Abstract
Abstract A search for microscopic black holes and string balls is presented, based on a data sample of pp collisions at $ \sqrt{s}=8 $ TeV recorded by the CMS experiment at the Large Hadron Collider and corresponding to an integrated luminosity of 12 fb−1. No excess of events with energetic multiparticle final states, typical of black hole production or of similar new physics processes, is observed. Given the agreement of the observations with the expected standard model background, which is dominated by QCD multijet production, 95% confidence level limits are set on the production of semiclassical or quantum black holes, or of string balls, corresponding to the exclusions of masses below 4.3 to 6.2 TeV, depending on model assumptions. In addition, model-independent limits are set on new physics processes resulting in energetic multiparticle final states.
Highlights
Background ttbarUncertainty V+JetsUncertainty ttbar V+Jets M D = TeV3.5 4.5 MD (TeV), M min BH TeV, n MD M min QBH Pull (σ)
A search for micros√copic black holes and string balls is presented, based on a data sample of pp collisions at s = 8 TeV recorded by the CMS experiment at the Large Hadron Collider and corresponding to an integrated luminosity of 12 fb−1
Given the agreement of the observations with the expected standard model background, which is dominated by QCD multijet production, 95% confidence level limits are set on the production of semiclassical or quantum black holes, or of string balls, corresponding to the exclusions of masses below 4.3 to 6.2 TeV, depending on model assumptions
Summary
The central feature of CMS is a 3.8 T superconducting solenoid of 6 m internal diameter that encloses a silicon pixel and strip tracker, a lead-tungstate crystal electromagnetic calorimeter (ECAL), and a brass/scintillator hadron calorimeter (HCAL). The ECAL is a finely segmented calorimeter that uses crystals situated in a barrel region (|η| < 1.48) and two endcaps that extend to |η| = 3.0. The first level (L1) trigger ensures negligible dead time and is responsible for reducing the event rate to 100 kHz using the information from calorimeters and muon detectors. For the earlier part of the data taking, we utilized HT triggers that use jets reconstructed using the particle-flow (PF) technique [19], which are corrected for the calorimeter response to calculate the HT variable. The trigger is measured to be fully efficient for jet-enriched collision events with HT above 1 TeV
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