Publication at Faculty of Mathematics and Physics |
2012
Abstract
We report the observation of two narrow structures in the mass spectra of the pi(+/-) Y(nS) (n = 1, 2, 3) and pi(+/-) h(b)(mP) (m = 1, 2) pairs that are produced in association with a single charged pion in Y(5S) decays. The measured masses and widths of the two structures averaged over the five final states are M-1 = (10 607.2 +/- 2.0) MeV/c(2), Gamma(1) =(18.4 +/- 2.4) MeV, and M-2 = (10 652.2 +/- 1.5) MeV/c(2), Gamma(2) = (11.5 +/- 2.2) MeV.
The results are obtained with a 121.4 fb(-1) data sample collected with the Belle detector in the vicinity of the Y(5S) resonance at the KEKB asymmetric-energy e(+)e(-) collider.