The measurement of the 4-jet cross section at LHC as a probe of new physics

We investigate the possibility to look for new physics by the measurement of the 4-jet cross section at the LHC. In particular, we consider a model with scalar colour octet and a su persymmetric model with parity violation. In both models pair produced new particles decay into 2 j ets, thus leading to 4-jet events. Therefore, a detailed analysis of 4-jet events might disco ver new physics. The main background comes from standard QCD 4-jet events. We have found that an integrated luminosity allows to discover scalar octets(squarks) with a mass up to 900 GeV(1100 GeV). To keep backgrounds under control and eventually to separate new physics signal a good dijet mass resolution is essential.