カルフォルニア大学
https://archive.org/search?query=Free+energy+vacuum
Vacuum Energy Density in the Quantum Yang – Mills Theory
by V. Gogokhia; G. G. Barnafoldi
https://archive.org/details/arxiv-0708.0163/mode/2up
Vacuum energy on orbifold factors of spheres
by Peter Chang; J. S. Dowker
https://archive.org/details/arxiv-hep-th9210013/mode/2up