The European Physical Journal C

, Volume 51, Issue 4, pp 867–873 | Cite as

Initial-state parton shower kinematics for NLO event generators

  • Shigeru OdakaEmail author
  • Yoshimasa Kurihara
Regular Article - Theoretical Physics


We are developing a consistent method to combine tree-level event generators for hadron collision interactions with those including one additional QCD radiation from the initial-state partons, based on the limited leading-log (LLL) subtraction method, aiming at an application to NLO event generators. In this method, a boundary between non-radiative and radiative processes necessarily appears at the factorization scale (μF). The radiation effects are simulated using a parton shower (PS) in non-radiative processes. It is therefore crucial in our method to apply a PS which well reproduces the radiation activities evaluated from the matrix-element (ME) calculations for radiative processes. The PS activity depends on the applied kinematics model. In this paper we introduce two models for our simple initial-state leading-log PS: a model similar to the ’old’ PYTHIA-PS and a pT-prefixed model motivated by ME calculations. PS simulations employing these models are tested using W-boson production at LHC as an example. Both simulations show a smooth matching to the LLL subtracted W+1 jet simulation in the pT distribution of W bosons, and the summed pT spectra are stable against a variation of μF, despite that the pT-prefixed PS results in an apparently harder pT spectrum.


Parton Shower Parton Distribution Function Subtraction Method Hard Interaction Smooth Match 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag / Società Italiana di Fisica 2007

Authors and Affiliations

  1. 1.High Energy Accelerator Research Organization (KEK)TsukubaJapan

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