Search for the Decay $B_s^0 \longrightarrow \pi ^0 \pi ^0$ at $\varUpsilon (5S)$ Resonance Using Belle Detector

Abstract

The decay $B_s^0\rightarrow \pi ^0\pi ^0$ is a neutral, charmless, non-leptonic, charged current mediated and strangeness non-conserving decay whose theoretical branching fraction(BF) within the Standard Model(SM) is predicted to be $0.40 \times 10^{-6}$ [1], calculated in the framework of flavor SU(3) symmetry . The analysis reported in this paper is based on full data sample available at Belle with an integrated luminosity of $121.4 fb^{-1}$. This will be the first attempt to search for this rare decay using the Belle dataset. The decay process was first studied in the year 1995, by the L3 experiment [2] using three million hadronic Z decays with an efficiency of approximately $8\%$. In the absence of any signal, an upper limit on the BF was set at $2.4 \times 10^{-4}$ at $90\%$ confidence level. We expect to achieve the SM sensitivity for this decay using higher statistics available at Belle which is close to 14 million $B_s^0\bar{B}_s^0$ pairs and adoption of newer background suppression techniques such as Neural Networks and better statistical tools for PDF modelling.