129,293 research outputs found

    Theoretical dark matter halo kinematics and triaxial shape

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    In a recent paper, Salvador-Sol\'e et al. (2012) have derived the typical inner structure of dark matter haloes from that of peaks in the initial random Gaussian density field, determined by the power-spectrum of density perturbations characterising the hierarchical cosmology under consideration. In the present paper, we extend this formalism to the typical kinematics and triaxial shape of haloes. Specifically, we establish the link between such halo properties and the power-spectrum of density perturbations through the typical shape of peaks. The trends of the predicted typical halo shape, pseudo phase-space density and anisotropy profiles are in good agreement with the results of numerical simulations. Our model sheds light on the origin of the power-law-like pseudo phase-space density profile for virialised haloes.Comment: 18 pages, 6 figures. Published in MNRA

    A Comparison of the LVDP and {\Lambda}CDM Cosmological Models

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    We compare the cosmological kinematics obtained via our law of linearly varying deceleration parameter (LVDP) with the kinematics obtained in the {\Lambda}CDM model. We show that the LVDP model is almost indistinguishable from the {\Lambda}CDM model up to the near future of our universe as far as the current observations are concerned, though their predictions differ tremendously into the far future.Comment: 6 pages, 5 figures, 1 table, matches the version to be published in International Journal of Theoretical Physic

    The actual content of quantum theoretical kinematics and mechanics

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    First, exact definitions are supplied for the terms: position, velocity, energy, etc. (of the electron, for instance), such that they are valid also in quantum mechanics. Canonically conjugated variables are determined simultaneously only with a characteristic uncertainty. This uncertainty is the intrinsic reason for the occurrence of statistical relations in quantum mechanics. Mathematical formulation is made possible by the Dirac-Jordan theory. Beginning from the basic principles thus obtained, macroscopic processes are understood from the viewpoint of quantum mechanics. Several imaginary experiments are discussed to elucidate the theory

    On the treatment of the Δ\Delta-contribution in electromagnetic pppp-knockout reactions

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    The treatment of the Δ\Delta-current and its contribution in the exclusive 16^{16}O(e,epp)14(e,e'pp)^{14}C and 16^{16}O(γ,pp)14(\gamma,pp)^{14}C knockout reactions are investigated in combination with the effects of correlations. Different parametrizations of the effective Δ\Delta-current and different treatments of correlations in the two-nucleon overlap function are considered. The results are presented and discussed for a suitable choice of kinematics. It is found that the investigation of different mutually supplementing kinematics is necessary to resolve the uncertainties in the theoretical ingredients and extract clear and unambiguous information on correlations.Comment: 15 pages, 9 figures, EPJA styl

    Current data on the globular cluster Palomar 14 are not inconsistent with MOND

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    Certain types of globular clusters have the very important property that the predictions for their kinematics in the Newtonian and modified Newtonian dynamics (MOND) contexts are divergent. Here, we caution the recent claim that the stellar kinematics data (using 17 stars) of the globular cluster Palomar 14 are inconsistent with MOND. We compare the observations to the theoretical predictions using a Kolmogorov-Smirnov test, which is appropriate for small samples. We find that, with the currently available data, the MOND prediction for the velocity distribution can only be excluded with a very low confidence level, clearly insufficient to claim that MOND is falsified.Comment: Research note accepted for publication in A&

    Left-right asymmetry for pion and kaon production in the semi-inclusive deep inelastic scattering process

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    We analyze the left-right asymmetry in the semi-inclusive deep inelastic scattering (SIDIS) process without introducing any weighting functions. With the current theoretical understanding, we find that the Sivers effect plays a key role in our analysis. We use the latest parametrization of the Sivers and fragmentation functions to reanalyze the π±\pi^\pm production process and find that the results are sensitive to the parametrization. We also extend our calculation on the K±K^{\pm} production, which can help us know more about the Sivers distribution of the sea quarks and the unfavored fragmentation processes. HERMES kinematics with a proton target, COMPASS kinematics with a proton, deuteron, and neutron target (the information on the neutron target can be effectively extracted from the 3^3He target), and JLab kinematics (both 6 GeV and 12 GeV) with a proton and neutron target are considered in our paper.Comment: 7 latex pages, 11 figures, final version for publication, with references update

    Differential ttˉt\bar{t} Cross Section Measurements as a Function of Variables other than Kinematics

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    An overview of cross section measurements as a function of jet multiplicities and jet kinematics in association with ttˉt\bar{t} production is presented. Both the ATLAS and the CMS collaborations performed a large number of measurements at different center-of-mass energies of the LHC using various ttˉt\bar{t} decay channels. Theoretical predictions of these quantities usually rely on parton shower simulations that strongly depends on tunable parameters and come with large uncertainties. The measurements are compared to various theoretical descriptions based on different combinations of matrix-element calculations and parton-shower models
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