Study of J/ψ and ψ(3686) decays to π⁺π^-η'

Using the data samples of 1.31 x 10(9) J/psi events and 4.48 x 10(8) psi(3686) events collected with the BESIII detector, partial wave analyses on the decays J/psi and psi(3686) pthornp -> pi(+)pi(-)eta' are performed with a relativistic covariant tensor amplitude approach. The dominant contribution is found to be J/psi and psi(3686) decays to rho eta' In the J/psi decay, the branching fraction B(J/psi -> rho eta') is determined to be (7.90 +/- 0.19(stat) +/- 0.49(sys)) x 10(-5). Two solutions are found in the psi(3686) decay, and the corresponding branching fraction B(psi(3686) -> rho eta') is (1.02 +/- 0.11(stat) +/- 0.24(sys)) x 10(-5) for the case of destructive interference, and (5.69 +/- 1.28(stat) +/- 2.36(sys)) x 10(-6) for constructive interference. As a consequence, the ratios of branching fractions between psi(3686) and J/psi decays to rho eta' are calculated to be (12.9 +/- 1.4(stat) +/- 3.1(sys))% and (7.2 +/- 1.6(stat) +/- 3.0(sys))%, respectively. We also determine the inclusive branching fractions of J/psi and psi(3686) decays to pi(+)pi(-)eta' to be (1.36 +/- 0.02(stat) +/- 0.08(sys)) x 10(-4) and (1.51 +/- 0.14(stat)) +/- 0.23(sys)) x 10(-5), respectively.