Extragalactic photon-ALP conversion at CTA 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...

Extragalactic diffuse gamma-ray emission at high energies

A diffuse and approximately isotropic high-energy photon background has been known to exist in the xray regime since 1962 [1] and a similar background was observed by the SAS-2 satellite at high energies [2]. Generally, isotropic or nearly isotropic emission may arise from extragalactic sources or an extended halo around the galaxy. It may result from superposition of many unresolved point sour...

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...