7,009 research outputs found
Continuity of the Explosive Percolation Transition
The explosive percolation problem on the complete graph is investigated via
extensive numerical simulations. We obtain the cluster-size distribution at the
moment when the cluster size heterogeneity becomes maximum. The distribution is
found to be well described by the power-law form with the decay exponent , followed by a hump. We then use the finite-size scaling method to
make all the distributions at various system sizes up to collapse
perfectly onto a scaling curve characterized solely by the single exponent
. We also observe that the instant of that collapse converges to a
well-defined percolation threshold from below as . Based on
these observations, we show that the explosive percolation transition in the
model should be continuous, contrary to the widely-spread belief of its
discontinuity.Comment: Some corrections during the revie
Two-gap and paramagnetic pair-breaking effects on upper critical field of SmFeAsO and SmFeAsOF single crystals
We investigated the temperature dependence of the upper critical field
[] of fluorine-free SmFeAsO and fluorine-doped
SmFeAsOF single crystals by measuring the resistive transition
in low static magnetic fields and in pulsed fields up to 60 T. Both crystals
show that 's along the c axis [] and in an -planar
direction [] exhibit a linear and a sublinear increase,
respectively, with decreasing temperature below the superconducting transition.
's in both directions deviate from the conventional one-gap
Werthamer-Helfand-Hohenberg theoretical prediction at low temperatures. A
two-gap nature and the paramagnetic pair-breaking effect are shown to be
responsible for the temperature-dependent behavior of and
, respectively.Comment: 21 pages, 8 figure
Neutron skin of Al with Skyrme and Korea-IBS-Daegu-SKKU density functionals
Recent measurement of the parity-violating (PV) asymmetry in the elastic
electron scattering on Al target evokes the interest in the distribution
of the neutron in the nucleus. In this work, we calculate the neutron skin
thickness () of Al with nonrelativistic nuclear structure
models. We focus on the role of the effective mass, symmetry energy and pairing
force. Models are selected to have effective masses in the range
where is the nucleon mass in free space, and stiffness of the symmetry
energy is varied by choosing the slope of the symmetry energy in the range 9.4
-- 100.5 MeV. Effect of pairing force is investigated by calculating
with and without pairing, and using two different forms of the pairing force.
With nine models, we obtain fm. The result is
independent of the effective mass, symmetry energy, and the form of pairing
force. However, is negative when the pairing force is switched off, so
the pairing force plays an essential role to make positive and
constrained in a narrow range. We also calculate the PV asymmetry () in the elastic electron-Al scattering in the Born approximation at
the kinematics of the Qweak experiment. We obtain a very narrow-ranged result
(2.07 -- 2.09) . The result is consistent with
the experiment and insensitive to the effective mass, symmetry energy and
pairing force.Comment: 5 pages, 2 figure
Spectrum of Eleven-dimensional Supergravity on a PP-wave Background
We calculate the spectrum of the linearized supergravity around the maximally
supersymmetric pp-wave background in eleven dimensions. The resulting spectrum
agrees with that of zero-mode Hamiltonian of a supermembrane theory on the
pp-wave background. We also discuss the connection with the Kaluza-Klein zero
modes of AdS_4 x S^7 background.Comment: 17 pages, no figures, LaTeX2e, typos correcte
N=(4,4) Type IIA String Theory on PP-Wave Background
We construct IIA GS superstring action on the ten-dimensional pp-wave
background, which arises as the compactification of eleven-dimensional pp-wave
geometry along the isometry direction. The background geometry has 24 Killing
spinors and among them, 16 components correspond to the non-linearly realized
kinematical supersymmetry in the string action. The remaining eight components
are linearly realized and shown to be independent of x^+ coordinate, which is
identified with the world-sheet time coordinate of the string action in the
light-cone gauge. The resultant dynamical N=(4,4) supersymmetry is
investigated, which is shown to be consistent with the field contents of the
action containing two free massive supermultiplets.Comment: latex, 15 pages; v2: typos corrected, polished, references adde
- …