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Abstract
Abstract A search for microscopic black holes in pp collisions at a center-of-mass energy of 7 TeV is presented. The data sample corresponds to an integrated luminosity of 4.7 fb−1 recorded by the CMS experiment at the LHC in 2011. Events with large total transverse energy have been analyzed for the presence of multiple energetic jets, leptons, and photons, which are typical signals of evaporating semiclassical and quantum black holes, and string balls. Agreement with the expected standard model backgrounds, which are dominated by QCD multijet production, has been observed for various combined multiplicities of jets and other reconstructed objects in the final state. Model-independent limits are set on new physics processes producing high-multiplicity, energetic final states. In addition, new model-specific indicative limits are set excluding semiclassical and quantum black holes with masses below 3.8 to 5.3 TeV and string balls with masses below 4.6 to 4.8 TeV . The analysis has a substantially increased sensitivity compared to previous searches.
Highlights
W+Jets ttbar Uncertainty Z+Jets M D = TeV, M min BH TeV, n MD1500 2000 2500 3000 3500 4000 4500 ST (GeV)hole signals for three parameter sets of the BlackMax nonrotating black hole model
In order to set exclusion limits on black hole production, we assign systematic uncertainties on the background estimate varying from 3% to 300% in the ST range used in this search
We first present the results of our search in a generic, model-independent way, which would allow others to probe additional models using parton-level Monte Carlo (MC) information, possibly augmented with a very basic detector simulation. To facilitate such an approach, we provide model-independent limits on the cross section times the acceptance for new physics production in high-ST inclusive final states for N ≥ 3, 4, 5, 6, 7, and 8
Summary
A detailed description of the CMS experiment can be found elsewhere [18]. The CMS detector consists of a 3.8 T superconducting solenoid enclosing a silicon pixel and strip tracker, a crystal electromagnetic calorimeter (ECAL), and a brass-scintillator hadronic calorimeter (HCAL). As in the previous analysis, we use data collected with a suite of HT triggers, where HT is defined as a scalar sum of the transverse energies (ET) of the jets above a threshold.. The minimum HT thresholds, as well as the minimum jet ET requirement for a jet to be counted towards HT, have been increased to account for pileup effects and to allow for the increased instantaneous luminosity of the LHC. In order to explore all possible black hole decay modes, the entire analysis was repeated using data collected with multimuon or missing transverse energy (ETmiss) triggers, but this yielded no events consistent with the expected black hole production
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