Search for boosted vector boson scattering $W^{\pm}W^{\pm}H$ production in final states with same-sign leptons and $b$-jets in proton-proton collisions at $\sqrt{s}=$13 TeV with the ATLAS detector

Abstract

A search for the electroweak production of a Higgs boson in association with a same-sign $W$ boson pair and two forward jets ($W^{\pm}W^{\pm}Hjj$) is presented. The full Run 2 proton-proton collision dataset recorded at a center-of-mass energy of $\sqrt{s}=13$ TeV by the ATLAS detector at the Large Hadron Collider is used, corresponding to an integrated luminosity of 140 fb$^{-1}$. The search targets events where both $W$ bosons decay leptonically, yielding a final state with two same-sign charged leptons, missing transverse momentum, and a Higgs boson candidate. The high-momentum Higgs-boson candidate decaying into a $b\bar{b}$ pair is reconstructed as a single large-radius jet. This process provides direct sensitivity to the quartic $WWHH$ interaction. Possible deviations from the Standard Model prediction are parameterized through the coupling modifier $κ_{WW}$, where $κ_{WW}=1$ corresponds to the Standard Model. No significant excess over the Standard Model prediction is observed. Upper limits at the 95% confidence level are set on the $W^{\pm}W^{\pm}Hjj$ production cross-section as a function of $κ_{WW}$. Observed (expected) values of $κ_{WW}$ outside the interval $-2.1 < κ_{WW} < 4.1$ ($-1.9 < κ_{WW} < 3.9$) are excluded.