First observation of a Upsilon(1D) state

Collaboration
Apr, 2004

Citations per year

20042009201420192024024681012
Abstract:
We present the first evidence for the production of Upsilon(1D) states in the four-photon cascade, Upsilon(3S)-->gamma chib(2P), chib(2P)-->gamma Upsilon(1D), Upsilon(1D)-->gamma chib(1P), chib(1P)-->gamma Upsilon(1S), followed by the Upsilon(1S) annihilation into e+e- or mu+mu-. The signal has a significance of 10.2 standard deviations. The measured product branching ratio for these five decays, (2.5+-0.5+-0.5)x10^(-5), is consistent with the theoretical estimates. The data are dominated by the production of one Upsilon(1D) state consistent with the J=2 assignment. Its mass is determined to be (10161.1+-0.6+-1.6) MeV, which is consistent with the predictions from potential models and lattice QCD calculations. We also searched for Upsilon(3S)-->gammachib(2P), chib(2P)-->gammaUpsilon(1D), followed by either Upsilon(1D)-->eta Upsilon(1S) or Upsilon(1D)-->pi+pi- Upsilon(1S). We find no evidence for such decays and set upper limits on the product branching ratios.
  • 14.40.Gx
  • 13.20.Gd
  • electron positron: colliding beams
  • electron positron: annihilation
  • Upsilon(10355): electroproduction
  • Upsilon(10355): radiative decay
  • Upsilon(10355): cascade decay
  • upsilon mesons: hadron spectroscopy
  • new particle: Upsilon(10161)
  • angular momentum: 2