Prospects for CP & P violation in ${\Lambda }_c^{+}$ decay at STCF

Abstract

CP violation is an excellent tool for probing flavor dynamics as we learnt first with $K_L\to 2\pi$ and later also with the weak decays of beauty mesons. LHCb 2019 data have shown CP violation for the first time in $D^0\to K^{-}{K}^{+}$ vs. $D^0\to {\pi }^{-}{\pi }^{+}$. Searching for CP asymmetries is of great interest in charm quark sector in the Standard Model (SM) or even more beyond it. In charm hadron decays, lots of work had focused on two-body final states, and the measurements of CP asymmetries in three- or four-body final states are rare. Dalitz plots have shown an excellent record for three-body final states, and more results are desired for four-body ones. In this work we study CP asymmetries in the decays ${\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+}{\pi }^0$/$\Lambda {\pi }^{+}{\pi }^{+}{\pi }^{-}$/$p{K}_S{\pi }^{+}{\pi }^{-}$, where the SM gives zero values for the first two channels, while $3.3\times 10^{-3}$ for the last one due to $K^0-{\bar{K}}^0$ oscillation. We performed a fast Monte Carlo simulation study by using electron-positron annihilation data of 1~${\text{ab}}^{-1}$ at center-of-mass energy $\sqrt{s}=4.64$ GeV. The data is expected to be available by the next generation Super Tau Charm Facility proposed by China and Russia with one year (or even less) data taking operation. The results indicate that a sensitivity at the level of 0.2$\sim$0.5% is accessible for these processes, which would be enough to measure nonzero CP-violating asymmetries as large as 1%.

Comments: final version, to appear in PRD