1,427 research outputs found

    Stabilization of internal space in noncommutative multidimensional cosmology

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    We study the cosmological aspects of a noncommutative, multidimensional universe where the matter source is assumed to be a scalar field which does not commute with the internal scale factor. We show that such noncommutativity results in the internal dimensions being stabilizedComment: 8 pages, 1 figure, to appear in IJMP

    Horizon Problem Remediation via Deformed Phase Space

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    We investigate the effects of a special kind of dynamical deformation between the momenta of the scalar field of the Brans-Dicke theory and the scale factor of the FRW metric. This special choice of deformation includes linearly a deformation parameter. We trace the deformation footprints in the cosmological equations of motion when the BD coupling parameter goes to infinity. One class of the solutions gives a constant scale factor in the late time that confirms the previous result obtained via another approach in the literature. This effect can be interpreted as a quantum gravity footprint in the coarse grained explanation. The another class of the solutions removes the big bang singularity, and the accelerating expansion region has an infinite temporal range which overcomes the horizon problem. After this epoch, there is a graceful exiting by which the universe enters in the radiation dominated era.Comment: 13 pages, 2 figures, to appear in GER

    ESTIMATION OF HORSE LEG MUSCLES FORCE DURING JUMPING

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    The purpose of the present study was to estimate horses’ leg muscle forces in jump height during jumping a spread fence of different heights. A digital camcorder was used (25 Hz) along with Ulead Studio program in order to obtain time, muscle lengths at rest, compression, extension, jump distance, and various angles in horse’s legs data. The total jump distance and time of flight for each horse were measured with a precision of 10m and 10s respectively. Biomechanical formulae have been established in order to evaluate the muscles stiffness coefficients. Three groups of leg muscles; serratus ventralis, biceps brachii, and radial carpal extensor were considered in this study and their forces were successfully estimated

    Semileptonic Dq→K1ℓνD_{q}\to K_{1}\ell \nu and nonleptonic D→K1πD\to K_1 \pi decays in three--point QCD sum rules and factorization approach

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    We analyze the semileptonic Dq→K1ℓνD_{q}\to K_1 \ell\nu transition with q=u,d,sq=u, d, s, in the framework of the three--point QCD sum rules and the nonleptonic D→K1πD\to K_1 \pi decay within the QCD factorization approach. We study DqD_{q} to K1(1270)K_1(1270) and K1(1400)K_1(1400) transition form factors by separating the mixture of the K1(1270)K_1(1270) and K1(1400)K_1(1400) states. Using the transition form factors of the D→K1D\to K_1 , we analyze the nonleptonic D→K1πD\to K_1 \pi decay. We also present the decay amplitude and decay width of these decays in terms of the transition form factors. The branching ratios of these channel modes are also calculated at different values of the mixing angle θK1\theta_{K_1} and compared with the existing experimental data for the nonleptonic case.Comment: 28 Pages, 20 Figures and 9 Table
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