D-0(D)over-bar-(0) oscillations as a probe of quark-hadron duality

It is usually argued that the Standard Model predicts slow D-0-(D) over bar (0) oscillations with DeltaM(D), Delta Gamma (D) less than or equal to 10( -3) Gamma (D) and that New Physics can reveal itself through DeltaM(D) exce eding 10(-3) Gamma (D). It is believed that the bulk of the effect is due t o long distance dynamics that cannot be described at the quark level. We po int out that in general the OPE yields soft GIM suppression scaling only li ke (m(s)/mu (hadr))(2) and even like m(s)/mu (hadr) rather than m(s)(4)/m(c )(4) of the simple quark box diagram. Such contributions can actually yield DeltaM(D), Delta Gamma (D) similar to O(10(-3))Gamma (D) without invoking additional long distance effects. They are reasonably suppressed as long as the OPE and local duality are qualitatively applicable in the 1/m(c) expan sion. We stress the importance of improving the sensitivity on Delta Gamma (D) as well as DeltaM(D) in a dedicated fashion as a laboratory for analyzi ng the onset of quark-hadron duality and comment on the recent preliminary study on Delta Gamma (D) by the FOCUS group. (C) 2001 Elsevier Science B.V. All rights reserved.