AutoDipole – Automated generation of dipole subtraction terms –

6,220

5,572

We discuss the theoretical bases that underpin the automation of the computations of tree-level and next-to-leading order cross sections, of their matching to parton shower simulations, and of the merging of matched samples that differ by light-parton multiplicities. We present a computer program, MadGraph5 aMC@NLO, capable of handling all these computations -parton-level fixed order, shower-matched, merged -in a unified framework whose defining features are flexibility, high level of parallelisation, and human intervention limited to input physics quantities. We demonstrate the potential of the program by presenting selected phenomenological applications relevant to the LHC and to a 1-TeV e + e − collider. While next-to-leading order results are restricted to QCD corrections to SM processes in the first public version, we show that from the user viewpoint no changes have to be expected in the case of corrections due to any given renormalisable Lagrangian, and that the implementation of these are well under way.

“…One can thus define [158] the purely four-dimensional part of the numerator that appears in eq. (2.59): 62) from whence one can obtain its (−2ǫ)-dimensional counterpart:…”

Section: Jhep07(2014)079mentioning

confidence: 99%

“…We stress that eq. (B.7) is exact, 62 and therefore so is the computation of a cross section starting from the weights for any given scale and PDF choice. A complete discussion, which includes all the relevant definitions of w i and b i for both fixed-order and MC@NLO cross sections, is given in ref.…”

Section: Jhep07(2014)079mentioning

confidence: 99%

The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations

Alwall

Frederix

Frixione

et al. 2014

6,220

5,572

“…Likewise, the color correlated Born squared amplitudes and the helicity correlated ones, both being necessary ingredients of NLO calculations employing a subtraction method, have been obtained by properly modifying the routines generated by MadGraph. Cross checks have been performed with AutoDipole [28]. Moreover, factorization in the soft and collinear limits has been explicitly checked in double and quadruple precision.…”

Section: Jhep01(2012)137mentioning

confidence: 99%

Hadronic top-quark pair-production with one jet and parton showering

Alioli

Moch

Uwer

2012

135

137

We present a calculation of heavy-flavor production in hadronic collisions in association with one jet matched to parton shower Monte Carlo programs at next-toleading order in perturbative QCD. Top-quark decays are included and spin correlations in the decay products are taken into account. The calculation builds on existing results for the radiative corrections to heavy-quark plus one jet production and uses the POWHEG BOX for the interface to the parton shower programs PYTHIA or HERWIG. A broad phenomenological study for the Large Hadron Collider and the Tevatron is presented. In particular we study -as one important sample application -the impact of the parton shower on the top-quark charge asymmetry.

“…Infrared singularities were then removed with the dipole subtraction method [43]. QCD finiteness was checked against AutoDipole 1.2.3 [44], and the integrated QED dipole was shown to reproduce well the pointlike contribution to the photon fragmentation function. The total NLO calculation was finally shown to agree with JETPHOX [16,17].…”

Section: Jhep03(2018)081mentioning

confidence: 99%

Prompt photon production and photon-jet correlations at the LHC

Klasen

Klein-Bösing

Poppenborg

2018

Next-to-leading order predictions matched to parton showers are compared with recent ATLAS data on isolated photon production and CMS data on associated photon and jet production in pp and pPb collisions at different centre-of-mass energies of the LHC. We find good agreement and, as expected, considerably reduced scale uncertainties compared to previous theoretical calculations. Predictions are made for the ratio of inclusive photons over decay photons R γ , an important quantity to evaluate the significance of additional photon sources, e.g. thermal radiation from a Quark-Gluon-Plasma, and for distributions in the parton momentum fraction in lead ions x obs Pb , that could be determined by ALICE, ATLAS, CMS and LHCb in ongoing analyses of photon+jet production in pPb collisions at √ s N N = 5.02 TeV. These data should have an important impact on the determination of nuclear effects such as shadowing at low x.