![]() ![]() The discovery that neutrinos have a very small mass, at least a million times lighter than the electron, raises the possibility that neutrinos get their mass from unknown processes, that may not be related to the recently discovered Higgs boson. Most neutrinos pass right through the Earth without ever interacting with any single atom.īecause neutrinos were produced in great abundance in the early universe and rarely interact with matter, there are a lot of them in the universe. ![]() Since neutrinos do not interact electrically or strongly, they almost never interact with any other particle. The sun produces millions of neutrinos in the internal fusion reactions that power it. Neutrinos are produced in a variety of interactions. The tauon has a very short lifetime – 100,000 times shorter than that of the muon. ![]() It is the most massive of the leptons, having a mass about 3,490 times the mass of the electron and 17 times that of the muon. The tauon was discovered in high-energy particle collision experiments between 19 by Martin Perl with his colleagues at Stanford Linear Accelerator Center in California. ![]() The discovery of this particle was so surprising that Nobel laureate Isidor Isaac Rabi exclaimed: “Who ordered that?” The average sea level muon flux (or concentration) is about one muon per square centimetre per minute.Īmerican physicists Carl Anderson and Seth Neddermeyer were studying cosmic rays when they discovered the muon in 1936. Muons make up more than half of the cosmic radiation at sea level, the remainder being mostly electrons, positrons and photons. The “Compact” Muon Solenoid detector at the Large Hadron Collider at CERN. It can be created in cosmic rays at different heights above the earth. Muons have mass 207 times larger than electrons and a lifetime of 2.20 microseconds. Muons and tauons are heavier and highly unstable versions of the electron. It was the first particle of antimatter that was discovered. The electron’s antiparticle, the positron, is identical in mass but has a positive charge. It is the smallest charged particle we know of and is very stable. It is directly tied to the chemical properties of almost all atoms. Associated to each charged lepton, there are three distinct kinds of neutrinos:įor each of these leptons there is also an associated anti-particle, which has the same mass but opposite charge. The three electrically neutral leptons are the neutrinos (ν). For further reinterpretation a model-independent limit on potential signals for various transverse mass thresholds is also presented.An electron beam. In addition, the existence of a W' boson with universal fermion couplings is excluded at 95% confidence level, for W' masses below 2.7 TeV. Masses below 2.0 to 2.7 TeV are excluded, depending on the model parameters. These results substantially extend previous constraints on this model. Limits are set on a model in which the W' decays preferentially to fermions of the third generation. A signal would appear as an excess of events in kinematic regions where the standard model background is low. Download a PDF of the paper titled Search for W' decaying to tau lepton and neutrino in proton-proton collisions at sqrt(s) = 8 TeV, by CMS Collaboration Download PDF Abstract:The first search for a heavy charged vector boson in the final state with a tau lepton and a neutrino is reported, using 19.7 inverse femtobarns of LHC data at sqrt(s) = 8 TeV. ![]()
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