Coannihilation with a chargino and gauge boson pair production at one-loop

TL;DR

This paper calculates electroweak one-loop corrections to neutralino relic density in the MSSM, revealing new effects at one-loop level and introducing an automated computational tool for these complex calculations.

Contribution

It provides a complete one-loop correction calculation for neutralino annihilation and coannihilation processes, including an automatic tool and a gauge invariant renormalization scheme.

Findings

One-loop corrections significantly affect annihilation predictions.

New effects appear at one-loop not present at tree-level.

The developed tool automates complex MSSM calculations.

Abstract

We present a complete calculation of the electroweak one-loop corrections to the relic density within the MSSM framework. In the context of the neutralino as dark matter candidate, we review different scenarios of annihilation and coannihilation with a chargino. In particular we investigate predictions for the annihilation into gauge boson pairs for different kinds of neutralino: bino-, wino- and higgsino-like. We present some interesting effects which are not present at tree-level and show up at one-loop. To deal with the large number of diagrams occuring in the calculations, we have developed an automatic tool for the computation at one-loop of any process in the MSSM. We have implemented a complete on-shell gauge invariant renormalization scheme, with the possibility of switching to other schemes. We emphasize the variations due to the choice of the renormalization scheme, in particular the one-loop definition of the parameter tan(beta).