1,515 research outputs found
Affleck-Dine baryogenesis in inflating curvaton scenario with O(TeV) mass moduli curvaton
We study the Affleck-Dine (AD) baryogenesis in the inflating curvaton
scenario, when the curvaton is a moduli field with O(TeV) mass. A
moduli field with such mass is known to be free from the Polonyi problem, and
furthermore its decay products can explain the present cold dark matter
abundance. In our scenario, it further explains the primordial curvature
perturbation and the present baryon density all together. The current
observational bound on the baryon isocurvature perturbation, which severely
constrains the AD baryogenesis with the original oscillating moduli curvaton
scenario, is shown to put practically negligible constraint if we replace the
oscillating curvaton with the inflating curvaton.Comment: 1+21pages v2: minor correction v3: included short reviews, added
refs, fixed typo
STM characterization of the Si-P heterodimer
We use scanning tunneling microscopy (STM) and Auger electron spectroscopy to
study the behavior of adsorbed phosphine (PH) on Si(001), as a function
of annealing temperature, paying particular attention to the formation of the
Si-P heterodimer. Dosing the Si(001) surface with 0.002 Langmuirs of
PH results in the adsorption of PH (x=2,3) onto the surface and
some etching of Si to form individual Si ad-dimers. Annealing to 350C
results in the incorporation of P into the surface layer to form Si-P
heterodimers and the formation of short 1-dimensional Si dimer chains and
monohydrides. In filled state STM images, isolated Si-P heterodimers appear as
zig-zag features on the surface due to the static dimer buckling induced by the
heterodimer. In the presence of a moderate coverage of monohydrides this static
buckling is lifted, rending the Si-P heterodimers invisible in filled state
images. However, we find that we can image the heterodimer at all H coverages
using empty state imaging. The ability to identify single P atoms incorporated
into Si(001) will be invaluable in the development of nanoscale electronic
devices based on controlled atomic-scale doping of Si.Comment: 6 pages, 4 figures (only 72dpi
AdS(3) Solutions of IIB Supergravity from D3-branes
We consider pure D3-brane configurations of IIB string theory which lead to
supersymmetric solutions containing an AdS factor. They can provide new
examples of AdS/CFT examples on D3-branes whose worldvolume is
partially compactified. When the internal 7 dimensional space is non-compact,
they can be identified as supersymmetric fluctuations of higher dimensional AdS
solutions and are in general dual to 1/8-BPS operators thereof. We find that
supersymmetry requires the 7 dimensional space take the form of a warped U(1)
fibration over a 6 dimensional Kahler manifold.Comment: 10 pages, no figure, JHEP3.cls; v3: corrected errors in the published
versio
3N Scattering in a Three-Dimensional Operator Formulation
A recently developed formulation for a direct treatment of the equations for
two- and three-nucleon bound states as set of coupled equations of scalar
functions depending only on vector momenta is extended to three-nucleon
scattering. Starting from the spin-momentum dependence occurring as scalar
products in two- and three-nucleon forces together with other scalar functions,
we present the Faddeev multiple scattering series in which order by order the
spin-degrees can be treated analytically leading to 3D integrations over scalar
functions depending on momentum vectors only. Such formulation is especially
important in view of awaiting extension of 3N Faddeev calculations to
projectile energies above the pion production threshold and applications of
chiral perturbation theory 3N forces, which are to be most efficiently treated
directly in such three-dimensional formulation without having to expand these
forces into a partial wave basis.Comment: 25 pages, 0 figure
Neutron matter at zero temperature with auxiliary field diffusion Monte Carlo
The recently developed auxiliary field diffusion Monte Carlo method is
applied to compute the equation of state and the compressibility of neutron
matter. By combining diffusion Monte Carlo for the spatial degrees of freedom
and auxiliary field Monte Carlo to separate the spin-isospin operators, quantum
Monte Carlo can be used to simulate the ground state of many nucleon systems
(A\alt 100). We use a path constraint to control the fermion sign problem. We
have made simulations for realistic interactions, which include tensor and
spin--orbit two--body potentials as well as three-nucleon forces. The Argonne
and two nucleon potentials plus the Urbana or Illinois
three-nucleon potentials have been used in our calculations. We compare with
fermion hypernetted chain results. We report results of a Periodic Box--FHNC
calculation, which is also used to estimate the finite size corrections to our
quantum Monte Carlo simulations. Our AFDMC results for models of pure
neutron matter are in reasonably good agreement with equivalent Correlated
Basis Function (CBF) calculations, providing energies per particle which are
slightly lower than the CBF ones. However, the inclusion of the spin--orbit
force leads to quite different results particularly at relatively high
densities. The resulting equation of state from AFDMC calculations is harder
than the one from previous Fermi hypernetted chain studies commonly used to
determine the neutron star structure.Comment: 15 pages, 15 tables and 5 figure
Some general properties of the renormalized stress-energy tensor for static quantum states on (n+1)-dimensional spherically symmetric black holes
We study the renormalized stress-energy tensor (RSET) for static quantum
states on (n+1)-dimensional, static, spherically symmetric black holes. By
solving the conservation equations, we are able to write the stress-energy
tensor in terms of a single unknown function of the radial co-ordinate, plus
two arbitrary constants. Conditions for the stress-energy tensor to be regular
at event horizons (including the extremal and ``ultra-extremal'' cases) are
then derived using generalized Kruskal-like co-ordinates. These results should
be useful for future calculations of the RSET for static quantum states on
spherically symmetric black hole geometries in any number of space-time
dimensions.Comment: 9 pages, no figures, RevTeX4, references added, accepted for
publication in General Relativity and Gravitatio
Casimir Effect of Graviton and the Entropy Bound
In this note we calculate the Casimir effect of free thermal gravitons in
Einstein universe and discuss how it changes the entropy bound condition
proposed recently by Verlinde [hep-th/0008140] as a higher dimensional
generalization of Cardy's formula for conformal field theories (CFT). We find
that the graviton's Casimir effect is necessary in order not to violate
Verlinde's bound for weakly coupled CFT. We also comment on the implication of
this new Cardy's formula to the thermodynamics of black -brane.Comment: 10 pages; v2. a typo correcte
Charged particle densities from Au+Au collisions at sqrt{s_{NN}}=130 GeV
We present charged particle densities as a function of pseudorapidity and
collision centrality for the 197Au+197Au reaction at sqrt{s_{NN}}=130 GeV. An
integral charged particle multiplicity of 3860+/-300 is found for the 5% most
central events within the pseudorapidity range -4.7 <= eta <= 4.7. At
mid-rapidity an enhancement in the particle yields per participant nucleon pair
is observed for central events. Near to the beam rapidity, a scaling of the
particle yields consistent with the ``limiting fragmentation'' picture is
observed. Our results are compared to other recent experimental and theoretical
discussions of charged particle densities in ultra-relativistic heavy-ion
collisions.Comment: 14 pages, 4 figures; to be published in Phys. Lett.
Holographic Uniformization
We derive and study supergravity BPS flow equations for M5 or D3 branes
wrapping a Riemann surface. They take the form of novel geometric flows
intrinsically defined on the surface. Their dual field-theoretic interpretation
suggests the existence of solutions interpolating between an arbitrary metric
in the UV and the constant-curvature metric in the IR. We confirm this
conjecture with a rigorous global existence proof.Comment: 52 pages, 3 figure
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