Total Attenuation of Various Elements at Different Photon Energies

Hadronic photon-photon interactions at high energies.

Photon-photon collisions are investigated in the framework of the two-component Dual Parton Model. The model contains contributions from direct, resolved soft and resolved hard interactions. All free parameters of the model are determined in fits to hadronhadron and photon-hadron cross section data. The model is shown to agree well to hadron production data from hadron-hadron and photon-hadron ...

Photon Bunching at TeV Energies

Harwit, Protheroe, and Biermann (1999) recently proposed that BoseEinstein photon bunching might significantly affect the interpretation of Cerenkov counts of TeV gamma photons. Here, we show that a combination of two recent results of Aharonian et al. (2000) and Aharonian et al. (2001) permits us to set new, more stringent upper limits of ∼< 10% on the fractional amount of photon bunching in t...

Photon Interactions Liverpool, at High Energies

Two-Photon Processes at Intermediate Energies∗

Exclusive hadron production processes in photon-photon collisions provide important tests of QCD at the amplitude level, particularly as measures of hadron distribution amplitudes and skewed parton distributions. The determination of the shape and normalization of the distribution amplitudes has become particularly important in view of their importance in the analysis of exclusive semi-leptonic...

Nuclear shadowing at low photon energies

We calculate the shadowing effect in nuclear photoabsorption at low photon energies (1-3 GeV) within a multiple scattering approach. We avoid some of the high energy approximations that are usually made in simple Glauber theory like the narrow width and the eikonal approximation. We find that the main contribution to nuclear shadowing at low energies stems from ρ0 mesons with masses well below ...