Article

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
ABSTRACT
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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    • ", where φ 1,2 are azimuthal angles of the two jets measured from the production plane of the Higgs boson pair (∆φ is irrelevant to the production plane as is clear from its definition). ∆φ is the observable which is sensitive to the property of the Higgs boson in the process pp → Hjj [44][45][46][47] 49] and thus has been the subject of many studies. The processes pp → Gjj [47] and pp → Q ¯ Qjj [50] exhibit strong correlations in φ + . "
    [Show abstract] [Hide abstract] ABSTRACT: Azimuthal angle correlations of two jets in the process $pp\to HHjj$ are studied. The loop induced $\mathcal{O}(\alpha_s^4 \alpha_{}^2)$ gluon fusion (GF) sub-process and the $\mathcal{O}(\alpha_{}^4)$ weak boson fusion (WBF) sub-process are considered. The GF sub-process exhibits strong correlations in the azimuthal angles $\phi_{1,2}^{}$ of the two jets measured from the production plane of the Higgs boson pair and the difference between these two angles $\phi_1^{}-\phi_2^{}$, and a very small correlation in the sum of them $\phi_1^{}+\phi_2^{}$. The impact of using a finite top mass $m_t^{}$ value on the correlations is found crucial. The transverse momentum of the Higgs boson can be used to enhance or suppress the correlations. The impact of a non-standard value for the triple Higgs self-coupling on the correlations is found much smaller than that on other observables, such as the invariant mass of the two Higgs bosons. The peak shifts of the azimuthal angle distributions reflect the magnitude of parity violation in the $gg\to HH$ amplitude and the dependence of the distributions on parity violating phases is analytically clarified. The WBF sub-process also produces correlated distributions and it is found that they are not induced by the quantum effect of the intermediate weak bosons but mainly by a kinematic effect. This kinematic effect is a characteristic feature of the WBF sub-process and is not observed in the GF sub-process. It is found that the correlations are different in the GF and in the WBF sub-processes. As part of the process dependent information, they will be helpful in the analyses of both the GF sub-process and the WBF sub-process at the LHC.
    Preview · Article · Mar 2016
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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]. "
    [Show abstract] [Hide abstract] 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 Higgs boson in the VBF channel is phenomenologically highly relevant, as it allows to measure the couplings between electroweak gauge bosons and the Higgs boson. It also provides sensitivity to the CP -structure of the Higgs couplings [141], as well as access to possible anomalous couplings in both the Higgs sector and the electroweak sector of the Standard Model. "
    [Show abstract] [Hide abstract] ABSTRACT: We present a detailed phenomenological analysis of the production of a Standard Model Higgs boson in association with up to three jets. We consider the gluon fusion channel using an effective theory in the large top-quark mass limit. Higgs boson production in gluon fusion constitutes an irreducible background to the vector boson fusion (VBF) process; hence the precise knowledge of its characteristics is a prerequisite for any measurement in the VBF channel. The calculation is carried out at next-to-leading order (NLO) in QCD in a fully automated way by combining the two programs GoSam and Sherpa. We present numerical results for a large variety of observables for both standard cuts and VBF selection cuts. We find that for all jet multiplicities the NLO corrections are sizeable. This is particularly true in the presence of kinematic selections enhancing the VBF topology, which are based on vetoing additional jet activity. In this case, precise predictions for the background can be made using our calculation by taking the difference between the inclusive H+2 jets and the inclusive H+3 jets result.
    Full-text · Article · Jun 2015 · Journal of High Energy Physics
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