Jets, R-paramater (resolution)

1. Jul 9, 2009

malawi_glenn

Hello,

I was wondering about this R-parameter that we have in Jet finding algorithms, what is it? How does it change the "physics" when we do jet findings in analysis?

Any good introductory material would be really great if I could acquire it :-)

2. Jul 9, 2009

blechman

I'm not sure, but if you're talking about cone jets (at the Tevatron, for example):

$$R^2 = \Delta\eta^2+\Delta\phi^2$$

which is the size of the cone in (pseudo)rapidity-asimuth space (roughly the analog of $\delta$ in Sterman-Weinberg cone jets).

3. Jul 9, 2009

malawi_glenn

I am talking about jet algorithms in packages such as FastJet, where "rparamter" is an input.

e.g. this is a concrete example:

FastJets(Final state ,Algorithm = FastJets::KT, rparamter = 0.5)