68 research outputs found
Electromagnetic Interaction of Massive Spin-3 State from String Theory
In the given work we study an interaction of second massive state of an open
boson string with the constant electromagnetic field. This state contains
massive fields with spins 3 and 1. Using the method of an open string BRST
quantization, we receive gauge-invariant lagrangian, describing the
electromagnetic interaction of these fields. From the explicit view of
transformations and lagrangian it follows that the presence of external
constant e/m field leads to the mixing of the given level states. Most likely
that the presence of the external field will lead to the mixing of the states
at other mass string levels as well.Comment: 17 pages, LaTeX, no figure
Gauged extended supergravity without cosmological constant: no-scale structure and supersymmetry breaking
We consider the interplay of duality symmetries and gauged isometries of
supergravity models giving N-extended, spontaneously broken supergravity with a
no-scale structure. Some examples, motivated by superstring and M-theory
compactifications are described.Comment: AMS-LaTeX, 16 pages. Invited paper to appear in the review section of
the IJMP
Plastic deformation in advanced tungsten-based alloys for fusion applications studied by mechanical testing and TEM
Double Parton Scattering Singularity in One-Loop Integrals
We present a detailed study of the double parton scattering (DPS)
singularity, which is a specific type of Landau singularity that can occur in
certain one-loop graphs in theories with massless particles. A simple formula
for the DPS singular part of a four-point diagram with arbitrary
internal/external particles is derived in terms of the transverse momentum
integral of a product of light cone wavefunctions with tree-level matrix
elements. This is used to reproduce and explain some results for DPS
singularities in box integrals that have been obtained using traditional loop
integration techniques. The formula can be straightforwardly generalised to
calculate the DPS singularity in loops with an arbitrary number of external
particles. We use the generalised version to explain why the specific MHV and
NMHV six-photon amplitudes often studied by the NLO multileg community are not
divergent at the DPS singular point, and point out that whilst all NMHV
amplitudes are always finite, certain MHV amplitudes do contain a DPS
divergence. It is shown that our framework for calculating DPS divergences in
loop diagrams is entirely consistent with the `two-parton GPD' framework of
Diehl and Schafer for calculating proton-proton DPS cross sections, but is
inconsistent with the `double PDF' framework of Snigirev.Comment: 29 pages, 8 figures. Minor corrections and clarifications added.
Version accepted for publication in JHE
An All-Cryogenic THz Transmission Spectrometer
This paper describes a THz transmission spectrometer for the spectral range
of 2-65 cm^-1 (100 GHz to 2 THz) with a spectral resolution of at least 1.8
cm^-1 (50 GHz) where the source, sample, and detector are all fully contained
in a cryogenic environment. Cyclotron emission from a two-dimensional electron
gas heated with an electrical current serves as a magnetic field tunable
source. The spectrometer is demonstrated at 4.2 K by measuring the resonant
cyclotron absorption of a second two dimensional electron gas. Unique aspects
of the spectrometer are that 1) an ultra-broadband detector is used and 2) the
emitter is run quasi-continuously with a chopping frequency of only 1 Hz. Since
optical coupling to room temperature components is not necessary, this
technique is compatible with ultra-low temperature (sub 100 mK) operation.Comment: 7 pages, 5 figures. Author affiliation and funding acknowledgements
clarifie
N=4 gauged supergravity and a IIB orientifold with fluxes
We analyze the properties of a spontaneously broken D=4, N=4 supergravity
without cosmological constant, obtained by gauging translational isometries of
its classical scalar manifold. This theory offers a suitable low energy
description of the super-Higgs phases of certain Type-IIB orientifold
compactifications with 3-form fluxes turned on. We study its N=3,2,1,0 phases
and their classical moduli spaces and we show that this theory is an example of
no-scale extended supergravity.Comment: Misprints corrected. Version appeared on NJP 4 (2002)7
Evaluating the effectiveness of combined use of non-thermal atmospheric pressure plasma and frequently-modulated electric field signal in skin wound healing
Background. Scientists around the world are interested in applying physical phenomena to various fields of science. The development of entire areas united by one concept (‘plasma medicine’, etc.) stands as an outstanding example. This study focuses on only two concepts of interest, which are plasma jet and electric field, as far as results of their combined use in clinical practice and in surgery remain understudied. Objective. Experimental evaluation of the effectiveness of physical methods of treatment in skin wound healing. Material and Methods. Animal testing involved 45 small laboratory animals (rats). They were divided into 5 groups of 9 according to methods for experimental wound healing. To generate the plasma jet, a portable generator was used, which is the original development of specialists of the Peter the Great St. Petersburg Polytechnic University. Planimetric and histological measurements were analysed. The antibacterial effectiveness of methods under research was investigated using Staphylococcus aureus 209P, cultivated in vitro on 6- and 12-millimeter discs. Discussion. A combination of non-thermal atmospheric pressure plasma and frequency-modulated electric field signal exhibited the ability to accelerate eschar separation by 52.1% (p < 0.05) and stimulate restorative regeneration by 56% (p < 0.05). Combination of physical methods of treatment demonstrated pronounced antibacterial effect. A histological examination on biopsy sample on the 21st day of observation revealed formed (mature) granulations and large number of newly formed vessels. The cellular composition of epidermal basement membrane showed high level of differentiation. Conclusion. The data obtained suggest that the use of the proposed methods in clinical practice will improve the treatment process of the patients with wounds of different etiology
Multiple Parton Interactions in Z+jets production at the LHC. A comparison of factorized and non--factorized double parton distribution functions
We examine the contribution of Multiple Parton Interactions to Z+n-jets
production at the LHC, n=2,3,4, where the Z boson is assumed to decay
leptonically. We compare the results obtained with the correlated GS09 double
parton distribution function with those obtained with two instances of fully
factorized single parton distribution functions: MSTW2008LO and CTEQ6LO. It
appears quite feasible to measure the MPI contribution to Z+2/3/4 jets already
in the first phase of the LHC with a total luminosity of one inverse femtobarn
at 7 TeV. If as expected the trigger threshold for single photons is around 80
GeV, Z+2-jets production may well turn out to be more easily observable than
the gamma+3-jets channel. The MPI cross section is dominated by relatively soft
events with two jets balancing in transverse momentum.Comment: 15 pages, 3 plot
Terahertz Crystal
FIELD: chemistry. SUBSTANCE: invention relates to terahertz (THz) materials, namely to crystals in demand for use in medicine, pharmaceuticals, customs remote control and other areas. The terahertz crystal according to the invention is characterized by being made on the basis of single-phase solid solutions of the AgCl - AgBr system, containing silver chloride and bromide at the following ratio of ingredients, wt. % : silver chloride - 0.0 to 90.0; silver bromide - 90.0 to 10.0. EFFECT: invention allows to form crystals transmitting emission in a wide spectral range, from terahertz to millimeter, infrared and visible ranges with high optical transparency from non-toxic, non-hygroscopic, plastic materials. 1 cl.Изобретение относится к терагерцовым (ТГц) материалам, а именно к кристаллам востребованных для применения в медицине, фармацевтике, таможенном дистанционном контроле и в других областях. Терагерцовый кристалл согласно изобретению характеризуется тем, что выполнен на основе однофазных твердых растворов системы AgCl - AgBr, содержит хлорида и бромида серебра при следующем соотношении ингредиентов, мас. %: хлорид серебра - 0,0-90,0; бромид серебра - 90,0-10,0. Изобретение обеспечивает возможность формировать кристаллы, пропускающие излучение в широкой спектральной области - от терагерцового до миллиметрового, инфракрасного и видимого диапазонов с высокой оптической прозрачностью из нетоксичных, негигроскопичных, пластичных материалов
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