Jia, Z. S., Li, G., Shi, P. P., & Zhang, Z. H. (2024). Production of hidden-heavy and double-heavy hadronic molecules at the Z factory of CEPC. Phys. Rev. D, 110(1), 014031–15pp.
Abstract: With a clean environment and high collision energy, the Circular Electron Positron Collider (CEPC) would be an excellent facility for heavy flavor physics. Using the Monte Carlo event generator P ythia , we simulate the production of the charmed (bottom) hadron pairs in the electron-positron collisions at the Z factory of CEPC, and the inclusive production rates for typical candidates of the hidden/double-charm and hidden/double-bottom S- wave hadronic molecules are estimated at an order-of-magnitude level with the final state interactions after the hadron pair production. The predicted cross sections for the hidden-charm meson-meson molecules X (3872) and Z(c) (3900) are at pb level, which are about two to three orders of magnitude larger than the production cross sections for the double-charm meson-meson molecules T-cc and T-cc*, as the double-charmed ones require the production of two pairs of c (c) over bar from the Z boson decay. The production cross sections for the hidden-charm pentaquark states P-c and P-cS as meson-baryon molecules are a few to tens of fb, which are about one magnitude larger than those of the possible hidden-charm baryon-antibaryon and double-charm meson-baryon molecules. In the bottom sector, the production cross sections for the Z b states as B-(*())(B) over bar* molecules are about tens to hundreds of fb, indicating 106-107 6 -10 7 events from a two-year operation of CEPC, and the expected events from the double-bottom molecules are about 2-5 orders of magnitude smaller than the Z b states. Our results shows great prospects of probing heavy exotic hadrons at CEPC.
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Shi, P. P., Baru, V., Guo, F. K., Hanhart, C., & Nefediev, A. (2024). Production of the X(4014) as the Spin-2 Partner of X(3872) in e + e – Collisions. Chin. Phys. Lett., 41(3), 031301–7pp.
Abstract: In 2021, the Belle collaboration reported the first observation of a new structure in the psi(2S)gamma final state produced in the two-photon fusion process. In the hadronic molecule picture, this new structure can be associated with the shallow isoscalar D*D* bound state and as such is an excellent candidate for the spin-2 partner of the X(3872) with the quantum numbers J(PC) = 2(++) conventionally named X-2. In this work we evaluate the electronic width of this new state and argue that its nature is sensitive to its total width, the experimental measurement currently available being unable to distinguish between different options. Our estimates demonstrate that the planned Super tau-Charm Facility offers a promising opportunity to search for and study this new state in the invariant mass distributions for the final states J/psi gamma and psi(2S)gamma.
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