5,082 research outputs found
Vortex density spectrum of quantum turbulence
The fluctuations of the vortex density in a turbulent quantum fluid are
deduced from local second-sound attenuation measurements. These measurements
are performed with a micromachined open-cavity resonator inserted across a flow
of turbulent He-II near 1.6 K. The power spectrum of the measured vortex line
density is compatible with a (-5/3) power law. The physical interpretation,
still open, is discussed.Comment: Submitted to Europhys. Let
Quasielastic Charged Current Neutrino-nucleus Scattering
We provide integrated cross sections for quasielastic charged-current
neutrino-nucleus scattering. Results evaluated using the phenomenological
scaling function extracted from the analysis of experimental data are
compared with those obtained within the framework of the relativistic impulse
approximation. We show that very reasonable agreement is reached when a
description of final-state interactions based on the relativistic mean field is
included. This is consistent with previous studies of differential cross
sections which are in accord with the universality property of the superscaling
function.Comment: 5 pages, 3 figures, to be published in Phys. Rev. Let
Superscaling and neutral current quasielastic neutrino-nucleus scattering
The superscaling approach is applied to studies of neutral current neutrino
reactions in the quasielastic regime. Using input from scaling analyses of
electron scattering data, predictions for high-energy neutrino and antineutrino
cross sections are given and compared with results obtained using the
relativistic Fermi gas model. The influence of strangeness content inside the
nucleons in the nucleus is also explored.Comment: 28 pages, 8 figures, accepted for publication in Phys.Rev.
Inelastic electron-nucleus scattering and scaling at high inelasticity
Highly inelastic electron scattering is analyzed within the context of the
unified relativistic approach previously considered in the case of quasielastic
kinematics. Inelastic relativistic Fermi gas modeling that includes the
complete inelastic spectrum - resonant, non-resonant and Deep Inelastic
Scattering - is elaborated and compared with experimental data. A
phenomenological extension of the model based on direct fits to data is also
introduced. Within both models, cross sections and response functions are
evaluated and binding energy effects are analyzed. Finally, an investigation of
the second-kind scaling behavior is also presented.Comment: 39 pages, 13 figures; formalism extended and slightly reorganized,
conclusions extended; to appear in Phys. Rev.
Pionic correlations and meson-exchange currents in two-particle emission induced by electron scattering
Two-particle two-hole contributions to electromagnetic response functions are
computed in a fully relativistic Fermi gas model. All one-pion exchange
diagrams that contribute to the scattering amplitude in perturbation theory are
considered, including terms for pionic correlations and meson-exchange currents
(MEC). The pionic correlation terms diverge in an infinite system and thus are
regularized by modification of the nucleon propagator in the medium to take
into account the finite size of the nucleus. The pionic correlation
contributions are found to be of the same order of magnitude as the MEC.Comment: 14 pages, 15 figure
Using Electron Scattering Superscaling to predict Charge-changing Neutrino Cross Sections in Nuclei
Superscaling analyses of few-GeV inclusive electron scattering from nuclei
are extended to include not only quasielastic processes, but now also into the
region where -excitation dominates. It is shown that, with reasonable
assumptions about the basic nuclear scaling function extracted from data and
information from other studies of the relative roles played by correlation and
MEC effects, the residual strength in the resonance region can be accounted for
through an extended scaling analysis. One observes scaling upon assuming that
the elementary cross section by which one divides the residual to obtain a new
scaling function is dominated by the transition and employing a
new scaling variable which is suited to the resonance region. This yields a
good representation of the electromagnetic response in both the quasielastic
and regions. The scaling approach is then inverted and predictions are
made for charge-changing neutrino reactions at energies of a few GeV, with
focus placed on nuclei which are relevant for neutrino oscillation
measurements. For this a relativistic treatment of the required weak
interaction vector and axial-vector currents for both quasielastic and
-excitation processes is presented.Comment: 42 pages, 9 figures, accepted for publication in Physical Review
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