The Invisible Higgs Decay Width in the Add Model at the LHC

Abstract

Assuming flat universal extra dimensions, we demonstrate that for a light Higgs boson the process $pp\to W^{\ast }{W}^{\ast }+X\to Higgs,graviscalars+X\to invisible+X$ will be observable at the $5\sigma$ level at the LHC for the portion of the Higgs-graviscalar mixing ($\xi$) and effective Planck mass ($M_D$) parameter space where channels relying on visible Higgs decays fail to achieve a $5\sigma$ signal. Further, we show that even for very modest values of $\xi$ the invisible decay signal probes to higher $M_D$ than does the ($\xi$-independent) jets/$\text{gam}$ + missing energy signal from graviton radiation. We also discuss various effects, such as Higgs decay to two graviscalars, that could become important when $m_h/M_D$ is of order 1.

Comments: 6 pages, 2 figures, To appear in the Proceedings of the Les Houches Workshop 2003: ``Physics at TeV Colliders'', ed. F. Boudjema