![]() ![]() ![]() To separate the W’ signal events from the standard model background events, CMS physicists select events with specific properties: the charged lepton and neutrino must be very energetic, the ratio of their energies has to be almost one, and they have to be back-to-back in the plane perpendicular to the beam axis. We sum the transverse momenta of all the detected particles in the event and assign the missing transverse momentum (generally called MET) to the neutrinos. Nevertheless, their presence can be inferred by momentum conservation in the transverse plane. The charged leptons can be accurately detected and measured in the CMS detector, whereas neutrinos are weakly interacting particles that will escape the detector without a signal. ![]() In this analysis, the events where the W’ decays to a lepton and neutrino are taken into account because leptons are extremely clean signatures in the detector and give lower contributions from standard model processes that mimic this signature than the hadronic channels. The W’ boson is usually predicted as a carbon copy of the W boson in the standard model, but it is very heavy, so it can also decay into the two heaviest quarks. Such new particles could be a new charged W’ boson particle decaying into one charged lepton (electron or muon) and a neutrino in the proton-proton collision events recorded in the CMS detector. If these new phenomena exist in the real world, LHC is best positioned to observe them. Interestingly, many of these new theories have in common that they introduce new massive particles or differences in the behavior of known particles. There are many open questions: Is the mass of Higgs natural or fine-tuned? If natural, what new physics (symmetry) governs this? How does gravity play with the other forces? Are there more space dimensions than the familiar three? Do all forces unify at high energy? Many compelling theoretical ideas of new physics beyond the standard model have been proposed to address the open questions. Still, it is clear that the standard model is not the final theory. for the heavy neutrino mass up to 400 GeV or so at √=14 TeV LHC.Experimental evidence from the last half-century has established the standard model as a foundational theory of particle physics. ![]() We find that with the cut-based analysis, the light-heavy neutrino mixing parameter |V e N| 2 can be probed down to ∼1 0 -4 at 95% C.L. We use both cut-based and multivariate analysis techniques to make a realistic calculation of the relevant signal and background events, including detector effects for a generic linear collider detector. In the e -e - beam mode, we study the prospects of the lepton number violating process of e -e -→W -W -, mediated by a heavy Majorana neutrino. However, since this mode is insensitive to the Majorana nature of the heavy neutrinos, we also study a new production channel e +e -→N e ±W ∓, which leads to a same-sign dilepton plus four jet final state, thus directly probing the lepton number violation in e +e - colliders. In the e +e - beam mode, we consider various production and decay modes of the heavy neutrino (N ), and find that the final state with e +2 j + \updiag1 E, arising from the e +e -→N ν production mode, is the most promising channel. In particular, we focus on the planned electron-positron colliders, operating in two different beam modes, namely, e +e - and e -e. We discuss the future prospects of heavy neutrino searches at next generation lepton colliders. ![]()
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