First observation of a Upsilon(1D) state
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We present the first evidence for the production of (1D) states in the four-photon cascade, (3S) b(2P), b(2P)(1D), (1D) b(1P), b(1P)(1S) , followed by the (1S) annihilation into e+e- or +-. The signal has a significance of 10.2 standard deviations. The measured product branching ratio for these five decays, (2.50.50.5)10-5, is consistent with the theoretical estimates. The data are dominated by the production of one (1D) state consistent with the J=2 assignment. Its mass is determined to be (10161.10.61.6) MeV, which is consistent with the predictions from potential models and lattice QCD calculations. We also searched for (3S)b(2P), b(2P) (1D), followed by either (1D)(1S) or (1D)+-(1S). We find no evidence for such decays and set upper limits on the product branching ratios.