4,359 research outputs found
Kakutani Dichotomy on Free States
Two quasi-free states on a CAR or CCR algebra are shown to generate
quasi-equivalent representations unless they are disjoint.Comment: 12 page
Quark-Hadron Duality and Parity Violating Asymmetry of Electroweak Reactions in the Delta Region
A dynamical model of electroweak pion production reactions in the Delta(1232)
region has been extended to include the neutral current contributions for
examining the local Quark-Hadron Duality in neutrino-induced reactions and for
investigating how the axial N-Delta form factor can be determined by the parity
violating asymmetry of N(\vec{e},e') reactions. We first show that the recent
data of (e,e') structure functions F_1 and F_2, which exhibit the Quark-Hadron
Duality, are in good agreement with our predictions. For possible future
experimental tests, we then predict that the structure functions F_1, F_2, and
F_3 for (\nu,e) and (\nu,\nu') processes also show the similar Quark-Hadron
Duality. The spin dependent structure functions g_1 and g_2 of (e,e') have also
been calculated from our model. It is found that the local Quark-Hadron Duality
is not seen in the calculated g_1 and g_2, while our results for g_1 and some
polarization observables associated with the exclusive p(\vec{e},e' pi) and
\vec{p}(\vec{e},e' pi) reactions are in reasonably good agreement with the
recent data. In the investigation of parity violating asymmetry A of
N(\vec{e},e') reactions, it is found that the non-resonant contribution is
small at the Delta peak and a measurement of A can be used to distinguish two
previously determined axial N-Delta transition form factors. The predicted
asymmetry A are also compared with the Parton Model predictions for future
experimental investigations of Quark-Hadron Duality.Comment: 28 pages, 19 figures v2; figures and references adde
Debye mass and heavy quark potential in a PNJL quark plasma
We calculate the Debye mass for the screening of the heavy quark potential in
a plasma of massless quarks coupled to the temporal gluon background governed
by the Polyakov loop potential within the PNJL model in RPA approximation. We
give a physical motivation for a recent phenomenological fit of lattice data by
applying the calculated Debye mass with its suppression in the confined phase
due to the Polyakov-loop to a description of the temperature dependence of the
singlet free energy for QCD with a heavy quark pair at infinite separation. We
compare the result to lattice data.Comment: 6 pages, 1 figure, contribution to Proceedings of the 6th
International Conference on "Critical Point and Onset of Deconfinement", to
appear in Phys. At. Nucl., vol. 7
Highly efficient planar perovskite solar cells through band alignment engineering
The simplification of perovskite solar cells (PSCs), by replacing the mesoporous electron selective layer (ESL) with a planar one, is advantageous for large-scale manufacturing. PSCs with a planar TiO2 ESL have been demonstrated, but these exhibit unstabilized power conversion efficiencies (PCEs). Herein we show that planar PSCs using TiO2 are inherently limited due to conduction band misalignment and demonstrate, with a variety of characterization techniques, for the first time that SnO2 achieves a barrier-free energetic configuration, obtaining almost hysteresis-free PCEs of over 18% with record high voltages of up to 1.19 V
Heterogeneous Diffusion in Highly Supercooled Liquids
The diffusivity of tagged particles is demonstrated to be very heterogeneous
on time scales comparable to or shorter than the relaxation time
( the stress relaxation time) in a highly supercooled
liquid via 3D molecular dynamics simulation. The particle motions in the
relatively active regions dominantly contribute to the mean square
displacement, giving rise to a diffusion constant systematically larger than
the Einstein-Stokes value. The van Hove self-correlation function is
shown to have a long distance tail which can be scaled in terms of
for t \ls 3\tau_{\alpha}. Its presence indicates heterogeneous diffusion in
the active regions. However, the diffusion process eventually becomes
homogeneous on time scales longer than the life time of the heterogeneity
structure ().Comment: 4 pages, 5 figure
One-neutron knockout reaction of 17C on a hydrogen target at 70 MeV/nucleon
First experimental evidence of the population of the first 2- state in 16C
above the neutron threshold is obtained by neutron knockout from 17C on a
hydrogen target. The invariant mass method combined with in-beam gamma-ray
detection is used to locate the state at 5.45(1) MeV. Comparison of its
populating cross section and parallel momentum distribution with a Glauber
model calculation utilizing the shell-model spectroscopic factor confirms the
core-neutron removal nature of this state. Additionally, a previously known
unbound state at 6.11 MeV and a new state at 6.28(2) MeV are observed. The
position of the first 2- state, which belongs to a member of the lowest-lying
p-sd cross shell transition, is reasonably well described by the shell-model
calculation using the WBT interaction.Comment: 15 pages, 3 figure
J/\Psi production, polarization and Color Fluctuations
The hard contributions to the heavy quarkonium-nucleon cross sections are
calculated based on the QCD factorization theorem and the nonrelativistic
quarkonium model. We evaluate the nonperturbative part of these cross sections
which dominates at GeV at the Cern Super Proton
Synchrotron (SPS) and becomes a correction at TeV at
the CERN Large Hadron Collider (LHC). \J production at the CERN SPS is well
described by hard QCD, when the larger absorption cross sections of the
states predicted by QCD are taken into account. We predict an -dependent
polarization of the states. The expansion of small wave packets is
discussed.Comment: 13 pages REVTEX, 1 table, 2 PostScript, corrected some typo
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