[Moller_simulation] Neutral Meson Generation

Seamus Riordan riordan at jlab.org
Fri Apr 21 16:23:49 EDT 2017

Hi everyone,

I know the following is deprecated, but at the very least I'm hoping 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 doesn't work.  From the standard Clebsch Gordan coefficient
argument, pi0 = 2pi+ for gamma p -> Delta -> Npi.  This means for
deuterium 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.


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

Physics Division Building 203           Room C265
Argonne National Laboratory
9700 S. Cass Ave 
Argonne, IL  60439

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