Hadronic transitions between bottomonium states
Abstract
The bottomonium system is comprised of bound bb quark-antiquark states. The triplet states, $\Upsilon$(nS) and $\chi$(nP), have been observed. The singlet states, $\eta\sb{\rm b}$(nS) and h$\sb{\rm b}$(nP), are predicted to exist but have not been observed. The hadronic transitions $\rm\Upsilon(3S)\to\pi\sp+\pi\sp-\Upsilon(1S),\ \Upsilon(3S)\to\pi\sp+\pi\sp-\Upsilon(2S),\ \Upsilon(2S)\to\pi\sp+\pi\sp-\Upsilon(1S)$ have been studied using data collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR). Measurements of the branching ratio and invariant mass spectrum for $\rm\Upsilon(3S)\to\pi\sp+\pi\sp-\Upsilon(1S)$ and $\rm\Upsilon(3S)\to\pi\sp+\pi\sp-\Upsilon(2S)$ are reported. The measured rates are $$\eqalign{Br(\Upsilon(3{\rm S})&\to\pi\sp+\pi\sp-\Upsilon(1{\rm S})) = (4.52\pm 0.35)\%\cr Br(\Upsilon(3{\rm S})&\to\pi\sp+\pi\sp-\Upsilon(2S)) = (3.32\pm 0.52)\%\cr}$$A measurement of the branching ratio $\rm\Upsilon(3S)\to\Upsilon(2S)+X$ and a determination of the rates for $\Upsilon(3S)\to\Upsilon(2S)\pi\sp0\pi\sp0$ and $\rm \Upsilon(3S)\to\Upsilon(2S)\gamma\gamma$ is achieved by examining the $\rm\Upsilon(2S)\to\pi\sp+\pi\sp-\Upsilon(1S)$ transitions. The measured rates are $$\eqalign{Br(\Upsilon(3{\rm S})&\to\Upsilon(2{\rm S})+X) = (10.2\pm 0.9)\%\cr Br(\Upsilon(3{\rm S})&\to\Upsilon(2{\rm S})\gamma\gamma) = (4.83\pm 0.76)\%\cr Br(\Upsilon(3{\rm S})&\to\Upsilon(2{\rm S})\pi\sp0\pi\sp0) = (1.99 \pm 0.43)\%\cr}$$A 90% confidence level upper limit of the branching ratio for $\Upsilon(3{\rm S})\to\pi\sp+\pi\sp- h\sb{b}$ is reported and the first evidence of $\pi\sp+\pi\sp-$ transitions between $\chi$ states is reported. The measured rates are $$\eqalign{\quad Br(\Upsilon(3{\rm S})\to\pi\sp+\pi\sp- h\sb{b})&< 0.18\%\cr Br(\chi\sb{b0}(2P)\to\pi\sp+\pi\sp-\chi\sb{b0}(1P)) &< 6.6\%\cr Br(\chi\sb{b1}(2P)\to\pi\sp+\pi\sp-\chi\sb{b1}(1P)) &= (2.4\pm 1.8)\%\cr Br(\chi\sb{b2}(2P)\to\pi\sp+\pi\sp-\chi\sb{b2}(1P)) &< 3.1\%.\cr}$$
Degree
Ph.D.
Advisors
Shibata, Purdue University.
Subject Area
Particle physics
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