A QCD sum rules calculation of the J/ψD s * Ds strong coupling constant Bruno Osório Rodrigues, Mirian Enriqueta Bracco, Marcelo Chiapparini and Angelo Cerqueira Eur. Phys. J. A, 51 3 (2015) 28 Published online: 06 March 2015 DOI: 10.1140/epja/i2015-15028-9