2,486 research outputs found
Gauge coupling Unification and SO(10) in 5D
We analyze the gauge unification in minimal supersymmetric SO(10) grand
unified theories in 5 dimensions. The single extra spatial dimension is
compactified on the orbifold S^1/(Z_2 x Z_2') reducing the gauge group to that
of Pati-Salam SU(4)_c x SU(2)_L x SU(2)_R. The Standard Model gauge group is
achieved by the further brane-localized Higgs mechanism on one of the fixed
points. There are two main different approaches developed in literature. Higgs
mechanism can take place on the Pati Salam brane, or on the SO(10) preserving
brane. We show, both analytically and numerically, that in the first case a
natural and succesfull gauge coupling unification can be achieved, while the
second case is highly disfavoured. For completeness, we consider either the
case in which the brane breaking scale is near the cutoff scale or the case in
which it is lower than the compactification scale.Comment: 18 Pages and 8 PostScript Figure
Fermion masses and proton decay in a minimal five-dimensional SO(10) model
We propose a minimal SO(10) model in 5 space-time dimensions. The single
extra spatial dimension is compactified on the orbifold S^1/(Z_2 x Z_2')
reducing the gauge group to that of Pati-Salam. The breaking down to the
standard model group is obtained through an ordinary Higgs mechanism taking
place at the Pati-Salam brane, giving rise to a proper gauge coupling
unification. We achieve a correct description of fermion masses and mixing
angles by describing first and second generations as bulk fields, and by
embedding the third generation into four multiplets located at the Pati-Salam
brane. The Yukawa sector is simple and compact and predicts a neutrino spectrum
of normal hierarchy type. Concerning proton decay, dimension five operators are
absent and the essentially unique localization of matter multiplets implies
that the minimal couplings between the super-heavy gauge bosons and matter
fields are vanishing. Non-minimal interactions are allowed but the resulting
dimension six operators describing proton decay are too suppressed to produce
observable effects, even in future, super-massive detectors.Comment: 21 pages, 3 figure
Recreation Demand of Consumer with Experiential Marketing in Festival
AbstractExperiential marketing that allows visitors to fully participate and appreciate festival activities con be coupled with strategies of market segmentation, which is of great benefit to industrial and cultural activities. In this study, we used factor analysis method to understand the perception factor of visitors participate the Sweet Taiwan Year Festival in Tainan country of Taiwan. And segmented festival market by cluster analysis based on delineated experiential perception factors. The empirical result of this study shows that experiential perception clusters and the visitor type have become the most important factors in influencing the experiential value, the relation quality and the relation outcome
Seasonal variation in sonic muscles in the fawn cusk-eel <i>Lepophidium profundorum</i>
The fawn cusk-eel Lepophidium profundorum (Ophidiidae) has an unusual sound-producing system with sexually dimorphic sets of antagonistic muscles. Outside the mating season, the dorsal and ventral muscles are well developed and larger in males than in females, but the tiny intermediate muscles are smaller, suggesting a minor role, if any, in male advertisement call production. We examined summer individuals with more developed gonads and find a fourfold hypertrophy of the intermediate but not the other muscles. This result suggests androgen dependence and an important role in sound production for the intermediate muscle. Even though both sexes gain weight in the summer, the ventral and dorsal muscles in females lose weight, suggesting that sound production is less important in females and that muscle mass may be used to support egg growth
Optimal Sizes of Dielectric Microspheres for Cavity QED with Strong Coupling
The whispering gallery modes (WGMs) of quartz microspheres are investigated
for the purpose of strong coupling between single photons and atoms in cavity
quantum electrodynamics (cavity QED). Within our current understanding of the
loss mechanisms of the WGMs, the saturation photon number, n, and critical atom
number, N, cannot be minimized simultaneously, so that an "optimal" sphere size
is taken to be the radius for which the geometric mean, (n x N)^(1/2), is
minimized. While a general treatment is given for the dimensionless parameters
used to characterize the atom-cavity system, detailed consideration is given to
the D2 transition in atomic Cesium (852nm) using fused-silica microspheres, for
which the maximum coupling coefficient g/(2*pi)=750MHz occurs for a sphere
radius a=3.63microns corresponding to the minimum for n=6.06x10^(-6). By
contrast, the minimum for N=9.00x10^(-6) occurs for a sphere radius of
a=8.12microns, while the optimal sphere size for which (n x N)^(1/2) is
minimized occurs at a=7.83microns. On an experimental front, we have fabricated
fused-silica microspheres with radii a=10microns and consistently observed
quality factors Q=0.8x10^(7). These results for the WGMs are compared with
corresponding parameters achieved in Fabry-Perot cavities to demonstrate the
significant potential of microspheres as a tool for cavity QED with strong
coupling.Comment: 12 pages, 14 figure
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
Small BGK waves and nonlinear Landau damping
Consider 1D Vlasov-poisson system with a fixed ion background and periodic
condition on the space variable. First, we show that for general homogeneous
equilibria, within any small neighborhood in the Sobolev space W^{s,p}
(p>1,s<1+(1/p)) of the steady distribution function, there exist nontrivial
travelling wave solutions (BGK waves) with arbitrary minimal period and
traveling speed. This implies that nonlinear Landau damping is not true in
W^{s,p}(s<1+(1/p)) space for any homogeneous equilibria and any spatial period.
Indeed, in W^{s,p} (s<1+(1/p)) neighborhood of any homogeneous state, the long
time dynamics is very rich, including travelling BGK waves, unstable
homogeneous states and their possible invariant manifolds. Second, it is shown
that for homogeneous equilibria satisfying Penrose's linear stability
condition, there exist no nontrivial travelling BGK waves and unstable
homogeneous states in some W^{s,p} (p>1,s>1+(1/p)) neighborhood. Furthermore,
when p=2,we prove that there exist no nontrivial invariant structures in the
H^{s} (s>(3/2)) neighborhood of stable homogeneous states. These results
suggest the long time dynamics in the W^{s,p} (s>1+(1/p)) and particularly, in
the H^{s} (s>(3/2)) neighborhoods of a stable homogeneous state might be
relatively simple. We also demonstrate that linear damping holds for initial
perturbations in very rough spaces, for linearly stable homogeneous state. This
suggests that the contrasting dynamics in W^{s,p} spaces with the critical
power s=1+(1/p) is a trully nonlinear phenomena which can not be traced back to
the linear level
The Off-diagonal Goldberger-Treiman Relation and Its Discrepancy
We study the off-diagonal Goldberger-Treiman relation (ODGTR) and its
discrepancy (ODGTD) in the N, Delta, pi sector through O(p^2) using heavy
baryon chiral perturbation theory. To this order, the ODGTD and axial vector N
to Delta transition radius are determined solely by low energy constants. Loop
corrections appear at O(p^4). For low-energy constants of natural size, the
ODGTD would represent a ~ 2% correction to the ODGTR. We discuss the
implications of the ODGTR and ODGTD for lattice and quark model calculations of
the transition form factors and for parity-violating electroexcitation of the
Delta.Comment: 11 pages, 1 eps figur
- …