Off-shell effects in Higgs processes at a linear collider and implications for the LHC

Understand

The importance of off-shell contributions is discussed for $H\to VV^{(*)}$ with $V\in\{Z,W\}$ for large invariant masses $m_{VV}$ involving a standard model (SM)-like Higgs boson with $m_H=125$GeV at a linear collider (LC).

• Both dominant production processes $e^+e^-\to ZH\to ZVV^{(*)}$ and $e^+e^-\to\nu\bar\nu H\to\nu\bar\nu VV^{(*)}$ are taken into account, and the signal processes are compared with background yielding the same final state.
• The relative size of the off-shell contributions is strongly dependent on the centre-of-mass energy.
• These contributions can have an important impact on the determination of cross sections and branching ratios.