Search for the Decay \(B_s^0\rightarrow J/\psi \pi ^0\) at  \(\Upsilon (5S)\) Resonance

We report the preliminary results from a search for the decay \(B_s^0\rightarrow J/\psi \pi \) using 121.4 \(\text {fb}^{-1}\) of data collected at \(\Upsilon (5S)\) resonance state by the Belle detector at the KEKB asymmetric energy \(e^+e^-\) collider located at the High Energy Accelerator Research Organisation, KEK, in Japan. In the Standard Model, the decay is expected to be rare, proceeding through the W-boson exchange and annihilation processes. The quantitative amplitudes predictions for such transitions have resisted attempts and differ significantly between approaches. The QCD factorization (QCDF) approach suffers significant uncertainties due to the end-point singularities, whereas the perturbative QCD (pQCD) does not differentiate among exchange and annihilation topologies. Nevertheless, pQCD provides more precise predictions in the charmless decays. However, annihilation topologies with charm in the final state have not been studied in detail. The experimental investigation of the issue is very desirable since the decay mode has the potential to advance the field. The present experimental upper limit of \(1.2\times 10^{-3}\) at 90% confidence level (CL) on the branching ratio of \(B_s^0\rightarrow J/\psi \pi \) was set by L3 collaboration in 1997. This analysis will be the first attempt to search for this decay using the available dataset from the Belle experiment with an expectation of reaching the SM sensitivity.