Speaker
Description
CP violation was first observed more than 50 years ago. Although its effect has been studied in meson decays for a long time, we still have no observation of CP violation in weakly decaying baryons. Baryons consisting of one or more heavy quarks, so called hyperons, $Y$, can be used to search for CP-violating mechanisms beyond the Standard Model. At the BESIII experiment in Beijing, strange hyperon and anti-hyperon pairs can be produced simultaneously through the process $e^{+}e^{-}\to J/\psi \to Y\bar{Y}$. The BESIII experiment has collected the world’s largest $J/\psi$ data sample and the symmetric, excellent detector conditions and low background contributions allows for a clean environment for CP-tests in the strange sector. This is done by measuring and comparing the CP-odd decay parameters of the hyperon together with the anti-hyperon. The CP-symmetry tests can be performed in processes like e.g. $J/\psi \to\Lambda\bar{\Lambda}$, $J/\psi \to\Sigma\bar{\Sigma}$ and $J/\psi \to\Xi\bar{\Xi}$. Recently it was shown that for the process $J/\psi \to \Lambda\bar{\Lambda}$ the CP-odd asymmetry decay parameter for the decay $\Lambda\to p \pi^{-}$ was nearly twenty percent larger compared to the PDG tabulated value. Another example is the $J/\psi \to\Xi\bar{\Xi}$ which allows for accessing the $\Xi$ decay parameters and perform three independent CP tests in a single measurement. In the talk, we will give an outline of the methods, present recent results and give prospects for the future from the BESIII experiment.