20,664 research outputs found
Understanding of double-curvature shaped magnetoimpedance profiles in Joule-annealed and tensioned microwires at 8-12 GHz
We have investigated for the first time the combined effect of current and
stress on the GMI characteristics of vanishing-magnetostrictive Co-rich
microwires at microwave frequency. As the current-annealed wire is subject to
certain tensile stress, one can observe a drastic transformation of field
dependence of MI profiles from smooth shape of a broad peak to deformed shape
of a sharp peak with the emergence of a kink on each side. It follows that
three different regions- core, inner and outer shell -have been formed by the
combined effect of Joule annealing, current generated magnetic field and the
tensile stress. A critical field sees a drop of field sensitivity from outer to
inner shell and shifts to lower value with increasing annealing current. We
successfully adapted our core-shell model to a core-shell-shell model by
designating different anisotropy field for each region to satisfactorily
resolve the unique double-curvature shaped peaks in the field derivative MI
profiles.Comment: 10 pages, 3 figures, for 59th MMM conferenc
3D structure of hadrons by generalized distribution amplitudes and gravitational form factors
Generalized distribution amplitudes (GDAs) are one type of three-dimensional
structure functions, and they are related to the generalized distribution
functions (GPDs) by the - crossing of the Mandelstam variables. The GDA
studies provide information on three-dimensional tomography of hadrons. The
GDAs can be investigated by the two-photon process , and the GPDs are studied by the deeply virtual Compton scattering . The GDA studies had been pure theoretical topics, although the
GPDs have been experimentally investigated, because there was no available
experimental measurement. Recently, the Belle collaboration reported their
measurements on the differential cross
section, so that it became possible to find the GDAs from their measurements.
Here, we report our analysis of the Belle data for determining the pion GDAs.
From the GDAs, the timelike gravitational form factors and
can be calculated, which are mechanical (pressure, shear force)
and mass (energy) form factors, respectively. They are converted to the
spacelike form factors by using the dispersion relation, and then gravitational
radii are evaluated for the pion. The mass and mechanical radii are obtained
from and as fm and fm, whereas the experimental charge radius is fm for the charged pion. Future
developments are expected in this new field to explore gravitational physics in
the quark and gluon level.Comment: 6 pages, LaTeX, 1 style file, 8 figure files, Proceedings of the XXV
International Workshop on Deep-Inelastic Scattering and Related Subjects,
April 3-7, 2017, University of Birmingham, U
Anderson localization in generalized discrete time quantum walks
We study Anderson localization in a generalized discrete time quantum walk -
a unitary map related to a Floquet driven quantum lattice. It is controlled by
a quantum coin matrix which depends on four angles with the meaning of
potential and kinetic energy, and external and internal synthetic flux. Such
quantum coins can be engineered with microwave pulses in qubit chains. The
ordered case yields a two-band eigenvalue structure on the unit circle which
becomes completely flat in the limit of vanishing kinetic energy. Disorder in
the external magnetic field does not impact localization. Disorder in all the
remaining angles yields Anderson localization. In particular, kinetic energy
disorder leads to logarithmic divergence of the localization length at spectral
symmetry points. Strong disorder in potential and internal magnetic field
energies allows to obtain analytical expressions for spectrally independent
localization length which is highly useful for various applications.Comment: 11 pages, 14 figure
A pQCD-based description of heavy and light flavor jet quenching
We present a successful description of the medium modification of light and
heavy flavor jets within a perturbative QCD (pQCD) based approach. Only the
couplings involving hard partons are assumed to be weak. The effect of the
medium on a hard parton, per unit time, is encoded in terms of three
non-perturbative, related transport coefficients which describe the transverse
momentum squared gained, the elastic energy loss and diffusion in elastic
energy transfer. A fit of the centrality dependence of the suppression and the
azimuthal anisotropy of leading hadrons tends to favor somewhat larger
transport coefficients for heavy quarks. Imposing additional constraints based
on leading order (LO) Hard Thermal Loop (HTL) effective theory, leads to a
worsening of the fit.Comment: v2, 4 pages, 3 figure
Microwave spectroscopy on a double quantum dot with an on-chip Josephson oscillator
We present measurements on microwave spectroscopy on a double quantum dot
with an on-chip microwave source. The quantum dots are realized in the
two-dimensional electron gas of an AlGaAs/GaAs heterostructure and are weakly
coupled in series by a tunnelling barrier forming an 'ionic' molecular state.
We employ a Josephson oscillator formed by a long Nb/Al-AlO/Nb junction as
a microwave source. We find photon-assisted tunnelling sidebands induced by the
Josephson oscillator, and compare the results with those obtained using an
externally operated microwave source.Comment: 6 pages, 4 figure
Energy and momentum deposited into a QCD medium by a jet shower
Hard partons moving through a dense QCD medium lose energy by radiative
emissions and elastic scatterings. Deposition of the radiative contribution
into the medium requires rescattering of the radiated gluons. We compute the
total energy loss and its deposition into the medium self-consistently within
the same formalism, assuming perturbative interaction between probe and medium.
The same transport coefficients that control energy loss of the hard parton
determine how the energy is deposited into the medium; this allows a parameter
free calculation of the latter once the former have been computed or extracted
from experimental energy loss data. We compute them for a perturbative medium
in hard thermal loop (HTL) approximation. Assuming that the deposited
energy-momentum is equilibrated after a short relaxation time, we compute the
medium's hydrodynamical response and obtain a conical pattern that is strongly
enhanced by showering.Comment: 4 pages, 3 figures, revtex4, intro modified, typos correcte
Phonon Effects on Spin-Charge Separation in One Dimension
Phonon effects on spin-charge separation in one dimension are investigated
through the calculation of one-electron spectral functions in terms of the
recently developed cluster perturbation theory together with an optimized
phonon approach. It is found that the retardation effect due to the finiteness
of phonon frequency suppresses the spin-charge separation and eventually makes
it invisible in the spectral function. By comparing our results with
experimental data of TTF-TCNQ, it is observed that the electron-phonon
interaction must be taken into account when interpreting the ARPES data.Comment: 5 pages, 5 figures, minor differences with the published version in
Physical Review Letter
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