Strong decays of the newly observed D(2550), D(2600), D(2750), and D(2760)

The strong decay properties of the newly observed D(2550), D(2600), D(2750), and D(2760) are studied in a constituent quark model. It is predicted that the D(2760) and D(2750) seem to be two overlapping resonances. The Dd2760_ could be identified as the 1(3)D(3) with J(P) = 3(-), while the D(2750) is most likely to be the high- mass mixed state vertical bar 1D(2)'> H (J(P) = 2(-)) via the 1(1)D(2)-1(3)D(2) mixing. The D(2600) favors the low- mass mixed state vertical bar(SD)(1)>(L) (J(P) = 1(-)) via the 1(3)D(1)-2(3)S(1) mixing. The D(2550) as the 2(1)S(0) assignment bears controversies for its too- broad width given in experiments.