Abstract
A search for Higgs boson pair production in the boverline{b}W{W}^{*} decay mode is performed in the boverline{b}mathit{ell nu qq} final state using 36.1 fb−1 of proton-proton collision data at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. No evidence of events beyond the background expectation is found. Upper limits on the non-resonant pp → HH production cross section of 10 pb and on the resonant production cross section as a function of the HH invariant mass are obtained. Resonant production limits are set for scalar and spin-2 graviton hypotheses in the mass range 500 to 3000 GeV.
Highlights
A search for Higgs boson pair production in the bbW W ∗ decay mode is performed in the bb νqq final state using 36.1 fb−1 of proton-proton collision data at a centreof-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider
The dominant background in the bbW W ∗ final state is ttproduction, with smaller contributions from W bosons produced in association with jets (W +jets) and multijet events in which a jet is misidentified as a lepton
The mass of the HH system (mHH) distribution of the multijet background is estimated by subtracting the prompt-lepton Monte Carlo (MC) backgrounds from the data in the 1-tag region, where the 1-tag region is defined as the region where all selections are applied except that the large-R jet is required to have only one track jet tagged as a b jet
Summary
The ATLAS detector [27] is a general-purpose particle detector at the Large Hadron Collider optimised to discover and measure a broad range of physics processes. The graviton signal samples were generated at leading order (LO) with Madgraph aMC@NLO [30] using the NNPDF2.3 [31] LO parton distribution function (PDF) set, and Pythia 8.186 [32] to model the parton showers and hadronisation process with a set of tuned underlyingevent parameters called the A14 tune [33]. The non-resonant signal samples were simulated with Madgraph aMC@NLO + Herwig++ using the CT10 PDF set; and the same approach for the inclusion of finite mt effects was used [37]. The effect of multiple pp interactions in the same and neighbouring bunch crossings (pile-up) was included by overlaying minimum-bias collisions, simulated with Pythia 8.186, on each generated signal and background event. The generated samples were processed through a Geant4-based detector simulation [54, 55] with the standard ATLAS reconstruction software used for collision data
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