72,446 research outputs found

    Relativistic description of nuclear matrix elements in neutrinoless double-β\beta decay

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    Neutrinoless double-β\beta (0νββ0\nu\beta\beta) decay is related to many fundamental concepts in nuclear and particle physics beyond the standard model. Currently there are many experiments searching for this weak process. An accurate knowledge of the nuclear matrix element for the 0νββ0\nu\beta\beta decay is essential for determining the effective neutrino mass once this process is eventually measured. We report the first full relativistic description of the 0νββ0\nu\beta\beta decay matrix element based on a state-of-the-art nuclear structure model. We adopt the full relativistic transition operators which are derived with the charge-changing nucleonic currents composed of the vector coupling, axial-vector coupling, pseudoscalar coupling, and weak-magnetism coupling terms. The wave functions for the initial and final nuclei are determined by the multireference covariant density functional theory (MR-CDFT) based on the point-coupling functional PC-PK1. The low-energy spectra and electric quadrupole transitions in 150{}^{150}Nd and its daughter nucleus 150{}^{150}Sm are well reproduced by the MR-CDFT calculations. The 0νββ0\nu\beta\beta decay matrix elements for both the 01+→01+0_1^+\rightarrow 0_1^+ and 01+→02+0_1^+\rightarrow 0_2^+ decays of 150{}^{150}Nd are evaluated. The effects of particle number projection, static and dynamic deformations, and the full relativistic structure of the transition operators on the matrix elements are studied in detail. The resulting 0νββ0\nu\beta\beta decay matrix element for the 01+→01+0_1^+\rightarrow 0_1^+ transition is 5.605.60, which gives the most optimistic prediction for the next generation of experiments searching for the 0νββ0\nu\beta\beta decay in 150{}^{150}Nd.Comment: 17 pages, 9 figures; table adde

    Management of Digital Video Broadcasting Services in Open Delivery Platforms

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    The future of Digital Video Broadcasting (DVB) is moving towards solutions offering an efficient way of carrying interactive IP multimedia services over digital terrestrial broadcasting networks to handheld terminals. One of the most promising technologies is Digital Video Broadcasting-Handheld (DVB-H), at present under standardisation. Services deployed via this type of DVB technologies should enjoy reliability comparable to TV services and high quality standards. However, the market at present does not provide effective and economical solutions for the deployment of such services over multi-domain IP networks, due to their high level of unreliability. This paper focuses on service management, service level agreement (SLA) and network performance requirements of DVB-H services. Experimental results are presented concerning QoS sensitivity to network performance of DVB-H services delivered over a multi-domain IP network. Moreover, a solution for efficient and cost effective service management via QoS monitoring and control and network SLA design is proposed. The solution gives DVB-H operators the possibility of fully managing service QoS without being tied to third party operators

    VISHNU hybrid model for viscous QCD matter at RHIC and LHC energies

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    In this proceeding, we briefly describe the viscous hydrodynamics + hadron cascade hybrid model VISHNU for relativistic heavy ion collisions and report the current status on extracting the QGP viscosity from elliptic flow data.Comment: 4 pages, 1 figure, the proceedings of 7th International Workshop on Critical Point and Onset of Deconfinement, Wuhan, China, Nov. 7-11, 201

    Connections of activated hopping processes with the breakdown of the Stokes-Einstein relation and with aspects of dynamical heterogeneities

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    We develop a new extended version of the mode-coupling theory (MCT) for glass transition, which incorporates activated hopping processes via the dynamical theory originally formulated to describe diffusion-jump processes in crystals. The dynamical-theory approach adapted here to glass-forming liquids treats hopping as arising from vibrational fluctuations in quasi-arrested state where particles are trapped inside their cages, and the hopping rate is formulated in terms of the Debye-Waller factors characterizing the structure of the quasi-arrested state. The resulting expression for the hopping rate takes an activated form, and the barrier height for the hopping is ``self-generated'' in the sense that it is present only in those states where the dynamics exhibits a well defined plateau. It is discussed how such a hopping rate can be incorporated into MCT so that the sharp nonergodic transition predicted by the idealized version of the theory is replaced by a rapid but smooth crossover. We then show that the developed theory accounts for the breakdown of the Stokes-Einstein relation observed in a variety of fragile glass formers. It is also demonstrated that characteristic features of dynamical heterogeneities revealed by recent computer simulations are reproduced by the theory. More specifically, a substantial increase of the non-Gaussian parameter, double-peak structure in the probability distribution of particle displacements, and the presence of a growing dynamic length scale are predicted by the extended MCT developed here, which the idealized version of the theory failed to reproduce. These results of the theory are demonstrated for a model of the Lennard-Jones system, and are compared with related computer-simulation results and experimental data.Comment: 13 pages, 5 figure

    Systematic study of nuclear matrix elements in neutrinoless double-beta decay with a beyond mean-field covariant density functional theory

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    We report a systematic study of nuclear matrix elements (NMEs) in neutrinoless double-beta decays with a state-of-the-art beyond mean-field covariant density functional theory. The dynamic effects of particle-number and angular-momentum conservations as well as quadrupole shape fluctuations are taken into account with projections and generator coordinate method for both initial and final nuclei. The full relativistic transition operator is adopted to calculate the NMEs. The present systematic studies show that in most of the cases there is a much better agreement with the previous non-relativistic calculation based on the Gogny force than in the case of the nucleus 150^{150}Nd found in Song et al. [Phys. Rev. C 90, 054309 (2014)]. In particular, we find that the total NMEs can be well approximated by the pure axial-vector coupling term with a considerable reduction of the computational effort.Comment: 9 pages with 7 figures and 3 table

    Dynamical Systems On Three Manifolds Part II: 3-Manifolds,Heegaard Splittings and Three-Dimensional Systems

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    The global behaviour of nonlinear systems is extremely important in control and systems theory since the usual local theories will only give information about a system in some neighbourhood of an operating point. Away from that point, the system may have totally different behaviour and so the theory developed for the local system will be useless for the global one. In this paper we shall consider the analytical and topological structure of systems on 2- and 3- manifolds and show that it is possible to obtain systems with 'arbitrarily strange' behaviour, i.e., arbitrary numbers of chaotic regimes which are knotted and linked in arbitrary ways. We shall do this by considering Heegaard Splittings of these manifolds and the resulting systems defined on the boundaries.Comment: 15 pages with 9 pictures. Accepted by Int. J. of Bifurcation and Chao

    Quark Orbital Angular Momentum in the Baryon

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    Analytical and numerical results, for the orbital and spin content carried by different quark flavors in the baryons, are given in the chiral quark model with symmetry breaking. The reduction of the quark spin, due to the spin dilution in the chiral splitting processes, is transferred into the orbital motion of quarks and antiquarks. The orbital angular momentum for each quark flavor in the proton as a function of the partition factor κ\kappa and the chiral splitting probability aa is shown. The cancellation between the spin and orbital contributions in the spin sum rule and in the baryon magnetic moments is discussed.Comment: 26 pages, 3 figures, revised version with minor eq. no and ref. no. corrections. Discussion on the Λ\Lambda spin and a new ref. are adde

    CSU FIRE 2 cirrus field experiment: Description of field deployment phase

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    The Colorado State University (CSU) surface observing systems are described. These systems were deployed at the Parsons, Kansas site during the FIRE 2 Cirrus Special Observing Period (SOP) from 13 Nov. - 7 Dec. 1991. The geographical coordinates of the site containing most of the CSU instrumentation are 37 deg. 18 min N. latitude and 96 deg. 30 min. W. longitude; site elevation was 269 meters. In addition, one surface meteorological and broadband flux observing site was maintained at the Tri City Airport which is approximately 18 miles due west of Parsons (37 deg. 20 min. N. latitude, 95 deg. 30 min. 30 sec. W. longitude). A map of the locations of the CSU deployment sites is presented. At the main Parsons site, the instrumentation was located directly adjacent to and north of a lake. Under most cirrus observing conditions, when the wing had a significant southernly component, the lake was upwind of the observing site. The measurements and observations collected during the experiment are listed. These measurements may be grouped into five categories: surface meteorology; infrared spectral and broadband measurements; solar spectral and broadband measurements; upper air measurements; and cloud measurements. A summary of observations collected at the Parsons site during the SOP are presented. The wind profiler, laser ceilometer, surface meteorology and surface broadband radiation instrumentation were operated on a continuous basis. All other systems were operated on an 'on demand' basis when cloud conditions merited the collection of data
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