1,305 research outputs found
CP Violation and the Absence of Second Class Currents in Charmless B Decays
The absence of second class currents together with the assumption of
factorization for non-leptonic B decays provide new constraints on CP
observables in decay B to a0(980)(to eta pi) pi. The kinematics of this decay
do not allow interference between the oppositely charged resonances in the
Dalitz plot as in B0 to rho(770)pi. Nonetheless, under the assumption of
factorization,the a0pi two-body time-dependent isospin analysis leads to a more
robust extraction of the angle alpha than in the rhopi isospin-pentagon
analysis. The absence of second class currents might lead to enhanced direct CP
violation and/or allows for a test of some assumptions made in the alpha
analysis in other decays like B to a0rho, B to b1(1235)pi, B to a0 a0, B to
eta(eta')pipi and B to b1 a0. The effects from non-factorizable contributions
on the determination of alpha are estimated by means of a numerical study.Comment: 8 pages, 2 figures, Latex. Accepted for publication in Eur.Phys.J.
Agent modelling of cluster formation processes in regional economic systems
The subject matter of this research is the processes of the spontaneous clustering in the regional economy. The purpose is the development and approbation of the modeling algorithm of these processes. The hypothesis: the processes of spontaneous clustering in the social and economic environment are supposed to proceed not linearly, but intermittently. The following methods are applied: agent imitating modeling with an application of FOREL and k-means algorithms. The modeling algorithm is realized in the Python 3 programming language. The course regularities of clustering processes in the region are revealed: 1) the clustering processes are intensifying, the production uniformity is increasing; 2) the increase of the level of production uniformity leads to the leveling of customer behavior; 3) the producers of high-differentiated production reduce the level of its differentiation or leave the cluster; 4) the stages of steady functioning are illustrative for clustering processes, their change is followed with arising of bifurcation points; 5) the activation of clustering processes in regional economy leads to the revenue increase of the cluster participants, each of producers and of consumers, and to the growth of synergetic effect values. These results testify the nonlinearity of processes of clustering and ambiguity of their effects. The following conclusions have been drawn: 1) a modeling of the processes of spontaneous clustering in regional economy has showed that they proceed not linearly, a steady progressive development is followed with leaps; 2) the clustering of regional economy leads to the growth of the efficiency indicators of activities of cluster-concerned entities; 3) initiation and activation of the clustering processes requires a certain environment
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N and C isotropic composition of different varieties of terrestrial diamonds and carbonado
During the course of this research an instrument utilising combustion as a means of gas extraction capable of N, C, Ar and He analysis has been developed and the entire analytical procedure has been automated.
N and C isotopic analysis has been performed on eclogitic and peridotitic diamonds (mainly from Yakutian kimberlites and the Roberts Victor kimberlite pipe). Diamonds with unusual (light and heavy relative to the peak of δ13C distribution of mantle diamonds) carbon isotopic signatures were considered for the research so that diamonds in the range of δ13C from -30‰to +2.8‰ were characterised for δ15N. The results together with data obtained previously by the others define fields for eclogitic and peridotitic diamonds on a plot of δ15N vs. δ13C. The model of mantle nitrogen and carbon evolution is discussed.
A comprehensive comparison between carbonado and other known forms of microcrystalline diamond (framesites and shock diamonds) has been made for a number of parameters: N and C isotopic composition and N content; 4He content; morphology of the inner structure of diamond aggregates. It can be concluded that carbonado is generally similar to frame sites and all facts known about carbonado can be explained on the grounds of common mantle origin involving subducted carbon and nitrogen. Since extremely high 4He concentrations are encountered in carbonado this parameter is considered to be the most singular feature of this diamond variety and the radial distribution of 4He in single diamond crystals has been studied. A 4He content comparable with that in carbonado was found in the 30 µm skin of diamond crystals (up to 1.4 x 10-2 ) suggesting that carbonado could acquire high 4He concentration in the same geological processes as single diamond crystals and making carbonado indistinguishable from mantle diamonds in terms of He content. An additional result of the investigation is that the maximum of 4He diffusion coefficient for diamond at mantle P,T conditions can be estimated (≈4 x 10-21 ) from the 4He zoning identified in the interior of a diamond crystal from the Finsch kimberlite.
A number of diamonds of impact origin from Popigai crater and Ebeliakh river placer deposits were studied for N, C and Ar isotopic compositions. It was concluded that diamonds from these two localities have resulted from separate impact events and that diamond aggregates studied are most probably consist of a mixture of different Ar and N carriers (e.g. two types of diamond grains
Corrections For Two Photon Decays of chi_{c0} and chi_{c2} and Color Octet Contributions
Using the fact that the c-quark inside a charmonium moves with a small
velocity v in the charmonium rest-frame, one can employ an expansion in v to
study decays of charmonia and results at the leading order for chi_{c0,2} -->
gamma gamma exist in the literature. We study corrections at the
next-to-leading order in the framework of nonrelativistic QCD(NRQCD)
factorization. The study presented here is different than previous approaches
where chi_{c0,2} is taken as a bound-state of a c cbar pair and a
nonrelativistic wave-function is used for the pair. We find that the
corrections are consist not only of relativistic corrections, but also of
corrections from Fock state components of chi_{c0,2} in which the c cbar pair
is in a color-octet state. For chi_{c2} there is also a contribution from a
Fock state component in which the pair is in a F-wave state. We determine the
factorization formula for decay widths in the form of NRQCD matrix elements
representing nonperturbative effects related to chi_{c0,2}, and calculate the
perturbative coefficients at tree-level. Because the NRQCD matrix elements are
unknown, a detailed prediction for the decay chi_{c0,2} --> gamma gamma can not
be made, but the effect of these corrections can be determined at certain
level. Estimations show that the effect is significant and can not be
neglected.Comment: 8 pages, 2 figures; typo in Eq.(24) and Eq.(26) are corrected. add
one referenc
Experimental Summary on Hadronic Decays: A TAU98 Review
Selected results on hadronic decays of the tau lepton from the TAU98 Workshop
are reviewed. A comprehensive picture emerges for strange particle branching
fractions, and exploration of resonant substructure of both strange and
non-strange decays is seen to have matured substantially.Comment: 10 pages, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Применение технологии Embedded SIM для обеспечения информационной безопасности в сетях сотовой связи
The article describe the general classification of threats to information security of cellular operators’ networks, the main security threats to subscriber devices in the networks of cellular operators, embedded SIM technology and the possibility of using this technology to ensure the security of subscriber devices. The statistics on the registered cases of the implementation of threats to information security on subscriber devices is analyzed. A high-level architecture for the protection of subscriber devices using eSIM technology is proposed. В статье рассматриваются общая классификация угроз информационной безопасности сетей операторов сотовой связи, основные угрозы безопасности абонентским устройствам в сетях операторов сотовой связи, технология embedded SIM и возможность ее использования для обеспечения безопасности абонентских устройств. Проанализирована статистика по зарегистрированным случаям реализации угроз информационной безопасности на абонентских устройствах. Предложена высокоуровневая архитектура системы защиты абонентских устройств с использованием технологии eSIM.
Characterization of photon counting pixel detectors based on semi-insulating GaAs sensor material
Hybrid semiconductor pixel detectors are considered of high interest for synchrotron applications like diffraction and imaging experiments. However, at photon energies above 30 keV, high-Z sensor materials have to be used due to the weak absorption of the most commonly used sensor material, for instance silicon wafers with a thickness of a few hundred μm. Besides materials like CdTe and Ge, semi-insulating, chromium compensated SI-GaAs(Cr) proves to be a promising sensor material for applications with X-rays in the mid-energy range up to ~60 keV. In this work, material characterisation of SI-GaAs(Cr) wafers by electrical measurements and synchrotron white beam topography as well as the characterization and application of pixel detector assemblies based on Medipix readout chips bump-bonded to 500 μm thick SI-GaAs(Cr) sensors are presented. The results show a very homogeneous material with high resistivity and good electrical properties of the electrons as well as a very promising imaging performance of the detector assemblies
Agent modelling of cluster formation processes in regional economic systems
The subject matter of this research is the processes of the spontaneous clustering in the regional economy. The purpose is the development and approbation of the modeling algorithm of these processes. The hypothesis: the processes of spontaneous clustering in the social and economic environment are supposed to proceed not linearly, but intermittently. The following methods are applied: agent imitating modeling with an application of FOREL and k-means algorithms. The modeling algorithm is realized in the Python 3 programming language. The course regularities of clustering processes in the region are revealed: 1) the clustering processes are intensifying, the production uniformity is increasing; 2) the increase of the level of production uniformity leads to the leveling of customer behavior; 3) the producers of high-differentiated production reduce the level of its differentiation or leave the cluster; 4) the stages of steady functioning are illustrative for clustering processes, their change is followed with arising of bifurcation points; 5) the activation of clustering processes in regional economy leads to the revenue increase of the cluster participants, each of producers and of consumers, and to the growth of synergetic effect values. These results testify the nonlinearity of processes of clustering and ambiguity of their effects. The following conclusions have been drawn: 1) a modeling of the processes of spontaneous clustering in regional economy has showed that they proceed not linearly, a steady progressive development is followed with leaps; 2) the clustering of regional economy leads to the growth of the efficiency indicators of activities of cluster-concerned entities; 3) initiation and activation of the clustering processes requires a certain environment
Vector and Axial-Vector Spectral Functions and QCD
We present new results of the tau hadronic spectral function analysis using
data accumulated by the ALEPH detector at LEP during the years 1991-94. In
addition to the vector spectral functions, the axial-vector spectral functions
and, separately, the tau --> 3pi nu as well as the tau --> pi 2pi0 nu spectral
functions are determined from their respective unfolded, i.e., physical
invariant mass spectra. The spectral functions are applied to QCD chiral sum
rules in order to extract information about saturation at the tau mass scale.
Using the the semi-leptonic tau decay rate for vector and axial-vector currents
in addition to spectral moments, we obtain precise measurements of the strong
coupling constant alpha_s(M_tau) and the contributing non-perturbative power
terms. The evolution to the Z mass yields alpha_s(M_Z) = 0.1219 +/- 0.0019.Comment: 15 pages, 12 figures, LaTex, Talk given at the Fourth International
Workshop on Tau Lepton Physics (TAU96), Colorado, September 199
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