Revisiting C and CP Violation in Η→π^+π^-Π^0 Decay

The decay eta -> pi(+)pi(-) pi(0) is an ideal process in which to study flavor-conserving C and CP violation beyond the Standard Model. We deduce the C- and CP-odd quark operators that contribute to eta -> pi(+)pi(-) pi(0) originating from the mass-dimension-six Standard Model effective field theory. The corresponding hadronlevel operators that generate a nonvanishing I = 0 amplitude at order p(6) in the chiral effective theory are presented for the first time, to the best of our knowledge, in addition to the leading-order operators ascribed to the I = 2 final state. By fitting the KLOE-2 and the most recent BESIII experimental data, we determine the coefficients of the lowest-order I = 0 and I = 2 amplitudes and estimate the potential new physics energy scale. We also perform an impact study of the future eta -> pi(+)pi(-) pi(0) experiments.