Dresden 2013 – scientific programme

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T: Fachverband Teilchenphysik

T 14: Beyond the Standard Model (Theorie) 1

T 14.6: Talk

Monday, March 4, 2013, 12:15–12:30, WIL-A124

Improved predictions for interference effects of new physics — •Elina Fuchs, Silja C. Thewes, and Georg Weiglein — DESY Hamburg, Germany

The "narrow-width approximation" (NWA) is a convenient tool for the factorisation of a more complicated process into production and subsequent decay of a particle with a small width compared to its mass.

However, this approximation cannot be applied in the case of sizable interferences between propagator contributions of different particles that are close to their mass shell. For such cases, a generalisation of the usual NWA is analysed which allows for a consistent treatment of interference effects between nearly mass-degenerate particles. This can be useful for the application to processes for which the factorisation into different sub-processes is essential to enable the computation of higher-order contributions.

Phenomenological consequences with interference effects between neutral MSSM Higgs bosons will be presented for the example process of Higgs boson production and its subsequent decay from the decay of a heavy neutralino. Vertex corrections are included at the one-loop level, for which stable on-shell renormalisation schemes of the neutralino sector will be discussed. As a validation of the interference- and higher-order-improved NWA, the factorised approximation will be compared to the calculation of the full process at the one-loop level.