Berlin 2005 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 18: Physik mit schweren Ionen
HK 18.5: Group Report
Monday, March 7, 2005, 15:30–16:00, TU MA041
Ultraperipheral Collisions at RHIC and LHC — •Kai Hencken1, Gerhard Baur2, Ute Dreyer1, and Dirk Trautmann1 — 1Uni Basel — 2FZ Jülich
Ultraperipheral Collisions (UPC) use the strong Coulomb fields surrounding the ions at relativistic energies to study photon-photon and photon-hadron processes in collisions with an impact parameter b > 2R. RHIC has published results on UPC and ALICE, CMS and ATLAS plan to study UPCs in the future as part of their HI program.
STAR/RHIC has recently measured electron-positron pairs at small impact parameter (b ≈ 20fm). We compare their results with our QED calculation with good agreement.
Coherent vector meson production in photon-nucleus collisions has been measured for the ρ at STAR/RHIC. Interference occurs in these processes as the role of the two ions can be exchanged. We study the transverse momentum distribution of this process especially for b. The results can be compared with the STAR measurements and are of importance for future experiments at the LHC.
Inelastic pair production offers the possibility to study quark pdfs inside nuclei, that is medium modifications, at moderate Q2 and small x. We compare results of a full calculation with the equivalent photon and lepton approximation.