Absolute Luminosity from Machine Parameters

The expected rates for proton proton collisions in the LHC are rather high. Monitoring can be based on several detector components and different physics channels can be used together and should allow for a good accuracy in the relative luminosity determination. The accuracy in the absolute luminosity determination may soon be limited by the uncertainty in the knowledge of the proton proton cross section at the LHC energy. Here we discuss the possibility to determine the absolute luminosity in the LHC from machine parameters, which does not require the knowledge of particle cross sections.