Heavy Quark Production at the TESLA Collider and its Sensitivity to the Gluon Content in Photon

Heavy quark production is studied at the high energy linear ee collider (LC) TESLA both in its nominal and Photon Collider (PC) mode. Leading order cross-sections are calculated for the production of heavy quarks, ee → ee Q(Q̄)X, at high transverse momenta. The sensitivity of this process to the gluon content in the photon is studied. An ee linear collider with a centre of mass system (CMS) energy in the range of 500 to 1000 GeV is the prime candidate for the next high energy accelerator project after the LHC. Recently TESLA [1] has completed a Technical Design Report for such a collider. For the study of a future electron-positron Linear Collider (LC) it is important to examine the physics potential of its main and possible additional options. Such an option is the Photon (or Compton) Collider (PC) in which high energy real photons can be obtained by backscattering photons from a laser beam on the electron or positron beam [2, 3]. This way an excellent tool for the study of γγ collisions at high energies can be provided. In high energy ee collisions the hadronic final state is predominantly produced in γγ interactions where the virtual photons (γ) are almost on mass shell. Their scattering can be effectively described with the interaction of real photons with energy spectra given by the Weizsäcker-Williams (WW) approximation [4]. Such a spectrum is generally quite soft, as shown in Fig. 1. In contrast, a Photon Collider, based on Compton scattering, provides beams of real photons which are much harder than those from a WW distribution (see Fig. 1). Furthermore these photons can be produced