Order Electroweak Corrections Research Articles

Logarithmic EW corrections at one-loop

We present a fully automated implementation of next-to-leading order electroweak (NLO EW) corrections in the logarithmic approximation in OpenLoops. For energies above the electroweak scale NLO EW corrections are logarithmically enhanced and in tails of kinematic distributions of crucial LHC processes yield correction factors of several tens of percent. The implementation of the logarithmic Sudakov EW approximation in the amplitude generator OpenLoops is fully general, largely model independent, it supports the computation of EW corrections to resonant processes, and it is suitable for extensions to the two-loop NNLO EW level. The implementation is based on an efficient representation of the logarithmic approximation in terms of an effective vertex approach. Investigating a set of representative LHC processes we find excellent agreement between the logarithmic approximation and full one-loop results in observables where the assumptions of the EW Sudakov approximation are fulfilled.

Two-loop electroweak corrections to the Higgs boson rare decay process H→Zγ

Recently, the ATLAS and CMS collaborations jointly announced the first evidence of the rare Higgs boson decay channel H→Zγ, with a ratio of 2.2±0.7 times the leading order standard model (SM) prediction. In order to face this challenge, it is urgent to produce an even more accurate calculation within the SM. To this end, we calculate in this paper the next-to-leading order (NLO) electroweak (EW) corrections to the H→Zγ process, in which the NLO quantum chromodynamics (QCD) corrections were found tiny. Our calculation finds that the inclusion of NLO EW corrections greatly enhances the prediction reliability. To tame the theoretical uncertainty, we adopt five different renormalization schemes. Combining our result with previous NLO QCD corrections and the signal-background interference, we conclude that the excess in H→Zγ cannot be explained within the SM. In fact, the incompatibility between the SM prediction and the LHC measurement of the concerned process is exacerbated upon considering the higher order EW corrections, which implies that something beyond the SM could be involved. Published by the American Physical Society 2024

Electroweak Corrections to Double Higgs Production at the LHC.

We present the results for the complete next-to-leading order electroweak corrections to pp→HH at the Large Hadron Collider, focusing on the dominant gluon-gluon fusion process. While the corrections at the total cross-section level are approximately -4%, those near the energy of HH production threshold exceed +15%, and corrections at the high-energy region are around -10%, leading to a shape distortion for the differential distributions. Our findings substantially diminish the theoretical uncertainties associated with this pivotal process, providing valuable input for understanding the shape of the Higgs boson potential upon comparison with experimental measurements.

QCD corrections to the Golden decay channel of the Higgs boson

Future colliders aim to provide highly precise experimental measurements of the properties of the Higgs boson. In order to benefit from these precision machines, theoretical errors in the Higgs sector observables have to match at least the experimental uncertainties. The theoretical uncertainties in the Higgs sector observables can be reduced by including missing higher-order terms in their perturbative calculations. In this direction, we compute the mixed QCD-electroweak corrections at \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{O}\\left({\\alpha \\alpha }_{s}\\right)$$\\end{document} to the Higgs decay into four charged leptons by considering the golden decay channel, H → e+e−μ+μ−. Due to color conservation, these corrections receive contributions only from the two-loop virtual diagrams. In the complex mass scheme, we find that the mixed QCD-electroweak corrections to the partial decay width, relative to the leading order predictions, are positive and about 0.27% for αs(MZ). Relative to the next-to-leading order electroweak corrections, the mixed QCD-electroweak corrections are found to be approximately 18% for αs(MZ). With respect to the leading order, we observe a flat effect of the mixed QCD-electroweak corrections on the invariant mass distribution of the lepton pairs with fixed QCD coupling. The ϕ distribution, due to the mixed QCD-electroweak corrections, follows a (1 − cos ϕ) dependence.

NLO electroweak corrections to doubly-polarized W+W-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$W^+W^-$$\\end{document} production at the LHC

We present new results of next-to-leading order (NLO) electroweak corrections to doubly-polarized cross sections of W+W-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$W^+W^-$$\\end{document} production at the LHC. The calculation is performed for the leptonic final state of e+μeμ-ν¯μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$e^{+}\\mu _{e} \\mu ^{-} {\\bar{\ u }}_{\\mu }$$\\end{document} using the double-pole approximation in the diboson center-of-mass frame. NLO QCD corrections and subleading contributions from the gg, bb¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$b{\\bar{b}}$$\\end{document}, γγ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma \\gamma $$\\end{document} induced processes are taken into account in the numerical results. We found that NLO EW corrections are small for angular distributions but can reach tens of percent for transverse momentum distributions at high energies, e.g. reaching -40%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-40\\%$$\\end{document} at pT,e≈300\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p_{T,e}\\approx 300$$\\end{document} GeV. In these high pT\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p_T$$\\end{document} regions, EW corrections are largest for the doubly-transverse mode.

Electroweak corrections to g + g → Hl,h and Hl,h→ γ + γ in the Higgs-singlet extension of the Standard model

We calculate the next-to-leading order electroweak corrections for Higgs-boson production in gluon fusion and the Higgs-boson decay into two photons or gluons in the real Higgs-singlet extension of the Standard model (HSESM). For the light Higgs-boson of the HSESM the electroweak corrections for these processes are of the same order of magnitude as in the Standard model. For the heavy Higgs-boson of the HSESM the electroweak corrections can become large depending on the considered scenario.

Next-to-leading order electroweak corrections to gg → HH and gg → gH in the large-mt limit

We compute two-loop electroweak corrections to Higgs boson pair and Higgs plus jet production, taking into account all sectors of the Standard Model. All diagrams with virtual top quarks are computed in an expansion for large top quark mass up to order 1/mt8\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {m}_t^8 $$\\end{document} or more. We present analytic results for the form factors and discuss the convergence properties. For the process gg → gH we also consider QCD corrections in the large-mt limit.

Combining QED and QCD transverse-momentum resummation for W and Z boson production at hadron colliders

In this article, we consider the transverse momentum (qT) distribution of W and Z bosons produced in hadronic collisions. We combine the qT resummation for QED and QCD radiation including the QED soft emissions from the W boson in the final state. In particular, we perform the resummation of enhanced logarithmic contributions due to soft and collinear emissions at next-to-leading accuracy in QED, leading-order accuracy for mixed QED-QCD and next-to-next-to-leading accuracy in QCD. In the small-qT region we consistently include in our results the next-to-next-to-leading order (i.e. two loops) QCD corrections and the next-to-leading order (i.e. one loop) electroweak corrections. The matching with the fixed-order calculation at large qT has been performed at next-to-leading order in QCD (i.e. at mathcal{O}left({alpha}_S^2right) ) and at leading order in QED. We show numerical results for W and Z production at the Tevatron and the LHC. Finally, we consider the effect of combined QCD and QED resummation for the ratio of W and Z qT distributions, and we study the impact of the QED corrections providing an estimate of the corresponding perturbative uncertainties.

Doubly-polarized WZ hadronic cross sections at NLO QCD + EW accuracy

We present new results for next-to-leading order (NLO) electroweak (EW) corrections to double polarization signals in the WZ production channel at the LHC using the e^+nu _e mu ^+ mu ^- final state. It is found that the EW corrections are most sizable in the transverse momentum distributions of the doubly longitudinal polarization, being around -,10% compared to the NLO QCD prediction at p_{T,e}approx 200 GeV, which is in the accessible energy range of the current LHC data.

Radiative corrections to decays of charged Higgs bosons in two Higgs doublet models

We calculate the next-to-leading order (NLO) electroweak (EW) corrections to decay rates of charged Higgs bosons for various decay modes in the four types of two Higgs doublet models (THDMs) with the softly broken discrete Z2 symmetry. Decay branching ratios of charged Higgs bosons are evaluated including NLO EW corrections, as well as QCD corrections up to next-to-next-to-leading order (NNLO). We comprehensively study impacts of the NLO EW corrections to the branching ratios in nearly alignment scenarios where the couplings constants of the Higgs boson with the mass of 125 GeV are close to those predicted in the standard model. Furthermore, in the nearly alignment scenario, we discuss whether or not the four types of THDMs can be distinguished via the decays of charged Higgs bosons. We find that characteristic predictions of charged Higgs branching ratios can be obtained for all types of the THDMs, by which each type of the THDMs is separated, and information on the internal parameters of the THDMs can be extracted from the magnitudes of the various decay branching ratios.

One-loop corrections to the Higgs boson invisible decay in the dark doublet phase of the N2HDM

The Higgs invisible decay width may soon become a powerful tool to probe extensions of the Standard Model with dark matter candidates at the Large Hadron Collider. In this work, we calculate the next-to-leading order (NLO) electroweak corrections to the 125 GeV Higgs decay width into two dark matter particles. The model is the next-to-minimal 2-Higgs-doublet model (N2HDM) in the dark doublet phase, that is, only one doublet and the singlet acquire vacuum expectation values. We show that the present measurement of the Higgs invisible branching ratio, BR(H → invisible < 0.11), does not lead to constraints on the parameter space of the model at leading order. This is due to the very precise measurements of the Higgs couplings but could change in the near future. Furthermore, if NLO corrections are required not to be unphysically large, no limits on the parameter space can be extracted from the NLO results.

On the evaluation of two-loop electroweak box diagrams for e+e\u2212 \u2192 HZ production

Precision studies of the Higgs boson at future e+e− colliders can help to shed light on fundamental questions related to electroweak symmetry breaking, baryogenesis, the hierarchy problem, and dark matter. The main production process, e+e−→ HZ, will need to be controlled with sub-percent precision, which requires the inclusion of next-to-next-to-leading order (NNLO) electroweak corrections. The most challenging class of diagrams are planar and non-planar double-box topologies with multiple massive propagators in the loops. This article proposes a technique for computing these diagrams numerically, by transforming one of the sub-loops through the use of Feynman parameters and a dispersion relation, while standard one-loop formulae can be used for the other sub-loop. This approach can be extended to deal with tensor integrals. The resulting numerical integrals can be evaluated in minutes on a single CPU core, to achieve about 0.1% relative precision.

Searching for New Physics with \(\bar {\mathcal {B}}(B_{s,d}\to \mu \bar \mu )/\Delta M_{s,d}\)

We reemphasize that the ratio $R_{s\mu} \equiv \overline{\mathcal{B}}(B_s\to\mu\bar\mu)/\Delta M_s$ is a measure of the tension of the Standard Model (SM) with latest measurements of $\overline{\mathcal{B}}(B_s\to\mu\bar\mu)$ that does not suffer from the persistent puzzle on the $|V_{cb}|$ determinations from inclusive versus exclusive $b\to c\ell\bar\nu$ decays and which affects the value of the CKM element $|V_{ts}|$ that is crucial for the SM predictions of both $\overline{\mathcal{B}}(B_s\to\mu\bar\mu)$ and $\Delta M_s$, but cancels out in the ratio $R_{s\mu}$. In our analysis we include higher order electroweak and QED corrections und adapt the latest hadronic input to find a tension of about $2\sigma$ for $R_{s\mu}$ measurements with the SM independently of $|V_{ts}|$. We also discuss the ratio $R_{d\mu}$ which could turn out, in particular in correlation with $R_{s\mu}$, to be useful for the search for New Physics, when the data on both ratios improves. Also $R_{d\mu}$ is independent of $|V_{cb}|$ or more precisely $|V_{td}|$.

Precise predictions for double-Higgs production via vector-boson fusion

Theoretical predictions with next-to-next-to-leading order (NNLO) QCD accuracy combined with the next-to-leading order (NLO) electroweak (EW) corrections are presented for differential observables of the double-Higgs production process via vector-boson fusion. While the QCD corrections were previously known, the EW ones are computed here for the first time. The numerical results are obtained for a realistic experimental set-up at the LHC and are presented in the form of fiducial cross sections and differential distributions. Within this setup we find that the VBF approximation employed in the NNLO QCD correction is accurate at the sub-percent level. We find that the NLO EW corrections within the fiducial volume are -,6.1%, making them of almost the same order as the NLO QCD corrections. In some kinematic regions they can grow as large as -,30% making them the dominant radiative corrections. When the EW corrections are combined with the NNLO QCD corrections we find a total correction of -,14.8%. The results presented here thus comprise the state-of-the-art theoretical predicition for the double-Higgs production via vector-boson fusion, which will be of value to the high-luminosity programme at the LHC.

One-loop corrections to the two-body decays of the neutral Higgs bosons in the complex NMSSM

Since no direct signs of new physics have been observed so far indirect searches in the Higgs sector have become increasingly important. With the discovered Higgs boson behaving very standard model (SM)-like, however, indirect new physics manifestations are in general expected to be small. On the theory side, this makes precision predictions for the Higgs parameters and observables indispensable. In this paper, we provide in the framework of the CP-violating next-to-minimal supersymmetric extension of the SM (NMSSM) the complete next-to-leading order (SUSY-)electroweak corrections to the neutral Higgs boson decays that are on-shell and non-loop induced. We also investigate possible gauge-dependence issues in the decays of light Higgs bosons into fermion pairs. Together with the also provided SUSY-QCD corrections to colored final states, the newly calculated SUSY-electroweak corrections are implemented in the Fortran code NMSSMCALC which already includes the state-of-the art QCD corrections. The new code is called NMSSMCALCEW. This way we provide the NMSSM Higgs boson decays and branching ratios at presently highest possible precision and thereby contribute to the endeavor of searching for New Physics at present and future colliders.

Electroweak corrections to the angular coefficients in finite-p_TZ-boson production and dilepton decay

We present next-to-leading order (NLO) electroweak corrections to the dominant five angular coefficients parametrizing the Drell–Yan process in the Z-boson mass peak range for finite-p_T vector boson production. The results are presented differentially in the vector boson transverse momentum. The Lam–Tung violating difference A_0-A_2 is examined alongside the coefficients. A single lepton transverse momentum cut is needed in the case of electroweak corrections to avoid a double singularity in the photon induced diagrams, and the dependence on the value of this cut is examined. We compare the electroweak corrections to the angular coefficients to the NLO QCD corrections, including the single lepton cut. The size of the single lepton cut is found to affect the two coefficients A_0 and A_2 to largest extent. The relative size of the electroweak corrections to the coefficients is moderate for all single lepton cut values, and by extrapolation to the inclusive results, is moderate also for the full dilepton phase space case. However, for the Lam–Tung violation, there is a significant contribution from the electroweak corrections for low p_T of the lepton pair.

Top quark pair production at complete NLO accuracy with NNLO+NNLL′ corrections in QCD * * L. L. Yang and X. Wang are supported in part by the National Natural Science Foundation of China (11975030, 11635001, 11575004). X. Wang is also supported in part by the Cluster of Excellence PRISMA+ (project ID 39083149). D. J. S. is supported under the ERC

We describe predictions for top quark pair differential distributions at hadron colliders, by combining the next-to-next-to-leading order quantum chromodynamics calculations and next-to-leading order electroweak corrections with double resummation at the next-to-next-to-leading logarithmic accuracy of threshold logarithms and small-mass logarithms. To the best of our knowledge, this is the first study to present such a combination, which incorporates all known perturbative information. Numerical results are presented for the invariant-mass distribution, transverse-momentum distribution, and rapidity distributions.

Electroweak and QCD corrections to Z and W pole observables in the standard model EFT

We compute the next-to-leading order QCD and electroweak corrections to $Z$ and $W$ pole observables using the dimension-6 Standard Model effective field theory and present numerical results that can easily be included in global fitting programs. Limits on SMEFT coefficient functions are presented at leading order and at next-to-leading order under several assumptions.

Relic density of dark matter in the inert doublet model beyond leading order: The heavy mass case

A full renormalisation of the Inert Doublet Model (IDM) is presented and exploited for a precise calculation of the relic density of Dark Matter (DM) at one-loop. In this first paper, we study the case of a DM candidate with $m_{\rm DM} \sim 500$ GeV. In this regime, the co-annihilation channels are important. We therefore compute, for a wide range of relative velocities, the full next-to-leading order electroweak corrections to 7 annihilation/co-annihilation processes that contribute $\sim$ 70\% to the relic density of DM. These corrected cross-sections are interfaced with {\tt micrOMEGAs} to obtain the one-loop correction to the freeze-out relic density. Due to the accurate measurement of this observable, the one-loop corrections are relevant. We discuss the one-loop renormalisation scheme dependence and point out the influence, at one-loop, of a parameter that solely describes the scattering in the dark sector. A tree-level computation of the relic density is not sensitive to this parameter.

Precision study of production including parton shower effects at CERN Large Hadron Collider * * Supported in part by the National Natural Science Foundation of China (11775211 and 11535002), the Applied Basic Research Programs of Yunnan Provincial Science and Technology Department (2016FB008) and the CAS Center for Excellence in Particle Physics (CCEPP)

The precision study of production with subsequent and decays at the Large Hadron Collider (LHC) aids in the investigation of Higgs gauge couplings and the search for new physics beyond the standard model. In this study, we calculate the shower-matched next-to-leading order QCD and electroweak (EW) corrections from the annihilation and photon-induced channels to the production at the LHC. We deal with the subsequent decays of Higgs and bosons by adopting the MADSPIN method. Both the integrated cross section and some kinematic distributions of , H, and their decay products are provided. We find that the QCD correction significantly enhances the leading-order differential cross section, while the EW correction from the annihilation channel obviously suppresses it, especially in the high energy phase-space region, due to the Sudakov effect. The - and -induced relative corrections are positive and insensitive to the transverse momenta of , H, and their decay products. These photon-induced corrections compensate the negative -initiated EW correction, and become the dominant EW contribution as the increment of the colliding energy. The parton shower (PS) effects on kinematic distributions are not negligible. The relative PS correction to the b-jet transverse momentum distribution can exceed 100% in the high region. Moreover, we investigate the scale and PDF uncertainties, and find that the theoretical error of the -corrected integrated cross section mainly originates from the renormalization scale dependence of the QCD correction.