686 research outputs found

    One-loop corrections to the instanton transition in the two-dimensional Abelian Higgs model

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    We present an evaluation of the fluctuation determinant which appears as a prefactor in the instanton transition rate for the two-dimensional Abelian Higgs model. The corrections are found to change the rate at most by a factor of 2 for 0.4 < M_W/M_H < 2.0.Comment: DO-TH-94/17, 20 pages, 4 figures appended as uucompressed .eps files, LaTeX, needs epsfig.st

    Pion Decay Constant at Finite Temperature in the Nonlinear Sigma Model

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    We calculate the pion decay constant near the critical temperature of the O(N)O(N) nonlinear sigma model in the large NN limit. Making use of the known low temperature behavior, we construct a Pad\'{e} approximant to obtain the behavior of fπ(T)f_\pi(T) at all temperatures.Comment: 8 pages, one latex file and one postscript file (uses psfig). Uuencode

    Observational physics of mirror world

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    The existence of the whole world of shadow particles, interacting with each other and having no mutual interactions with ordinary particles except gravity is a specific feature of modern superstring models, being considered as models of the theory of everything. The presence of shadow particles is the necessary condition in the superstring models, providing compensation of the asymmetry of left and right chirality states of ordinary particles. If compactification of additional dimensions retains the symmetry of left and right states, shadow world turns to be the mirror one, with particles and fields having properties strictly symmetrical to the ones of corresponding ordinary particles and fields. Owing to the strict symmetry of physical laws for ordinary and mirror particles, the analysis of cosmological evolution of mirror matter provides rather definite conclusions on possible effects of mirror particles in the universe. A general qualitative discussion of possible astronomical impact of mirror matter is given, in order to make as wide as possible astronomical observational searches for the effects of mirror world, being the unique way to test the existence of mirror partners of ordinary particles in the Nature

    Archimedean-type force in a cosmic dark fluid: II. Qualitative and numerical study of a multistage Universe expansion

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    In this (second) part of the work we present the results of numerical and qualitative analysis, based on a new model of the Archimedean-type interaction between dark matter and dark energy. The Archimedean-type force is linear in the four-gradient of the dark energy pressure and plays a role of self-regulator of the energy redistribution in a cosmic dark fluid. Because of the Archimedean-type interaction the cosmological evolution is shown to have a multistage character. Depending on the choice of the values of the model guiding parameters,the Universe's expansion is shown to be perpetually accelerated, periodic or quasiperiodic with finite number of deceleration/acceleration epochs. We distinguished the models, which can be definitely characterized by the inflation in the early Universe, by the late-time accelerated expansion and nonsingular behavior in intermediate epochs, and classified them with respect to a number of transition points. Transition points appear, when the acceleration parameter changes the sign, providing the natural partition of the Universe's history into epochs of accelerated and decelerated expansion. The strategy and results of numerical calculations are advocated by the qualitative analysis of the instantaneous phase portraits of the dynamic system associated with the key equation for the dark energy pressure evolution.Comment: 15 pages, 12 figures, Part II, typos corrected, Fig.4 replaced, references correcte

    Structure and three-body decay of 9^9Be resonances

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    The complex-rotated hyperspherical adiabatic method is used to study the decay of low-lying 9^9Be resonances into one neutron and two α\alpha-particles. We investigate the six resonances above the break-up threshold and below 6 MeV: 1/2±1/2^\pm, 3/2±3/2^\pm and 5/2±5/2^\pm. The short-distance properties of each resonance are studied, and the different angular momentum and parity configurations of the 8^8Be and 5^5He two-body substructures are determined. We compute the branching ratio for sequential decay via the 8^8Be ground state which qualitatively is consistent with measurements. We extract the momentum distributions after decay directly into the three-body continuum from the large-distance asymptotic structures. The kinematically complete results are presented as Dalitz plots as well as projections on given neutron and α\alpha-energy. The distributions are discussed and in most cases found to agree with available experimental data.Comment: 12 pages, 10 figures. To appear in Physical Review

    Research Of Quality Indicators Of Protein-fat Mixture From Flax And Sesame Seeds For Nutrition Of Athletes

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    The aim of the research is to determine the microbiological stability of a protein-fat mixture of flax and sesame seeds that allows to correct its storage life. A protein-fat mixture has a high content of irreplaceable amino acids ВСАА and polyunsaturated fatty acids of w-3group, so it may be positioned as a component of nutrition for athletes. Flax and sesame seeds, cultivated in Ukraine, were used as research materials. The product was created, based on comminuted flax and sesame seeds in ratio 1:1. There were determined organoleptic (outlook, taste, smell, color) and physical-chemical (mass share of moisture, ash, protein, fat, acidic, peroxide, anisidine number) parameters of the product. There was determined the microbiological stability of the protein-fat mixture of the increased food value for athletes nutrition after 6 months. It has been proved, that as opposite to the control sample, the protein-fat mixture of the developed composition manifests its microbiological stability by the following parameters: content of mesophilic aerobic and facultative anaerobic microorganisms, molds, yeast, bacteria of the colon bacillus group and pathogenic microorganisms. The control sample that is comminuted flax seeds doesn\u27t manifest at the end of the storage term any correspondence of microbiological parameters by the content of mesophilic aerobic and facultative anaerobic microorganisms, molds, and bacteria of the colon bacillus group. This regularity is explained by the presence of lignans, sesamol and sesamoline, with preservative properties in the developed product. The obtained data may be used for reasoning recipes of products, based on the protein-fat mixture and correction of the food supplements ratio in them

    The Zipf law for random texts with unequal probabilities of occurrence of letters and the Pascal pyramid

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    We model the generation of words with independent unequal probabilities of occurrence of letters. We prove that the probability p(r)p(r) of occurrence of words of rank rr has a power asymptotics. As distinct from the paper published earlier by B. Conrad and M. Mitzenmacher, we give a brief proof by elementary methods and obtain an explicit formula for the exponent of the power law.Comment: 4 page
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