Gaining analytic control of parton showers
arXiv:0705.1719 · doi:10.1103/PhysRevD.76.114017
Abstract
Parton showers are widely used to generate fully exclusive final states needed to compare theoretical models to experimental observations. While, in general, parton showers give a good description of the experimental data, the precise functional form of the probability distribution underlying the event generation is generally not known. The reason is that realistic parton showers are required to conserve four-momentum at each vertex. In this paper we investigate in detail how four-momentum conservation is enforced in a standard parton shower and why this destroys the analytic control of the probability distribution. We show how to modify a parton shower algorithm such that it conserves four-momentum at each vertex, but for which the full analytic form of the probability distribution is known. We then comment how this analytic control can be used to match matrix element calculations with parton showers, and to estimate effects of power corrections and other uncertainties in parton showers.
12 pages, 6 figures, v2: final journal version
References in corpus (34)
- PYTHIA 6.4 Physics and Manual
- PYTHIA 6.2 Physics and Manual
- A New Method for Combining NLO QCD with Shower Monte Carlo Algorithms
- HERWIG 6.5: an event generator for Hadron Emission Reactions With Interfering Gluons (including supersymmetric processes)
- High-Energy-Physics Event Generation with PYTHIA 6.1
- Matching NLO QCD computations and parton shower simulations
- An effective field theory for collinear and soft gluons: heavy to light decays
- Soft-Collinear Factorization in Effective Field Theory
- QCD Matrix Elements + Parton Showers
- Summing Sudakov logarithms in B -> X_s + gamma in effective field theory
- Invariant Operators in Collinear Effective Theory
- Matching NLO QCD and parton showers in heavy flavour production
- Transverse-Momentum-Ordered Showers and Interleaved Multiple Interactions
- SHERPA 1.alpha, a proof-of-concept version
- Correcting the Colour-Dipole Cascade Model with Fixed Order Matrix Elements
- Multijet matrix elements and shower evolution in hadronic collisions: W b bbar + n jets as a case study
- Matrix Elements and Parton Showers in Hadronic Interactions
- New formalism for QCD parton showers
- Matching Matrix Elements and Parton Showers with HERWIG and PYTHIA
- QCD Radiation off Heavy Particles
- W Production in an Improved Parton-Shower Approach
- Matching Parton Showers to NLO Computation
- W+jets Matrix Elements and the Dipole Cascade
- A Positive-Weight Next-to-Leading-Order Monte Carlo for Z Pair Hadroproduction
- Implementing the ME+PS merging algorithm
- A Positive-Weight Next-to-Leading-Order Monte Carlo for e+e- Annihilation to Hadrons
- Herwig++ 1.0: An Event Generator for e+e- Annihilation
- Event Generation from Effective Field Theory
- APACIC++, A PArton Cascade In C++, version 1.0
- Improving jet distributions with effective field theory
- Next-to-leading order QCD calculations with parton showers I: collinear singularities
- Next-to-leading order QCD jet production with parton showers and hadronization
- Next-to-leading order QCD calculations with parton showers II: soft singularities
- QCD (&) Event Generators
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- WHIZARD: Simulating Multi-Particle Processes at LHC and ILC
- Strategies to Identify Boosted Tops
- A simple shower and matching algorithm
- Les Houches 2015: Physics at TeV Colliders Standard Model Working Group Report
- Fully Unintegrated Parton Correlation Functions and Factorization in Lowest Order Hard Scattering
- Lepton Jets in (Supersymmetric) Electroweak Processes
- Parton showers from the dipole formalism
- An Overview of Transverse Momentum Dependent Factorization and Evolution
- GenEvA (I): A new framework for event generation
- An Analytic Initial-State Parton Shower