Radiative and flavor-violating transitions of leptons from interactions with color-octet particles

It has recently been proposed that neutrino mass could originate from Yukawa interactions of leptons with new colored particles. This raises the interesting possibility of testing mass generation through copious production of those particles at hadron colliders. A realistic assessment of this, however, should take into account how large those interactions could be, based on available precision results. In this work we make a systematic analysis of the flavor structure in Yukawa couplings, provide a convenient parametrization, and investigate the rare radiative and pure leptonic decays of the muon and tau leptons. For general values of the parameters, the muon decays set stringent constraints on the couplings, and all rare tau decays are far below the current experimental sensitivity. However, there is room in parameter space in which the muon decays could be significantly suppressed by destructive interference between colored particles without generically reducing the couplings themselves. This is also the region of parameters that is relevant to collider physics. We show that for this part of parameter space some tau decays can reach or are close to the current level of precision.Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)7ARTICLE1null8