Difference hard / semi-hard scattering

[earth2]

Hey folks,

another question.
What is the difference between hard and semi-hard scattering events?
In terms of energy I found for both s >> t, so where does the difference lie?

Thanks,
Earth's

 

[humanino]

Can you be more specific, where did read "semi-hard", what was the context ? To my knowledge, this is used in hadronic collisions when the virtuality of the involved partons is large compared to lambda_QCD but small compared to s.

 

[earth2]

Ok, i just found the answer here: http://www-subatech.in2p3.fr/~photons/subatech/physics/potpourri/node23.html

hard: truly perturbative
semi-hard: perturbative + non-perturbative effects

Thanks anyway!
earth2

 

[humanino]

I think the plot in your link A+B->C+X is referred to as "hard scattering" and explicitly shows vertex (or structure) functions which are non-perturbative.

No matter what you do with QCD, you will always have confinement at least on one side (that is, you may not have it only in a plasma). Confinement is non-perturbative.

Your link says

By hard processes one usually means clearly perturbative processes with momentum or mass scales of the order of several tens of GeV.
[...]
Semi-hard processes refers to QCD-processes where partons with transverse momenta of a few GeV are produced.