Knizhnik-Zamolodchikov-Bernard equations on Riemann surfaces

Knizhnik-Zamolodchikov-Bernard equations for twisted conformal blocks on compact Riemann surfaces with marked points are written explicitly in a general projective structure in terms of correlation functions in the theory of twisted b-c systems. It is checked that on the moduli space the equations provide a flat connection with the spectral parameter.Comment: 23 page

QCD Factorization for the Pion Diffractive Dissociation Into Two Jets

We report a detailed study of the process of pion diffraction dissociation into two jets with large transverse momenta. We find that the standard collinear factorization does not hold in this reaction. The structure of non-factorizable contributions is discussed and the results are compared with the experimental data. Our conclusion is that the existing theoretical uncertainties do not allow, for the time being, for a quantitative extraction of the pion distribution amplitude. (Talk presented at the Workshop on Exclusive Processes at High Momentum Transfer, Jefferson News, VA, May 15-18, 2002)Comment: 6 pages, latex, two figure

Deep I-band Imaging of z=5.99 Quasar

Deep I-band imaging was carried out to search for the optical counterpart of the X-ray jet candidate near SDSS 1306+0356, reported by Schwartz (2002, astro-ph/0202190). The data suggest that the extended X-ray source may be a jet, related to a galaxy rather than to the quasar itself.Comment: 2 page letter, accepted for publication in Astronomy and Astrophysics Slight changes to the figure

Allowed charge transfers between coherent conductors driven by a time-dependent scatterer

We derive constraints on the statistics of the charge transfer between two conductors in the model of arbitrary time-dependent instant scattering of non-interacting fermions at zero temperature. The constraints are formulated in terms of analytic properties of the generating function: its zeroes must lie on the negative real axis. This result generalizes existing studies for scattering by a time-independent scatterer under time-dependent bias voltage.Comment: 5 pages, no figures, corrected misprints and minor changes in version

Factorization of quantum charge transport for non-interacting fermions

We show that the statistics of the charge transfer of non-interacting fermions through a two-lead contact is generalized binomial, at any temperature and for any form of the scattering matrix: an arbitrary charge-transfer process can be decomposed into independent single-particle events. This result generalizes previous studies of adiabatic pumping at zero temperature and of transport induced by bias voltage.Comment: 13 pages, 3 figures, typos corrected, references adde

On the Coulomb corrections to the total cross section of the interaction of the π+π−\pi^+\pi^- atom with ordinary atoms at high energy

The size of $\pi^+\pi^-$ atom in the low lying states is considerably smaller than the radius of atomic screening. Due to that we can neglect this screening calculating the contribution of multi-photon exchanges. We obtain the analytic formula for Coulomb corrections which works with a very good accuracy for the ground state of $\pi^+\pi^-$ atom.Comment: 9 pages, LATEX with 1 Postscript figur