Speaker
Description
Using Compton scattering of 0.5 \mum laser photons on existing 17.5 GeV (spent) electron beams from European XFEL one can obtain a gamma-gamma collider with W<12 GeV . This energy region is not covered by Super-B collider or LHC (the later due QCD backgrounds). Such a collider will be a nice place for application of modern technologies: powerful lasers, optical cavities, SC linacs and low-emittance electron sources. Physics program: spectroscopy of C+ resonances in various J^P states (b\bar{b}, four quark states, quark molecules and other exotics). Variable circular and linear photon polarization will help to determine quantum numbers. Using a large distance between the interaction and the conversion point, it is possible to obtain quasi-monochromatic collisions and thus to measure the total gamma-gamma section in the region below 12 GeV with a high accuracy. Variable photon polarization allows you to measure separately polarization components of the cross section (σ_perp,σ_paral, σ_0, σ_2).
