The two hemispheres method for multijet BSM searches

A new method for identifying hints of possible beyond the standard model (BSM) signals produced at the Large Hadron Collider (LHC) with high jet multiplicity final states is proposed. In particular, the QCD background is estimated in a data driven way. Based on the simplified picture where QCD multijet events are created from a 2 → 2 process followed by cascade branching of the outcoming partons, the proposed "Two Hemisphere Method" (THm) divides events to two hemispheres and predicts the distribution of the number of jets in a predefined high multiplicity signal region. Validation of the above-mentioned assumption was performed using LO, NLO, and NNLO simulations, showing no effect of higher order calculations on the prediction accuracy. The sensitivity of the method was examined on topologically distinct scenarios of BSM multijet signatures and was able to show comparable sensitivity to other methods used in previous analyses. Since the sources of the uncertainties in this new approach are very different from the current methods, the procedures complement one another.