Related papers: Angular ordering and parton showers for non-global…
We present a new Monte Carlo event generator for the production of a top-quark pair in association with a $W^\pm$ boson at hadron colliders in the POWHEG-BOX framework. We consider the next-to-leading-order QCD corrections to the $pp\to…
We study contributions from nonperturbative effects and parton showering in NLO event generators, and present applications to jet final states. We find pT-dependent and rapidity-dependent corrections which can affect the shape of observed…
Parton shower event generators typically approximate evolution of QCD color so that only contributions that are leading in the limit of an infinite number of colors are retained. Our parton shower generator, Deductor, has used an "LC+"…
When parton distributions are falling steeply as the momentum fractions of the partons increases, there are effects that occur at each order in $\alpha_s$ that combine to affect hard scattering cross sections and need to be summed. We show…
Modified Altarelli-Parisi splitting functions were recenty proposed to model multi-parton radiation in a dense medium and describe jet quenching, one of most striking features of heavy-ion collisions. We implement medium-modified splitting…
Soft-drop grooming of hadron-collision final states has the potential to significantly reduce the impact of non-perturbative corrections, and in particular the underlying-event contribution. This eventually will enable a more direct…
High-quality simulated data is crucial for particle physics discoveries. Therefore, parton shower algorithms are a major building block of the data synthesis in event generator programs. However, the core algorithms used to generate parton…
We present a selection of results from our recent study of $pp\to t\bar{t}W^\pm$ production matched to partons showers at NLO QCD at the LHC. Theoretical predictions are obtained at perturbative orders $\mathcal{O}(\alpha_s^3\alpha)$ and…
Methodology of including QCD NLO corrections in the quark--gluon Monte Carlo shower is outlined. The work concentrates on two issues: (i) constructing leading order (LO) parton shower Monte Carlo from scratch, such that it rigorously…
A new generation of parton distribution functions with increased precision and quantitative estimates of uncertainties is presented. This work includes a full treatment of available experimental correlated systematic errors for both new and…
We present a simple formalism for parton-shower Markov chains. As a first step towards more complete uncertainty bands, we incorporate a comprehensive exploration of the ambiguities inherent in such calculations. To reduce this uncertainty,…
We present a general method to match fully differential next-to-next-to-leading (NNLO) calculations to parton shower programs. We discuss in detail the perturbative accuracy criteria a complete NNLO+PS matching has to satisfy. Our method is…
Parton showers are accurate for soft and/or collinear emission, but for a good description of the whole of phase space they need to be supplemented by matrix element corrections. In this paper, we discuss matrix element corrections to the…
The second-order QCD matrix elements give a very good agreement with experimental data on the angular distributions of the four-jet events in e+e- collisions at the Z0 resonance energy. Unfortunately the description of the sub-jet structure…
We present results for the Higgsstrahlung process within the GENEVA Monte Carlo framework. We combine the fully differential NNLO calculation with the higher-order resummation in the 0-jettiness resolution variable (beam-thrust). The…
We describe a general method that enables us to obtain all the singular terms of helicity amplitudes of n-parton processes at one loop. The algorithm uses helicity amplitudes at tree level and simple color algebra. We illustrate the method…
We study the simulation of initial-state radiation in angular-ordered parton showers in order to investigate how different interpretations of the ordering variable affect the logarithmic accuracy of such showers. This also enables us to…
In this article we describe simulations of Higgs boson production via the gluon fusion and Higgs-strahlung processes, using the positive weight next-to-leading-order (NLO) matching scheme, POWHEG, in the Herwig++ 2.3 event generator. This…
We study the collinear splitting functions needed for next-to-next-to-leading order calculations of jet production in the vacuum and in dense QCD matter. These splitting functions describe the probability of a parton to evolve into…
Parton shower algorithms are key components of theoretical predictions for high-energy collider physics. Work towards more accurate parton shower algorithms is thus pursued along many different avenues. The systematic treatment of…