First observation of aΥ(1D)state

Abstract

We present the first evidence for the production of Υ(1D) states in the four-photon cascade, Υ(3S) → γχ b (2P ), χ b (2P ) → γΥ(1D), Υ(1D) → γχ b (1P ), χ b (1P ) → γΥ(1S), followed by the Υ(1S) annihilation into e + e − or µ + µ − . 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) • 10 −5 , is consistent with the theoretical estimates. The data are dominated by the production of one Υ(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 Υ(3S) → γχ b (2P ), χ b (2P ) → γΥ(1D), followed by either Υ(1D) → ηΥ(1S) or Υ(1D) → π + π − Υ(1S). We find no evidence for such decays and set upper limits on the product branching ratios.

Bottomonium spectrum revisited

“…Experimentalists have been only able to distinguish the Υ(1 3 D 2 ) state of the triplet Υ(1 3 D J ) [15,16]. In Ref.…”

“…Despite the S-wave and P -wave bottomonium states were first observed in the 1970s and 1980s, the triplet Υ(1 3 D J ) has been observed recently [15] distinguishing only the Υ(1 3 D 2 ) state [16]. The mass of the Υ 2 (1D) was measured to be (10164.5 ± 0.8 ± 0.5) MeV.…”

Higher bottomonium zoo

“…However, this is not enough to make people satisfied because many of experimental information is still incomplete, including the total width and branching ratios of some significant decay channels, which still require both of experimental and theoretical efforts. With regard to the search for a D-wave bottomonium in the experiments, there also has some progresses by the CLEO and BaBar Collaborations [21,22], where spin-triplet Υ(1 3 D 2 ) was observed with a 5.8 σ significance while confirmation of Υ(1 3 D 1 ) and Υ(1 3 D 3 ) states is dubious on account of lower significance [22].…”

Covariant Spectator Theory of heavy–light and heavy mesons and the predictive power of covariant interaction kernels

“…[27]. There is weak evidence (at 1.8σ) that the Υ(1D) has been seen [28,29]. rable to the typical rms deviations reported in [8].…”