37,837 research outputs found
Monopole Excitation to Cluster States
We discuss strength of monopole excitation of the ground state to cluster
states in light nuclei. We clarify that the monopole excitation to cluster
states is in general strong as to be comparable with the single particle
strength and shares an appreciable portion of the sum rule value in spite of
large difference of the structure between the cluster state and the
shell-model-like ground state. We argue that the essential reasons of the large
strength are twofold. One is the fact that the clustering degree of freedom is
possessed even by simple shell model wave functions. The detailed feature of
this fact is described by the so-called Bayman-Bohr theorem which tells us that
SU(3) shell model wave function is equivalent to cluster model wave function.
The other is the ground state correlation induced by the activation of the
cluster degrees of freedom described by the Bayman-Bohr theorem. We
demonstrate, by deriving analytical expressions of monopole matrix elements,
that the order of magnitude of the monopole strength is governed by the first
reason, while the second reason plays a sufficient role in reproducing the data
up to the factor of magnitude of the monopole strength. Our explanation is made
by analysing three examples which are the monopole excitations to the
and states in O and the one to the state in C.
The present results imply that the measurement of strong monopole transitions
or excitations is in general very useful for the study of cluster states.Comment: 11 pages, 1 figure: revised versio
Operator ordering and Classical soliton path in Two-dimensional N=2 supersymmetry with Kahler potential
We investigate a 2-dimensional N=2 supersymmetric model which consists of n
chiral superfields with Kahler potential. When we define quantum observables,
we are always plagued by operator ordering problem. Among various ways to fix
the operator order, we rely upon the supersymmetry. We demonstrate that the
correct operator order is given by requiring the super Poincare algebra by
carrying out the canonical Dirac bracket quantization. This is shown to be also
true when the supersymmetry algebra has a central extension by the presence of
topological soliton. It is also shown that the path of soliton is a straight
line in the complex plane of superpotential W and triangular mass inequality
holds. And a half of supersymmetry is broken by the presence of soliton.Comment: 13 pages, typos correcte
Inflation in Random Landscapes with two energy scales
We investigate inflation in a multi-dimensional landscape with a hierarchy of
energy scales, motivated by the string theory, where the energy scale of Kahler
moduli is usually assumed to be much lower than that of complex structure
moduli and dilaton field. We argue that in such a landscape, the dynamics of
slow-roll inflation is governed by the low-energy potential, while the initial
condition for inflation are determined by tunneling through high-energy
barriers. We then use the scale factor cutoff measure to calculate the
probability distribution for the number of inflationary e-folds and the
amplitude of density fluctuations , assuming that the low-energy landscape
is described by a random Gaussian potential with a correlation length much
smaller than . We find that the distribution for has a unique
shape and a preferred domain, which depends on the parameters of the low-energy
landscape. We discuss some observational implications of this distribution and
the constraints it imposes on the landscape parameters.Comment: 39 pages, 3 figures; (v2) minor change
Pump- and Probe-polarization Analyses of Ultrafast Carrier Dynamics in Organic Superconductors
We investigated photo-excited carrier relaxation dynamics in the strongly correlated organic superconductors kappa-(BEDT-TTF)(2)Cu(NCS)(2) and kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Br, using different polarizations of pump and probe pulses. Below the glasslike transition temperature (T (g)) anisotropic responses for probe polarization were observed in both compounds. Decomposing the data into anisotropic and isotropic components, we found the anisotropic component shows no pump polarization dependence, meaning that dissipative excitation process was dominant for the anisotropic carrier relaxation. This behavior indicates that the appearance of anisotropic responses can be associated with spatial symmetry breaking due to structural change of BEDT-TTF molecules
Localization Properties of Electronic States in Polaron Model of poly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers
We numerically investigate localization properties of electronic states in a
static model of poly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers with
realistic parameters obtained by quantum-chemical calculation. The randomness
in the on-site energies caused by the electron-phonon coupling are completely
correlated to the off-diagonal parts. In the single electron model, the effect
of the hydrogen-bond stretchings, the twist angles between the base pairs and
the finite system size effects on the energy dependence of the localization
length and on the Lyapunov exponent are given. The localization length is
reduced by the influence of the fluctuations in the hydrogen bond stretchings.
It is also shown that the helical twist angle affects the localization length
in the poly(dG)-poly(dC) DNA polymer more strongly than in the
poly(dA)-poly(dT) one. Furthermore, we show resonance structures in the energy
dependence of the localization length when the system size is relatively small.Comment: 6 pages, 6 figure
Metastability of R-Charged Black Holes
The global stability of R-charged AdS black holes in a grand canonical
ensemble is examined by eliminating the constraints from the action, but
without solving the equations of motion, thereby constructing the reduced
action of the system. The metastability of the system is found to set in at a
critical value of the chemical potential which is conjugate to the R-charge.
The relation among the small black hole, large black hole and the instability
is discussed. The result is consistent with the metastability found in the
AdS/CFT-conjectured dual field theory. The "renormalized" temperature of AdS
black holes, which has been rather ad hoc, is suggested to be the boundary
temperature in the sense of AdS/CFT correspondence. As a byproduct of the
analysis, we find a more general solution of the theory and its properties are
briefly discussed.Comment: 36 pages, 7 figures, v2 is the published version. the exposition is
made slightly shorter and hopefully cleare
Hydrodynamical effects in internal shock of relativistic outflows
We study both analytically and numerically hydrodynamical effects of two
colliding shells, the simplified models of the internal shock in various
relativistic outflows such as gamma-ray bursts and blazars. We pay particular
attention to three interesting cases: a pair of shells with the same rest mass
density (``{\it equal rest mass density}''), a pair of shells with the same
rest mass (``{\it equal mass}''), and a pair of shells with the same bulk
kinetic energy (``{\it equal energy}'') measured in the intersteller medium
(ISM) frame. We find that the density profiles are significantly affected by
the propagation of rarefaction waves. A split-feature appears at the contact
discontinuity of two shells for the ``equal mass'' case, while no significant
split appears for the ``equal energy'' and ``equal rest mass density'' cases.
The shell spreading with a few ten percent of the speed of light is also shown
as a notable aspect caused by rarefaction waves. The conversion efficiency of
the bulk kinetic energy to internal one is numerically evaluated. The time
evolutions of the efficiency show deviations from the widely-used inellastic
two-point-mass-collision model.Comment: 29 pages, 16 figures, accepted by Ap
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