Abstract
The radiatively-induced splitting of masses in electroweak multiplets is relevant for both collider phenomenology and dark matter. Precision two-loop corrections of $\mathcal{O}$(MeV) to the triplet mass splitting in the wino limit of the minimal supersymmetric standard model can affect particle lifetimes by up to $40\%$. We improve on previous two-loop self-energy calculations for the wino model by obtaining consistent input parameters to the calculation via two-loop renormalisation-group running, and including the effect of finite light quark masses. We also present the first two-loop calculation of the mass splitting in an electroweak fermionic quintuplet, corresponding to the viable form of minimal dark matter (MDM). We place significant constraints on the lifetimes of the charged and doubly-charged fermions in this model. We find that the two-loop mass splittings in the MDM quintuplet are not constant in the large-mass limit, as might naively be expected from the triplet calculation. This is due to the influence of the additional heavy fermions in loop corrections to the gauge boson propagators.
Highlights
Dark matter as the lightest component of an electroweak multiplet remains a viable explanation for the observed relic abundance
As electroweak mass splittings have already been studied at the two-loop level in the wino limit of the MSSM [7,55], we are able to compare our results to the previous ones, and in the process demonstrate the impacts of the improvements that we have made in this paper
We have presented a two-loop calculation of mass splitting in electroweak multiplets, in the wino limit of the MSSM and in the minimal dark matter (MDM) fermionic quintuplet model
Summary
Dark matter as the lightest component of an electroweak multiplet remains a viable explanation for the observed relic abundance. One feature of this type of dark matter model is the potential for a striking signature in the form of a disappearing charged track in a collider experiment. This is due to an order 100 MeV radiatively-induced mass difference between the neutral multiplet component, and the heavier charged components. Radiative corrections from massive gauge bosons push the physical masses of the charged components slightly above that of the neutral component [1,2]. As we will show, due to the strong dependence on the mass splitting, two-loop corrections can result in up to a 40% change in the lifetime of a charged
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