On the reinterpretation of non-resonant searches for Higgs boson pairs

Alexandra Carvalho,Ken Mimasu,Florian Goertz,Maxime Gouzevitch,Anamika Aggarwal

doi:10.1007/jhep02(2021)049

Abstract

The detection of production of a pair of Higgs bosons before the end of LHC operation would be a clear evidence of New Physics (NP). As searches for non-resonant production of Higgs pairs are being designed it is of particular importance to be able to conveniently present current experimental results in terms of limits in the most ‘model-independent’ fashion possible. To this end, in this article we provide an analytic parametrization of the differential Higgs-pair production at the LHC in the effective field theory (EFT) extension of the SM. It results from a fit to the theory prediction for the gg → hh cross section at the 13 TeV LHC. Subsequently the resulting formula is used for a reweighing technique that allows to recast exclusion bounds from ATLAS and CMS hh → gamma gamma boverline{b} searches to any point of the considered EFT parameter space. We demonstrate with a fast simulation of the LHC detectors that with this approach it is possible to cover the continuous EFT parameter space, taking correctly into account the efficiencies of signal selections, without the necessity of rerunning a large number of full detector simulations. Finally, the resulting exclusion bounds are confronted with several explicit models, such as setups with additional scalars, including 2HDM, vector-like fermions, and minimal composite Higgs models, which are mapped to the EFT.

Highlights

Examining the production of pairs of Higgs bosons h is a crucial task in the long term strategy of the LHC
Of particular importance regarding the search for physics beyond the Standard Model (SM) are differential observables, such as the distribution of the invariant mass of the Higgs pairs mhh, since they are especially sensitive to the effects of new physics (NP)
The impact of c2 on the bounds is further quantified in the right plot, where we show the effect of setting this coefficient to ±1, which shifts the contours left or right — in agreement with the tendencies observable in the left plot

Summary

Introduction

As we eventually want to confront corresponding experimental results with theory, we need to assume a theoretical framework, which in our case would be the effective field theory (EFT) extension of the SM, supplementing it with higher dimensional operators This captures the effects of any yet undiscovered physics beyond the SM, given that it is separated from the latter by a mass gap and in particular is significantly heavier than the scales probed experimentally. Having at hand analytic formulae which translate between observables in a realistic collider environment and effective couplings would be of utmost importance for the experimental results to be interpreted appropriately, either by the collaborations themselves or by theorists. In the end, it furnishes the missing link between theoretical models and measurements at colliders

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Methods

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Conclusion