This page documents my reading on higgs models that couple only to bosons.

### Summary and Conclusion

It appears as if there are fundamental reasons that limit the production Xsection for WH to be no larger than what we have
for standard model higgs production. "Bosophilic" higgs is thus really a misnomer, because the fermionic coupling ffH is
turned off without enhancing the bosonic coupling VVH much if any. These types of models should thus really called
fermiphobic higgs rather than bosophilic.

From a practical point of view it means that we could use Pythia WH production from the Standard Model,
and simply correct the BR(H->WW) according to the plots below.

However, looking at the BR plots below it seems that we gain at most a factor 10 in BR at around 115GeV over the standard model.
Though, a more useful way of looking at it is in comparison with Shih-Chieh's gg->H->WW analysis which is most sensitive
at mH~160GeV. The fermiphobic models guarantee the same BR at lower mH. The only advantage from these models is thus
the increase of Higgs production. Baer and Wells paper indicates a WH Xsection for mH~115GeV of close to 200fb. In comparison,
the Xsection for gg->H at mH~160GeV is about a factor two larger than this. Shih-Chieh's analysis is thus about a factor 10 favored in
expected yield because it has an additional factor 5 advantage in BR as it has one less 20% factor of BR(W->lnu) than any WWW->3l & MET analysis.

Bottom line, I don't think a search for fermiphobic higgs in WWW -> 3l & MET final state is worth doing!

### Theory Papers

#### Higgs Hunter's Guide

Chapter 4 provides a general analysis of Two-Higgs Doublet Models. In particular, Eq. 4.6 describes a sum rule for HVV couplings that basically guarantees that the Standard Model (single Higgs doublet) sets something of an uper bound on the HWW coupling. Having additional doublet or singlet Higgs fields will generally decrease the couplings because the sum of the coupling squared is fixed.

#### H.E. Haber, Gordon L. Kane, T. Sterling (Nucl.Phys.B161:493,1979)

This is the original reference outlining the physics of Two-Higgs doublet models and how they may lead to fermiphobic higgs.
The idea as best as I understood it is that the two vevs decouple such that one couples to bosons, while the other couples to
fermioins. The masses of the two neutral higgs can thus be quite different, with the lower mass higgs possibly coupling only to
bosons, and not to fermions, at least not at tree level. As best as I understood, this is changing the branching fractions by turning off
the partial width to fermions without significantly enhancing the partial width to bosons. The total width thus decreases, and the
WH production Xsection remains largely unchanged.

#### Stange-Marciano-Willenbrock Paper:

This paper discusses prospects for low mass Higgs searches at the Tevatron. The only thing interesting
in here is the chapter on bosophilic Higgs, where it has plots for the branching fraction versus mH
for both the standard model higgs as well as bosophilic higgs.

#### Baer and Wells Paper

This paper discusses the exact signature we are interested in: Trilepton plus MET. It uses a theorist Monte Carlo analysis to estimate the
sensitivity of the Tevatron for four different Higgs scenarios, including the standard model one. The key plot is given below. It again reinforces the notion that only the BR's but not the production Xsection changes. The sensitivity is thus increased only at low mH. At high mH the
H BR to WW is dominant anyway even in the standard model. These kinds of models thus do not make the Higgs hunt easier for large mH.
The significance plotted here is literally standard deviations based on a simple signal/sqrt(background) event count after some cuts.

-- FkW - 02 Nov 2006