Higgs Physics

Higgs observables are also included wihtin the list of physical observables currently available in the $\texttt{HEPfit}$ code. These include the experimental measurements for the Higgs signal strengths measured by the ATLAS and CMS collaborations at the LHC at 7 and 8 TeV, as well as from CDF and D0 at Tevatron. All the individual experimental categories are available for the following final states:

• $H\rightarrow \gamma\gamma$
• $H\rightarrow Z Z$
• $H\rightarrow W^+ W^-$
• $H\rightarrow \tau^+ \tau^-$
• $H\rightarrow b \bar{b}$

The theoretical predictions for these signal strengths can be computed as \begin{equation} \mu = \sum_i w_i r_i,\nonumber \end{equation} where the sum runs over all the production mechanism that can contribute to each category. The weights and individual signal strength for each channel are given by \begin{equation} w_i=\frac{\epsilon_i \left[\sigma_\mathrm{SM}\times\mathrm{BR}_\mathrm{SM}\right]_i}{\sum_j \epsilon_j^\mathrm{SM} \left[\sigma_\mathrm{SM}\times\mathrm{BR}_\mathrm{SM}\right]_j}, ~~~~r_i=\frac{\left[\sigma\times\mathrm{BR}\right]_i}{\left[\sigma_\mathrm{SM}\times\mathrm{BR}_\mathrm{SM}\right]_i}.\nonumber \end{equation} The experimental efficiencies, $\epsilon_i$, are taken to be approximately equal to the Standard Model ones, which is a good approximation if new physics effects are small.

In the current version of $\texttt{HEPfit}$ the theoretical predictions for Higgs observables are implemented for the following new physics scenarios:

• The Standard Model with modified Higgs couplings ($\kappa$ framework).
• The dimension six Standard Model Effective Lagrangian (SMEFT).
• Two-Higgs-Doublet models.