Production of singlet P-wave $c\bar{c}$ and $b\bar{b}$ states

Abstract

No spin-singlet $b\bar{b}$ quarkonium state has yet been observed. In this paper we discuss the production of the singlet P-wave $b\bar{b}$ and $c\bar{c}$ ${}^1{P}_1$ states $h_b$ and $h_c$. We consider two possibilities. In the first the ${}^1{P}_1$ states are produced via the electromagnetic cascades $\text{ups}(3S)\to {\eta }_b(2S)+\gamma \to h_b+\gamma \gamma \to {\eta }_b+\gamma \gamma \gamma$ and ${\psi }^{\prime }\to {\eta }_c^{\prime }+\gamma \to h_c+\gamma \gamma \to {\eta }_c+\gamma \gamma \gamma$. A more promising process consists of single pion transition to the ${}^1{P}_1$ state followed by the radiative transition to the $1^1{S}_0$ state: $\text{ups}(3S)\to h_b+{\pi }^0\to {\eta }_b+{\pi }^0+\gamma$ and ${\psi }^{\prime }\to h_c+{\pi }^0\to {\eta }_c+{\pi }^0+\gamma$. For a million $\text{ups}(3S)$ or ${\psi }^{\prime }$'s produced we expect these processes to produce several hundred events.

Comments: 13 pages, LaTeX, 1 figure, to be published Phys. Rev. D. Some equation numbers and one table number corrected