Abstract
We study the prospects of observing the non-resonant di-Higgs pair production in the Standard Model (SM) at the high luminosity run of the 14 TeV LHC (HL-LHC), upon combining multiple final states chosen on the basis of their yield and cleanliness. In particular, we consider the boverline{b}gamma gamma, boverline{b}{tau}^{+}{tau}^{-}, boverline{b}W {W}^{ast }, W {W}^{ast}gamma gamma and 4W channels mostly focusing on final states with photons and/or leptons and study 11 final states. We employ multivariate analyses to optimise the discrimination between signal and backgrounds and find it performing better than simple cut-based analyses. The various differential distributions for the Higgs pair production have non-trivial dependencies on the Higgs self-coupling (λhhh). We thus explore the implications of varying λhhh for the most sensitive search channel for the double Higgs production, viz., boverline{b}gamma gamma . The number of signal events originating from SM di-Higgs production in each final state is small and for this reason measurement of differential distributions may not be possible. In order to extract the Higgs quartic coupling, we have to rely on the total number of events in each final state and these channels can be contaminated by various new physics scenarios. Furthermore, we consider various physics beyond the standard model scenarios to quantify the effects of contamination while trying to measure the SM di-Higgs signals in detail. In particular, we study generic resonant heavy Higgs decays to a pair of SM-like Higgs bosons or to a pair of top quarks, heavy pseudoscalar decaying to an SM-like Higgs and a Z-boson, charged Higgs production in association with a top and a bottom quark and also various well-motivated supersymmetric channels. We set limits on the cross-sections for the aforementioned new physics scenarios, above which these can be seen as excesses over the SM background and affect the measurement of Higgs quartic coupling. We also discuss the correlations among various channels which can be useful to identify the new physics model.
Highlights
Background hbb tthZh bbγγ∗ Fake 1 TotalSignal √Significance (S/ B)(b) variables mbb, pT,γγ, ∆Rb1γ1 and ∆Rbb showed the maximal prowess in discriminating the signal from the background
We study the prospects of observing the non-resonant di-Higgs pair production in the Standard Model (SM) at the high luminosity run of the 14 TeV LHC (HL-LHC), upon combining multiple final states chosen on the basis of their yield and cleanliness
2.3.1 The 2b2 + E/ T channel Inspired by the CMS HL-LHC studies [131], we focus on the dileptonic mode of the bbW W ∗ channel in this part
Summary
For these channels and for the rest where we do not perform a cut-based analysis, we perform a multivariate analysis in order to capture the full machinery of an optimised search For such studies, we choose numerous discriminatory variables, depending on the analysis and use the TMVA framework [117] to discriminate between the signal and background samples. We systematically modulate the BDT optimisation procedure with sufficiently large number of signal and background samples and always ensure a KS test value greater than 0.1 for both signal and background With this machinery in hand, we outline and detail the prospects of the non-resonant di-Higgs process in various final states . We note that all our generated samples are at a centre of mass energy of 14 TeV and the final analyses are performed for an integrated luminosity of 3 ab−1
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
