Search for quantum black hole production in high-invariant-mass lepton + jet final states using pp collisions at √s = 8 TeV and the ATLAS detector

This Letter presents a search for quantum black-holeproduction using 20.3 fb(-1) of data collected with the ATLAS detector in pp collisions at the LHC at root s = 8 TeV. The quantum black holesare assumed to decay into a final state characterized by a lepton(electron or muon) and a jet. In either channel, no event with a lepton-jet invariant massof 3.5 TeV or more is observed, consistent with the expected background. Limits are set on the product of cross sections and branching fractionsfor the lepton+ jet final states of quantum black holesproduced in a search region for invariant massesabove 1 TeV. The combined 95% confidence level upper limit on this product for quantum black holeswith threshold mass above 3.5 TeV is 0.18 fb. This limit constrains the threshold quantum black-holemass to be above 5.3 TeV in the model considered.