Search for CP violation in D s + → K S 0 K − π + π + $$ {D}_{(s)}^{+}\to {K}_S^0{K}^{-}{\pi}^{+}{\pi}^{+} $$ decays using triple and quadruple products

Abstract

Abstract We perform the first search for CP violation in D s + → K S 0 K − π + π + $$ {D}_{(s)}^{+}\to {K}_S^0{K}^{-}{\pi}^{+}{\pi}^{+} $$ decays. We use a combined data set from the Belle and Belle II experiments, which study e + e − collisions at center-of-mass energies at or near the Υ(4S) resonance. We use 980 fb −1 of data from Belle and 428 fb −1 of data from Belle II. We measure six CP-violating asymmetries that are based on triple products and quadruple products of the momenta of final-state particles, and also the particles’ helicity angles. We obtain a precision at the level of 0.5% for D + → K S 0 K − π + π + $$ {D}^{+}\to {K}_S^0{K}^{-}{\pi}^{+}{\pi}^{+} $$ decays, and better than 0.3% for D s + → K S 0 K − π + π + $$ {D}_s^{+}\to {K}_S^0{K}^{-}{\pi}^{+}{\pi}^{+} $$ decays. No evidence of CP violation is found. Our results for the triple-product asymmetries are the most precise to date for singly-Cabibbo-suppressed D + decays. Our results for the other asymmetries are the first such measurements performed for charm decays.

Keywords

• Charm Physics
• CP Violation
• e +-e − Experiments