TY - JOUR
T1 - Importance of a consistent choice of αS in the matching of AlpGen and Pythia
AU - Katzy, J.
AU - Mangano, M. L.
AU - Messina, A.
AU - Mijović, L.
AU - Skands, P.
PY - 2012
Y1 - 2012
N2 - We consider the impact of varying αs choices (and scales) on each side of the so-called "matching scale" in MLM-matched matrix-element + parton-shower predictions of collider observables. We explain how inconsistent prescriptions can lead to counter-intuitive results and present a few explicit examples, focusing mostly on W/Z+jets processes. We give a specific prescription for how to improve the consistency of the matching and also address how to perform consistent tune variations (e. g., of the renormalization scale) around a central choice. Comparisons to several collider processes are included to illustrate the properties of the resulting improved matching, relying on AlpGen + Pythia 6, with the latter using the so-called Perugia 2011 tunes, developed as part of this effort. Our observations, nevertheless, apply to the large class of tools where matrix-element generators are merged with independent codes for the parton-shower evolution.
AB - We consider the impact of varying αs choices (and scales) on each side of the so-called "matching scale" in MLM-matched matrix-element + parton-shower predictions of collider observables. We explain how inconsistent prescriptions can lead to counter-intuitive results and present a few explicit examples, focusing mostly on W/Z+jets processes. We give a specific prescription for how to improve the consistency of the matching and also address how to perform consistent tune variations (e. g., of the renormalization scale) around a central choice. Comparisons to several collider processes are included to illustrate the properties of the resulting improved matching, relying on AlpGen + Pythia 6, with the latter using the so-called Perugia 2011 tunes, developed as part of this effort. Our observations, nevertheless, apply to the large class of tools where matrix-element generators are merged with independent codes for the parton-shower evolution.
UR - http://www.scopus.com/inward/record.url?scp=84864238044&partnerID=8YFLogxK
U2 - 10.1140/epjc/s10052-012-2078-y
DO - 10.1140/epjc/s10052-012-2078-y
M3 - Article
AN - SCOPUS:84864238044
SN - 1434-6044
VL - 72
SP - 1
EP - 16
JO - European Physical Journal C
JF - European Physical Journal C
IS - 7
M1 - 2078
ER -