Two Early Exotics Searches With Dijet Events In The ATLAS Detector

This document summarises two exotic searches in dijet events. In the first search, narrow resonances of the dijet invariant mass from the decay of new heavy particles have been investigated. A time-integrated luminosity of 3.1 $ extrm{pb}^{-1}$ from 7 TeV collision data in LHC has been used. No significant evidence of new particles is found, and upper limits have been set on the product of the cross-section and detector acceptance. The theoretical model considered is the composite excited quark production, decaying to dijets. A 95% confidence-level mass exclusion region of the composite excited quark q* has been determined ($0.50 < m_{q*} < 1.53 TeV$). In the second search, dijet centrality ratio distributions have been measured in the ATLAS detector, with an integrated luminosity of 3.1 $ extrm{pb}^{-1}$. A search for quark compositeness using the model of quark 4-fermion contact interactions has been performed, and such interactions have been excluded at 95% CL for a compositeness scale below 2.0 TeV.