How to find a Higgs boson with a mass between 155 and 180 GeV at the CERN LHC

Abstract

We reconsider the signature of events with two charged leptons and missing energy as a signal for the detection of the Standard Model Higgs boson in the mass region M (Higgs)=155-180 GeV. It is shown that a few simple experimental criteria allow to distinguish events originating from the Higgs boson decaying to H → W + W − from the non resonant production of W + W − X at the LHC. With this set of cuts, signal to background ratios of about one to one are obtained, allowing a 5-10 σ detection with about 5 f b −1 of luminosity. This corresponds to less than one year of running at the initial lower luminosity L = 10 33 cm −2 s −1 . This is significantly better than for the hitherto considered Higgs detection mode H → Z 0 Z 0 * → 2ℓ + 2ℓ − , where in this mass range about 100 f b −1 of integrated luminosity are required for a 5 σ signal.

Gluon-inducedW-boson pair production at the LHC

“…Although it formally enters only at next-to-next-to-leading order, the importance of the gluon-fusion process is enhanced by experimental Higgs search cuts. These cuts exploit the longitudinal boost and the spin correlations of the W W system to suppress W -pair continuum production through quark-antiquark annihilation [11,12].…”

EffectiveK-factors for gg H WW at the LHC

“…The strategy to separate signal events of the type pp → H → W + W − → ℓ + νℓ ′ −ν from the various backgrounds is based on the ideas described in Ref. [5]. The signal selection proceeds in two steps.…”

“…However, the situation is different if, in addition to some particle identification, the event kinematics has to be exploited to separate the signal from backgrounds. A typical example is the proposed Higgs search in the mass range 155-180 GeV [5], where the identification of the decay H → W + W − → ℓ + νℓ ′ −ν requires a jet veto in order to remove tt events. In addition, other cuts are required, which exploit the spin correlations between the W bosons and the resulting transverse momentum (p T ) spectra of the charged leptons.…”

“…In Section 2 the reweighting technique is introduced. In Section 3 we use PYTHIA to determine the detection efficiency as a function of p H T , using selection criteria based on the ideas given in [5]. These selection criteria are relatively robust and it can be expected that only minor modifications are needed in more accurate detector simulations.…”

An update on the next-to-leading order Monte Carlo MCFM

“…?? we see that shape of contribution of W t process to Dittmar-Dreiner angle [22] modified at next-to-leading order.…”