147,563 research outputs found
New line-interactive UPS system with DSP-based active power-line conditioning
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Diffractive meson production from virtual photons with odd charge-parity exchange
We calculate the cross section of diffractive charge-parity C=+1 neutral
meson production in virtual photon proton collision at high energies. Due to
the opposite C-parities of photon and meson M (M = eta_C, pi^0, a_2) this
process probes the t-channel C=-1 odderon exchange which is described here as
noninteracting three-gluon exchange. Estimates for the cross section of the
inelastic diffractive process gamma^* p -> eta_C X_p are presented. The total
cross section of diffractive \eta_C meson photoproduction is found to be 47 pb.
The cross sections for the diffractive production of light mesons (pi^0, a_2)
in \gamma^* p collisions are of the same order if the photon virtuality Q^2 is
m^2_C.Comment: LaTeX, 19 pages, 8 ps-figs, epsfi
Non-perturbative effects in the energy-energy correlation
The fully resummed next-to-leading-order perturbative calculation of the
energy-energy correlation in annihilation is extended to include the
leading non-perturbative power-behaved contributions computed using the
``dispersive method'' applied earlier to event shape variables. The correlation
between a leading (anti)quark and a gluon produces a non-perturbative 1/Q
contribution, while non-perturbative effects in the quark-antiquark correlation
give rise to a smaller contribution . In the back-to-back region,
the power-suppressed contributions actually decrease much more slowly, as small
non-integer powers of 1/Q, as a result of the interplay with perturbative
effects. The hypothesis of a universal low-energy form for the strong coupling
relates the coefficients of these contributions to those measured for other
observables.Comment: 41 pages, LaTeX, 4 figures, uses JHEP.cl
Symplectically harmonic cohomology of nilmanifolds
This paper can be considered as an extension to our paper [On symplectically
harmonic forms on six-dimensional nilmanifolds, Comment. Math. Helv. 76 (2001),
n 1, 89-109]. Also, it contains a brief survey of recent results on
symplectically harmonic cohomology.Comment: 18 page
Absorption in Ultra-Peripheral Nucleus-Atom Collisions in Crystal
The Glauber theory description of particle- and nucleus-crystal Coulomb
interactions at high-energy is developed. The allowance for the lattice thermal
vibrations is shown to produce strong absorption effect which is of prime
importance for quantitative understanding of the coherent Coulomb excitation of
ultra-relativistic particles and nuclei passing through the crystal.Comment: 8 pages, LaTe
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