123,136 research outputs found
Spin-Spin Interactions in Gauge Theory of Gravity, Violation of Weak Equivalence Principle and New Classical Test of General Relativity
For a long time, it is generally believed that spin-spin interactions can
only exist in a theory where Lorentz symmetry is gauged, and a theory with
spin-spin interactions is not perturbatively renormalizable. But this is not
true. By studying the motion of a spinning particle in gravitational field, it
is found that there exist spin-spin interactions in gauge theory of gravity.
Its mechanism is that a spinning particle will generate gravitomagnetic field
in space-time, and this gravitomagnetic field will interact with the spin of
another particle, which will cause spin-spin interactions. So, spin-spin
interactions are transmitted by gravitational field. The form of spin-spin
interactions in post Newtonian approximations is deduced. This result can also
be deduced from the Papapetrou equation. This kind of interactions will not
affect the renormalizability of the theory. The spin-spin interactions will
violate the weak equivalence principle, and the violation effects are
detectable. An experiment is proposed to detect the effects of the violation of
the weak equivalence principle.Comment: 17 pages, no figur
Application of Navier-Stokes analysis to stall flutter
A solution procedure was developed to investigate the two-dimensional, one- or two-dimensional flutter characteristics of arbitrary airfoils. This procedure requires a simultaneous integration in time of the solid and fluid equations of motion. The fluid equations of motion are the unsteady compressible Navier-Stokes equations, solved in a body-fitted moving coordinate system using an approximate factorization scheme. The solid equations of motion are integrated in time using an Euler implicit scheme. Flutter is said to occur if small disturbances imposed on the airfoil attitude lead to divergent oscillatory motions at subsequent times. The flutter characteristics of airfoils in subsonic speed at high angles of attack and airfoils in high subsonic and transonic speeds at low angles of attack are investigated. The stall flutter characteristics are also predicted using the same procedure
Hidden symmetry and quantum phases in spin-3/2 cold atomic systems
Optical traps and lattices provide a new opportunity to study strongly
correlated high spin systems with cold atoms. In this article, we review the
recent progress on the hidden symmetry properties in the simplest high spin
fermionic systems with hyperfine spin , which may be realized with atoms
of Cs, Be, Ba, Ba, and Hg. A {\it generic}
SO(5) or isomorphically, ) symmetry is proved in such systems with the
s-wave scattering interactions in optical traps, or with the on-site Hubbard
interactions in optical lattices. Various important features from this high
symmetry are studied in the Fermi liquid theory, the mean field phase diagram,
and the sign problem in quantum Monte-Carlo simulations. In the s-wave quintet
Cooper pairing phase, the half-quantum vortex exhibits the global analogue of
the Alice string and non-Abelian Cheshire charge properties in gauge theories.
The existence of the quartetting phase, a four-fermion counterpart of the
Cooper pairing phase, and its competition with other orders are studied in one
dimensional spin-3/2 systems. We also show that counter-intuitively quantum
fluctuations in spin-3/2 magnetic systems are even stronger than those in
spin-1/2 systems
Unimpeded permeation of water through helium-leak-tight graphene-based membranes
Permeation through nanometer pores is important in the design of materials
for filtration and separation techniques and because of unusual fundamental
behavior arising at the molecular scale. We found that submicron-thick
membranes made from graphene oxide can be completely impermeable to liquids,
vapors and gases, including helium, but allow unimpeded permeation of water
(H2O permeates through the membranes at least 10^10 times faster than He). We
attribute these seemingly incompatible observations to a low-friction flow of a
monolayer of water through two dimensional capillaries formed by closely spaced
graphene sheets. Diffusion of other molecules is blocked by reversible
narrowing of the capillaries in low humidity and/or by their clogging with
water
Applying mesh conformation on shape analysis with missing data
A mesh conformation approach that makes use of deformable generic meshes has been applied to establishing correspondences between 3D shapes with missing data. Given a group of shapes with correspondences, we can build up a statistical shape model by applying principal component analysis (PCA). The conformation at first globally maps the generic mesh to the 3D shape based on manually located corresponding landmarks, and then locally deforms the generic mesh to clone the 3D shape. The local deformation is constrained by minimizing the energy of an elastic model. An algorithm was also embedded in the conformation process to fill missing surface data of the shapes. Using synthetic data, we demonstrate that the conformation preserves the configuration of the generic mesh and hence it helps to establish good correspondences for shape analysis. Case studies of the principal component analysis of shapes were presented to illustrate the successes and advantages of our approach
Two Higgs Bi-doublet Model With Spontaneous P and CP Violation and Decoupling Limit to Two Higgs Doublet Model
The two Higgs bi-doublet left-right symmetric model (2HBDM) as a simple
extension of the minimal left-right symmetric model with a single Higgs
bi-doublet is motivated to realize both spontaneous P and CP violation while
consistent with the low energy phenomenology without significant fine tuning.
By carefully investigating the Higgs potential of the model, we find that
sizable CP-violating phases are allowed after the spontaneous symmetry
breaking. The mass spectra of the extra scalars in the 2HBDM are significantly
different from the ones in the minimal left-right symmetric model. In
particular, we demonstrate in the decoupling limit when the right-handed gauge
symmetry breaking scale is much higher than the electroweak scale, the 2HBDM
decouples into general two Higgs doublet model (2HDM) with spontaneous CP
violation and has rich induced sources of CP violation. We show that in the
decoupling limit, it contains extra light Higgs bosons with masses around
electroweak scale, which can be directly searched at the ongoing LHC and future
ILC experiments.Comment: 19 pages, discussions on fine-tuning problem added. Version to appear
in Phys.Rev.
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