Pineda, Antonio (Pineda Ruiz)2010-05-062010-05-0619970556-2821https://hdl.handle.net/2445/12459Leading nonperturbative effects to fine and hyperfine splittings were calculated some time ago. Recently, they have been used in order to obtain realistic numerical results for the lower levels in bottomonium systems. We point out that a contribution of the same order O ( Λ 4 QCD / m 3 α 2 s ) has been overlooked. We calculate it in this paper.4 p.application/pdfeng(c) The American Physical Society, 1997Partícules (Física nuclear)Particles (Nuclear physics)info:eu-repo/semantics/article508361info:eu-repo/semantics/openAccess