6,317 research outputs found
The Fractional Quantum Hall effect in an array of quantum wires
We demonstrate the emergence of the quantum Hall (QH) hierarchy in a 2D model
of coupled quantum wires in a perpendicular magnetic field. At commensurate
values of the magnetic field, the system can develop instabilities to
appropriate inter-wire electron hopping processes that drive the system into a
variety of QH states. Some of the QH states are not included in the
Haldane-Halperin hierarchy. In addition, we find operators allowed at any field
that lead to novel crystals of Laughlin quasiparticles. We demonstrate that any
QH state is the groundstate of a Hamiltonian that we explicitly construct.Comment: Revtex, 4 pages, 2 figure
Stability of accretion disk around rotating black holes: a pseudo-general-relativistic fluid dynamical study
We discuss the solution of accretion disk when the black hole is chosen to be
rotating. We study, how the fluid properties get affected for different
rotation parameters of the black hole. We know that no cosmic object is static
in Universe. Here the effect of the rotation of the black hole to the
space-time is considered following an earlier work of the author, where the
pseudo-Newtonian potential was prescribed for the Kerr geometry. We show that,
with the inclusion of rotation of the black hole, the valid disk parameter
region dramatically changes and disk becomes unstable. Also we discuss about
the possibility of shock in accretion disk around rotating black holes. When
the black hole is chosen to be rotating, the sonic locations of the accretion
disk get shifted or disappear, making the disk unstable. To bring it in the
stable situation, the angular momentum of the accreting matter has to be
reduced/enhanced (for co/counter-rotating disk) by means of some physical
process.Comment: 24 Latex pages including 7 figures; Accepted for publication in
Astrophysical Journa
Study of Dissipative Collisions of Ne (7-11 MeV/nucleon) + Al
The inclusive energy distributions of complex fragments (3 Z 9)
emitted in the reactions Ne (145, 158, 200, 218 MeV) + Al have
been measured in the angular range 10 - 50. The fusion-fission and
the deep-inelastic components of the fragment yield have been extracted using
multiple Gaussian functions from the experimental fragment energy spectra. The
elemental yields of the fusion-fission component have been found to be fairly
well exlained in the framework of standard statistical model. It is found that
there is strong competition between the fusion-fission and the deep-inelastic
processes at these energies. The time scale of the deep-inelastic process was
estimated to be typically in the range of 10 - 10 sec.,
and it was found to decrease with increasing fragment mass. The angular
momentum dissipations in fully energy damped deep-inelastic process have been
estimated from the average energies of the deep-inelastic components of the
fragment energy spectra. It has been found that, the estimated angular momentum
dissipations, for lighter fragments in particular, are more than those
predicted by the empirical sticking limit.Comment: 16 pages, 9 figure
Evidence of large nuclear deformation of S formed in Ne + C reaction
Deformations of hot composite S formed in the reaction Ne
( 7 -- 10 MeV/nucleon) + C have been estimated from the respective
inclusive -particle evaporation spectra. The estimated deformations for
S have been found to be much larger than the `normal' deformations
of hot, rotating composites at similar excitations. This further confirms the
formation of highly deformed long-lived configuration of Ne + C
at high excitations ( 70 -- 100 MeV) -- which was recently indicated from
the analysis of the complex fragment emission data for the same system.
Exclusive -particle evaporation spectra from the decay of hot composite
S also show similar behaviour.Comment: 9 pages, 6 figure
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