Measurement of time-dependent $CP$ asymmetries in $B^0\rightarrow J/\psi\pi^0$ decays

We present new results on the measurement of $CP$ asymmetries in $B^0\rightarrow J/\psi \pi^0$ decays using approximately 230 million $\Upsilon(4S)\rightarrow B\bar{B}$ decays collected by the BaBar detector at the PEP-II asymmetric-energy $B$ factory. The Cabibbo-suppressed $b\rightarrow ccd$ tree amplitude has a time-dependent asymmetry in these decays that is related to the unitarity triangle angle $\beta$. Penguin amplitudes in these decays contribute at the same order, thus the measured $CP$ asymmetry probes the size of the penguin decay amplitudes.