Four Statements about the Fourth Generation

This summary of the Workshop "Beyond the 3-generation SM in the LHC era" presents a brief discussion of the following four statements about the fourth generation: 1) It is not excluded by EW precision data; 2) It addresses some of the currently open questions; 3) It can accommodate emerging possible hints of new physics; 4) LHC has the potential to discover or fully exclude it.Comment: Summary of the "Beyond the 3-generation SM in the LHC era" Workshop, CERN, September 4-5, 2008; 7 pages. V2: updated bibliography and minor typos fixed. To appear in PMC Physics

Possible Discovery Channel for New Charged Leptons at the LHC

We propose a channel for the possible discovery of new charged leptons at the Large Hadron Collider. The proposed final state contains three same-sign leptons, making this new channel practically back- groundless. The method is illustrated for two different cases: the four-family Standard Model and the Grand Unified Theory based on the E6 gauge group. An example study taking 250 GeV as the charged lepton mass shows that in both models, about 8 signal events can be expected at 14 TeV center-of-mass energy with 1 fb^-1 of integrated luminosity. Although the event yield might not be sufficient for detailed measurements of the charged lepton properties, it would be sufficient to claim discovery through a counting experiment.Comment: 8 pages, 4 figures. v2 update includes an estimate of the backgrounds, consideration of the EW oblique parameters, and minor improvements. v3 update includes detector acceptance and ttbar backgroun