The forgotten Scaler story:
Plotting the
mfilt versus b values from the
UCD scaler
analysis for all energies gives the upper figure which shows a clear
deviation for the extrapolation 2 AGeV data. As a guidance I ran a few
thousand UrQMD events at 4 AGeV (b=0-15fm) and plotted the charged particle
multiplicity (minus the initial 178 protons) versus the impact parameter.
A comparison indicates that the 2 AGeV data have a problem matching
mfilt to an impact parameter for larger impact parameters. How was this taken
into account?
BEM calculations
We have published some papers with BEM calculations. In the theory only paper
it was established that
BEM (without momentum dependence) basically
shows a straight line dependence on
log(EBeam). The inclusion of the
momentum dependence resulted into a shift
towards higher beam energies but the basic functional form didn't change.
The bending for the soft EOS is mainly caused by the 1AGeV value. Assuming
a
softening of the EOS bends the beam energy
dependence towards what is observed in the
published data.
How do we justify trying BEM with an intermediate EOS of k=300MeV? The insert
the phase transition picture shows what kind of rho/rho0 dependence would
be needed to reproduce the shape of the excitation function (here I assume that
k=300MeV is in between k=380MeV and k=220MeV and doesn't show any funky
deviation from their behaviour). Since for my feeling k=300MeV bounces too much
around I plotted the values I got from Paul as function of log(EBeam) and put
them on the same scale. It was a bit surprising to see that
without pt cut the main change seem to be between
k=220MeV and k=300MeV while the difference between k=300MeV and k=380MeV is
marginal. Furthermore the calculations have changed. Previously the hard EOS
had a (small) negative v2 value at 6 AGeV and was well separated from the
soft EOS while now it is positive and very close to the soft EOS. Using the
straight line dependence as guidance, the b=1.5fm k=380MeV looks odd as does
the b=7.5 fm k=220MeV.
v2 as function of log(Ebeam) high pt cut show the
same closeness of k=300MeV and k=380MeV. b=5.5 k=300MeV is clearly off.
Concluding: BEM values have changed significantly since publication of
elliptic flow manuscript but basic straight line dependence for hard eos
was preserved. At least one value is completely off (6AGeV with pt cut,
k=300 MeV,b=5.5fm)
pt dependence
What should be shown is the full differential pt dependence. Out of the box
(which is pretty much the only thing Paul can do) it looks good and not much
cleanup/further analysis is needed. Here are
2 AgeV,
4 AgeV and
6 AgeV
except for the 4 AGeV where I suspect from the qm kaon flow analysis that I
lost about half of the stats, these plots contain all states there are. The
cuts are abs(ycm)<0.1 and 5< b <8. To get more stats one could open up the
ycm cut (remember Sorge used 0.7!). For the low pt's one would need to assess
the pion contamination but with the Paul's enrichment technique I don't see a
problem there.