Abstract
A search for pair production of third-generation scalar leptoquarks decaying to top quark and tau lepton pairs is presented using proton-proton collision data at a center-of-mass energy of sqrt(s) = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 inverse femtobarns. The search is performed using events that contain an electron or a muon, a hadronically decaying tau lepton, and two or more jets. The observations are found to be consistent with the standard model predictions. Assuming that all leptoquarks decay to a top quark and a tau lepton, the existence of pair produced, charge -1/3, third-generation leptoquarks up to a mass of 685 GeV is excluded at 95% confidence level. This result constitutes the first direct limit for leptoquarks decaying into a top quark and a tau lepton, and may also be applied directly to the pair production of bottom squarks decaying predominantly via the R-parity violating coupling lambda'[333].
Highlights
Reconstruction and identification of physics objectsThe CMS apparatus is a multipurpose particle detector with a superconducting solenoid of 6 m internal diameter, which provides a magnetic field of 3.8 T
Background estimationMain component containing misidentified muons & τ leptons estimated using data eventsEstimated via simulation, corrections applied for τ lepton misidentification rate and top quark and W pT distributions Search regions2 search regions binned in |η|8 search regions in 4 τ lepton pT regions for μτh and eτh channelsThe characteristics of the simulated tt+jets and W+jets events have been found to contain discrepancies when compared with measurements of the pT spectrum of top quarks [51] and the leading jet [52], respectively
A search for pair production of third-generation scalar leptoquarks decaying to top quark and τ√lepton pairs is presented using proton-proton collision data at a center-ofmass energy of s = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb−1
Summary
The CMS apparatus is a multipurpose particle detector with a superconducting solenoid of 6 m internal diameter, which provides a magnetic field of 3.8 T. Within the volume of the solenoid are a silicon pixel and strip tracker, a lead tungstate crystal electromagnetic calorimeter, and a brass and scintillator hadron calorimeter, each composed of a barrel and two endcap sections. Electron candidates are obtained by reconstructing trajectories from hits in the tracker layers and energy depositions in the electromagnetic calorimeter with a Gaussian sum filter [25]. ST is the scalar pT sum of all objects in the event, including muons, hadronically decaying τ leptons, electrons, jets, and ETmiss. |η| is the pseudorapidity defined as |η| = − ln tan (θ/2), where θis the average absolute polar angle of all electrons, muons, and hadronically decaying τ leptons in an event as measured from the beam-axis in the lab frame, and is used as a measure of the event centrality
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