5,100 research outputs found
Spin alignment of vector meson in e+e- annihilation at Z0 pole
We calculate the spin density matrix of the vector meson produced in e+e-
annihilation at Z^0 pole. We show that the data imply a significant
polarization for the antiquark which is created in the fragmentation process of
the polarized initial quark and combines with the fragmenting quark to form the
vector meson. The direction of polarization is opposite to that of the
fragmenting quark and the magnitude is of the order of 0.5. A qualitative
explanation of this result based on the LUND string fragmentation model is
given.Comment: 15 pages, 2 fgiures; submitted to Phys. Rev.
Spin Alignment of Vector Meson in High Energy Reactions
The recent data on the polarization of vector meson at LEP show that the
vector mesons favor the helicity zero state. We calculate the helicity density
matrix of vector meson which contains a polarized fragmenting quark by adding
the spin of the fragmenting quark and that of the antiquark created in the
fragmentation. The data at LEP imply a significant polarization for the
antiquark in the opposite direction as that of the fragmenting quark. We extend
the calculations to other reactions and make predictions for vector mesons in
deeply inelastic lepton-nucleon scatterings and polarized collisions.Comment: 4 pages,3 figures, Talk given at 3rd Circum-Pan-Pacific Symposium on
"High Energy Spin Physics", Beijing, China, Oct.8-13, 200
Helicity hardens the gas
A screw generally works better than a nail, or a complicated rope knot better
than a simple one, in fastening solid matter, but a gas is more tameless.
However, a flow itself has a physical quantity, helicity, measuring the
screwing strength of the velocity field and the degree of the knottedness of
the vorticity ropes. It is shown that helicity favors the partition of energy
to the vortical modes, compared to others such as the dilatation and pressure
modes of turbulence; that is, helicity stiffens the flow, with nontrivial
implications for aerodynamics, such as aeroacoustics, and conducting fluids,
among others
Interconnecting bilayer networks
A typical complex system should be described by a supernetwork or a network
of networks, in which the networks are coupled to some other networks. As the
first step to understanding the complex systems on such more systematic level,
scientists studied interdependent multilayer networks. In this letter, we
introduce a new kind of interdependent multilayer networks, i.e.,
interconnecting networks, for which the component networks are coupled each
other by sharing some common nodes. Based on the empirical investigations, we
revealed a common feature of such interconnecting networks, namely, the
networks with smaller averaged topological differences of the interconnecting
nodes tend to share more nodes. A very simple node sharing mechanism is
proposed to analytically explain the observed feature of the interconnecting
networks.Comment: 9 page
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