2,418 research outputs found
Photoinduced coherent oscillations in the one-dimensional two-orbital Hubbard model
We study photoinduced ultrafast coherent oscillations originating from
orbital degrees of freedom in the one-dimensional two-orbital Hubbard model. By
solving the time-dependent Schr\"odinger equation for the numerically exact
many-electron wave function, we obtain time-dependent optical response
functions. The calculated spectra show characteristic coherent oscillations
that vary with the frequency of probe light. A simple analysis for the dominant
oscillating components clarifies that these photoinduced oscillations are
caused by the quantum interference between photogenerated states. The
oscillation attributed to the Raman-active orbital excitations (orbitons)
clearly appears around the charge-transfer peak.Comment: 5 pages, 5 figure
Systematics of Gamow-Teller strengths in mid-fp-shell nuclei
We show that the presently available data on the Gamow-Teller (GT) strength
in mid-fp-shell nuclei are proportional to the product of the numbers of
valence protons and neutron holes in the full fp-shell. This observation leads
to important insights into the mechanism for GT quenching and to a simple
parametrization of the Gamow-Teller strengths important for electron capture by
fp-shell nuclei in the early stage of supernovae.Comment: 9 pages + 1 figure, Caltech preprint MAP-16
Thomas-Ehrman shifts in nuclei around ^{16}O and role of residual nuclear interaction
The asymmetry in the energy spectra between mirror nuclei (the Thomas-Ehrman
shifts) around O is investigated from a phenomenological viewpoint. The
recent data on proton-rich nuclei indicates that the residual nuclear
interaction is reduced for the loosely bound s-orbit by as much as 30%, which
originates in the broad radial distribution of the proton single-particle wave
function.Comment: to appear in Phys. Lett. B, with 3 eps figure
Pulsed UCN production using a Doppler shifter at J-PARC
We have constructed a Doppler-shifter-type pulsed ultra-cold neutron (UCN)
source at the Materials and Life Science Experiment Facility (MLF) of the Japan
Proton Accelerator Research Complex (J-PARC). Very-cold neutrons (VCNs) with
136- velocity in a neutron beam supplied by a pulsed neutron
source are decelerated by reflection on a m=10 wide-band multilayer mirror,
yielding pulsed UCN. The mirror is fixed to the tip of a 2,000-rpm rotating arm
moving with 68- velocity in the same direction as the VCN. The
repetition frequency of the pulsed UCN is and the time width
of the pulse at production is . In order to increase the UCN
flux, a supermirror guide, wide-band monochromatic mirrors, focus guides, and a
UCN extraction guide have been newly installed or improved. The
-equivalent count rate of the output neutrons with longitudinal
wavelengths longer than is ,
while that of the true UCNs is . The spatial density at
production is . This new UCN source enables us to
research and develop apparatuses necessary for the investigation of the neutron
electric dipole moment (nEDM).Comment: 32 pages, 15 fugures. A grammatical error was fixe
Sub-Gaussian short time asymptotics for measure metric Dirichlet spaces
This paper presents estimates for the distribution of the exit time from
balls and short time asymptotics for measure metric Dirichlet spaces. The
estimates cover the classical Gaussian case, the sub-diffusive case which can
be observed on particular fractals and further less regular cases as well. The
proof is based on a new chaining argument and it is free of volume growth
assumptions
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