相关论文: Understanding Bottom Production
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 present a next-to-leading order (NLO) calculation of $t\bar{t}$ production in hadronic collisions interfaced to shower generators according to the POWHEG method. We start from an NLO result from previous work, obtained in the zero width…
We present a novel next-to-next-to-leading order (NNLO) QCD calculation matched to parton shower for the production of a pair of $Z$ bosons decaying to four massless leptons, $p p \to \ell^+ \ell^- \ell'^+ \ell'^- + X$, at the LHC. Spin…
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…
We calculate the cross section of the process e^+e^- \to t\bar t near threshold by resumming Coulomb-like terms with next-to-next-to-leading (NNLO) accuracy. The nonrelativistic Green function formalism and the method of ``direct matching''…
In this talk we report on the state of the art on the calculation of cross section at next-to-next-to-leading (NNLO) accuracy.
Based on a counting scheme that explicitly takes into account the large momentum sqrt(M m_pi) characteristic for pion production in nucleon-nucleon collisions we calculate all diagrams for the reaction NN --> NN pi at threshold up to…
We present a next-to-next-to-leading order (NNLO) QCD calculation of the bottom-induced contributions to the production of a Higgs boson plus a jet, i.e. the process $p p \rightarrow H +j$ to $\mathcal{O}(y_b^2 \alpha_s^3)$. We work in the…
We compute the dominant term in the expansion in rho=1-M_W/m_t of the unknown next-to-next-to-leading order (NNLO) nonresonant contributions to the e+ e- -> W+ W- b bbar total cross section at energies close to the top-antitop threshold.…
The next-to-leading order (NLO) QCD radiative corrections to W+W- production at hadron colliders are well understood. We combine NLO perturbative QCD calculations with soft-gluon resummation of threshold logarithms to find a next-to-next-to…
We present theoretical predictions for selected differential cross sections for the process $pp \to t \bar{t} B$ at the LHC, where $B$ can be a Higgs ($H$), a $Z$ or a $W$ boson. The predictions are calculated in the direct QCD framework up…
The production of four bottom quarks is an important benchmark channel for Higgs analyses and searches for new physics at the LHC. We report on the calculation of the next-to-leading order QCD corrections to the process pp -> b anti-b b…
The cross section for bottom quark production at fixed-target energies is calculated for a wide range of beam momenta. A detailed analysis is given for the HERA-B experiment. We consider both the order $\alpha_s^3$ cross section and the…
We present the predictions at next-to-leading order (NLO) in the strong coupling for the single-top cross section in the t channel at the Tevatron and the LHC. Our calculation starts from the 2 -> 3 Born amplitude g q -> t bbar q', keeping…
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…
We present the resummed predictions for a vector boson pair production at the LHC. We have performed threshold resummation to next-to-next-to-leading logarithmic (NNLL) accuracy, and then matched them to next-to-next-to-leading order (NNLO)…
We present the first calculation for the hadroproduction of a $W$ boson in association with a massive bottom ($b$) quark-antiquark pair at next-to-next-to-leading order (NNLO) in QCD perturbation theory. We exploit the hierarchy between the…
We consider the production of an arbitrary number of colour-singlet particles near partonic threshold, and show that next-to-leading order cross sections for this class of processes have a simple universal form at next-to-leading power…
Accurate predictions for both signal and background events at the LHC are of paramount importance in order to confirm even the smallest deviations from Standard Model predictions. Next-to-leading order Monte Carlo event generators are an…
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…