109 research outputs found

    Fiducial polarization observables in hadronic WZ production: A next-to-leading order QCD+EW study

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    We present a study at next-to-leading-order (NLO) of the process pp→W±Z→ℓνlℓ′+ℓ′−pp \to W^\pm Z \to \ell \nu_l \ell'^+ \ell'^-, where ℓ,ℓ′=e,μ\ell,\ell' =e, \mu, at the Large Hadron Collider. We include the full NLO QCD corrections and the NLO electroweak (EW) corrections in the double-pole approximation. We define eight fiducial polarization coefficients directly constructed from the polar-azimuthal angular distribution of the decay leptons. These coefficients depend strongly on the kinematical cuts on the transverse momentum or rapidity of the individual leptons. Similarly, fiducial polarization fractions are also defined and they can be directly related to the fiducial coefficients. We perform a detailed analysis of the NLO QCD+EW fiducial polarization observables including theoretical uncertainties stemming from the scale variation and parton distribution function uncertainties, using the fiducial phase space defined by the ATLAS and CMS experiments. We provide results in the helicity coordinate system and in the Collins-Soper coordinate system, at a center-of-mass energy of 13 TeV. The EW corrections are found to be important in two of the angular coefficients related to the ZZ boson, irrespective of the kinematical cuts or the coordinate system. Meanwhile, those EW corrections are very small for the W±W^\pm bosons.Comment: Substantial improvement after useful comments from the anonymous referee: Numerical results for the EW corrections to the cross sections and distributions shifted by -5 (-2)% for ATLAS (CMS) cuts after fixing a bug in the momentum assignment in some cut and histogram routines; results for polarization observables marginally affected, hence conclusions for them unchanged; published versio

    On the triplet anti-triplet symmetry in 3-3-1 models

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    We present a detailed discussion of the triplet anti-triplet symmetry in 3-3-1 models. The full set of conditions to realize this symmetry is provided, which includes in particular the requirement that the two vacuum expectation values of the two scalar triplets responsible for making the W and Z bosons massive must be interchanged. We apply this new understanding to the calculation of processes that have a Z-Z' mixing.Comment: 14 page

    Polarisation at NLO in WZ production at the LHC

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    The pair production of a WW and a ZZ boson at the LHC is an important process to study the triple-gauge boson couplings as well as to probe new physics that could arise in the gauge sector. In particular the leptonic channel pp→W±Z→3ℓ+ν+Xp p \to W^\pm Z\to 3\ell +\nu + X is considered by ATLAS and CMS collaborations. Polarisation observables can help pinning down new physics and give information on the spin of the gauge bosons. Measuring them requires high statistics as well as precise theoretical predictions. We define in this contribution fiducial polarisation observables for the WW and ZZ bosons and we present theoretical predictions in the Standard Model at next-to-leading order (NLO) including QCD as well as NLO electroweak corrections, the latter in the double-pole approximation. We also show that this approximation works remarkably well for W±ZW^\pm Z production at the LHC by comparing to the full results.Comment: 6 pages, 2 figures, 2 tables. Contribution to the proceedings of the 54th Rencontres de Moriond, EW interactions and unified theory, March 16-23 2019, La Thuile, Ital

    Full NLO massive gauge boson pair production at the LHC

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    Electroweak gauge boson pair production is a very important process at the LHC as it probes the non-abelian structure of electroweak interactions and is a background process for many searches. We present full next-to-leading order predictions for the production cross sections and distributions of on-shell massive gauge boson pair production in the Standard Model, including both QCD and electroweak corrections. The hierarchy between the ZZ, WW and WZ channels, observed in the transverse momentum distributions, will be analyzed. We will also present a comparison with experimental data for the total cross sections including a study of the theoretical uncertainties.Comment: 4 pages, 4 figures. Proceeding of the inaugural conference "Windows on the Universe" (August 11-17, Quy Nhon, Vietnam) including updated results compared to arXiv:1307.433

    W-+ H+- production and CP asymmetry at the LHC

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    The dominant contributions to W-+ H+- production at the LHC are the tree-level b anti-b annihilation and the gg fusion. We perform for the case of the complex MSSM a complete calculation of the NLO EW corrections to the b anti-b annihilation channel and a consistent combination with other contributions including the standard and SUSY QCD corrections and the gg fusion, with resummation of the leading radiative corrections to the bottom-Higgs couplings and the neutral Higgs-boson propagators. We observe a large CP-violating asymmetry, arising mainly from the gg channel.Comment: 33 pages, 21 figures, a few typos corrected, one reference adde
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