Triple-Pomeron Matrix Model for Dispersive Corrections to Nucleon-Nucleus Total Cross Section

Dispersive corrections to the total cross section for high-energy scattering from a heavy nucleus are calculated using a matrix model, based on the triple-Pomeron behavior of diffractive scattering from a single nucleon, for the cross section operator connecting different states of the projectile nucleon . Energy-dependent effects due to the decrease in longitudinal momentum transfers and the opening of more channels with increasing energy are included. The three leading terms in an expansion in the number of inelastic transitions are evaluated and compared to exact results for the model in the uniform nuclear density approximation for the the scattering of nucleons from Pb^{208} for laboratory momenta ranging from 50 to 200 GeV/c.Comment: 16 pages, 2 figures, RevTex

Nuclear shadowing in deep inelastic scattering on nuclei: leading twist versus eikonal approaches

We use several diverse parameterizations of diffractive parton distributions, extracted in leading twist QCD analyses of the HERA diffractive deep inelastic scattering (DIS) data, to make predictions for leading twist nuclear shadowing of nuclear quark and gluon distributions in DIS on nuclei. We find that the HERA diffractive data are sufficiently precise to allow us to predict large nuclear shadowing for gluons and quarks, unambiguously. We performed detailed studies of nuclear shadowing for up and charm sea quarks and gluons within several scenarios of shadowing and diffractive slopes, as well as at central impact parameters. We compare these leading twist results with those obtained from the eikonal approach to nuclear shadowing (which is based on a very different space-time picture) and observe sharply contrasting predictions for the size and Q^2-dependence of nuclear shadowing. The most striking differences arise for the interaction of small dipoles with nuclei, in particular for the longitudinal structure function F_{L}^{A}.Comment: 43 pages, 16 figures, requires JHEP style fil

Measurement of total cross sections on hydrogen and deuterium

Total cross sections of {pi}{sup {+-}}, K{sup {+-}}, p and {bar p} on hydrogen and deuterium are to be measured at about eight energies between 20 GeV and the maximum available energy. An accuracy of about one part in one thousand will yield the energy dependence of cross sections, comparisons of cross sections within SU(3) supermultiplets, and stringent tests of high energy limiting theorems

Photon-Photon and Pomeron-Pomeron Processes in Peripheral Heavy Ion Collisions

We estimate the cross sections for the production of resonances, pion pairs and a central cluster of hadrons in peripheral heavy-ion collisions through two-photon and double-pomeron exchange, at energies that will be available at RHIC and LHC. The effect of the impact parameter in the diffractive reactions is introduced, and imposing the condition for realistic peripheral collisions we verify that in the case of very heavy ions the pomeron-pomeron contribution is indeed smaller than the electromagnetic one. However, they give a non-negligible background in the collision of light ions. This diffractive background will be more important at RHIC than at LHC.Comment: 22 pages, 1 Postscript figures, 4 tables, to appear in Phys. Rev.

Experimental studies of elementary particle interactions at high energies. Technical progress report

High energy physics research at Rockefeller University is discussed. Results of e/sup +/e/sup -/ pairs experiments at the CERN ISR are summarized along with particles associated with high p/sub T/ ..pi../sup 0/ triggers and direct single ..gamma.. rays. (GHT

INTRODUCTION

No abstract availabl

EXPERIMENTAL POSSIBILITIES WITH UA-6

Nous discutons certaines possibilités expérimentales avec un faisceau de protons polarisés au SPS et une cible gazeuse d'hydrogène polarisée.We discuss some experimental possibilities at the SPS with a polarized proton beam and a polarized hydrogen gas jet target