Primary decomposition of knot concordance and von neumann rho-invariants

We address the primary decomposition of the knot concordance group in terms of the solvable filtration and higher order von Neumann ρ- invariants by Cochran, Orr, and Teichner. We show that for a non-negative integer n, if the connected sum of two n-solvable knots with coprime Alexander polynomials is slice, then each of the knots has vanishing von Neumann ρ- invariants of order n. This gives positive evidence for the conjecture that nonslice knots with coprime Alexander polynomials are not concordant. As an application, we show that if K is one of Cochran-Orr-Teichner's knots which are the first examples of nonslice knots with vanishing Casson-Gordon invariants, then K is not concordant to any knot with Alexander polynomial coprime to that of K.