Abstract
A search for an excess of events with multiple high transverse momentum objects including charged leptons and jets is presented, using 20.3 fb^-1 of proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a centre-of-mass energy of sqrt(s) = 8 TeV. No excess of events beyond Standard Model expectations is observed. Using extra-dimensional models for black hole and string ball production and decay, exclusion contours are determined as a function of the mass threshold for production and the fundamental gravity scale for two, four and six extra dimensions. For six extra dimensions, mass thresholds of 4.8-6.2 TeV are excluded at 95% confidence level, depending on the fundamental gravity scale and model assumptions. Upper limits on the fiducial cross-sections for non-Standard Model production of these final states are set.
Highlights
Background estimationThe dominant sources of Standard Model background in this search are the production of W and Z bosons in association with jets, ttproduction and multi-jet processes
Mass thresholds of 4.8–6.2 TeV are excluded at 95% confidence level, depending on the fundamental gravity scale and model assumptions
The analysis considers events at high pT, defined as the scalar sum of the pT of the selected reconstructed objects, containing at least three high-pT objects, at least one of which must be a lepton
Summary
ATLAS [30] is a multipurpose detector with a forward-backward symmetric cylindrical geometry and nearly 4π coverage in solid angle. Closest to the beamline, the inner detector (ID) utilises fine-granularity pixel and microstrip detectors designed to provide precise track impact parameter and secondary vertex measurements. The inner detector (ID) utilises fine-granularity pixel and microstrip detectors designed to provide precise track impact parameter and secondary vertex measurements. These silicon-based detectors cover the pseudorapidity range |η| < 2.5. Liquid-argon calorimetry with copper absorbers is used in the hadronic end-cap calorimeters, which. The muon spectrometer (MS) measures the deflection of muon tracks within |η| < 2.7, using three stations of precision drift tubes (with cathode strip chambers in the innermost station for |η| > 2.0) located in a toroidal magnetic field of approximately 0.5 T and 1 T in the central and end-cap regions of ATLAS, respectively. The second and third levels use software algorithms to yield a recorded event rate of about 400 Hz
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