144,561 research outputs found
The nonperturbative closed string tachyon vacuum to high level
We compute the action of closed bosonic string field theory at quartic order
with fields up to level ten. After level four, the value of the potential at
the minimum starts oscillating around a nonzero negative value, in contrast
with the proposition made in [5]. We try a different truncation scheme in which
the value of the potential converges faster with the level. By extrapolating
these values, we are able to give a rather precise value for the depth of the
potential.Comment: 24 pages. v2: typos corrected, clarified extrapolation in scheme B,
and added extrapolated tachyon and dilaton vev's at the end of Section
Emergent Geometry and Quantum Gravity
We explain how quantum gravity can be defined by quantizing spacetime itself.
A pinpoint is that the gravitational constant G = L_P^2 whose physical
dimension is of (length)^2 in natural unit introduces a symplectic structure of
spacetime which causes a noncommutative spacetime at the Planck scale L_P. The
symplectic structure of spacetime M leads to an isomorphism between symplectic
geometry (M, \omega) and Riemannian geometry (M, g) where the deformations of
symplectic structure \omega in terms of electromagnetic fields F=dA are
transformed into those of Riemannian metric g. This approach for quantum
gravity allows a background independent formulation where spacetime as well as
matter fields is equally emergent from a universal vacuum of quantum gravity
which is thus dubbed as the quantum equivalence principle.Comment: Invited Review for Mod. Phys. Lett. A, 17 page
Identities in the Superintegrable Chiral Potts Model
We present proofs for a number of identities that are needed to study the
superintegrable chiral Potts model in the sector.Comment: LaTeX 2E document, using iopart.cls with iopams packages. 11 pages,
uses eufb10 and eurm10 fonts. Typeset twice! vs2: Two equations added. vs3:
Introduction adde
A Faddeev Calculation for Pentaquark in Diquark Picture with Nambu-Jona-Lasinio Type Interaction
A Bethe-Salpeter-Faddeev (BSF) calculation is performed for the pentaquark
in the diquark picture of Jaffe and Wilczek in which is a
diquark-diquark- three-body system.
Nambu-Jona-Lasinio (NJL) model is used to calculate the lowest order diagrams
in the two-body scatterings of and . With the use of coupling
constants determined from the meson sector, we find that
interaction is attractive while interaction is repulsive, and there is no
bound pentaquark state. A bound pentaquark can only be
obtained with unphysically strong vector mesonic coupling constants.Comment: 4 pages, 4 figure
A nonlinear indentity for the scattering phase of integrable models
A nonlinear identity for the scattering phase of quantum integrable models is
proved.Comment: 5 pages, Latex, no figure
Q-Dependent Susceptibilities in Ferromagnetic Quasiperiodic Z-Invariant Ising Models
We study the q-dependent susceptibility chi(q) of a series of quasiperiodic
Ising models on the square lattice. Several different kinds of aperiodic
sequences of couplings are studied, including the Fibonacci and silver-mean
sequences. Some identities and theorems are generalized and simpler derivations
are presented. We find that the q-dependent susceptibilities are periodic, with
the commensurate peaks of chi(q) located at the same positions as for the
regular Ising models. Hence, incommensurate everywhere-dense peaks can only
occur in cases with mixed ferromagnetic-antiferromagnetic interactions or if
the underlying lattice is aperiodic. For mixed-interaction models the positions
of the peaks depend strongly on the aperiodic sequence chosen.Comment: LaTeX2e, 26 pages, 9 figures (27 eps files). v2: Misprints correcte
Dynamics of moving bubbles in single and binary component systems
Dynamics of a single bubble moving in a quiescent liquid is analyzed for single and binary component systems. The transport of energy and/or mass at thermodynamic-phase equilibrium governs the dynamics of the bubble at its interface
Origin of the different conductive behavior in pentavalent-ion-doped anatase and rutile TiO
The electronic properties of pentavalent-ion (Nb, Ta, and
I) doped anatase and rutile TiO are studied using spin-polarized
GGA+\emph{U} calculations. Our calculated results indicate that these two
phases of TiO exhibit different conductive behavior upon doping. For doped
anatase TiO, some up-spin-polarized Ti 3\emph{d} states lie near the
conduction band bottom and cross the Fermi level, showing an \emph{n}-type
half-metallic character. For doped rutile TiO, the Fermi level is pinned
between two up-spin-polarized Ti 3\emph{d} gap states, showing an insulating
character. These results can account well for the experimental different
electronic transport properties in Nb (Ta)-doped anatase and rutile TiO.Comment: 4 pages, 5 figure
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