3,231 research outputs found

    Average formation length in string model

    Full text link
    The space-time scales of the hadronization process in the framework of string model are investigated. It is shown that the average formation lengths of pseudoscalar mesons, produced in semi-inclusive deep inelastic scattering (DIS) of leptons on different targets, depend from their electrical charges. In particular the average formation lengths of positively charged hadrons are larger than of negatively charged ones. This statement is fulfiled for all using scaling functions, for zz (the fraction of the virtual photon energy transferred to the detected hadron) larger than 0.15, for all nuclear targets and any value of the Bjorken scaling variable xBjx_{Bj}. In all cases, the main mechanism is direct production of pseudoscalar mesons. Including in consideration additional mechanism of production in result of decay of resonances, leads to decrease of average formation lengths. It is shown that the average formation lengths of positively (negatively) charged mesons are slowly rising (decreasing) functions of xBjx_{Bj}. The obtained results can be important, in particular, for the understanding of the hadronization process in nuclear environment

    Average formation lengths of baryons and antibaryons in string model

    Full text link
    In this work it is continued the investigation of the space-time scales of the hadronization process in the framework of string model. The average formation lengths of several widely using species of baryons (antibaryons) such as pp (pˉ\bar{p}), nn (nˉ\bar{n}), Δ\Delta (Δˉ\bar{\Delta}), Λ\Lambda (Λˉ\bar{\Lambda}) and Σ\Sigma (Σˉ\bar{\Sigma}) are studied. It is shown that they depend from electrical charges or, more precise, from quark contents of the hadrons. In particular, the average formation lengths of positively charged hadrons, for example protons, are considerably larger than of their negatively charged antiparticles, antiprotons. This statement is fulfilled for all nuclear targets and any value of the Bjorken scaling variable xBjx_{Bj}. The main mechanism is direct production. Additional production mechanism in result of decay of resonances gives small contribution. It is shown that the average formation lengths of protons (antiprotons) are slowly rising (decreasing) functions of xBjx_{Bj}, the ones of neutrons and antineutrons are slowly decreasing functions of xBjx_{Bj}. The shape and behavior of average formation lengths for baryons qualitatively coincide with the ones for pseudoscalar mesons obtained earlier.Comment: 7 pages, 6 figure

    Dynamical spin-spin coupling of quantum dots

    Full text link
    We carried out a nested Schrieffer-Wolff transformation of an Anderson two-impurity Hamiltonian to study the spin-spin coupling between two dynamical quantum dots under the influence of rotating transverse magnetic field. As a result of the rotating field, we predict a novel Ising type spin-spin coupling mechanism between quantum dots, whose strength is tunable via the magnitude of the rotating field. The strength of the new coupling could be comparable to the strength of the RKKY coupling. The dynamical coupling with the intristic RKKY coupling enables to construct a four level system of maximally entangled Bell states in a controllable manner

    Nuclear attenuation of high energy multi-hadron systems in the string model

    Full text link
    Nuclear attenuation of the multi-hadron systems in the string model is considered. The improved two-scale model with set of parameters obtained recently for the single hadron attenuation is used for calculation of the multiplicity ratios of the one-, two- and three-hadron systems electroproduced on nuclear and deuterium targets. The comparison of the features of the one-, two- and three-hadron systems is performed. The predictions of the model for multiplicity ratios of multi-hadron systems as functions of different convenient variables are presented.Comment: 7 pages, 6 figure

    Simple parameterization of nuclear attenuation data

    Full text link
    Based on the nuclear attenuation data obtained by the HERMES experiment on nitrogen and krypton nuclei, it is shown that the nuclear attenuation RMhR_M^{h} can be parametrised in a form of a linear polynomial P1=a11P_1=a_{11} + τa12\tau a_{12}, where τ\tau is the formation time, which depends on the energy of the virtual photon ν\nu and fraction of that energy zz carried by the final hadron. Three widely known parameterizations for τ\tau were used for the performed fit. The fit parameters a11a_{11} and a12a_{12} do not depend on ν\nu and zz
    • …
    corecore