Pion production cross sections

Overview

After some work, I have come to the conclusion that the wiser fits are the best to use, unless looking explicitly at resonant pion production.

Here are the main points:

1. Lightbody and O'Connell (EPC/GPC) works only for resonant production, otherwise it is useless. There should probably be some coded limits of applicability... warnings or something.
2. Inclusive production from MAID is better in this case as it includes polarization.
3. The original "Wiser fit" is for the mono-energetic photoproduction cross sections.
4. The FORTRAN wiser code I have calculates the photoproduction cross section from bremsstrahlung using a very crude description of the bremsstrahlung spectrum.
5. New photoproduction code uses correct description of bremsstrahlung spectrum. This is very similar to the spectrum used by Wiser in his original analysis.
6. Electroproduction cross section related to mono-energetic photoproduction cross section.

Data

• Alanakian, et.al., photoproduction on Carbon (1980)
• Inclusive pion electroproduction cross sections from d2n experiment. (HRS analysis from David Flay)
• Inclusive pion electroproduction cross sections from O'Connell's paper. (data source unknown)
• others...?

Alankian

Positive Pions	Negative Pions

O'Connell

d2n (David Flay)

Positive Pions	Negative Pions

Neutral Pion

How to get the neutral pion cross section from the chared pions?

Assume iso-spin symmetry to get neutron cross section. (p pi+ to n pi-, p pi- to n pi+) Then cross section for neutral pions is
( sig(pi+) + sig(pi-) )/2

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