Multi-Higgs Doublet Model: Can It Account for l^+l^-\gamma\gamma Events?

Abstract

Motivated by recent experiments at LEP ($Z \to l^+l^-\gamma\gamma$, with $M_{\gamma\gamma} \simeq 59 GeV$), we examine the possibility that such events are explained by a Bjorken process with a resonant Higgs ($M_{h^o} \simeq 59 GeV$) decaying to $\gamma\gamma$. Our model is an N-doublet-Higgs model without CP-violation. Under the simplifying assumption that $(N-k)$ doublets ($k \geq 1$) decouple from the fermion sector, we could explain the observed events if: i) $(N-1) \geq 2$ and ii) the masses of the corresponding $(N-1)$ neutral scalars are either completely or almost degenerate, i.e. the decay $Z \to l^+l^- \gamma\gamma$ proceeds now via several overlapping resonances.