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 supersymmetric model with R-parity violation. In both models pair produced new particles decay into 2 jets, thus leading to 4-jet events. Therefore, a detailed analysis of 4-jet events might discover new physics. The main background comes from standard QCD 4-jet events. We have found that an integrated luminosity L=10^4 pb-1 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.