A study on the in situ calibration of the absolute energy of hadron calorimeters

A study on the in situ calibration of the absolute energy scale of hadron calorimeters is presented. The basic idea is to use a physics process, namely Drell–Yan production of tau pairs with the subsequent decay of the tau into a single hadron and a tau-neutrino. The energy of the two charged, isolated hadrons with opposite sign can be measured in the calorimeters. Together with the momentum measurement from tracking detectors the ratio E/p can then be used to get the absolute energy calibration. The process of Drell–Yan production of tau pairs is very abundant at LHC energies, and at a promising level at the TEVATRON energy in view of the future improved luminosity. The enormous rate from background processes mainly coming from QCD jet production can be handled to a negligible level by using appropriate kinematical cuts. At LHC energies the cut variables described could also serve to separate other physics channels from the background such as the Standard Model H0→τ+τ− or the supersymmetric A0→τ+τ−.