Determining the Structure of Higgs Couplings at the CERN Large Hadron Collider

Department of Physics, University of Wisconsin, Madison, Wisconsin, USA.
Physical Review Letters (Impact Factor: 7.51). 03/2002; 88(5):051801. DOI: 10.1103/PhysRevLett.88.051801
Source: PubMed


Higgs boson production via weak boson fusion at the CERN Large Hadron Collider has the capability to determine the dominant CP nature of a Higgs boson, via the tensor structure of its coupling to weak bosons. This information is contained in the azimuthal angle distribution of the two outgoing forward tagging jets. The technique is independent of both the Higgs boson mass and the observed decay channel.

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    • "Angular correlations between jets produced together with heavy particles have been studied actively for a long time, because they can provide important information about the heavy particles [1] [2] [3] [4] [5] [6] [7]. For instance it has been shown that the distribution of the azimuthal angle difference ∆φ = φ 1 − φ 2 between two partons in the gluon fusion production of a Higgs boson plus the two partons is very sensitive to a charge-conjugation and parity (CP) property of the Higgs boson [1] [2] [3] [4] [5]. By observing the ∆φ distribution and comparing it with theoretical predictions, we can measure CP violation in the Higgs sector [3] [4]. "
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    ABSTRACT: A tree level merging algorithm which guarantees the leading order (LO) accuracy of angular correlations between jets is proposed and studied. The algorithm is designed so that n-jet events are generated exclusively according to the LO n-parton production cross section and each of the n-jet is close to each of the n-parton in terms of the jet measure. As a result, the LO accuracy of angular correlations between the n-jet is robust. Furthermore, as long as the n-jet events are exclusively subjects to a study, only the LO n-parton production cross section is needed and hence event generation is efficient. Correlations in the azimuthal angle difference between the two highest transverse momentum jets with large rapidity separations in the top quark pair production are evaluated as examples. The algorithm is validated by discussing numerical differences between its predictions and the predictions of a well-established merging algorithm.
    Preview · Article · Sep 2015
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    • "The production of a Standard-Model (SM) Higgs boson (H 0 ) through the so-called vector-boson-fusion (VBF) mechanism features the secondlargest cross section among the H 0 production channels in hadronic collisions and, although smaller than the gluon-fusion one by about one order of magnitude, it still provides useful complementary informations. After the discovery of a SM-Higgs-like particle [1] [2], the emphasis is rapidly shifting towards the determination of its properties, and in this respect VBF may play an increasingly important role, owing to its sensitivity to various combinations of Higgs couplings [3], which can be studied by considering different decay channels. However, the very distinctive features of VBF, with two jets lying relatively close to the beam line and travelling in opposite directions, render it a challenging case, given that rather severe cuts have to be applied in order to reduce backgrounds (among which, in the coupling measurement perspective, one may count the contamination due to gg → H 0 ). "
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    ABSTRACT: We present a study of Higgs hadroproduction through vector-boson fusion at the NLO in QCD matched with parton showers. We discuss the matching systematics affecting this process through a comparison of the aMC@NLO predictions with the POWHEG and the pure-NLO ones.
    Preview · Article · Apr 2013 · Physics Letters B
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    • "By distinguishing between the CP even and the CP odd coupling terms one obtains information about the CP quantum number of the particle and by distinguishing between the standard model coupling term and the anomalous coupling terms one can test whether the coupling exists at leading order or is mediated by particle loops. In this section a hypothesis test is described in which the shape of the distribution of the azimuthal angles between the tagging jets ∆φ jj is used, as suggested in [2], to distinguish between the different couplings. The method is applied to the case of a standard model Higgs boson for which the prospects for the experimental exclusion of the anomalous couplings are investigated. "
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    ABSTRACT: The prospects for the measurement of the tensor structure of the vertex between a standard model Higgs boson and two weak gauge bosons using the distribution of the azimuthal angles between the two tagging jets in the weak boson fusion channel are studied in a Monte Carlo analysis using the fast simulation of the ATLAS detector. The decay channels H→τ+τ-→ll+4ν, H→τ+τ-→lh+3ν at mH=120GeV and H→W+W-→llνν at mH=160GeV are used in the analysis. For a standard model Higgs boson it is found that purely anomalous couplings are expected to be excluded at a confidence level corresponding to 2σ or more at mH=120GeV and more than 5σ at mH=160GeV from 30fb-1 of data. With a value of 1 roughly reproducing the standard model cross section for a purely anomalous coupling, the standard deviation in a measurement of a contribution of a CP even anomalous coupling in addition to the standard model coupling is estimated to be 0.20 at mH=120GeV and 0.09 at mH=160GeV.
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