7,125 research outputs found
The effect of reionization on the CMB-density correlation
In this paper we show how the rescattering of CMB photons after cosmic
reionization can give a significant linear contribution to the
temperature-matter cross-correlation measurements. These anisotropies, which
arise via a late time Doppler effect, are on scales much larger than the
typical scale of non-linear effects at reionization; they can contribute to
degree scale cross-correlations and could affect the interpretation of similar
correlations resulting from the integrated Sachs-Wolfe effect. While expected
to be small at low redshifts, these correlations can be large given a probe of
the density at high redshift, and so could be a useful probe of the cosmic
reionization history.Comment: 8 pages, 8 figure
Exclusive Production of Neutral Vector Mesons at the Electron-Proton Collider HERA
The first five years of operation of the multi-purpose experiments ZEUS and
H1 at the electron-proton storage ring facility HERA have opened a new era in
the study of vector-meson production in high-energy photon-proton interactions.
The high center-of-mass energy available at this unique accelerator complex
allows investigations in hitherto unexplored kinematic regions, providing
answers to long-standing questions concerning the energy-dependence of the rho,
omega, phi, and J/psi production cross sections. The excellent angular
acceptance of these detectors, combined with that of specialized tagging
detectors at small production angles, has permitted measurements of elastic and
inelastic production processes for both quasi-real photons and those of
virtuality exceeding the squared mass of the vector meson. This report provides
a quantitative picture of the present status of these studies, comparing them
to the extensive measurements in this field at lower energies and summarizing
topical developments in theoretical work motivated by the new data.Comment: This replacement serves to correct an error in Eq. 3.41. An improved
version of this review will appear in book form as Nr. 140 in the series
Springer Tracts in Modern Physics on 6.October. 90 pages including 34 figure
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