We report a search for the decay $B^0\to J/\psi \varphi$, using a sample of $657\times {10}^6$ $B\overline{B}$ pairs collected with the Belle detector at the ${\rm Y}(4S)$ resonance. No statistically significant signal is found and an upper limit for the branching fraction is determined to be $\mathcal{B}(B^0\to J/\psi \varphi )<9.4\times {10}^{-7}$ at 90% confidence level.

• Received 21 May 2008

DOI:https://doi.org/10.1103/PhysRevD.78.011106