8,971 research outputs found

    What brakes the Crab pulsar?

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    Optical observations provide convincing evidence that the optical phase of the Crab pulsar follows the radio one closely. Since optical data do not depend on dispersion measure variations, they provide a robust and independent confirmation of the radio timing solution. The aim of this paper is to find a global mathematical description of Crab pulsar's phase as a function of time for the complete set of published Jodrell Bank radio ephemerides (JBE) in the period 1988-2014. We apply the mathematical techniques developed for analyzing optical observations to the analysis of JBE. We break the whole period into a series of episodes and express the phase of the pulsar in each episode as the sum of two analytical functions. The first function is the best-fitting local braking index law, and the second function represents small residuals from this law with an amplitude of only a few turns, which rapidly relaxes to the local braking index law. From our analysis, we demonstrate that the power law index undergoes "instantaneous" changes at the time of observed jumps in rotational frequency (glitches). We find that the phase evolution of the Crab pulsar is dominated by a series of constant braking law episodes, with the braking index changing abruptly after each episode in the range of values between 2.1 and 2.6. Deviations from such a regular phase description behave as oscillations triggered by glitches and amount to fewer than 40 turns during the above period, in which the pulsar has made more than 2.0e10 turns. Our analysis does not favor the explanation that glitches are connected to phenomena occurring in the interior of the pulsar. On the contrary, timing irregularities and changes in slow down rate seem to point to electromagnetic interaction of the pulsar with the surrounding environment.Comment: 11 pages, 8 figures, 3 tables; accepted for publication in Astronomy & Astrophysic

    Phenomenological Issues in Supersymmetry with Non-holomorphic Soft Breaking

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    We present a through discussion of motivations for and phenomenological issues in supersymmetric models with minimal matter content and non-holomorphic soft-breaking terms. Using the unification of the gauge couplings and assuming SUSY is broken with non-standard soft terms, we provide semi-analytic solutions of the RGEs for low and high choices of tan\beta which can be used to study the phenomenology in detail. We also present a generic form of RGIs in mSUGRA framework which can be used to derive new relations in addition to those existing in the literature. Our results are mostly presented with respect to the conventional minimal supersymmetric model for ease of comparison.Comment: 34 page

    One- and Two-Nucleon Structure form Green's Function Theory

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    We review some applications of self-consistent Green's function theory to studies of one- and two-nucleon structure in finite nuclei. Large-scale microscopic calculations that employ realistic nuclear forces are now possible. Effects of long-range correlations are seen to play a dominant role in determining the quenching of absolute spectroscopic factors. They also enhance considerably (e,e'pn) cross sections in superparallel kinematics, in agreement with observations.Comment: Proceedings of the International Symposium on "Forefronts of Researches in Exotic Nuclear Structures" (Niigata2010)

    Bipartite Bell inequalities for hyperentangled states

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    We show that bipartite Bell inequalities based on the Einstein-Podolsky-Rosen criterion for elements of reality and derived from the properties of some hyperentangled states allow feasible experimental verifications of the fact that quantum nonlocality grows exponentially with the size of the subsystems, and Bell loophole-free tests with currently available photodetection efficiencies.Comment: REVTeX4, 5 page

    Neutrino Mass Squared Differences in the Exact Solution of a 3-3-1 Gauge Model without Exotic Electric Charges

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    The mass splittings for the Majorana neutrinos in the exact solution of a particular 3-3-1 gauge model are computed here in detail. Since both sin2θ130\sin^{2}\theta_{13}\simeq0 and the mass splittings ratio rΔ0.033r_{\Delta}\simeq0.033 are taken into account, the analytical calculations seem to predict an inverted mass hierarchy and a mixing matrix with a texture based on a very close approximation to the bi-maximal mixing. The resulting formulas for the mass squared differences can naturally accomodate the available data if the unique free parameter (aa) gets very small values (1015\sim10^{-15}). Consequently, the smallness of the parameter requires (according to our method) a large breaking scale 106107\sim10^{6}-10^{7} TeV in the model. Hence, the results concerning the neutrino mass splittings may lead to a more precise tuning in the exact solution of the 3-3-1 model of interest, being able - at the same time - to recover all the Standard Model phenomenology and predict the mass spectrum of the new gauge bosons Z,X,YZ^{\prime},X,Y in accordance with the actual data. The minimal absolute mass in the neutrino sector is also obtained - m00.0035m_{0}\simeq0.0035 eV - in the case of our suitable approximation for the bi-maxcimal mixing.Comment: 10 pages, no figure

    Spectral function at high missing energies and momenta

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    The nuclear spectral function at high missing energies and momenta has been determined from a self-consistent calculation of the Green's function in nuclear matter using realistic nucleon-nucleon interactions. The results are compared with recent experimental data derived from (e,epe,e'p) reactions on 12C^{12}C. A rather good agreement is obtained if the Green's functions are calculated in a non-perturbative way.Comment: 10 pages, 3 figure
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