649 research outputs found
Investigations of electroweak symmetry breaking mechanism for Higgs boson decays into four fermions
Models with extended Higgs boson sectors are of prime importance for
investigating the mechanism of electroweak symmetry breaking for Higgs decays
into four fermions and for Higgs-production in association with a vector
bosons. In the framework of the Two-Higgs-Doublet Model using two scenarios
obtained from the experimental measurements we presented next-to-leading-order
results on the four-fermion decays of light CP-even Higgs boson, . With the help of Monte Carlo program Prophecy 4f 3.0, we calculated the
values and for Higgs boson
decay channels ,
, . We didn't
find significant difference when accounting QCD corrections to EW processes in
the decay modes of Higgs boson. Using computer programs Pythia 8.2 and
FeynHiggs we calculated the following values:
and for VBF production processes,
and for
gluon fusion production process at 13 and 14 TeV and found good agreement with
experimental data.Comment: 4 pages, 2 figure
Studying the resonance production cross-section of the heavy vectors within Heavy Vector Triplet model
In the context of TeV-scale extensions of the Standard Model both the
experimental searches and the construction of phenomenological models for the
new heavy bosons searches are used by us. Heavy particles predicted by a the
Simplified Model constructed to describe only the on-shell resonance, have to
be compared with LHC data. Heavy bosons have certain properties that can be
calculated within the Heavy Vector Triplet model using the MadGraph computer
program. We have calculated the production cross sections of heavy particles
using the experimental constraints in the parameter space (, )
imposed on the benchmark scenario. The nature of the functional dependence of
the cross section at the basic parameters of the model on the mass of the new
boson, as well as the mechanism for the heavy particle production is studied.Comment: 9 pages, 9 figure
Magnetic and spectral properties of multi-sublattice oxides SrY2O4:Er3+ and SrEr2O4
SrEr2O4 is a geometrically frustrated magnet which demonstrates rather
unusual properties at low temperatures including a coexistence of long- and
short-range magnetic order, characterized by two different propagation vectors.
In the present work, the effects of crystal fields (CF) in this compound
containing four magnetically inequivalent erbium sublattices are investigated
experimentally and theoretically. We combine the measurements of the CF levels
of the Er3+ ions made on a powder sample of SrEr2O4 using neutron spectroscopy
with site-selective optical and electron paramagnetic resonance measurements
performed on single crystal samples of the lightly Er-doped nonmagnetic
analogue, SrY2O4. Two sets of CF parameters corresponding to the Er3+ ions at
the crystallographically inequivalent lattice sites are derived which fit all
the available experimental data well, including the magnetization and dc
susceptibility data for both lightly doped and concentrated samples.Comment: 14 pages, 9 figure
Magnetocaloric effect in pyrochlore antiferromagnet Gd2Ti2O7
An adiabatic demagnetization process is studied in Gd2Ti2O7, a geometrically
frustrated antiferromagnet on a pyrochlore lattice. In contrast to conventional
paramagnetic salts, this compound can exhibit a temperature decrease by a
factor of ten in the temperature range below the Curie-Weiss constant. The most
efficient cooling is observed in the field interval between 120 and 60 kOe
corresponding to a crossover between saturated and spin-liquid phases. This
phenomenon indicates that a considerable part of the magnetic entropy survives
in the strongly correlated state. According to the theoretical model, this
entropy is associated with a macroscopic number of local modes remaining
gapless till the saturation field. Monte Carlo simulations on a classical spin
model demonstrate good agreement with the experiment. The cooling power of the
process is experimentally estimated with a view to possible technical
applications. The results for Gd2Ti2O7 are compared to those for Gd3Ga5O12, a
well-known material for low temperature magnetic refrigeration.Comment: 6 pages, 4 figures, accepted versio
1H NMR spectroscopy study of structural water in rehydrated biocomposite of Spongilla lacustris freshwater demosponge origin
Biocomposites of sponge origin attract scientific attention due to their renewability as well as special properties. Dried skeletons of fresh water demosponge Spongilla lacustris represent unique kind of naturally occurring silica-chitin-based biocomposites with long history of their applications in dermatocosmetics. However, there is still a lack of knowledge on their physico-chemical properties in model systems. The aim of this work was to model drug systems based on S. lacustris powdered biocomposite, water and a hydrophobic medium, which served as an analog of an oil base. Both thermogravimetric analysis and 1H NMR spectroscopy study of structural water in rehydrated biocomposite lead to obtaining of interesting experimental data useful for preparation of biocosmetic products. © 2020, The Author(s).Deutsche Forschungsgemeinschaft, DFG: HE 394-3PPN/BEK/2018/1/00071Deutsche Forschungsgemeinschaft, DFGSächsisches Staatsministerium für Wissenschaft und Kunst, SMWK: 02010311This work was financially supported by German Research Foundation (DFG) Grant HE 394-3, SMWK Project 02010311 (Germany). M.W. is thankful for financial support from Polish National Agency for Academic Exchange (PPN/BEK/2018/1/00071) and support from Ministry of Science and Higher Education (Poland) as financial subsidy to PUT
Order by quenched disorder in the model triangular antiferromagnet RbFe(MoO4)2
We observe a disappearance of the 1/3 magnetization plateau and a striking change of the magnetic configuration under a moderate doping of the model triangular antiferromagnet RbFe(MoO4)2. The reason is an effective lifting of degeneracy of mean-field ground states by a random potential of impurities, which compensates, in the low-temperature limit, the fluctuation contribution to free energy. These results provide a direct experimental confirmation of the fluctuation origin of the ground state in a real frustrated system. The change of the ground state to a least collinear configuration reveals an effective positive biquadratic exchange provided by the structural disorder. On heating, doped samples regain the structure of a pure compound, thus allowing for an investigation of the remarkable competition between thermal and structural disorder
ОПЫТ ПРИМЕНЕНИЯ МЕТОДА ОПРЕДЕЛЕНИЯ МИНИМАЛЬНЫХ ИНГИБИРУЮЩИХ КОНЦЕНТРАЦИЙ В ЖИДКОЙ ПИТАТЕЛЬНОЙ СРЕДЕ ДЛЯ ВЫЯВЛЕНИЯ ЛЕКАРСТВЕННОЙ УСТОЙЧИВОСТИ НЕТУБЕРКУЛЕЗНЫХ МИКОБАКТЕРИЙ
Goal of the study: analysis of drug resistance of certain species of non-tuberculous mycobacteria through testing by minimum inhibitory concentrations on the fluid nutritional media.Materials and method: drug resistance of non-tuberculous mycobacteria was tested by the method of minimum inhibitory concentrations on the fluid nutritional media. 51 strains of non-tuberculous mycobacteria from the species of M. intracellulare, M. avium, M. kansasii, M. gordonae, M. fortuitum, M. abscessus were tested. The minimum inhibitory concentration of the drug for slow-growing non-tuberculous mycobacteria was defined using the panel of 13 drugs (SLOWMYCO) and for the fast-growing mycobacteria – the panel of 15 drugs RAPMYCO Sensititre (Trek Diagnostic System, Thermo Scientific, USA) was used. It was proved that the majority of tested fast growing mycobacteria were resistant to ceftriaxone, cefepime, cefoxitin but susceptible to amikacin; and slow growing non-tuberculous mycobacteria were susceptible to clarithromycin, linezolid and amikacin. Цель исследования: анализ лекарственной устойчивости некоторых видов нетуберкулезных микобактерий (НТМ) методом определения минимальных ингибирующих концентраций в жидкой питательной среде.Материалы и методы: лекарственную устойчивость НТМ определяли методом минимальных ингибирующих концентраций в жидкой питательной среде. Исследован 51 штамм НТМ, относящийся к видам M. intracellulare, M. avium, M. kansasii, M. gordonae, M. fortuitum, M. abscessus. Минимальную ингибирующую концентрацию препаратов для медленнорастущих НТМ определяли с использованием панели из 13 препаратов (SLOWMYCO), а для быстрорастущих микобактерий – из 15 препаратов RAPMYCO Sensititre (Trek Diagnostic System, Thermo Scientific, США). Показано, что большинство исследованных быстрорастущих НТМ нечувствительны к цефтриаксону, цефепиму, цефокситину, но чувствительны к амикацину, а медленнорастущие НТМ чувствительны к кларитромицину, линезолиду и амикацину.
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