Possible partner state of the y (2175)

Abstract

We study the Y(2175) using the method of QCD sum rules. There are two independent sss.s. interpolating currents with JPC=1 - , and we calculate both their diagonal and their off-diagonal correlation functions. We obtain two new currents that do not strongly correlate to each other, so they may couple to two different physical states: one of them couples to the Y(2175), while the other may couple to another state whose mass is evaluated to be 2.41±0.25 GeV. Evidence of the latter state can be found in the BABAR [B. Aubert (BABAR Collaboration), Phys. Rev. D 76, 012008 (2007)PRVDAQ1550-799810.1103/PhysRevD.76.012008], BESII [M. Ablikim (BES Collaboration), Phys. Rev. Lett. 100, 102003 (2008)PRLTAO0031-900710.1103/PhysRevLett.100.102003], Belle [C. P. Shen (Belle Collaboration), Phys. Rev. D 80, 031101 (2009)PRVDAQ1550-799810.1103/PhysRevD.80.031101], and BESIII [M. Ablikim (BESIII Collaboration), Phys. Rev. D 91, 052017 (2015)PRVDAQ1550-799810.1103/PhysRevD.91.052017] experiments.