Measuring the trilinear Higgs boson self--coupling at the 100 TeV hadron collider via multivariate analysis

Abstract

We perform a multivariate analysis of Higgs-pair production via the decay channel $HH\to b\bar{b}\gamma \gamma$ at the future 100 TeV $pp$ collider to determine the trilinear Higgs self--coupling (THSC) ${\lambda }_{3H}$, which takes the value of 1 in the standard model. We consider all known background processes. For the signal we adopt the most recent event generator of {\tt POWHEG-BOX-V2} to exploit the NLO distributions for Toolkit for Multivariate Data Analysis (TMVA). Through the technique of Boosted Decision Tree (BDT) analysis trained for ${\lambda }_{3H}=1$, compared to the the conventional cut-and-count approach, the signal-to-background ratio improves tremendously from about $1/10$ to $1$ and the significance can reach up to $20.5$ with a luminosity of 3 ab${}^{-1}$ without including systematic uncertainties. In addition, by implementing a likelihood fitting of the signal-plus-background $M_{\gamma \gamma bb}$ distribution with optimized bin sizes, it is possible to determine the THSC with the precision of 7.5\% at 68\% CL even at the early stage of 100 TeV hadron collider with 3 ab${}^{-1}$.

23 pages, 6 figures, 4 tables: Systematic uncertainties considered, Appendices and References added, To appear in PRD