Search for direct third-generation squark pair production in final states with missing transverse momentum and two b-jets in sqrt{s}=8 TeV pp collisions with the ATLAS detector

TL;DR

This paper reports a search for third-generation squark pair production in proton-proton collisions at 8 TeV using the ATLAS detector, finding no evidence of new physics and setting exclusion limits on squark masses.

Contribution

It presents the first search for bottom and top squarks in final states with missing transverse momentum and b-jets at 8 TeV, establishing new exclusion limits.

Findings

No excess events observed above Standard Model background.

Set 95% CL limits on third-generation squark masses.

Excluded certain regions of supersymmetric parameter space.

Abstract

The results of a search for pair production of supersymmetric partners of the Standard Model third-generation quarks are reported. This search uses 20.1 fb-1 of pp collisions at sqrt{s}=8 TeV collected by the ATLAS experiment at the Large Hadron Collider. The lightest bottom and top squarks (b1 and t1 respectively) are searched for in a final state with large missing transverse momentum and two jets identified as originating from b-quarks. No excess of events above the expected level of Standard Model background is found. The results are used to set upper limits on the visible cross section for processes beyond the Standard Model. Exclusion limits at the 95% confidence level on the masses of the third-generation squarks are derived in phenomenological supersymmetric R-parity-conserving models in which either the bottom or the top squark is the lightest squark. The b1 is assumed to decay via b1->b chi0 and the t via t1->b chipm, with undetectable products of the subsequent decay of the chipm due to the small mass splitting between the chipm and the chi0.