768 research outputs found

    Exploiting the WH/ZH symmetry in the search for New Physics

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    We suggest to isolate the loop-induced gluon-initiated component (gg→ZHgg\to ZH) for associated ZHZH production by using the similarity of the Drell-Yan-like component for ZHZH production to the WHWH process. We argue that the cross-section ratio of the latter two processes can be predicted with high theoretical accuracy. Comparing it to the experimental ZH/WHZH/WH cross-section ratio should allow to probe for New Physics in the gg→ZHgg\to ZH component at the HL-LHC. We consider typical BSM scenarios in order to exemplify the effect they would have on the proposed observable.Comment: 22 pages, 10 figures. v2: Minor changes; matches published versio

    Measurement of the t(t)over-bar production cross section in the dilepton channel in pp collisions at √s=8 TeV

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    The top-antitop quark (t (t) over bar) production cross section is measured in proton-proton collisions at root s = 8 TeV with the CMS experiment at the LHC, using a data sample corresponding to an integrated luminosity of 5.3 fb(-1). The measurement is performed by analysing events with a pair of electrons or muons, or one electron and one muon, and at least two jets, one of which is identified as originating from hadronisation of a bottom quark. The measured cross section is 239 +/- 2 (stat.) +/- 11 (syst.) +/- 6 (lum.) pb, for an assumed top-quark mass of 172.5 GeV, in agreement with the prediction of the standard model

    Higgs Strahlung at the Large Hadron Collider in the 2-Higgs-Doublet Model

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    We present a calculation of all relevant contributions to associated production of a Higgs boson with a weak gauge boson in the 2-Higgs-Doublet Model (2HDM) at the LHC, pp→Vϕpp \rightarrow V\phi, with ϕ∈{h,H0,A}\phi\in\{h,H^0,A\} and V∈{W,Z}V\in\{W,Z\}. While for the WϕW\phi mode, this mostly amounts to a simple rescaling of the Standard Model (SM) cross section, the ZϕZ\phi cross section depends on several 2HDM parameters. The ratio σWϕ/σZϕ\sigma^{W\phi}/\sigma^{Z\phi}, for which we present the currently most complete SM prediction, therefore appears to be a sensitive probe of possible New Physics effects. We study its numerical dependence on the top and bottom Yukawa couplings, including their sign. Furthermore, we consider the Wϕ/ZϕW\phi/Z\phi ratio in exemplary 2HDM scenarios and briefly address the effects in the boosted regime. Analogous studies for other 2HDM scenarios will become possible with an upcoming version of the program vh@nnlo which incorporates the 2HDM effects.Comment: 32 pages, 18 figures; v2: discussion of boosted regime added, typos corrected, references added, version published in JHE

    Higgs and Z boson associated production via gluon fusion in the SM and the 2HDM

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    We analyse the associated production of Higgs and ZZ boson via heavy-quark loops at the LHC in the Standard Model and beyond. We first review the main features of the Born 2→22\to 2 production, and in particular discuss the high-energy behaviour, angular distributions and ZZ boson polarisation. We then consider the effects of extra QCD radiation as described by the 2→32 \to 3 loop matrix elements, and find that they dominate at high Higgs transverse momentum. We show how merged samples of 0-- and 1--jet multiplicities, matched to a parton shower can provide a reliable description of differential distributions in ZHZH production. In addition to the Standard Model study, results in a generic two-Higgs-doublet-model are obtained and presented for a set of representative and experimentally viable benchmarks for Zh0Zh^0, ZH0ZH^0 and ZA0ZA^0 production. We observe that various interesting features appear either due to the resonant enhancement of the cross-section or to interference patterns between resonant and non-resonant contributions.Comment: 29 pages, 12 figure

    Associated production of Higgs boson with vector boson at threshold N3^3LO in QCD

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    We present the results for the associated production of Higgs boson with vector boson computed at threshold N3^3LO in QCD. We use the recently available result on the threshold contributions to the inclusive Drell-Yan production cross-section at third order in strong coupling constant. We have implemented it in the publicly available computer package vh@nnlo, thereby obtaining the numerical impact of threshold N3^3LO contributions for the first time. We find that the inclusion of such corrections do reduce theoretical uncertainties resulting from the renormalization scale.Comment: 14 pages, 3 figure

    Prospects for Higgs physics at energies up to 100 TeV

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    We summarise the prospects for Higgs boson physics at future proton-proton colliders with centre of mass (c.m.) energies up to 100 TeV. We first provide the production cross sections for the Higgs boson of the Standard Model from 13 TeV to 100 TeV, in the main production mechanisms and in subleading but important ones such as double Higgs production, triple production and associated production with two gauge bosons or with a single top quark. We then discuss the production of Higgs particles in beyond the Standard Model scenarios, starting with the one in the continuum of a pair of scalar, fermionic and vector dark matter particles in Higgs-portal models in various channels with virtual Higgs exchange. The cross sections for the production of the heavier CP-even and CP-odd neutral Higgs states and the charged Higgs states in two-Higgs doublet models, with a specific study of the case of the Minimal Supersymmetric Standard Model, are then given. The sensitivity of a 100 TeV proton machine to probe the new Higgs states is discussed and compared to that of the LHC with a c.m. energy of 14 TeV and at high luminosity.Comment: 61 pages, 16 figures, 6 tables; review article. v2: numbers and figures updated, aknowledgments modified, references added and typos corrected. Matches the published versio

    vh@nnlo-v2: new physics in Higgs Strahlung

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    Introducing version 2 of the code vh@nnlo [1], we study the effects of a number of new-physics scenarios on the Higgs-Strahlung process. In particular, the cross section is evaluated within a general 2HDM and the MSSM. While the Drell-Yan-like contributions are consistently taken into account by a simple rescaling of the SM result, the gluon-initiated contribution is supplemented by squark-loop mediated amplitudes, and by the s-channel exchange of additional scalars which may lead to conspicuous interference effects. The latter holds as well for bottom-quark initiated Higgs Strahlung, which is also included in the new version of vh@nnlo. Using an orthogonal rotation of the three Higgs CP eigenstates in the 2HDM and the MSSM, vh@nnlo incorporates a simple means of CP mixing in these models. Moreover, the effect of vector-like quarks in the SM on the gluon-initiated contribution can be studied. Beyond concrete models, vh@nnlo allows to include the effect of higher-dimensional operators on the production of CP-even Higgs bosons. Transverse momentum distributions of the final state Higgs boson and invariant mass distributions of the VÏ• final state for the gluon- and bottom-quark initiated contributions can be studied. Distributions for the Drell-Yan-like component of Higgs Strahlung can be included through a link to MCFM. vh@nnlo can also be linked to FeynHiggs and 2HDMC for the calculation of Higgs masses and mixing angles. It can also read these parameters from an SLHA-file as produced by standard spectrum generators. Throughout the manuscript, we highlight new-physics effects in various numerical examples, both at the inclusive level and for distributions
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