Revisiting 𝐢 and 𝐢⁒𝑃 violation in πœ‚β†’πœ‹+β’πœ‹βˆ’β’πœ‹0 decay

Revisiting 𝐢 and 𝐢⁒𝑃 violation in πœ‚β†’πœ‹+β’πœ‹βˆ’β’πœ‹0 decay

Jun Shi, Jian Liang, Susan Gardner.
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Abstract

The decay Ξ·β†’Ο€+Ο€βˆ’Ο€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 Ξ·β†’Ο€+Ο€βˆ’Ο€0 originating from the mass-dimension-six Standard Model effective field theory. The corresponding hadron-level operators that generate a nonvanishing I=0 amplitude at order p6 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 Ξ·β†’Ο€+Ο€βˆ’Ο€0 experiments.