8,546 research outputs found
The Chern-Simons Coefficient in Supersymmetric Non-abelian Chern-Simons Higgs Theories
By taking into account the effect of the would be Chern-Simons term, we
calculate the quantum correction to the Chern-Simons coefficient in
supersymmetric Chern-Simons Higgs theories with matter fields in the
fundamental representation of SU(n). Because of supersymmetry, the corrections
in the symmetric and Higgs phases are identical. In particular, the correction
is vanishing for N=3 supersymmetric Chern-Simons Higgs theories. The result
should be quite general, and have important implication for the more
interesting case when the Higgs is in the adjoint representation.Comment: more references and explanation about rgularization dpendence are
included, 13 pages, 1 figure, latex with revte
Kaluza-Klein Induced Gravity Inflation
A D-dimensional induced gravity theory is studied carefully in a
dimensional Friedmann-Robertson-Walker space-time. We try to extract
information of the symmetry breaking potential in search of an inflationary
solution with non-expanding internal-space. We find that the induced gravity
model imposes strong constraints on the form of symmetry breaking potential in
order to generate an acceptable inflationary universe. These constraints are
analyzed carefully in this paper.Comment: 10 pages, title changed, corrected some typos, two additional
comments adde
Communications platform payload definition study, executive summary
Large geostationary communications platforms have been investigated in a number of studies since 1974 as a possible means to more effectively utilize the geostationary orbital arc and electromagnetic spectrum and to reduce overall satellite communications system costs. This NASA Lewis sponsored study addresses the commercial feasibility of various communications platform payload concepts circa 1998. It defines promising payload concepts, estimates recurring costs and identifies critical technologies needed to permit eventual commercialization. Ten communications service aggregation scenarios describing potential groupings of services were developed for a range of conditions. Payload concepts were defined for four of these scenarios: (1) Land Mobile Satellite Service (LMSS), meet 100% of CONUS plus Canada demand with a single platform; (2) Fixed Satellite Service (FSS) (Trunking + Customer Premises Service (CPS), meet 20% of CONUS demands; (3) FSS (Trunking + video distribution), 10 to 13% of CONUS demand; and (4) FSS (20% of demand) + Inter Satellite Links (ISL) + TDRSS/TDAS Data Distribution
Inflationary Universe in Higher Derivative Induced Gravity
In an induced-gravity model, the stability condition of an inflationary
slow-rollover solution is shown to be . The presence of higher derivative terms
will, however, act against the stability of this expanding solution unless
further constraints on the field parameters are imposed. We find that these
models will acquire a non-vanishing cosmological constant at the end of
inflation. Some models are analyzed for their implication to the early
universe.Comment: 6 pages, two typos correcte
Nonmagnetic impurity perturbation to the quasi-two-dimensional quantum helimagnet LiCu2O2
A complete phase diagram of Zn substituted quantum quasi-two-dimensional
helimagnet LiCu2O2 has been presented. Helical ordering transition temperature
(T_h) of the original LiCu2O2 follows finite size scaling for less than ~ 5.5%
Zn substitution, which implies the existence of finite helimagnetic domains
with domain boundaries formed with nearly isolated spins. Higher Zn
substitution > 5.5% quenches the long-range helical ordering and introduces an
intriguing Zn level dependent magnetic phase transition with slight thermal
hysteresis and a universal quadratic field dependence for T_c (Zn > 0.055,H).
The magnetic coupling constants of nearest-neighbor (nn) J1 and
next-nearest-neighbor (nnn) J2 (alpha=J2/J1) are extracted from high
temperature series expansion (HTSE) fitting and N=16 finite chain exact
diagonalization simulation. We have also provided evidence of direct
correlation between long-range helical spin ordering and the magnitude of
electric polarization in this spin driven multiferroic material
Tunneling in Squeezing Ground
A criterion for identifying the squeezing potential of tunnel is proposed. Tunneling conditions, classified as slightly or non-squeezing, moderately squeezing and highly squeezing, were identified by relating the strength-stress (σcm/Po ) ratio to the development of plastic zone extent and the amount of tunnel closure. Actual case histories of tunneling in Taiwan show that this criterion predicts the tunnel performance quite well. This enables the identification of tunneling conditions expected which require special considerations in support design and excavation-support procedures
Partial Wave Analysis of Scattering with Nonlocal Aharonov-Bohm Effect and Anomalous Cross Section induced by Quantum Interference
Partial wave theory of a three dmensional scattering problem for an arbitray
short range potential and a nonlocal Aharonov-Bohm magnetic flux is
established. The scattering process of a ``hard shere'' like potential and the
magnetic flux is examined. An anomalous total cross section is revealed at the
specific quantized magnetic flux at low energy which helps explain the
composite fermion and boson model in the fractional quantum Hall effect. Since
the nonlocal quantum interference of magnetic flux on the charged particles is
universal, the nonlocal effect is expected to appear in quite general potential
system and will be useful in understanding some other phenomena in mesoscopic
phyiscs.Comment: 6 figure
One-dimensional transport in polymer nanofibers
We report our transport studies in quasi one-dimensional (1D) conductors -
helical polyacetylene fibers doped with iodine and the data analysis for other
polymer single fibers and tubes. We found that at 30 K < T < 300 K the
conductance and the current-voltage characteristics follow the power law: G(T)
~ T^alpha with alpha ~ 2.2-7.2 and I(V) ~ V^betta with betta ~ 2-5.7. Both G(T)
and I(V) show the features characteristic of 1D systems such as Luttinger
liquid or Wigner crystal. The relationship between our results and theories for
tunneling in 1D systems is discussed.Comment: 11 pages, 3 figures, accepted for publication in Phys. Rev. Letter
Kaluza-Klein Higher Derivative Induced Gravity
The existence and stability analysis of an inflationary solution in a
-dimensional anisotropic induced gravity is presented in this paper.
Nontrivial conditions in the field equations are shown to be compatible with a
cosmological model in which the 4-dimension external space evolves
inflationary, while, the D-dimension internal one is static. In particular,
only two additional constraints on the coupling constants are derived from the
abundant field equations and perturbation equations. In addition, a compact
formula for the non-redundant 4+D dimensional Friedmann equation is also
derived for convenience. Possible implications are also discussed in this
paper.Comment: 13 pages, typos/errors corrected, three additional appendices adde
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