132,491 research outputs found
Elastic pbar-d scattering and total pbar-d cross sections
Elastic pbar-d scattering is studied within the Glauber theory based on the
single- and double pbar-N scattering mechanisms. The full spin dependence of
the elementary pbar-N scattering amplitudes is taken into account and both the
S- and D-wave components of the deuteron are considered. The treatment of the
spin dependence is done in a (properly modified) formalism developed recently
by Platonova and Kukulin for the pd -> pd scattering process. Predictions for
differential cross sections and the spin observables A_y^d, A_y^pbar, A_xx,
A_yy are presented for antiproton beam energies between 50 and 300 MeV, using
amplitudes generated from the Nbar-N interaction model developed by the Juelich
group. Total polarized cross sections are calculated utilizing the optical
theorem. The efficiency of the polarization buildup for antiprotons in a
storage ring is investigated.Comment: 14 pages, 15 figures; some comments added, figure added, signs of
some spin-dependent cross sections correcte
Radiated noise from an externally blown flap
The far field noise from subsonic jet impingement on a wing-flap with a 45 deg bend was experimentally investigated. The test parameters are jet Mach number and flap length. For long flaps, the primary source mechanisms are found to be turbulent mixing and flow impingement. For short flaps, the interaction of turbulent flow with the flap trailing edge appears to strongly influence the radiated noise
Representations of derived from quantum flag manifolds
A relationship between quantum flag and Grassmann manifolds is revealed. This
enables a formal diagonalization of quantum positive matrices. The requirement
that this diagonalization defines a homomorphism leads to a left \Uh -- module
structure on the algebra generated by quantum antiholomorphic coordinate
functions living on the flag manifold. The module is defined by prescribing the
action on the unit and then extending it to all polynomials using a quantum
version of Leibniz rule. Leibniz rule is shown to be induced by the dressing
transformation. For discrete values of parameters occuring in the
diagonalization one can extract finite-dimensional irreducible representations
of \Uh as cyclic submodules.Comment: LaTeX file, JMP (to appear
New physical principles of contact thermoelectric cooling
We suggest a new approach to the theory of the contact thermoelectric cooling
(Peltier effect). The metal-metal, metal-n-type semiconductor, metal-p-type
semiconductor, p-n junction contacts are analyzed. Both degenerate and
non-degenerate electron and hole gases are considered. The role of
recombination in the contact cooling effect is discussed by the first time.Comment: 8 pages, 8 figures, revtex
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