Theoretical results for electroweak-boson and single-top production
Nikolaos Kidonakis
备注：
6 pages, 4 figures; presented at the XXIII International Workshop on Deep-Inelastic Scattering and Related Subjects, Dallas, Texas, 27 April - 1 May 2015; to appear in PoS(DIS2015)
I present results from recent high-order calculations for the production of electroweak bosons and top quarks. In particular, I discuss $W$ and $Z$ boson production at large transverse momentum, single-top production, and FCNC top production. Theoretical predictions which include higher-order soft-gluon corrections are presented for total cross sections and differential distributions at the LHC.
The current electroweak data and the constraints on the Higgs mass are discussed. Within the context of the Standard Model the data prefer a relatively light Higgs mass.
We analyze the potential of the CERN Large Hadron Collider (LHC) to study anomalous trilinear vector-boson interactions W^+ W^- γand W^+ W^- Z through the single production of electroweak gauge bosons via the weak boson fusion processes q q -> q q W (-> \ell^\pm ν) and q q -> q q Z(-> \ell^+ \ell^-) with \ell = e or μ. After a careful study of the standard model backgrounds, we show that the single production of electroweak bosons at the LHC can provide stringent tests on deviations of these vertices from the standard model prediction. In particular, we show that single gauge boson production …
We formulate the equivalence between the longitudinal weak-boson and the Goldstone boson as a criterion for sensitively probing the electroweak symmetry breaking mechanism and develop a precise power counting rule for chiral Lagrangian formulated electroweak theories. With these we semi-quatitatively analyze the sensitivities to various effective operators related to electrowaeak symmetry breaking via weak-boson scatterings at the CERN Large Hadron Collider (LHC).
In this comment we present an analysis of electroweak neutral triple gauge boson couplings projected out of the gauge sector of the extended non-commutative standard model. A brief overview of the current experimental situation is given.
We present strong indirect evidence for the contribution of bosonic electroweak corrections in the Standard Model. Although important conceptually, these corrections give subleading contributions in current high energy experiments, and it was previously thought that they are difficult to detect. We also discuss the separate contribution of the Higgs boson.
We analyse diffractive electroweak vector boson production in hadronic collisions and show that the single diffractive W boson production asymmetry in rapidity is a particularly good observable at the LHC to test the concept of the flavour symmetric pomeron parton distributions. It may also provide an additional constraint for the parton distribution functions in the proton.
The interactions of electroweak gauge bosons are severely constrained by the symmetries inferred from low energy observables. The exploration of the dynamics of electroweak symmetry breaking requires therefore both an experimental sensitivity and a theoretical precision that is better than the natural scale of deviations from minimal extrapolations of the low energy effective theory. Some techniques for obtaining improved theoretical predictions for precision tests at a future e^+e^- linear collider are discussed.
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We present some results of a new calculation of the O(alpha) electroweak radiative corrections to W boson production at hadron colliders with special emphasis on the transverse mass distribution.
If no light Higgs boson exist, the interaction among the gauge bosons becomes strong at high energies (~1TeV). The effects of strong electroweak symmetry breaking (SEWSB) could manifest themselves as anomalous couplings before they give rise to new physical states, thus measurement of all couplings and their possible deviation from Standard Model (SM) values could give valuable information for understanding the true nature of symmetry breaking sector. Here we present a detailed study of the measurement of quartic gauge couplings in weak boson scattering processes and a possibility for same mea…
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We discuss the O(alpha) electroweak radiative corrections to W boson production at the Tevatron and their effect on the W boson mass extracted by experiment. The results of a new calculation of the O(alpha) corrections are presented and compared with those of a previous calculation. We also briefly discuss the O(alpha) corrections to Z boson production at the Tevatron and two-photon radiation in W and Z events.
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Transverse and longitudinal electroweak gauge boson parton distribution functions (PDFs) are computed in terms of deep-inelastic scattering structure functions, following the recently developed method to determine the photon PDF. The calculation provides initial conditions at the electroweak scale for PDF evolution to higher energies. Numerical results for the $W^\pm$ and $Z$ transverse, longitudinal and polarized PDFs, as well as the $γZ$ transverse and polarized PDFs are presented.
A locally SU(2)xU(1)-invariant term of dimension six with effective interactions of the electroweak gauge and Higgs fields is examined. This term also contains higher derivatives of the fields. It yields nonstandard quartic gauge-boson self-interactions but neither nonstandard cubic self-interactions nor tree-level effects on presently measurable quantities.
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The current theoretical understanding of anomalous gauge boson couplings is reviewed, and the direct measurement of these couplings in present and future hadron collider experiments is briefly discussed.
The study of gauge bosons is interesting in two respects. The properties of gauge bosons are modified by higher order effects that are sensitive to mass scales not directly accessible to experiment. On the other hand interactions amongst gauge bosons are sensitive to the symmetry structure of the theory where especially the interactions involving longitudinally polarised bosons teach us about the mechanism of electroweak symmetry breaking. This article explains how far a linear collider can increase our knowledge about the properties of and the interactions amongst gauge bosons.
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Radiative corrections of strong and electroweak interactions are presented at next-to-leading order for Higgs-boson production in the weak-boson-fusion channel at the LHC. The calculation includes all weak-boson fusion and quark-antiquark annihilation diagrams as well as all related interferences. The electroweak corrections, which also include real corrections from incoming photons and leading heavy-Higgs-boson effects at two-loop order, are of the same size as the QCD corrections, viz. typically at the level of 5-10% for a Higgs-boson mass up to \sim 700 GeV. In general, they do not simply r…
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Until recently precision electroweak computations were fundamentally uncertain due to lack of knowledge about the existence of the Standard Model Higgs boson and its mass. For this reason substantial calculational machinery had to be carried along for each calculation that changed the Higgs boson mass and other parameters of the Standard Model. Now that the Higgs boson is discovered and its mass is known to within a percent, we are able to compute reliable semi-analytic expansions of electroweak observables. We present results of those computations in the form of expansion formulae. In additio…
The complete set of two-loop electroweak corrections to the decay width of the Higgs boson into two photons is presented. Two-loop contributions involving weak bosons and the top quark are computed in terms of an expansion in the Higgs external momentum. Adding these results to the previously known light fermion contributions, we find that the total electroweak corrections for a Higgs boson with 100 GeV <m_H < 150 GeV are moderate and negative, between -4% < delta_EW < 0%. Combination with the QCD corrections, which are small and positive, gives a total correction to the one-loop results of | …
We present results on the strong and electroweak NLO corrections to the production of a Higgs boson plus two hard jets via weak interactions at the LHC. The calculation includes all weak-boson fusion and quark-antiquark annihilation diagrams as well as all related interferences. We discuss corrections of different origin (QCD corrections of vector-boson-fusion type and interferences, electroweak corrections induced by quark or photonic initial states, heavy-Higgs-boson effects, etc.) and give some new results for distributions for a Higgs-boson mass of 200 GeV. The electroweak corrections are …
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We present a detailed evaluation of the bosonic two-loop electroweak corrections to the muon's anomalous magnetic moment. We study the Higgs mass dependence and find agreement with a previous evaluation in the large Higgs mass limit. We find $a_μ^{\rm EW bos}({two-loop})=(-22.2 \pm 1.6)\times 10^{-11}$, for $114 {\rm GeV} \le M_{\rm Higgs}\le 700 {\rm GeV}$.
The "non-linear" self-consistent theory of classical fields in the electroweak model is proposed. Homogeneous boson ground state solutions in the GSW model at the presence of a non-zero extended fermionic charge densities are reviewed and fully reinterpreted to make the theory with non-zero charge densities fruitful. Consequences of charge density fluctuations are proposed.
We analyse diffractive weak boson production in $pp$ collisions. We show that the measurement of $W$ boson production asymmetry in the diffractive $pp$ collisions is a valuable method to test the concept of the flavour symmetric pomeron parton distributions.
We have studied the effect of one-loop logarithmic electroweak radiative corrections on WZ and $Wγ$ production processes at the LHC. We present analytical results for the leading-logarithmic electroweak corrections to the corresponding partonic processes du -> WZ, Wgamma. Using the leading-pole approximation we implement these corrections into Monte Carlo programs for $pp\to lν_l l'\bar l', lν_lγ$. We find that electroweak corrections lower the predictions by 5-20% in the physically interesting region of large transverse momentum and small rapidity separation of the gauge bosons.
I review constraints on the Standard Model (SM) Higgs boson from high energy electroweak (EW) precision data. The same data set also strongly limits various mixing effects of hypothetical extra neutral gauge bosons (Z') with the ordinary Z. I also discuss low energy precision measurements which are sensitive to other aspects of Z' physics, such as the direct exchange amplitude and the flavor or CP violating sectors.
The soft function relevant for the production of an electroweak boson (photon, W, Z or H) with large transverse momentum at a hadron collider is computed at next-to-next-to-leading order. This is the first two-loop computation of a soft function involving three light-cone directions. With the result, the threshold resummation for these processes can now be performed at next-to-next-to-next-to-leading logarithmic accuracy.
A review of the calculation of the leading three-loop electroweak corrections to the rho-parameter, sin^2 theta_eff and the W-boson mass is presented. The heavy Higgs mass expansion and the renormalization are discussed.
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In this Snowmass 2013 white paper, we review the effective field theory approach for studies of non-standard electroweak interactions in electroweak vector boson pair and triple production and vector boson scattering. We present an overview of the implementation of dimension six and eight operators in MadGraph5, VBFNLO, and WHIZARD, and provide relations between the coefficients of these higher dimensions operators used in these programs and in the anomalous couplings approach. We perform a tuned comparison of predictions for multi-boson processes including non-standard electroweak interaction…
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The fit of precision electroweak data to the Minimal Standard Model currently gives an upper limit on the Higgs boson mass of 170 GeV at 95% confidence. Nevertheless, it is often said that the Higgs boson could be much heavier in more general models. In this paper, we critically review models that have been proposed in the literature that allow a heavy Higgs boson consistent with the precision electroweak constraints. All have unusual features, and all can be distinguished from the Minimal Standard Model either by improved precision measurements or by other signatures accessible to next-genera…
We compute the contribution of three-loop mixed QCD-electroweak corrections ($α_S^2α^2$) to the $gg \to H$ scattering amplitude. We employ the method of differential equations to compute the relevant integrals and express them in terms of Goncharov polylogarithms.
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