Experimental Study of chi_b(2P) --> pi pi chi_b(1P)
  We have searched for the di-pion transition chi_b(2P) -> pi pi chi_b(1P) in the CLEO III sample of Upsilon(3S) decays in the exclusive decay chain: Upsilon(3S) -> gamma chi_b(2P), chi_b(2P) -> pi pi chi_b(1P), chi_b(1P) -> gamma Upsilon(1S), Upsilon(1S) -> lepton pairs. Our studies include both pi+ pi- and pi0 pi0, each analyzed both in fully reconstructed events and in events with one pion undetected. We show that the null hypothesis is not substantiated. Under reasonable assumptions, we find the partial decay width to be Gamma[chi_b(2P) -> pi pi chi_b(1P)] = (0.83 +/- 0.22 +/- 0.08 +/- 0.19) keV, with the uncertainties being statistical, internal CLEO systematics, and common systematics from outside sources. 
C. Cawlfield, et al, CLEO Collaboration