What are scalar-isoscalar channels?

[hipa7]

TL;DR

I'm reading a paper on pion quasi-elastic scattering and the total cross section graph is shown as scalar -isoscalar channel and non-scalar-isoscalar channel, what are those channels?

I'm reading a paper on pion quasi-elastic scattering and the total cross section graph is shown as scalar -isoscalar channel and non-scalar-isoscalar channel, what are those channels? are they pion+n-->pion+n and pion+p --> pion +p?

 

[Meir Achuz]

They are probably pi-pi channels. Two pions can be in an isotopic spin 0 (scalar) state
or an isotopic spin 1 (non-scalar) state.
For angular momentum, they can be in a J=0 (scalar) or a J=1 (vector or non-scalar) state.
They can also be in higher J states, with even J being scalar and odd J being non-scalar.
A pi-N state must have isospin I-=1/2 or 3/2. I don't see how either could be described as
scalar or non-scalar. If it is pi-N scattering, then scalar or non-scalar must be referring to either even L or odd L (orbital angular momentum), and not to scalar or non-scalar Ispin..