Based on data samples collected with the BESIII detector at the BEPCII collider at 9 center-of-mass energies from 4.21 to 4.42 GeV, we search for the production of $e^+e^-to omegachi_{cJ}$ ($J$=0, 1, 2). The process $e^+e^-to omegachi_{c0}$ is observ
ed for the first time, and the Born cross sections at $sqrt{s}$=4.23 and 4.26 GeV are measured to be $(55.4pm 6.0pm 5.9)$ and $(23.7pm 5.3pm 3.5)$ pb, respectively, where the first uncertainties are statistical and the second are systematic. The $omegachi_{c0}$ signals at the other 7 energies and $e^+e^-to omegachi_{c1}$ and $omegachi_{c2}$ signals are not significant, and the upper limits on the cross sections are determined. By examining the $omegachi_{c0}$ cross section as a function of center-of-mass energy, we find that it is inconsistent with the line shape of the $Y(4260)$ observed in $e^+ e^-topi^+pi^-J/psi$. Assuming the $omegachi_{c0}$ signals come from a single resonance, we extract mass and width of the resonance to be $(4230pm8pm6)$ MeV/$c^2$ and $(38pm12pm2)$ MeV, respectively, and the statistical significance is more than $9sigma$.
Using a sample of $1.06times10^{8}~psi(3686)$ events collected with the BESIII detector at BEPCII, the decays $eta_{c}(2S)to pbar{p}$ and $h_{c}to pbar{p}$ are searched for, where $eta_c(2S)$ and $h_c$ are reconstructed in the decay chains $psi(3686)
togammaeta_{c}(2S)$, $eta_{c}(2S)to pbar{p}$ and $psi(3686)topi^{0}h_{c}$, $h_{c}to pbar{p}$, respectively. No significant signals are observed. The upper limits of the product branching fractions are determined to be $mathcal{B}(psi(3686)togammaeta_c(2S))timesmathcal{B}(eta_{c}(2S)to pbar{p})<1.4times10^{-6}$ and $mathcal{B}(psi(3686)topi^0h_c)timesmathcal{B}(h_{c}to pbar{p})<1.3times10^{-7}$ at the 90% C.L.. The branching fractions for $chi_{cJ}to pbar{p}$ $(J=0,~1,~2)$ are also measured to be $(24.5pm0.8pm1.3,~8.6pm0.5pm0.5,~8.4pm0.5pm0.5)times10^{-5}$, which are the worlds most precise measurements.
We introduce the notion of superstructure Mottness to describe the Mott and Wigner-Mott transition in doped strongly correlated electron systems at commensurate filling fractions away from one electron per site. We show that superstructure Mottness e
merges in an inhomogeneous electron system when the superstructure contains an odd number of electrons per supercell. We argue that superstructure Mottness exists even in the absence of translation symmetry breaking by a superlattice, provided that the extended or intersite Coulomb interaction is strong. In the latter case, superstructure Mottness offers a unifying framework for the Mott and Wigner physics and a nonperturbative, strong coupling description of the Wigner-Mott transition. We support our proposal by studying a minimal single-band ionic Hubbard $t$-$U$-$V$-$Delta$ model with nearest neighbor Coulomb repulsion $V$ and a two-sublattice ionic potential $Delta$. The model is mapped onto a Hubbard model with two effective ``orbitals representing the two sites within the supercell, the intra and interorbital Coulomb repulsion $U$ and $U^prime sim V$, and a crystal field splitting $Delta$. Charge order on the original lattice corresponds to orbital order. Developing a cluster Gutzwiller approximation, we study the effects and the interplay between $V$ and $Delta$ on the Mott and Wigner-Mott transitions at quarter-filling. We provide the mechanism by which the superlattice potential enhances the correlation effects and the tendency towards local moment formation, construct and elucidate the phase diagram in the unifying framework of superstructure Mottness.
