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Hidden Higgs Boson at the LHC and Light Dark Matter Searches

Xiao-Gang He, Jusak Tandean

Abstract

Recent LHC searches have not found a clear signal of the Higgs boson h of the standard model (SM) with three or four families in the mass range m_h = 120-600 GeV. If the Higgs had an unexpectedly large invisible branching ratio, the excluded m_h regions would shrink. This can be realized in the simplest weakly interacting massive particle dark matter (DM) model, which is the SM plus a real gauge-singlet scalar field D as the DM, via the invisible mode h -> DD. Current data allow this decay to occur for D-mass values near, but below, m_h/2 and those compatible with the light DM hypothesis. For such D masses, h -> DD can dominate the Higgs width depending on m_h, and thus sizable portions of the m_h exclusion zones in the SM with three or four families may be recovered. Increased luminosity at the LHC may even reveal a Higgs having SM-like visible decays still hiding in the presently disallowed regions. The model also accommodates well the new possible DM hints from CRESST-II and will be further tested by improved data from future DM direct searches.

Hidden Higgs Boson at the LHC and Light Dark Matter Searches

Abstract

Recent LHC searches have not found a clear signal of the Higgs boson h of the standard model (SM) with three or four families in the mass range m_h = 120-600 GeV. If the Higgs had an unexpectedly large invisible branching ratio, the excluded m_h regions would shrink. This can be realized in the simplest weakly interacting massive particle dark matter (DM) model, which is the SM plus a real gauge-singlet scalar field D as the DM, via the invisible mode h -> DD. Current data allow this decay to occur for D-mass values near, but below, m_h/2 and those compatible with the light DM hypothesis. For such D masses, h -> DD can dominate the Higgs width depending on m_h, and thus sizable portions of the m_h exclusion zones in the SM with three or four families may be recovered. Increased luminosity at the LHC may even reveal a Higgs having SM-like visible decays still hiding in the presently disallowed regions. The model also accommodates well the new possible DM hints from CRESST-II and will be further tested by improved data from future DM direct searches.

Paper Structure

This paper contains 2 equations, 3 figures, 1 table.

Figures (3)

  • Figure 1: (a) Darkon-Higgs coupling $\lambda$ as a function of darkon mass $m_D^{}$ for Higgs mass values $m_h^{}=115,150,200,450$ GeV in SM3+D. (b) The corresponding darkon-nucleon cross-section $\sigma_{\rm el}^{}$, compared to 90%-CL upper-limits from CoGeNT (magenta dotted curve) Aalseth:2010vx, CDMS (brown long-dashed curves) Akerib:2010pv, XENON10 (green dot-dashed curve) Angle:2011th, and XENON100 (black short-dashed curve) Aprile:2011hi, as well as two (cyan) areas representing the new CRESST-II result cresst and a dark-gray patch fitting both DAMA/LIBRA Bernabei:2010mq and CoGeNT Aalseth:2010vx signal data Hooper:2010uy. The black-dotted sections of the curves in (a), and also in the following figures, are disallowed by the direct-search limits in (b) as discussed in the text.
  • Figure 2: Branching ratio of $h\to DD$ as a function of $m_D^{}$ in (a) SM3+D and (b) SM4+D for $m_h^{}=115,150,200,450$ GeV.
  • Figure 3: Reduction factor $\cal R$ as a function $m_D^{}$ in (a) SM3+D and (b) SM4+D for $m_h^{}=115,150$, $200,450$ GeV.