Study of the Zc+ channel using lattice QCD

Recently experimentalists have discovered several charged charmoniumlike hadrons Z(c)(+) with unconventional quark content (c) over barc (d) over baru. We perform a search for Z(c)(+) with mass below 4.2 GeV in the channel I-G (J(PC)) = 1(+)(1(+-)) using lattice QCD. The major challenge is presented by the two-meson states J/psi pi, psi(2S)pi, psi(1D)pi, D (D) over bar (*), D*(D) over bar*, eta(c)rho that are inevitably present in this channel. The spectrum of eigenstates is extracted using a number of meson-meson and diquark-antidiquark interpolating fields. For our pion mass of 266 MeV we find all the expected two-meson states but no additional candidate for Z(c)(+) below 4.2 GeV. Possible reasons for not seeing an additional eigenstate related to Z(c)(+) are discussed. We also illustrate how a simulation incorporating interpolators with a structure resembling low-lying two-meson states seems to render a Z(c)(+) candidate, which is however not robust after further two-meson states around 4.2 GeV are implemented.