[Solid_software] Neutral Meson Generation

[Seamus Riordan]

Hi everyone,

I know the following is deprecated since we've abandoned Wiser, but I felt
compelled to at least get some correct intuition established.

I did some more exploration on how we calculate neutral mesons from
Wiser and I'm not satisfied with what was in there.  The argument I was
making that pion rates should be equal between flavors because deuterium
is isospin 0 was a bad argument (my apologies to Rich).  From the
standard Clebsch Gordan coefficient argument, pi0 = 2pi+ for
gamma p -> Delta -> Npi (you can see this approximately holds in MAID
for the P33).  This means for deuterium under that symmetry pi0 should
be a factor 4 larger than pi+ (or pi-) instead of equal as we had
it.  I corrected the eicRate SVN for completeness though no one should
still be using it.

I saw the K0 rates followed a similar logic, though the channels for
production are very different.  I played around on Kaon MAID and looking
at gamma p -> hyperon K, if you take Lambda and Sigma production to be
the main channels, K0 production was a factor 4 smaller than K+ (K+ L
and K+ S0 being about equal) which one might guess from simple quark
content arguments.  I didn't touch this part of the code for now.

I know it's not being used anymore, but I wanted to be complete.

Best,
Seamus

-- 
Seamus Riordan                          sriordan at anl.gov
Argonne National Laboratory             Office: (630) 252-4101
Assistant Physicist                     Fax:    (630) 252-3903

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