24 pages, 11 figures, 7 tables. Asymmetry plots and citations added, discussion of effects beyond NLO in QCD added. The discussion on PDF uncertainties has been extended. The version to appear in the European Physical Journal C
Recent discrepancies between theoretical predictions and experimental data in multi-lepton plus $b$-jets analyses for the $t\bar{t}W^\pm$ process, as reported by the ATLAS collaboration, have indicated that more accurate theoretical predictions and high precision observables are needed to constrain numerous new physics scenarios in this channel. To this end we employ NLO QCD computations with full off-shell top quark effects included to provide theoretical predictions for the ${\cal R}= σ_{t\bar{t}W^+}/σ_{t\bar{t}W^-}$ cross section ratio at the LHC with $\sqrt{s}=13$ TeV. Depending on the transverse momentum cut on the $b$-jet we obtain $2\% -3 \%$ theoretical precision on ${\cal R}$, which should help to shed some light on new physics effects that can reveal themselves only once sufficiently precise Standard Model theoretical predictions are available. Furthermore, triggered by these discrepancies we reexamine the charge asymmetry of the top quark and its decay products in the $t\bar{t}W^\pm$ production process. In the case of charge asymmetries, that are uniquely sensitive to the chiral nature of possible new physics in this channel, theoretical uncertainties below $15\%$ are obtained. Additionally, the impact of the top quark decay modelling is scrutinised by explicit comparison with predictions in the narrow-width approximation.
We report on a next-to-leading order QCD calculation of the cross section and the spin asymmetry for isolated large-p_T prompt photon production in collisions of transversely polarized protons. Corresponding measurements may be used at RHIC to determine the transversity parton distributions of the proton.
We have computed semi-inclusive spin asymmetries for proton and deuteron targets including next to leading order (NLO) QCD corrections and contributions coming from the target fragmentation region. These corrections have been estimated using NLO fragmentation functions, parton distributions and also a model for spin dependent fracture functions which is proposed here. We have found that NLO corrections are small but non-negligible in a scheme where gluons are polarised and that our estimate for target fragmentation effects does not modify significantly charged asymmetries but affects the so ca…
The decay bar B -> bar K* (-> bar K pi) l+ l- offers great opportunities to explore the physics at and above the electroweak scale by means of an angular analysis. We investigate the physics potential of the seven CP asymmetries plus the asymmetry in the rate, working at low dilepton mass using QCD factorization at next-to leading order (NLO). The b ->s CP asymmetries are doubly Cabibbo-suppressed \lesssim 1 % in the Standard Model and its extensions where the CKM matrix is the only source of CP violation. Three CP asymmetries are T-odd, and can be O(1) in the presence of non-standard CP viola…
We consider the next-to-leading order corrections, O(alpha_s), to forward-backward charge asymmetries for lepton-pair production in association with a large transverse momentum jet at large hadron colliders. We find that the leading order results are essentially confirmed. Although experimentally challenging and in practice with large backgrounds, these observables could provide a new determination of the weak mixing angle sin2 theta^lept_eff (M_Z^2) with a statistical precision for each lepton flavour of ~10^(-3) (7 x 10^{-3}) at LHC (Tevatron), and if b jets are identified, of the b quark Z …
This paper presents the first calculations of the parity-violating polarization asymmetry and forward-backward asymmetry of the $e^- e^+ \rightarrow μ^+ μ^- (γ)$ process at a center-of-mass energy of 10.58 GeV with up to one-loop electroweak radiative corrections. The calculations are relevant for future precision electroweak measurements at the Belle~II experiment, which is now collecting data at the SuperKEKB $e^- e^+$ collider with a center-of-mass energy at the mass of the $Υ(4S)$ resonance. In this paper we take under full control the bremsstrahlung process at the conditions of Belle II/S…
We present the full NLO QCD corrections to the production of a W^+W^- pair in association with two jets in hadronic collisions, which is an important background to New Physics and Higgs boson searches. We include leptonic decays of the W-bosons with full spin correlations. We find NLO corrections of the order of 10% for standard cuts at the LHC. The scale dependence is considerably reduced by the NLO corrections.
We revisited excited leptons ($\bar{l^*}l$) production through gauge mediation only at LHC, followed by their two body decays into Standard Model (SM) particles. We include the next-to-leading order (NLO) QCD corrections to these processes. We have shown that these corrections can be substantial and significant. We also show that the scale dependence of the NLO cross section is greatly reduced as compare to leading order (LO) cross section.
We present the tree-level and next-to-leading order (NLO) electroweak (EW) contributions to squark-squark production at the Large Hadron Collider (LHC) within the framework of the Minimal Supersymmetric Standard Model (MSSM).
The implementation of the full next-to-leading order (NLO) QCD corrections to electroweak Higgs boson plus three jet production at hadron colliders such as the LHC within the Matchbox NLO framework of the Herwig++ event generator is discussed. We present numerical results for integrated cross sections and kinematic distributions.
The dominant contribution to the Higgs production in association with bottom quark pair at the LHC is gluon-gluon fusion parton subprocess. We present a complete calculation of the next-to-leading order (NLO) electroweak (EW) corrections to this channel. The other small contributions with quarks in the initial state are calculated at tree level. We find that the NLO EW corrections can suppress the leading order (LO) contributions significantly.
We present the complete next-to-leading order (NLO) QCD and NLO electroweak (EW) corrections to the $W$-boson pair production associated with a hard jet at the LHC including the spin correlated $W$-boson leptonic decays. The dependence of the leading order (LO) and NLO corrected cross sections on the jet transverse momentum cut is investigated. In dealing with the subsequent resonant $W$-boson decays, we adopt the {\sc MadSpin} method where the spin correlation effect is included. We also provide the LO and NLO corrected distributions of the transverse momenta and rapidities of final products.…
In this work we investigate the NLO QCD+EW corrections to the top quark pair production and their effects on the spin correlation coefficients and asymmetries at fixed-order top quark pair production and LO decay in the dilepton channel, within the narrow-width approximation. The spin correlations are implicitly measured through the lepton kinematics. Moreover we study the EW effects to the leptonic differential distributions. We find that the EW corrections to the $t \bar t$ production are within the NLO QCD theoretical uncertainties for the spin correlation coefficients and the leptonic asym…
In this paper we present the NLO QCD + NLO EW corrections to the $ZZZ$ production with subsequent $Z$-boson leptonic decays at the LHC by adopting the improved narrow width approximation, which takes into account off-shell contributions and spin correlations. Integrated cross sections at $13$, $14$, $33$ and $100~{\rm TeV}$ hadron colliders and various kinematic distributions are presented. Our numerical results show that the jet emission correction accounts for a large part of the total QCD correction, especially in the high energy region. By applying a proper cut to the jet transverse moment…
The tri-boson production is one of the key processes for the study of quartic gauge couplings. Next-to-leading order (NLO) corrections are mandatory to reduce theoretical uncertainties. In this study, the most up-to-date predictions including NLO QCD and NLO EW corrections to the total cross section and distributions of the WWZ production at the LHC are presented. We show that the QCD correction is about 100% and the EW correction is of a few percent at the total cross section level. The EW correction however becomes significant in the high energy regime of the gauge boson transverse momentum …
The new methodology of adding QCD NLO corrections in the initial state Monte Carlo parton shower (hard process part) is presented using process of the heavy boson production at the LHC as an example. Despite the simplified model of the process, presented numerical results prove that the basic concept of the new methodology works correctly in the numerical environment of the Monte Carlo parton shower event generator. The presented method is an alternative to the well established methods, MC@NLO and POWHEG. Refinements of the new method with better computer CPU time efficiency are also discussed…
Novel PDFs taking into account resummation-improved matrix elements, albeit only in the fit of a reduced data set, allow for consistent NLO+NLL calculations of slepton pair production at the LHC. We apply a factorisation method to this process that minimises the effect of the data set reduction, avoids the problem of outlier replicas in the NNPDF method for PDF uncertainties and preserves the reduction of the scale uncertainty. For Run II of the LHC, left-handed selectron/smuon, right-handed and maximally mixed stau production, we confirm that the consistent use of threshold-improved PDFs part…
In this paper we study the Single Top and W boson associated photoproduction via the main reaction $\rm pp\rightarrow pγp\rightarrow pW^{\pm}t+Y$ at the 14 TeV Large Hadron Collider (LHC) up to next-to-leading order (NLO) QCD level assuming a typical LHC multipurpose forward detector. We use the Five-Flavor-Number Schemes (5FNS) with massless bottom quark assumption in the whole calculation. Our results show that the QCD NLO corrections can reduce the scale uncertainty. The typical K-factors are in the range of 1.15 to 1.2 which lead to the QCD NLO corrections of 15$%$ to 20$%$ correspond to t…
We give the first full next-to-leading order analytical results in Chiral Perturbation Theory for the charged Kaon K \to 3 pi slope g and decay rates CP-violating asymmetries. We have included the dominant Final State Interactions at NLO analytically and discussed the importance of the unknown counterterms. We find that the uncertainty due to them is reasonable just for Δg_C, i.e. the asymmetry in the K^+ \to pi^+ pi^+ pi^- slope g; we get Δg_C = -(2.4 +- 1.2) 10^{-5}. The rest of the asymmetries are very sensitive to the unknown counterterms. In particular, the decay rate asymmetries can chan…
We compute, for $t \bar t$ production at the LHC and at the Tevatron, several charge asymmetries to NLO QCD, including also the electromagnetic and weak-interaction corrections. We calculate these asymmetries both inclusively and with additional kinematic cuts and compare our results, where possible, with recent experimental results and with SM predictions. The $t \bar t$ asymmetries induce also corresponding asymmetries for the charged leptons from semileptonic top-quark decay. Although these asymmetries are, in the SM, smaller than the corresponding ones for top quarks, they are expected to …
In this talk we present results of our recent calculations of cross sections and distributions for the associate production of top-antitop quark pairs with a heavy boson (Higgs, W, Z) at the LHC, obtained using threshold resummation in direct QCD, i.e. in the Mellin-space approach.
We calculate the branching ratios and CP violating asymmetries of the four $B \to K \etap$ decays in the perturbative QCD (pQCD) factorization approach. Besides the full leading order contributions, the partial next-to-leading order (NLO) contributions from the QCD vertex corrections, the quark loops, and the chromo-magnetic penguins are also taken into account. The NLO pQCD predictions for the CP-averaged branching ratios are $Br(B^+ \to K^+ η) \approx 3.2 \times 10^{-6}$, $Br(B^\pm \to K^\pm \etar) \approx 51.0 \times 10^{-6}$, $Br(B^0 \to K^0 η) \approx 2.1 \times 10^{-6}$, and $Br(B^0 \to …
We report on state-of-the-art theoretical predictions for $pp\to t\bar{t}b\bar{b}$ including full off-shell effects in the di-lepton decay channel at NLO QCD accuracy. We briefly discuss the impact of NLO QCD corrections on differential distributions and also asses theoretical uncertainties from scale and PDF dependence. Furthermore, we propose a simple kinematic reconstruction in order to distinguish $b$ jets originating from top-quark decays from arising from gluon splittings.
We analyse the phenomenological consequences of target and current fragmentation contributions at next to leading order in semi-inclusive spin dependent deep inelastic scattering asymmetries.
The high luminosity that will be accumulated at the LHC will enable precise differential measurements of the hadronic production of a top--antitop-quark pair in association with a $\text{W}$ boson. Therefore, an accurate description of this process is needed for realistic final states. In this work we combine for the first time the NLO QCD and electroweak corrections to the full off-shell $\text{t}\overline{\text{t}}{\text{W}}^+$ production at the LHC in the three-charged-lepton channel, including all spin correlations, non-resonant effects, and interferences. To this end, we have computed the…
Higgs boson pair production is considered at next-to-leading order with special emphasis on the effect of a finite top quark mass. It is shown that, unlike for single-Higgs boson production, power-suppressed corrections are numerically important.
We compute the total cross section and the transverse momentum distribution for single charged slepton and sneutrino production at hadronic colliders including NLO supersymmetric and non-supersymmetric QCD corrections. The supersymmetric QCD corrections can be substantial. We also resum the gluon transverse momentum distribution and compare our results with two Monte Carlo generators. We compute branching ratios of the supersymmetric decays of the slepton and determine event rates for the like-sign dimuon final state at the Tevatron and at the LHC.
The process $pp \to W^+W^+jj$ gives rise to an exotic Standard Model signature at the LHC, involving high-$p_{\perp}$ like-sign leptons, missing energy and jets. In this brief article the motivation for study, along with selected results from the computation of NLO QCD corrections to the QCD-mediated part of this process\cite{us} are presented. It is shown that the corrections reduce the dependence of the cross-section on renormalisation and factorisation scales, and produce a relatively hard third jet in a significant fraction of events.
We calculate the next-to-leading order inclusive total cross sections for the associated production processes $pp\to \tilde{t}_i\tildeχ_k^-+X$ in the Minimal Supersymmetric Standard Model at the CERN LHC. Our results provide the theoretical predictions for the total cross sections for the above processes. The NLO QCD corrections in general enhance the leading order total cross sections significantly, and vastly reduce the dependence of the total cross sections on the renormalization/factorization scale, which leads to increased confidence in predictions based on these results.
The calculation of NLO QCD corrections to the production cross section of two bottom pairs at the LHC is briefly summarized. We describe the pp -> b anti-b b anti-b+X process both in the 4-flavor and 5-flavor scheme and investigate the effect of the finite bottom quark mass. The results for the total cross section and a few differential distributions are presented. They have been obtained with the Nagy-Soper subtraction formalism for real radiation at NLO. A comparison with results based on the traditional Catani-Seymour subtraction is also included.
We present the next-to-leading order QCD corrections to the associated production of the vector gauge boson ($Z/W^\pm$) and the graviton in the large extra dimension model at the LHC. We estimate the impact of the QCD corrections on the total cross sections as well as the differential distributions of the gauge bosons and find that they are significant. We also study the dependence of the cross sections on the arbitrary factorization scale and show the reduction in the scale uncertainties at NLO level. Further, we discuss the ultraviolet sensitivity of the theoretical predictions.
In this paper we present the full NLO QCD + NLO EW corrections to the $Z$-boson pair production in association with a hard jet at the LHC. The subsequent $Z$-boson leptonic decays are included by adopting both the naive NWA and MadSpin methods for comparison. Since the $ZZ+{\rm jet}$ production is an important background for single Higgs boson production and new physics search at hadron colliders, the theoretical predictions with high accuracy for the hadronic production of $ZZ+{\rm jet}$ are necessary. We present the numerical results of the integrated cross section and various kinematic dist…
We present predictions for the SM-Higgs-pair production channels of relevance at the LHC: gluon-gluon fusion, VBF, and top-pair, W, Z and single-top associated production. All these results are at the NLO accuracy in QCD, and matched to parton showers by means of the MC@NLO method; hence, they are fully differential. With the exception of the gluon-gluon fusion process, for which a special treatment is needed in order to improve upon the infinite-top-mass limit, our predictions are obtained in a fully automatic way within the publicly available MadGraph5_aMC@NLO framework. We show that for all…
The next-to-leading order (NLO) QCD corrections to top anti-top bottom anti-bottom (tTbB) production at the LHC reveal that the scale choice adopted in previous lowest-order simulations underestimates the tTbB cross section by a factor two. We discuss a new dynamical scale that stabilizes the perturbative predictions and describe the impact of the corrections on the shape of distributions. We also account for the techniques employed to compute the six-particle one-loop amplitudes with high CPU efficiency.
In this paper we calculate the next-to-leading order (NLO) QCD $[{\cal O}(α_s α^3)]$ and electroweak (EW) $[{\cal O}(α^4)]$ corrections to the $WWW$ production at the LHC and deal with the subsequent leptonic decays from $W$ bosons by adopting an improved narrow-width approximation which takes into account the spin correlation and finite-width effects. The NLO QCD correction from the real jet radiation is discussed, which significantly enhances the production rate, particularly in the high-energy region. We also provide the integrated cross section for the $WWW$ production and various kinemati…
The interpretation of experimental measurements at the LHC requires accurate theoretical predictions for exclusive observables, and in particular the summation of soft and collinear radiation to all orders in perturbation theory. We report on recent progress towards the automated calculation of multi-parton LHC cross sections at next-to-leading order in QCD, including the summation of next-to-leading logarithmic corrections through the combination with parton showers.
This paper is a follow-up of Ref.~\cite{Ravasio:2018lzi}, where we studied the impact of next-to-leading order calculations merged with parton shower generators (NLO+PS) of increasing accuracy in the extraction of the top mass at hadron colliders. Here we examined results obtained with the older (fortran-based) shower generators Pythia6.4 and Herwig6.5. Our findings are in line with what we found in our previous paper with the new, c++-based, generators Pythia8.2 and Herwig7.1.
Electroweak production of single top quarks is an as-yet-unverified prediction of the Standard model, potentially sensitive to new physics. Two of the single top quark productions channels have significant charge asymmetries at the LHC, while the much larger background from $t\bar{t}$ is nearly charge-symmetric. This can be used to reduce systematic uncertainties and make precision measurements of single top quark production.
The single vector-like top partner hadroproduction in association with top quark in the five and the six-flavour schemes at the LHC is investigated. The inclusive cross section and the differential distributions are evaluated for many benchmark scenarios at leading and next-to-leading orders, both for fixed-order and fixed-order matched to parton shower. The associated Higgs production with a top quark pair, where the final state arises from the decay of the vector-like top partner into a Higgs boson and a top quark, is examined.
We report on studies of next-to-leading order (NLO) QCD corrections to the process $pp\rightarrow e^+ν_eμ^+ν_μjj$ which is associated with vector-boson fusion (VBF) production of an intermediate $W^+W^+$ pair. The impact of s-channel diagrams and interference contributions in VBF kinematics is analyzed at leading order (LO) and found to be entirely negligible. The NLO corrections are around 5% of the LO cross section, and the scale dependence is reduced to about ~1%. We introduce a dynamic scale which improves the K factor in the high-energy tails of the distributions.
Presented are complete electroweak (EW) corrections at ${\cal O}(αα_{\mathrm s}^{\mathrm 2})$ to top-squark pair production at the Large Hadron Collider (LHC) within the framework of the Minimal Supersymmetric Standard Model (MSSM). At this order, effects from the interference of EW and QCD contributions have to be taken into account. Also photon-induced top-squark production is considered as additionnal partonic channel which arises from the non-zero photon density in the proton. Furthermore, the impact of MSSM parameters on the EW corrections is analyzed.
A short summary of results for top-quark pair production in association with a jet with NLO QCD off-shell effects at the LHC is given. The calculation is based on the matrix element for the $pp \to e^+ ν_e μ^-\barν_μb\bar{b} j$ process. All quantum effects are properly accounted for, which amounts to including all Feynman diagrams that result in this final state with interference effects as well as non-zero top-quark width effects. Results for total cross sections and a few differential distributions at the LHC Run1 energy of $\sqrt{s}=8$ TeV are presented. In addition, the size of top-quark o…
We present results on bottom hadron production asymmetries at the LHC within both the Lund string fragmentation model and the intrinsic bottom model. The main aspects of the models are summarized and specific predictions for pp collisions at 14 TeV are given. Asymmetries are found to be very small at central rapidities increasing to a few percent at forward rapidities. At very large rapidities intrinsic production could dominate but this region is probably out of reach of any experiment.
Achieving a precise description of multi-parton final states is crucial for many analyses at LHC. In this contribution we review the main features of the HELAC-NLO system for NLO QCD calculations. As a case study, NLO QCD corrections for tt + 2 jet production at LHC are illustrated and discussed.
The hadroproduction of prompt isolated photon pairs at high energies is studied in the NLO* framework of the Parton Reggeization Approach. The real part of the NLO corrections is computed, and the procedure for the subtraction of double counting between real parton emissions in the hard-scattering matrix element and unintegrated PDF is constructed for the amplitudes with Reggeized quarks in the initial state. The matrix element of the important NNLO subprocess RR->2gamma with full dependence on the transverse momenta of the initial-state Reggeized gluons is obtained. We compare obtained numeri…
We perform threshold resummation of soft gluon corrections to the total cross section and the invariant mass distribution for the process $pp \to t\bar{t}H$. The resummation is carried out at next-to-next-to-leading-logarithmic (NNLL) accuracy using the direct QCD Mellin space technique in the three-particle invariant mass kinematics. After presenting analytical expressions we discuss the impact of resummation on the numerical predictions for the associated Higgs boson production with top quarks at the LHC. We find that NLO+NNLL resummation leads to predictions for which the central values are…
We examine the effect of a general HZZ coupling through a study of the Higgs decay to leptons via Z bosons at the LHC. We discuss various methods for placing limits on additional couplings, including measurement of the partial width, threshold scans, and asymmetries constructed from angular observables. We find that only the asymmetries provide a definitive test of additional couplings. We further estimate the significances they provide.
We present a technique to calculate the cross sections and spin asymmetries for transversely polarized $pp$ collisions at NLO in QCD and report on the use of this technique for the processes $p^{\uparrow} p^{\uparrow} \to γX$, $p^{\uparrow} p^{\uparrow} \to πX$ and $p^{\uparrow} p^{\uparrow} \to l^+ l^- X$.
We consider the $HZ$ associated production at the $14~{\rm TeV}$ LHC in the littlest Higgs model (LHM) and study the corrections of the transverse momentum resummation and threshold resummation at the next-to-leading logarithmic (NLL) accuracy and the fixed-order prediction at the QCD next-to-leading order (NLO) including the contribution from the one-loop-induced $gg$-fusion channel. The QCD NLO+NLL effects on the integrated cross section and the distributions of transverse momentum and invariant mass of the $HZ$ system for the $HZ$ production in the LHM are discussed. The distributions of tr…
We calculate the production of a W boson in association with up to two jets including at least one b-jet to next-to-leading order (NLO) in QCD at the CERN Large Hadron Collider with 7 TeV center-of-mass energy. Both exclusive and inclusive event cross section and b-jet cross sections are presented. The calculation is performed consistently in the five-flavor-number scheme where both q anti-q' and bq (q =\= b) initiated parton level processes are included at NLO QCD. We study the residual theoretical uncertainties of the NLO predictions due to the renormalization and factorization scale depende…
We provide a qualitative and quantitative unified picture of the charge asymmetry in top quark pair production at hadron colliders in the SM and summarise the most recent experimental measurements.
We introduce a twiki page with collections of generated Monte Carlo event samples in proton-proton collisions at LHC energies including a heavy quark-antiquark pair in the final state. These samples are generated with the POWHEG method and can be used to prepare distributions at the NLO accuracy with first radiation treated according to the parton shower approach. Information related to each event is stored in the form prescribed by the Les Houches Accords. Standard parton shower Monte Carlo programs can be used to further evolve these events, and simulate events at the hadron level, ready for…
The production of a single top quark in association with a $\mathrm{Z}$ boson ($\mathrm{t}\mathrm{Z}\mathrm{j}$ production) at the LHC is a relevant probe of the electroweak sector of the Standard Model as well as a window to possible new-physics effects. The growing experimental interest in performing differential measurements for this process demands an improved theoretical modelling in realistic fiducial regions. In this article we present an NLO-accurate $\mathrm{t}\mathrm{Z}\mathrm{j}$ calculation that includes complete off-shell effects and spin correlations, combining QCD and electrowea…
We report the results of a computation of the full next-to-leading order QCD corrections to the production of two $b\bar{b}$ pairs at the LHC. This calculation at the parton level provides predictions for well separated $b$-jets. The results show that the next-to-leading order corrections lead to an enhancement of the cross-section for the central scale choice by roughly 50% with respect to the leading order result. The theoretical uncertainty estimated by variation of the renormalization and factorization scales is strongly reduced by the inclusion of next-to-leading order corrections.
The calculation of $t\bar{t}Z$ production including leptonic decays of both $Z$ boson and top quarks via a partially or fully off-shell calculation represents a definite step forward towards a more accurate description of events whose signatures originate from $t\bar{t}Z$ production. In this talk we review two studies that represent the state of the art of theoretical modeling of $t\bar{t}Z$ production by either performing the NLO QCD calculation of the fully decayed $pp\rightarrow e^+ν_eμ^-\barν_μb\bar{b}τ^+τ^-$ process (see Ref. [1]) or matching the NLO QCD calculation of $pp\rightarrow t\ba…
The dominant production process for heavy charged Higgs bosons at the LHC is the associated production with heavy quarks. We have calculated the next-to-leading-order supersymmetric QCD corrections to charged-Higgs production through the parton processes $q\bar{q},gg \to tbH^{\pm}$ and present results for total cross sections and differential distributions. The QCD corrections reduce the renormalization and factorization scale dependence and thus stabilize the theoretical predictions. We present a comparison of the next-to-leading-order results for the inclusive cross section with a calculatio…
We report on the calculation of the full next-to-leading order QCD corrections to the production of top anti-top bottom anti-bottom (ttbb) final states at the LHC, which deliver a serious background contribution to the production of a Higgs boson (decaying into a bottom anti-bottom pair) in association with a top anti-top pair. While the corrections significantly reduce the unphysical scale dependence of the leading-order cross section, our results predict an enhancement of the ttbb production cross section by a K-factor of about 1.8.
We compute the NLO QCD corrections to the loop-induced gluon fusion contribution in $W^+W^-$ production at the LHC. We consider the full leptonic process $pp\to \ell^+\ell^{\prime\, -}ν_{\ell}{\barν}_{\ell^\prime}+X$, by including resonant and non-resonant diagrams, spin correlations and off-shell effects. Quark-gluon partonic channels are included for the first time in the calculation, and our results are combined with NNLO predictions to the quark annihilation channel at the fully differential level. The computed corrections, which are formally of ${\cal O}(α_{\mathrm{S}}^3)$, increase the N…
