Torque for Shimano Alfine 8/11 Speed Internally Geared Hub Axle Nuts?
Here is how I found the answer (30-45 N-m):


Followed the link in the first comment on the question (or I could have done a search for something like "shimano alfine hub service pdf").
The link Gordon provided was led to several Shimano products identified only by part number, so I did another search for "shimano alfine 11 hub" and found a listing on Amazon with the part number (SG-700). Shimano's part numbers are pretty transparent – if you know the two letter code that they use for different components – so you might be able skip this step with a lucky guess.
From there I opened up the service manual and scanned it for the step where the cap nuts are tightened.