2,810,772 research outputs found
Effective Operator Treatment of the Lipkin Model
We analyze the Lipkin Model using effective operator techniques. We present
both analytical and numerical results for effective Hamiltonians. The accuracy
of the cluster approximation is investigated.Comment: To appear in Phys.Rev.
Bragg spectroscopy of an accelerating condensate with solitary-wave behaviour
We present a theoretical treatment of Bragg spectroscopy of an accelerating
condensate in a solitary-wave state. Our treatment is based on the
Gross-Pitaevskii equation with an optical potential representing the Bragg
pulse and an additional external time-dependent potential generating the
solitary-wave behaviour. By transforming to a frame translating with the
condensate, we derive an approximate set of equations that can be readily
solved to generate approximate Bragg spectra. Our analytic method is accurate
within a well defined parameter regime and provides physical insight into the
structure of the spectra. We illustrate our formalism using the example of
Bragg spectroscopy of a condensate in a time-averaged orbiting potential trap.Comment: 9 pages, 3 figure
Exploring Disordered Morphologies of Blends and Block Copolymers for Light-Emitting Diodes with Mesoscopic Simulations
Electronic charge reconstruction of doped Mott insulators in multilayered nanostructures
Dynamical mean-field theory is employed to calculate the electronic charge
reconstruction of multilayered inhomogeneous devices composed of semi-infinite
metallic lead layers sandwiching barrier planes of a strongly correlated
material (that can be tuned through the metal-insulator Mott transition). The
main focus is on barriers that are doped Mott insulators, and how the
electronic charge reconstruction can create well-defined Mott insulating
regions in a device whose thickness is governed by intrinsic materials
properties, and hence may be able to be reproducibly made.Comment: 9 pages, 8 figure
Baryon-to-entropy ratio in very high energy nuclear collisions
We compute as a function of rapidity the baryon number carried by quarks
and antiquarks with 2 GeV produced in Pb+Pb collisions at
TeV energies. The computation is carried out in lowest order QCD perturbation
theory using structure functions compatible with HERA results. At GeV
the initial gluon density is both transversally saturated and thermalised in
the sense that the energy/gluon equals to that of an ideal gas with the same
energy density. Even at these high energies the initial net baryon number
density at at fm will be more than the normal nuclear matter
density but the baryon-to-entropy ratio is only .
Further evolution of the system is discussed and the final baryon-to-entropy
ratio is estimated.Comment: 19 pages, including 10 ps-figure
Fractional Quantum Hall Hierarchy and the Second Landau Level
We generalize the fractional quantum Hall hierarchy picture to apply to
arbitrary, possibly non-Abelian, fractional quantum Hall states. Applying this
to the nu = 5/2 Moore-Read state, we construct new explicit trial wavefunctions
to describe the fractional quantum Hall effect in the second Landau level. The
resulting hierarchy of states, which reproduces the filling fractions of all
observed Hall conductance plateaus in the second Landau level, is characterized
by electron pairing in the ground state and an excitation spectrum that
includes non-Abelian anyons of the Ising type. We propose this as a unifying
picture in which p-wave pairing characterizes the fractional quantum Hall
effect in the second Landau level.Comment: 10 pages; v2: many additional details and discussion included to help
clarify the original results, including a composite fermion type formulation
of some of the states; v3: minor correction
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