LO Vs NLO Pdf's For Parton Shower MC's
LO Vs NLO Pdf's For Parton Shower MC's
LO Vs NLO Pdf's For Parton Shower MC's
ok for sea
Impact on UE tunes
5L significantly steeper at low
x and Q2
Rick Field has produced a
tune based on CTEQ6.1
Ricks tune
Study
Torbjorn Sjostrand
NLO 6.1
K-factor=1.15
LO 6.1
LO 6L1
One possibility
yW+
For example, the shape of the W+ rapidity
distribution is significantly different than the
NLO result if the LO pdf is used, but very
similar if the NLO pdf is used.
Discussion
Torbjorn is uncomfortable with the idea of using
a NLO pdf with Pythia (even though
experimenters are doing worse, mixing LO and
NLO pdfs)
Can we think of a hybrid pdf for use in Monte
Carlos?
Wu Ki suggested using NLO evolution in the LO
fit
Ive heard that Robert Thorne is trying to relax
the sum rule constraints for LO fits
Can we try to limit the low-x and high-x
differences which are due not to evolution
effects, I believe, but to the LO matrix elements
used in fitting the DIS data?