The Single Top Quark Associated Production by using CMS 2012 data, LHC

The measurement of the production cross-section for both the inclusive and exclusive cases are reported. The top quark being the heaviest particle in the Standard Model (SM) has been discovered about two decades ago but many of its properties have still not been fully investigated. The production cross-section of single top quark in association with a Z boson is an unmeasured rare SM process and also an irreducible background to many important searches at the Large Hadron Collider (LHC). The process is studied by using the three final state leptons (electrons, muons) for an integrated luminosity of 19.7 fb¿1 recorded by the CMS detector at the LHC using 8 TeV center-of-mass energy of proton-proton (pp) collisions. The predicted cross-section times branching ratio for this process is 0.008±0.001 pb at the Next-to-Leading Order (NLO) in Quantum Chromodynamics (QCD), which is comparable to the measured cross-section ¿ = 0.018 (stat.)±0.011 (Syst.)±0.004 pb. The significance of the tqZ inclusive cross-section as well as the exclusive one for all the leptonic combinations is also described. The observed significance of inclusive channel is reported to be 1.80, which is consistent to SM.