Paramyxovirus Persistence

The hunting of the MR model

“…Further, since both s-channel Z exchange and t-channel slepton exchange are required to make σγ large enough, the sleptons can weigh no more than about 140 GeV in the MR model (see fig. 7 and [3]); this point will be crucial to our discussion of slepton searches in Section 7. To determine the lightest allowed photino mass (the one giving Ωγh 2 = 1), we maximize the slepton contribution to σγ by making the sleptons degenerate at the lightest experimentally [6] allowed mass (65 GeV).…”

“…As discussed in [3], this correction to the Higgs masses is quite significant; without it, LEP When m A rises a bit above m Z , the channel A →zH γ becomes kinematically accessible and it immediately dominates. Likewise, the A →w +w− and A → tt channels each take over once they are allowed.…”

“…At one loop, there are corrections due to loops involving the squarks and the top quark. In the MR model, the only [3] one-loop correction to the mass matrix (3.1) is a term added to the (2,2) entry (if we neglect the bottom squark contribution which is negligible in the allowed region of tan β). If the renormalization point is chosen so as to maintain the tree level vacuum expectation of the Higgs fields, this term takes the form 1…”

“…When this class of models was first considered [1], LEP data on the non-observation of light Higgs bosons appeared to exclude the minimal such model (MR model). Once the large size of radiative corrections to Higgs masses from a very heavy top quark became apparent [2], the model was reexamined [3] and pronounced viable.…”

“…Experimental signatures involving gaugino production were considered in [1]; these are useful because they apply equally well to many non-minimal U (1) R symmetric models. The phenomenological implications of cosmological constraints on the lightest superpartner (the photino) were considered in [3]; those results will be revisited and applied in this work.…”