Patrick Janot edited Gobal Higgs fit .tex  almost 11 years ago

Commit id: 5628e7a94c996cd91ed929711020d696a8085649

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The accuracies on the Higgs boson couplings are obtained here from a fit to all observables reported in Tables~\ref{tab:HiggsBranching} and~\ref{tab:WWFusion} for TLEP and ILC. In a first attempt, the fit closely followed the logic presented in Ref.~\cite{cite:1207.2516} in order to reproduce the results for the ILC at 250 GeV. As large differences were observed in this first attempt with respect to Ref.~\cite{cite:1207.2516}, it was quickly realized that the ILC numbers presented therein are actually a combined fit of the LHC and the ILC projections. The results of this combined fit could indeed be reproduced faithfully, which in turn gives strong confidence in the claims made below.  The results of the standalone fits, however, are better suited to compare the LHC, ILC and TLEP relative merits in terms of Higgs coupling and width measurements. Other two assumptions made in Ref.~\cite{cite:1207.2516} consists {\it (i)} in bounding from above the couplings to the Z and the W to the standard model couplings; and {\it (ii)} in saturating the exotic decay width by the sole invisible Higgs boson decays. While reasonable, these assumptions introduce some model dependency which are not called for when it comes to measures the Higgs boson properties in a truly model-independent manner. These two assumptions were there removed from the fit, the result of which are presented in the first two columns of Table~\ref{tab:FitResults}. For completeness, the results of the fit with these two assumptions in are also given in the last two columns of the same Table.  from which the constraint that the Higgs boson couplings to the W and the Z be not larger than those predicted in the standard model is eventually removed. For a comparison with the LHC, the fit is first performed under the assumption that the total Higgs boson decay width is the sum of the partial decay widths in standard model particles, i.e., that there is no decays into exotic particles, as is done in Ref.~\cite{Barger_Ishida_Keung_2012}. In a second step, this assumption is removed as well for the comparison between TLEP and ILC.