is sufficiently
far from a phase transition. We further consider the effect of adding massive
scalar or fermionic matter and show that the Bekenstein bound is satisfied when
the Casimir energy is regularized under the constraint that it vanishes in the
large mass limit. These calculations can be generalized straightforwardly for
the case of a different number of spatial dimensions.Comment: 32 pages, 12 figures. v2: Clarifications added. JHEP versio
Magnetic effects in a holographic Fermi-like liquid
We explore the magnetic properties of the Fermi-like liquid represented by
the D3-D7' system. The system exhibits interesting magnetic properties such as
ferromagnetism and an anomalous Hall effect, which are due to the Chern-Simons
term in the effective gravitational action. We investigate the spectrum of
quasi-normal modes in the presence of a magnetic field and show that the
magnetic field mitigates the instability towards a striped phase. In addition,
we find a critical magnetic field above which the zero sound mode becomes
massive.Comment: 18 pages, 15 figure
Comments on scaling limits of 4d N=2 theories
We revisit the study of the maximally singular point in the Coulomb branch of
4d N=2 SU(N) gauge theory with N_f=2n flavors for N_f= 2, we find
that the low-energy physics is described by two non-trivial superconformal
field theories coupled to a magnetic SU(2) gauge group which is infrared free.
(In the special case n=2, one of these theories is a theory of free
hypermultiplets.) This observation removes a possible counter example to a
conjectured a-theorem.Comment: 13 page
Chiral primary one-point functions in the D3-D7 defect conformal field theory
JHEP is an open-access journal funded by SCOAP3 and licensed under CC BY 4.0archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2012-81 slaccitation: %%CITATION = ARXIV:1210.7015;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2012-81 slaccitation: %%CITATION = ARXIV:1210.7015;%%C.F.K. and D.Y. were supported in part by FNU through grant number 272-08-0329.
G.W.S. is supported by NSERC of Canada and by the Villum foundation through their
Velux Visiting Professor program
Microfluidic devices powered by integrated elasto-magnetic pumps (article)
This is the final version. Available on open access from the Royal Society of Chemistry via the DOI in this recordThe dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.2863We show how an asymmetric elasto-magnetic system provides a novel integrated pumping solution for lab-on-a-chip and point of care devices. This monolithic pumping solution, inspired by Purcell's 3-link swimmer, is integrated within a simple microfluidic device, bypassing the requirement of external connections. We experimentally prove that this system can provide tuneable fluid flow with a flow rate of up to 600 μL h-1. This fluid flow is achieved by actuating the pump using a weak, uniform, uniaxial, oscillating magnetic field, with field amplitudes in the range of 3-6 mT. Crucially, the fluid flow can be reversed by adjusting the driving frequency. We experimentally prove that this device can successfully operate on fluids with a range of viscosities, where pumping at higher viscosity correlates with a decreasing optimal driving frequency. The fluid flow produced by this device is understood here by examining the non-reciprocal motion of the elasto-magnetic component. This device has the capability to replace external pumping systems with a simple, integrated, lab-on-a-chip component.Engineering and Physical Sciences Research Council (EPSRC)European Union Horizon 2020Medical Research Council (MRC)Royal SocietyWellcome Trus
Flavor from M5-branes
We study various aspects of the defect conformal field theory that arises
when placing a single M5-brane probe in AdS_4 x S^7. We derive the full set of
fluctuation modes and dimensions of the corresponding dual operators. We argue
that the latter does not depend on the presence of a non-trivial magnetic flux
on the M5-brane world-volume. Finally we give a mass to the hypermultiplet
living on the defect, and compute the resulting mesonic spectrum.Comment: 19 page
Quantum Hall Effect in a Holographic Model
We consider a holographic description of a system of strongly coupled
fermions in 2+1 dimensions based on a D7-brane probe in the background of
D3-branes, and construct stable embeddings by turning on worldvolume fluxes. We
study the system at finite temperature and charge density, and in the presence
of a background magnetic field. We show that Minkowski-like embeddings that
terminate above the horizon describe a family of quantum Hall states with
filling fractions that are parameterized by a single discrete parameter. The
quantization of the Hall conductivity is a direct consequence of the
topological quantization of the fluxes. When the magnetic field is varied
relative to the charge density away from these discrete filling fractions, the
embeddings deform continuously into black-hole-like embeddings that enter the
horizon and that describe metallic states. We also study the thermodynamics of
this system and show that there is a first order phase transition at a critical
temperature from the quantum Hall state to the metallic state.Comment: v2: 27 pages, 12 figures. There is a major revision in the
quantitative analysis. The qualitative results and conclusions are unchanged,
with one exception: we show that the quantum Hall state embeddings, which
exist for discrete values of the filling fraction, deform continuously into
metallic state embeddings away from these filling fraction
Phylogenetic autocorrelation and evolutionary diversity of Carnivora (Mammalia) in Conservation Units of the New World
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