3,180 research outputs found
Scalar Nonets in Pole-Dominated QCD Sum Rules
The light scalar nonets are studied using the QCD sum rules for the
tetraquark operators. The operator product expansion for the correlators is
calculated up to dimension 12 and this enables us to perform analyses retaining
sufficient pole-dominance. To classify the light scalar nonets, we investigate
the dependence on current quark mass and flavor dynamics. Especially, to
examine the latter, we study separately SU(3) singlet and octet states, and
show that the number of annihilation diagrams is largely responsible for their
differences, which is also the case even after the inclusion of the finite
quark mass. Our results support the tetraquark picture for isosinglets, while
that for octets is not conclusive yet.Comment: 4 pages, 3 figure, Talk given at Chiral Symmetry in Hadron and
Nuclear Physics (Chiral07), November 13-16, 2007, Osaka Univ., Japa
Orbital Optimization in the Active Space Decomposition Model
We report the derivation and implementation of orbital optimization
algorithms for the active space decomposition (ASD) model, which are extensions
of complete active space self-consistent field (CASSCF) and its
occupation-restricted variants in the conventional multiconfiguration
electronic-structure theory. Orbital rotations between active subspaces are
included in the optimization, which allows us to unambiguously partition the
active space into subspaces, enabling application of ASD to electron and
exciton dynamics in covalently linked chromophores. One- and two-particle
reduced density matrices, which are required for evaluation of orbital gradient
and approximate Hessian elements, are computed from the intermediate tensors in
the ASD energy evaluation. Numerical results on
4-(2-naphthylmethyl)-benzaldehyde and [3]cyclophane and model Hamiltonian
analyses of triplet energy transfer processes in the Closs systems are
presented. Furthermore model Hamiltonians for hole and electron transfer
processes in anti-[2.2](1,4)pentacenophane are studied using an
occupation-restricted variant
Gap Condition and Self-Dualized Super Yang-Mills Theory for ADE Gauge Group on K3
We try to determine the partition function of super Yang-Mills
theoy for ADE gauge group on K3 by self-dualizing our previous ADE partition
function. The resulting partition function satisfies gap condition.Comment: 17 page
Properties of Scalar-Quark Systems in SU(3)c Lattice QCD
We perform the first study for the bound states of colored scalar particles
("scalar quarks") in terms of mass generation with quenched SU(3)
lattice QCD. We investigate the bound states of , and
("scalar-quark hadrons"), as well as the bound states of
and quarks , i.e., , and
("chimera hadrons"). All these new-type hadrons including have a large
mass of several GeV due to large quantum corrections by gluons, even for zero
bare scalar-quark mass at . We find a similar
-dependence between and , which
indicates their similar structure due to the large mass of . From this
study, we conjecture that all colored particles generally acquire a large
effective mass due to dressed gluons
Accurate retrieval of structural information from laser-induced photoelectron and high-harmonic spectra by few-cycle laser pulses
By analyzing ``exact'' theoretical results from solving the time-dependent
Schr\"odinger equation of atoms in few-cycle laser pulses, we established the
general conclusion that differential elastic scattering and photo-recombination
cross sections of the target ion with {\em free} electrons can be extracted
accurately from laser-generated high-energy electron momentum spectra and
high-order harmonic spectra, respectively. Since both electron scattering and
photoionization (the inverse of photo-recombination) are the conventional means
for interrogating the structure of atoms and molecules, this result shows that
existing few-cycle infrared lasers can be implemented for ultrafast imaging of
transient molecules with temporal resolution of a few femtoseconds.Comment: 4 pages, 4 figure
Hadron-hadron interaction from SU(2) lattice QCD
We evaluate interhadron interactions in two-color lattice QCD from
Bethe-Salpeter amplitudes on the Euclidean lattice. The simulations are
performed in quenched SU(2) QCD with the plaquette gauge action at and the Wilson quark action. We concentrate on S-wave scattering states
of two scalar diquarks. Evaluating different flavor combinations with various
quark masses, we try to find out the ingredients in hadronic interactions.
Between two scalar diquarks (, the lightest baryon in SU(2)
system), we observe repulsion in short-range region, even though present quark
masses are not very light. We define and evaluate the "quark-exchange part" in
the interaction, which is induced by adding quark-exchange diagrams, or
equivalently, by introducing Pauli blocking among some of quarks. The repulsive
force in short-distance region arises only from the "quark-exchange part", and
disappears when quark-exchange diagrams are omitted. We find that the strength
of repulsion grows in light quark-mass regime and its quark-mass dependence is
similar to or slightly stronger than that of the color-magnetic interaction by
one-gluon-exchange (OGE) processes. It is qualitatively consistent with the
constituent-quark model picture that a color-magnetic interaction among quarks
is the origin of repulsion. We also find a universal long-range attractive
force, which enters in any flavor channels of two scalar diquarks and whose
interaction range and strength are quark-mass independent. The weak quark-mass
dependence of interaction ranges in each component implies that meson-exchange
contributions are small and subdominant, and the other contributions, {\it ex.}
flavor exchange processes, color-Coulomb or color-magnetic interactions, are
considered to be predominant, in the quark-mass range we evaluated.Comment: 14 pages, 20 figure
Low-lying Dirac eigenmodes and monopoles in 3+1D compact QED
We study the properties of low-lying Dirac modes in quenched compact QED at
, employing () lattices and the
overlap formalism for the fermion action. We pay attention to the spatial
distributions of low-lying Dirac modes below and above the ``phase transition
temperature'' . Near-zero modes are found to have universal
anti-correlations with monopole currents, and are found to lose their temporal
structures above exhibiting stronger spatial localization properties. We
also study the nearest-neighbor level spacing distribution of Dirac eigenvalues
and find a Wigner-Poisson transition.Comment: 10 pages, 10 figures, 1 tabl
Bose-Fermi Pair Correlations in Attractively Interacting Bose-Fermi Atomic Mixtures
We study static properties of attractively interacting Bose-Fermi mixtures of
uniform atomic gases at zero temperature. Using Green's function formalism we
calculate boson-fermion scattering amplitude and fermion self-energy in the
medium to lowest order of the hole line expansion. We study ground state energy
and pressure as functions of the scattering length for a few values of the
boson-fermion mass ratio and the number ratio . We find that
the attractive contribution to energy is greatly enhanced for small values of
the mass ratio. We study the role of the Bose-Fermi pair correlations in the
mixture by calculating the pole of the boson-fermion scattering amplitude in
the medium. The pole shows a standard quasiparticle dispersion for a Bose-Fermi
pair, for . For small values of the mass ratio, on the other
hand, a Bose-Fermi pair with a finite center-of-mass momentum experiences a
strong attraction, implying large medium effects. In addition, we also study
the fermion dispersion relation. We find two dispersion branches with the
possibility of the avoided crossings. This strongly depends on the number rario
.Comment: 14 pages, 27 figure
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