Search for Black Holes in pp Collisions at sqrt(s) = 7 TeV

A search for microscopic black hole production in $pp$ collisions at a center-of-mass energy of 7 TeV by the CMS experiment at the LHC is presented using a 2011 data sample corresponding to an integrated luminosity of approximately 1.09~fb$^{-1}$. This corresponds to a thirty-fold increase in statistics compared to a previous search based on 2010 data. Events with large total transverse energy have been analyzed for the presence of multiple energetic jets, leptons, and photons, typical of a signal from an evaporating black hole. A good agreement with the expected standard model backgrounds, dominated by QCD multijet production, has been observed for various multiplicities of the final state. Stringent model-independent limits on new physics production in high-multiplicity energetic final states have been set, along with model-specific limits on semi-classical black hole masses in the 4 -- 5~TeV range for a variety of model parameters. This extends substantially the sensitivity of the 2010 analysis. The first limits on production of string balls at hadron colliders with minimum mass of 4.1 -- 4.5~TeV have been set.