Complete One-loop Electroweak Corrections Research Articles

Higgs decays to ZZ and Zγ in the standard model effective field theory: An NLO analysis

We calculate the complete one-loop electroweak corrections to the inclusive $H\rightarrow ZZ$ and $H\rightarrow Z\gamma$ decays in the dimension-$6$ extension of the Standard Model Effective Field Theory (SMEFT). The corrections to $H\rightarrow ZZ$ are computed for on-shell $Z$ bosons and are a precursor to the physical $H\rightarrow Z f {\overline{f}}$ calculation. We present compact numerical formulas for our results and demonstrate that the logarithmic contributions that result from the renormalization group evolution of the SMEFT coefficients are larger than the finite NLO contributions to the decay widths. As a by-product of our calculation, we obtain the first complete result for the finite corrections to $G_\mu$ in the SMEFT.

Electroweak radiative corrections to single top production

Radiative corrections to the single top s and t channel production processes are revisited. Complete one-loop electroweak corrections are calculated within the SANC system. New is a study of the regularisation of the top-legs associated infrared divergences with aid of the complex mass of the top quark. A comparison of these electroweak corrections with those computed by the conventional method is presented both for top production and decays. Standard FORM and FORTRAN SANC modules are created. These modules are compiled into a package sanc_cc_v1.40, which may be downloaded from SANC project homepages. Many numerical results are presented at the partonic level with the aim to demonstrate the correct working of modules. These modules are intended to be used in Monte Carlo generators for single top production at the LHC. Where possible, we compare our results with those existing in the literature; in particular, a comprehensive comparison with results of the CompHEP system is given.

One-loop corrections to the Drell–Yan process in SANC

Radiative corrections to the neutral current Drell–Yan-like processes are considered. Complete one-loop electroweak corrections are calculated within the SANC system. Theoretical uncertainties are discussed. Numerical results are presented for typical conditions of LHC experiments.

One-loop corrections to the Drell–Yan process in SANC: the charged current case

Radiative corrections to the charged current Drell–Yan processes are revisited. Complete one-loop electroweak corrections are calculated within the automatic SANC system. Electroweak scheme dependence and the choice of the factorization scale are discussed. Comparisons with earlier calculations are presented.

Full one-loop electroweak and NLO QCD corrections to the associated production of chargino and neutralino at hadron colliders

We study the process of the association production of chargino and neutralino including the NLO QCD and the complete one-loop electroweak corrections in the framework of the minimal supersymmetric standard model(MSSM) at the Fermilab Tevatron and the CERN Large Hadron Collider (LHC). In both the NLO QCD and one-loop electroweak calculations we apply the algorithm of the phase-space slicing(PSS) method. We find that the NLO QCD corrections generally increase the Born cross sections, while the electroweak relative corrections decrease the Born cross section in most of the chosen parameter space. The NLO QCD and electroweak relative corrections typically have the values of about 32% and -8% at the Tevatron, and about 42% and -6% at the LHC respectively. The results show that both the NLO QCD and the complete one-loop electroweak corrections to the processes $p \bar p/pp \to \widetilde{\chi}_1^{\pm} \widetilde{\chi}_2^0+X$ are generally significant and should be taken into consideration in precision experimental analysis.

Full one-loop supersymmetric corrections to charged Higgs boson pair production inγγcollisions

The complete one-loop electroweak corrections to charged Higgs boson pair production in $\ensuremath{\gamma}\ensuremath{\gamma}$ collision mode at linear colliders in the minimal supersymmetric standard model (MSSM), are calculated in this paper. We discuss the dependence of the corrections to the subprocess $\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}{H}^{+}{H}^{\ensuremath{-}}$ on the related parameters, such as the colliding energy, charged Higgs boson mass ${M}_{{H}^{\ifmmode\pm\else\textpm\fi{}}}$ and some supersymmetric parameters $\mathrm{tan}\ensuremath{\beta}$, ${M}_{\mathrm{SUSY}}$ and gaugino mass parameter ${M}_{2}$. We find that the corrections generally reduce the Born cross sections and the relative one-loop corrections to both the subprocess typically in the range of $\ensuremath{-}10%$ to $\ensuremath{-}30%$. We also present the numerical results at the SPS1a' point from the supersymmetry parameter analysis (SPA) project. We conclude that the full one-loop electroweak corrections to subprocess $\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}{H}^{+}{H}^{\ensuremath{-}}$ and the parent process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}{H}^{+}{H}^{\ensuremath{-}}$ are significant and therefore should be considered in precise analysis of charged Higgs boson pair productions via $\ensuremath{\gamma}\ensuremath{\gamma}$ collision at future linear colliders.

Radiative corrections to pair production of charged Higgs bosons in collisions

Abstract Charged Higgs particles are a common feature of many extensions of the Standard Model. While its existence with masses up to the TeV scale can be probed at the Tevatron Run II and LHC hadron colliders, a precise determination of its properties would have to wait for a high energy e + e − linear collider. We have computed the complete one-loop electroweak corrections to the cross-section for charged Higgs bosons pair production in e + e − collisions, in the framework of general Two Higgs Doublet Models, as well as the Minimal Supersymmetric Standard Model. A study is presented for typical values of the model parameters, showing the general behaviour of the corrections.

BHAGENE3, a Monte Carlo event generator for lepton pair production and wide-angle Bhabha scattering in e+e− collisions near the Z peak

A new Monte Carlo event generator for wide-angle Bhabha scattering and muon pair production in e + e − collisions is described. The program includes complete one-loop electroweak corrections, and QED radiative corrections. The O( α) QED correction uses the exact matrix element. Higher-order QED corrections are included in an improved soft photon approximation with exponentiation of initial state radiation. Events are generated in the full phase space of the final state including explicit mass effects in the region of collinear mass singularities. The program is intended for centre of mass energies around and above the Z peak and for Bhabha scattering at angles greater than 10°.

Two-loop O(GF2MH4) corrections to the fermionic decay rates of the Higgs boson.

We calculate the dominant ${\rm O}\left(G_F^2M_H^4\right)$ two-loop electroweak corrections to the fermi\-onic decay widths of a heavy Higgs boson in the Standard Model. Use of the Goldstone-boson equivalence theorem reduces the problem to one involving only the physical Higgs boson $H$ and the Goldstone bosons $w^\pm$ and $z$ of the unbroken theory. The two-loop corrections are opposite in sign to the one-loop electroweak corrections, exceed the one-loop corrections in magnitude for $M_H>1114\ {\rm GeV}$, and increase in relative magnitude as $M_H^2$ for larger values of $M_H$. We conclude that the perturbation expansion in powers of $G_FM_H^2$ breaks down for $M_H\approx 1100\ {\rm GeV}$. We discuss briefly the QCD and the complete one-loop electroweak corrections to $H\rightarrow b\bar{b}, \,t\bar{t}$, and comment on the validity of the equivalence theorem. Finally we note how a very heavy Higgs boson could be described in a phenomenological manner.