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Karel Kolar

Publications and source records attributed to Karel Kolar.

4 recordsLinked to original sources
arXiv2012

Investigation of the factorization scheme dependence of finite order perturbative QCD calculations: searching for approximately ZERO factorization scheme

The possibility of an improvement of current NLO Monte Carlo event generators by means of choosing a suitable factorization scheme is studied. The optimal factorization scheme for combining initial state parton showers and NLO hard scattering cross-sections is the ZERO factorization scheme, in which all NLO splitting functions vanish. However, it has turned out that the ZERO factorization scheme has a limited range of practical applicability. Hence, this paper is focused on searching for a factorization scheme which is applicable at the NLO in the full range of x relevant for QCD phenomenology and simultaneously close to the ZERO factorization scheme (i.e. the corresponding NLO splitting functions are close to zero).

hep-ph↗
arXiv2011

Investigation of the factorization scheme dependence of finite order perturbative QCD calculations

The freedom associated with the definition of parton distribution functions is analyzed and formulae governing the dependence of parton distribution functions and hard scattering cross-sections on unphysical quantities associated with the renormalization and factorization procedure are derived. The issue of the specification of factorization schemes via the corresponding higher order splitting functions is discussed in detail. A numerical analysis of the practical applicability of the so called ZERO factorization scheme, which could be useful for the construction of consistent NLO Monte Carlo event generators, is presented.

hep-ph↗
arXiv2010

On qualitative aspects of the choice of factorization schemes at NLO

Although the choice of a factorization scheme is as important as the choice of a factorization scale, the dependence of theoretical predictions (at finite order) on the choice of a factorization scheme has been little investigated. This is due to the fact that the freedom in the choice of a factorization scheme is enormous, even at NLO. One of the reason why to study factorization schemes is the possible exploitation of the freedom in their choice in the construction of NLO Monte Carlo event generators with NLO initial state parton showers. However, the ZERO factorization scheme, which should be optimal for such Monte Carlo event generators, has turned out to be practically inapplicable although it appears at first sight as reasonable. A detailed analysis has then shown that if some given NLO splitting functions do not satisfy a certain nontrivial condition, then the corresponding factorization scheme has some restrictions on its practical applicability. Relevant technical details of the discussed issues are the content of this short contribution.

hep-ph↗