Hadronic production of a Higgs boson in association with two jets at ...

6.5. LHC results 157troweak process is expected to dominate once appropriate search cuts are employed,the remaining fraction of events originating from gluon fusion must be taken intoaccount when considering potential measurements of the Higgs coupling to W andZ bosons.To address this issue, in this section we present a brief study of the rate of eventsexpected using typical weak boson fusion search cuts. In addition to the cuts alreadyimposed (Eq. (6.14)), these correspond to,|η j1 − η j2 | > 4.2 , η j1 · η j2 < 0 , (6.15)where j 1 and j 2 are the two jets with the highest transverse momenta. These cutspick out the distinctive signature of two hard jets in opposite hemispheres separatedby a large distance in pseudorapidity. This is illustrated in Fig6.3, where we comparethe distributions of the jet pseudorapidity difference (without these cuts) in bothgluon fusion and weak boson fusion. We note in passing that the shape of thisdistribution for the weak boson fusion process is slightly altered at NLO, whilst theshape of the prediction for the gluon fusion process is essentially unchanged.In Fig 6.4 we show the dependence of the cross section on the c.o.m. energy,from √ s = 7 TeV (corresponding to the initial running in 2010-11) to √ s = 14 TeV(design expectations). We show the cross section both before and after applicationof the additional weak boson fusion search cuts given in Eq. (6.15), together withthe corresponding results for the WBF process (also calculated using MCFM [99]).The QCD corrections to both processes decrease slightly as √ s is increased, whilstthe ratio of the gluon fusion to WBF cross sections after the search cuts are appliedincreases from 20% at 7 TeV to 35% at 14 TeV. This indicates that, viewed as abackground to the weak boson fusion process, the hadronic Higgs + 2 jet process isless troublesome at energies below the nominal design value.6.5.2 Dynamic versus fixed scale choicesWe wish to study the effects of different scale choices on our results. It has been noted[179–181] in W +3j calculations that certain fixed scale choices do a rather poor job