Review on low and high mass spectroscopy

Changzheng YUAN
2011 Proceedings of 35th International Conference of High Energy Physics — PoS(ICHEP 2010)   unpublished
We review the most recent experimental progress in the hadron spectroscopy, up to bottomonium mass. This covers the search for the J PC = 1 −+ exotic state, the states in J/ψ decays, the spinsinglets of heavy quarkonium, and the charmoniumlike XY Z states. PoS(ICHEP 2010)569 Review on low and high mass spectroscopy Chang-Zheng Yuan States in J/ψ decays With newly accumulated 106 M ψ(2S) and 226 M J/ψ events, BESIII experiment [2] confirmed the existence of the threshold enhancement in J/ψ → γ
more » ... final state, with mass agrees with the BESII measurement, and the width less than 8 MeV at the 90% confidence level (C.L.). In an analysis of the J/ψ → γη π + π − , three resonances are observed. The X(1835) has a mass of 1838 ± 3 MeV, in good agreement with BESII result, and a width of 180 ± 9 MeV, which is larger than the BESII measurement. The two new structures are at 2124 MeV and 2371 MeV, with widthes around 100 MeV. In the ηπ + π − invariant mass recoiling against an ω in J/ψ decays, besides the known f 1 (1285) and η(1405), a state at 1873 ± 11 MeV with a width of 82 ± 19 MeV is seen, it could be the hadronic production of the X(1835) observed in η π + π − mode, although the mass difference is large. The nature of these states is unknown, with the possibilities of being the excited η or η states, the glueballs, the pp molecular states, and so on. Spin-singlet charmonium and bottomonium states The P-wave charmonium spin-singlet state h c is studied at BESIII with 106 M ψ(2S) events accumulated in 2009 [3, 4] . Clear signals are observed for ψ(2S) → π 0 h c with and without the subsequent radiative decay h c → γη c . First measurements of the absolute branching ratios
doi:10.22323/1.120.0569 fatcat:gefmwxqvtzfgjj25z4ei4gwtj4