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Register a new userSlepton and Electroweakino pair production with aNNLO+NNLL precision
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The level of experimental precision that will be achieved with LHC Run-III data and in the forthcoming High Luminosity stage calls for equally accurate theoretical predictions to compare with. Here we present updated cross section calculations for the electroweak production of SUSY particles at the LHC with aNNLO+NNLL (approximate next-to-next-to-leading-order plus next-to-next-to-leading-logarithmic) accuracy. Results are shown for slepton pair production and for electroweakinos pair production in their mostly higgsino or gaugino configuration, finding a further significant reduction of the factorisation and renormalisation scale dependence that stabilises the predictions to the permil level.
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We present a calculation of slepton pair production at the LHC at next-to-next-to-leading logarithmic (NNLL) accuracy, matched to approximate next-to-next-to-leading order (aNNLO) QCD corrections. We collect the relevant analytical formulae, discuss the matching of logarithmically enhanced and fixed-order results and describe the transformation of parton densities and hadronic cross sections to and from Mellin space. Numerically, we find a moderate increase of invariant-mass distributions and total cross sections with respect to our previous results at next-to-leading logarithmic (NLL) accuracy matched to next-to-leading order (NLO), and more importantly a further significant reduction of the factorisation and renormalisation scale dependence that stabilises our predictions to the permil level. The dependence on other supersymmetric parameters like squark and gluino masses and sbottom mixing that enter only at NLO is found to be weak, i.e. less than two percent, as expected.
We present a calculation of higgsino and gaugino pair production at the LHC at next-to-next-to-leading logarithmic (NNLL) accuracy, matched to approximate next-to-next-to-leading order (aNNLO) QCD corrections. We briefly review the formalism for the resummation of large threshold logarithms and highlight the analytical results required at aNNLO+NNLO accuracy. Our numerical results are found to depend on the mass and nature of the produced charginos and neutralinos. The differential and total cross sections for light higgsinos, which like sleptons are produced mostly at small x and in the s-channel, are found to be again moderately increased with respect to our previous results. The differential and total cross sections for gauginos are, however, not increased any more due to the fact that gauginos, like squarks, are now constrained by ATLAS and CMS to be heavier than about 1 TeV, so that also t- and u-channels play an important role. The valence quarks probed at large x then also induce substantially different cross sections for positively and negatively charged gauginos. The higgsino and gaugino cross sections are both further stabilized at aNNLO+NNLL with respect to the variation of renormalization and factorization scales. We also now take mixing in the squark sector into account and study the dependence of the total cross sections on the squark and gluino masses as well as the trilinear coupling controlling the mixing in particular in the sbottom sector.
We compute the total top-quark pair production cross section at the Tevatron and LHC based on approximate NNLO results, and on the summation of threshold logarithms and Coulomb enhancements to all orders with next-to-next-to-leading logarithmic (NNLL) accuracy, including bound-state effects. We find sigma_{tbar t} = 7.22^{+0.31+0.71}_{-0.47-0.55} pb at Tevatron and sigma_{tbar t} = 162.6^{+7.4+15.4}_{-7.6-14.7} pb at LHC with 7 TeV c.o.m. energy, for m_t=173.3 GeV. The implementation of joint soft and Coulomb resummation, its ambiguities, and the present theoretical uncertainty are discussed in detail. We further obtain new approximate results at N3LO.
We present a precision calculation of the transverse-momentum and invariant-mass distributions for supersymmetric particle pair production at hadron colliders, focusing on Drell-Yan like slepton pair and slepton-sneutrino associated production at the CERN Large Hadron Collider. We implement the joint resummation formalism at the next-to-leading logarithmic accuracy with a process-independent Sudakov form factor, thus ensuring a universal description of soft-gluon emission, and consistently match the obtained result with the pure perturbative result at the first order in the strong coupling constant, i.e. at O(alpha_s). We also implement three different recent parameterizations of non-perturbative effects. Numerically, we give predictions for ~e_R ~e_R^* production and compare the resummed cross section with the perturbative result. The dependence on unphysical scales is found to be reduced, and non-perturbative contributions remain small.
We present results for the total top-pair production cross section at the Tevatron and the LHC. Our predictions supplement fixed-order results with resummation of soft logarithms and Coulomb singularities to next-to-next-to-leading (NNLL) logarithmic accuracy and include top-antitop bound-state effects. The effects of resummation, the dependence on the PDF set used, the residual sources of theoretical uncertainty and their implication for measurements of the top-quark mass are discussed.
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