BitCoin Price Index -Studies on Relation to Network Hashrate and Block Difficulty? Are there any available studies, articles or blog posts on this topic?

I am currently working on a market analysis including major bitcoin exchanges and the bitcoin price index. I'm specifically interested in the relevance of the network hashrate and block difficulty for spikes and drops in the BitCoin Price Index.

I have had some discussions with few traders, and there seemingly is no such study. I expect no surprises, but I feel like this should be measured, described and written down, rather than passed on by hearsay and witty comments. 

Hence, I'm looking for anything related to the above mentioned topic, to compile it into a single piece for future reference.
I know of one researcher off hand who has worked in this area, Adam Hayes. You can find his papers on the subject at:


http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2648366
http://www.economicpolicyresearch.org/econ/2015/NSSR_WP_052015.pdf


You could also look around on http://arxiv.org/. Just searching for 'bitcoin price', I found:


http://arxiv.org/pdf/1406.0268.pdf
http://arxiv.org/pdf/1405.4498.pdf