The top induced backgrounds to Higgs production in the WW -> llvv decay channel at NLO in QCD

Abstract

We present the complete NLO contributions to the pp -> e^+ v_e mu^- vbar_m b bbar + X process in the four flavour scheme, i.e. with massive b quarks, and its contribution to the H -> WW -> llvv measurement in the 1-jet bin at the LHC. This background process includes top pair, single top and non-top quark-resonant contributions. The uncertainty at NLO from renormalisation and factorisation scale dependence is about +30% -20%. We show that the NLO corrections are relatively small, and that separating this background in top pair, Wt and b-quark associated llvv is a fair approximation.

Figures (5)

• Figure 1: Representative LO diagrams for top pair (a), $Wt$ (b) and $b$-quark associated $ll\nu\nu$ (c) contributions to $pp \to e^+ \nu_e \mu^- \bar{\nu}_{\mu} b \bar{b}+X$ production. Top quarks are denoted by double fermion lines.
• Figure 2: Top quark invariant mass computed by taking the invariant mass of the positron, electron-neutrino and the jet containing the $b$ quark, using the same parameters and cuts as in Ref. Denner:2012yc for the $pp \to e^+ \nu_e \mu^- \bar{\nu}_{\mu} b \bar{b}+X$ process. The LO (black solid) and NLO (green dashed) predictions in the 5F scheme and NLO in the 4F scheme (blue solid) are plotted. The green dotted lines show the scale uncertainty on the NLO 5F result.
• Figure 3: Invariant mass of the charged lepton pair for the $pp \to e^+ \nu_e \mu^- \bar{\nu}_{\mu} b \bar{b}+X$ process in the 4F scheme, with the Higgs measurement cuts, apart from the cut on the charged lepton invariant mass $m_{ll}<50$ GeV.
• Figure 4: Azimuthal separation of the charged leptons for the $pp \to e^+ \nu_e \mu^- \bar{\nu}_{\mu} b \bar{b}+X$ process in the 4F scheme, with the Higgs measurement cuts, apart from the cut on the charged lepton invariant mass $|\Delta\phi_{ll}|<1.8$.
• Figure 5: Higgs transverse mass for the $pp \to e^+ \nu_e \mu^- \bar{\nu}_{\mu} b \bar{b}+X$ process in the 4F scheme, with the Higgs measurement cuts.