257 research outputs found
S-matrix bootstrap for resonances
We study the -matrix element of a generic, gapped and
Lorentz invariant QFT in space time dimensions. We derive an analytical
bound on the coupling of the asymptotic states to unstable particles (a.k.a.
resonances) and its physical implications. This is achieved by exploiting the
connection between the S-matrix phase-shift and the roots of the S-matrix in
the physical sheet. We also develop a numerical framework to recover the
analytical bound as a solution to a numerical optimization problem. This later
approach can be generalized to spacetime dimensions.Comment: Minor typos corrected, matches published versio
Localization and real Jacobi forms
We calculate the elliptic genus of two dimensional abelian gauged linear
sigma models with (2,2) supersymmetry using supersymmetric localization. The
matter sector contains charged chiral multiplets as well as Stueckelberg fields
coupled to the vector multiplets. These models include theories that flow in
the infrared to non-linear sigma models with target spaces that are non-compact
Kahler manifolds with U(N) isometry and with an asymptotically linear dilaton
direction. The elliptic genera are the modular completions of mock Jacobi forms
that have been proposed recently using complementary arguments. We also compute
the elliptic genera of models that contain multiple Stueckelberg fields from
first principles.Comment: 19+1 pages, LaTeX. Minor correctio
On superconformal anyons
In d=2+1 dimensions, there exist field theories which are non-relativistic
and superconformal. These theories describe two species of anyons, whose spins
differ by 1/2, interacting in a harmonic trap. We compute the dimensions of
chiral primary operators. These operators receive large anomalous dimensions
which are related to the unusual angular momentum properties of anyons.
Surprisingly, we find that the dimensions of some chiral primary operators
violate the unitarity bound and we trace this to the fact that the associated
wavefunctions become non-normalisable. We also study BPS non-perturbative
states in this theory: these are Jackiw-Pi vortices. We show that these emerge
at exactly the point where perturbative operators hit the unitarity bound. To
describe the low-energy dynamics of these vortices, we construct a novel type
of supersymmetric gauged linear sigma model.This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/JHEP01(2016)13
S-matrix bootstrap for resonances
We study the -matrix element of a generic, gapped and
Lorentz invariant QFT in space time dimensions. We derive an analytical
bound on the coupling of the asymptotic states to unstable particles (a.k.a.
resonances) and its physical implications. This is achieved by exploiting the
connection between the S-matrix phase-shift and the roots of the S-matrix in
the physical sheet. We also develop a numerical framework to recover the
analytical bound as a solution to a numerical optimization problem. This later
approach can be generalized to spacetime dimensions.Comment: Minor typos corrected, matches published versio
Characterization of shifts of koala (Phascolarctos cinereus) intestinal microbial communities associated with antibiotic treatment.
Koalas (Phascolarctos cinereus) are arboreal marsupials native to Australia that eat a specialized diet of almost exclusively eucalyptus leaves. Microbes in koala intestines are known to break down otherwise toxic compounds, such as tannins, in eucalyptus leaves. Infections by Chlamydia, obligate intracellular bacterial pathogens, are highly prevalent in koala populations. If animals with Chlamydia infections are received by wildlife hospitals, a range of antibiotics can be used to treat them. However, previous studies suggested that koalas can suffer adverse side effects during antibiotic treatment. This study aimed to use 16S rRNA gene sequences derived from koala feces to characterize the intestinal microbiome of koalas throughout antibiotic treatment and identify specific taxa associated with koala health after treatment. Although differences in the alpha diversity were observed in the intestinal flora between treated and untreated koalas and between koalas treated with different antibiotics, these differences were not statistically significant. The alpha diversity of microbial communities from koalas that lived through antibiotic treatment versus those who did not was significantly greater, however. Beta diversity analysis largely confirmed the latter observation, revealing that the overall communities were different between koalas on antibiotics that died versus those that survived or never received antibiotics. Using both machine learning and OTU (operational taxonomic unit) co-occurrence network analyses, we found that OTUs that are very closely related to Lonepinella koalarum, a known tannin degrader found by culture-based methods to be present in koala intestines, was correlated with a koala's health status. This is the first study to characterize the time course of effects of antibiotics on koala intestinal microbiomes. Our results suggest it may be useful to pursue alternative treatments for Chlamydia infections without the use of antibiotics or the development of Chlamydia-specific antimicrobial compounds that do not broadly affect microbial communities
The Conformal Spectrum of Non-Abelian Anyons
We study the spectrum of multiple non-Abelian anyons in a harmonic trap. The system is described by Chern-Simons theory, coupled to either bosonic or fermionic non-relativistic matter, and has an SO(2,1) conformal invariance. We describe a number of special properties of the spectrum, focussing on a class of protected states whose energies are dictated by their angular momentum. We show that the angular momentum of a bound state of non-Abelian anyons is determined by the quadratic Casimirs of their constituents
A new geometry of scintillating crystals with Strip SiPMs: a PET detector with precise position and time determination
Measurement of the Time-of-Flight (TOF) of the 511 keV gammas brings an
important reduction of statistical noise in the PET image, with higher
precision time measurements producing clearer images. Scintillating crystals
are used to convert the 511 keV annihilation photon to an electron of ~511 KeV
energy via the photoelectric effect; it is necessary to determine with
precision the position and time of this conversion within the scintillating
crystal. We propose using an array of crystals cut into a specific geometry
discussed below; these crystals are read out by an array of strip SiPMs. This
technique allows individual time measurements of the first arriving
photo-electrons and to extract the best time resolution using a specific
algorithm. The final result is a precise determination of the 3D position (that
includes the depth of interaction) of the photoelectric interaction and an
improved time measurement.Comment: 15 pages, 17 figures, Published in JINS
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