First observation of the decayK+→e+νeμ+μ−

Abstract

Experiment 865 at the Brookhaven AGS has observed the decay K + → e + νeµ + µ − . The branching ratio extracted is (1.72±0.37(stat)±0.17(syst)±0.19(model))×10 −8 where the third term in the error results from the use of a model to extrapolate into a kinematic region dominated by background.

Low scale leptogenesis in a hybrid model of the scotogenic type I and III seesaw models

“…This feature requires the mass of the right-handed neutrinos in the ordinary seesaw model to be more than 10 9 GeV [5] under the constraint of neutrino oscillation data as long as resonant leptogenesis [6] is not supposed. We find the similar feature in the scotogenic type I seesaw model [7], which is a well-known model for both neutrino masses and dark matter (DM) [8,9]. In this model, the right-handed neutrinos whose masses are in TeV ranges could have a chance to be each candidate for DM and a mother field of leptogenesis [10].…”

Radiative seesaw models linking to dark matter candidates inspired by the DAMPE excess

“…We have heavy neutral gauge boson Z ′ after U(1) e+µ−τ gauge symmetry breaking. The mass of Z ′ is given by Let us consider the active neutrino mass matrix at one-loop level [26], which consists of two types of diagrams; m I ν and m II ν as shown in Fig. 1.…”

Large Hadron Collider and Dark Matter

“…It may appear that the presence of a Higgs field is completely independent from the question of Dark Matter, but it is not so. On one side, there are very popular models where the Dark Matter is part of an extended Higgs sector, like the Inert DM model (Barbieri et al 2006;Ma 2006), recently compared to the LHC Higgs evidence in Goudelis et al (2013); on the other side, it is important to ask if the DM couples to the Higgs field. In the last years the possibility that the DM couples to the SM only via the Higgs fields has been very thoroughly studied in the "Higgs portal" models (Chu et al 2012;Englert et al 2011;Kanemura et al 2010;Lebedev et al 2012;Lopez-Honorez et al 2012;Mambrini 2011;McDonald 1994).…”