Extracting the light quark mass ratio m_u/m_d from bottomonia transitions

We propose a new method to extract the light quark mass ratio $m_u\mathrm{/}{m}_d$ using the $\mathrm{{\rm Y}}(4S)\to h_b{\pi }^0(\eta )$ bottomonia transitions. The decay amplitudes are dominated by the light quark mass differences, and the corrections from other effects are rather small, allowing for a precise extraction. We also discuss how to reduce the theoretical uncertainty with the help of future experiments. As a by-product, we show that the decay $\mathrm{{\rm Y}}(4S)\to h_b\eta$ is expected to be a nice channel for searching for the $h_b$ state.