Measurements of branching fractions for electromagnetic transitions involving the χbJ(1P) states

Using (9.32, 5.88) million {Upsilon}(2S,3S) decays taken with the CLEO III detector, we obtain five product branching fractions for the exclusive processes {Upsilon}(2S){yields}{gamma}{chi}{sub b0,1,2}(1P){yields}{gamma}{gamma}{Upsilon}(1S) and {Upsilon}(3S){yields}{gamma}{chi}{sub b1,2}(1P){yields}{gamma}{gamma}{Upsilon}(1S). We observe the transition {chi}{sub b0}(1P){yields}{gamma}{Upsilon}(1S) for the first time. Using the known branching fractions for B[{Upsilon}(2S){yields}{gamma}{chi}{sub bJ}(1P)], we extract values for B[{chi}{sub bJ}(1P){yields}{gamma}{Upsilon}(1S)] for J=0, 1, 2. In turn, these values can be used to unfold the {Upsilon}(3S) product branching fractions to obtain values for B[{Upsilon}(3S){yields}{gamma}{chi}{sub b1,2}(1P)] for the first time individually. Comparison of these with each other and with the branching fraction B[{Upsilon}(3S){yields}{gamma}{chi}{sub b0}] previously measured by CLEO provides tests of relativistic corrections to electric dipole matrix elements.