Researching Pi-N Scattering and Virtual Photon Excitation of Neucleons

[zhangyang]

Pi-N scattering is useful for research on neucleon resonance.But pi meson is not stable,how could it be controlled to collide with a neucleon?

While,virtual photon is also used to excite neucleon,it is internal line particle,which is determined by a reaction,so how hard could it be controlled accurately?

 

[zhangyang]

Sorry ,there is some error in my operation,I want to delate one of them.

 

[ChrisVer]

Pi-N scattering in which experiment?
For example you can get pi-N scattering by placing some "target" near the creation of the pion... (in fact a relativistic charged pion=momenta over some $m_\pi$'s, can travel for some meters before decaying. A momentum p~1GeV~10$m_\pi$ would bring the pion to travel for about L~80meters before decaying)

 

[vanhees71]

The pions only decay via the electro-weak interaction and thus are pretty long-lived ($\sim 2.6 \cdot 10^{-8} \; \text{s}$ for the charged pions). For a contempory pion-beam experiment at GSI (Darmstadt, Germany), see

https://hades-wiki.gsi.de/foswiki/bin/view/PionBeam/WebHome

 

[ChrisVer]

I happened to ask for a confirmation (which I got) yesterday about the formula I had deduced for a similar scenario:
https://www.physicsforums.com/threads/tau-momentum-for-decay-length.816902/
in that formula you could solve for l_{lab} instead of momentum (you can try different momenta p) and m the mass of the pion. The lifetime is given in Vanshee's post above.