150,008 research outputs found
Critical Dimension for Stable Self-gravitating Stars in AdS
We study the self-gravitating stars with a linear equation of state, , in AdS space, where is a constant parameter. There exists a critical
dimension, beyond which the stars are always stable with any central energy
density; below which there exists a maximal mass configuration for a certain
central energy density and when the central energy density continues to
increase, the configuration becomes unstable. We find that the critical
dimension depends on the parameter , it runs from to 10.1291 as
varies from to 1. The lowest integer dimension for a dynamically
stable self-gravitating configuration should be for any
rather than , the latter is the case of self-gravitating radiation
configurations in AdS space.Comment: Revtex, 11 pages with 7 eps figure
Yukawa Corrections from Four-Point Functions in Intersecting D6-Brane Models
We discuss corrections to the Yukawa matrices of the Standard Model (SM)
fermions in intersecting D-brane models due to four-point interactions.
Recently, an intersecting D-brane model has been found where it is possible to
obtain correct masses and mixings for all quarks as well as the tau lepton.
However, the masses for the first two charged leptons come close to the right
values but are not quite correct. Since the electron and muon are quite light,
it is likely that there are additional corrections to their masses which cannot
be neglected. With this in mind, we consider contributions to the SM fermion
mass matrices from four-point interactions. In an explicit model, we show that
it is indeed possible to obtain the SM fermion masses and mixings which are a
better match to those resulting from experimental data extrapolated at the
unification scale when these corrections are included. These corrections may
have broader application to other models.Comment: 24 pages, 4 figure
On quantum vertex algebras and their modules
We give a survey on the developments in a certain theory of quantum vertex
algebras, including a conceptual construction of quantum vertex algebras and
their modules and a connection of double Yangians and Zamolodchikov-Faddeev
algebras with quantum vertex algebras.Comment: 18 pages; contribution to the proceedings of the conference in honor
of Professor Geoffrey Maso
Effects of hadronic loops on the direct CP violation of
It is well known that the final state interaction plays an important role in
the decays of -meson. The contribution of the final state interaction which
is supposed to be long-distance effects, to the concerned processes can
interfere with that of the short-distance effects produced via the tree and/or
loop diagrams at quark-gluon level. The interference may provide a source for
the direct CP violation in the process . We find that a typical value of when the
final state interaction effect is taken into account can be about -22% which is
different from that without the final state interaction effect. Therefore, when
we extract information on CP violation from the data which will be available at
LHCb and the new experiments in -factories, the contribution from the final
state interaction must be included. This study may be crucial for searching new
physics in the future.Comment: 15 pages, 3 figures, 2 tables. More discussion adde
Superfluid density and competing orders in d-wave superconductors
We derive expressions for the superfluid density in the
low-temperature limit in d-wave superconductors, taking into account
the presence of competing orders such as spin-density waves, -pairing, etc. Recent experimental data for the thermal conductivity and
for elastic neutron scattering in LaSrCuO suggest there are
magnetic field induced anomalies that can be interpreted in terms of competing
orders. We consider the implications of these results for the superfluid
density and show in the case of competing spin-density wave order that the
usual Volovik-like depletion of is replaced by a slower
dependence on applied magnetic field. We find that it is crucial to include the
competing order parameter in the self-consistent equation for the impurity
scattering rate.Comment: 17 pages, RevTeX4, 6 EPS figures; final version published in PR
Quantum Decoherence in a D-Foam Background
Within the general framework of Liouville string theory, we construct a model
for quantum D-brane fluctuations in the space-time background through which
light closed-string states propagate. The model is based on monopole and vortex
defects on the world sheet, which have been discussed previously in a treatment
of 1+1-dimensional black-hole fluctuations in the space-time background, and
makes use of a T-duality transformation to relate formulations with Neumann and
Dirichlet boundary conditions. In accordance with previous general arguments,
we derive an open quantum-mechanical description of this D-brane foam which
embodies momentum and energy conservation and small mean energy fluctuations.
Quantum decoherence effects appear at a rate consistent with previous
estimates.Comment: 16 pages, Latex, two eps figures include
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