Abstract
High-pT Higgs production at hadron colliders provides a direct probe of the internal structure of the gg → H loop with the Hto boverline{b} decay offering the most statistics due to the large branching ratio. Despite the overwhelming QCD background, recent advances in jet substructure have put the observation of the ggto Hto boverline{b} channel at the LHC within the realm of possibility. In order to enhance the sensitivity to this process, we develop a two-stream convolutional neural network, with one stream acting on jet information and one using global event properties. The neural network significantly increases the discovery potential of a Higgs signal, both for high-pT Standard Model production as well for possible beyond the Standard Model contributions. Unlike most studies for boosted hadronically decaying massive particles, the boosted Higgs search is unique because double b-tagging rejects nearly all background processes that do not have two hard prongs. In this context — which goes beyond state-of-the-art two-prong tagging — the network is studied to identify the origin of the additional information leading to the increased significance. The procedures described here are also applicable to related final states where they can be used to identify additional sources of discrimination power that are not being exploited by current techniques.
Highlights
We apply our two-stage convolutional neural network to improve the bounds on the couplings cg and the combination + cH /2 as compared with the standard search
0.3 cg generated within quantum field theory), the best current bounds on the couplings cg and+cH /2 come from a combination of the most recent inclusive Higgs cross section measurements [129] and recent global fit of the Standard Model Effective Field Theory to all current Higgs and electroweak data performed in ref
The global fit provides current world averages of cg = 0.10(30), = −4.7(78), cH = −1.1(18), all consistent with zero at 2σ. These results are primarily driven by the LHC Run II Higgs measurements, all using 36.1 fb−1 (35.9 fb−1) of data from ATLAS (CMS), since the effect of possible other higher-dimension operators on the backgrounds is not included these bounds should be interpreted with care
Summary
[50] showed that there is information beyond traditional n-prong tagging and even beyond traditional color flow observables [51] This was explored in the context of boosted Higgs boson decays in ref. [77], boosted H → bb has a natural background estimation technique by using the localization of the Higgs boson in the jet mass distribution For this reason, the algorithms presented here may already be useful to enhance existing analysis efforts.
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