What is particle-particle or particle-hole susceptibility

[gefro]

what is particle-particle or particle-hole susceptibility in condensed matter physics?
what is it good for and where does it come from?

 

[Gokul43201]

How well do you know the Hubbard Model ? I know only a tiny bit, so I'll leave you with this link :

http://arxiv.org/PS_cache/cond-mat/pdf/9802/9802078.pdf