Your search +path:/sys/ +path:fs +path:/cgroup/ +(+path:system +path:. +path:slice) +path:/system-foo.slice/ +(+path:system-foo-bar +path:. +path:slice) +path:/system-foo-bar-baz.slice/ did not match any files.
Suggestions:

• Make sure all terms are spelled correctly.
• Try different keywords.
• Try more general keywords.
• Use 'wil*' cards if you are looking for partial match.