Search for new phenomena using final states with large jet multiplicities and missing transverse momentum with ATLAS in 20 fb$^{-1}$ of $\sqrt{s}=8\,$TeV proton-proton collisions

A search is presented for new particles decaying to large numbers of jets in association with missing transverse momentum, using 20.3 fb$^{-1}$ of $pp$ collision data at $\sqrt{s}=8\,$TeV collected by the ATLAS experiment at the Large Hadron Collider. The event selection requires missing transverse momentum, no isolated electrons or muons, and from 7 to $\geq$10 jets. The sensitivity of the search is enhanced by considering the number of $b$-tagged jets and the scalar sum of masses of large-radius ($R=1.0$) jets in an event. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of various simplified supersymmetry-inspired models, as well as a mSUGRA/CMSMM model with a lightest Higgs boson mass close to the mass of the recently observed boson.