Studying the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>D</mml:mi><mml:mn>1</mml:mn></mml:msub><mml:mi>D</mml:mi></mml:math> molecule in the Bethe-Salpeter equation approach
Physical review. D/Physical review. D.