==== 2HDM Studies ====

//Kristin Lohwasser, Ken Lane, Jon Butterworth, David Grellscheid, Lukas Pritchett, ...//

Other projects using [[contur|Contur]].

=== First look with default parameters ===

Made in Les Houches, Masses as below, Beta = 0.0813, MixH = 0.0883

  * [[http://www.hep.ucl.ac.uk/~jmb/Work/2hdm/wplots8/ATLAS_2016_I1426515/index.html|8 TeV WW plots]]

=== Proposed parameter scan from Ken ===

Start with:

  * m(h_1) = 125 GeV
  * m(h_2) = 30 GeV
  * m(h_3) = 30 GeV
  * beta = arcsin(v2/246 GeV) = 0.05084 for v2 = 12.5 GeV (and = 0.08139 20 GeV, if you feel ambitious)
  * mixh = beta - alpha for alpha = -0.435 x 10^{-2}  (and -0.695 x 10{-2} for v2 = 20 GeV; ditto)

The signal processes of interest are:

$$\begin{aligned}
\bar{q} q \rightarrow \gamma, Z \rightarrow h^+ h^- \rightarrow \mu^+ \mu^- + E_T^{\rm missing}
 \\ \bar{d} u \rightarrow W^+ \rightarrow h^+ h_2 \ {\rm AND}\ h^+ h_3 \rightarrow \mu^+ \mu^+ \mu^- + E_T^{\rm missing}, \\ {\rm (plus\ charge\ conjugate\ )} \\  \bar{q} q \rightarrow Z \rightarrow h_2 h_3 -> \bar{b} b \mu^+ \mu^-\end{aligned}$$

For these, you want to scan over $h^+$ mass from 95 GeV to 250 GeV.

=== Update from Jon 18 Sept ===

Here's a [[http://www.hep.ucl.ac.uk/~jmb/Work/LH/2HDM/8_WEAK/|first look]], for inclusive $h^+$ or $h^-$ production, 8 TeV, parameters as above and beta = 0.0508, mixh = 0.0547 and $m(h^{+/-}) = 100$ GeV.

Total cross section 1.8 pb.

Note that the ATLAS 4l result still has a lot of exclusion power, even though the $h_2 h_3$ production channel is switched off (with this switched on, the total cross section is ~346 pb). From looking at the Herwig logs, I think this contribution may come from events like $q\bar{q} \rightarrow h_2 h^+ \rightarrow h_2 h_3 \mu \nu$ with subsequent $h_2, h_3$ decays to muons.

However, you can see that the [[http://www.hep.ucl.ac.uk/~jmb/Work/LH/2HDM/8_WEAK/ATLAS_2016_I1426515/index.html|ATLAS WW measurement]] also has some exclusion - about 92%. I don't understand why the [[http://www.hep.ucl.ac.uk/~jmb/Work/LH/2HDM/8_WEAK/CMS_2017_I1467451/index.html|CMS H->WW]] one doesn't have an exclusion anywhere in the same league. Either the Higgs selection cuts suppress it or there is a bug/feature in the rivet routine (either ATLAS or CMS!). I will look into it.