Angular analysis of B → K^* e⁺ e⁻ in the low-q² region with new electron identification at Belle

We perform an angular analysis of the B→ K^* e⁺ e⁻ decay for the dielectron mass squared, q², range of $0.0008$ to 1.1200 ~GeV² /c⁴ using the full Belle data set in the K*0 → K⁺ π⁻ and K*+ → KS⁰ π⁺ channels, incorporating new methods of electron identification to improve the statistical power of the data set. This analysis is sensitive to contributions from right-handed currents from physics beyond the Standard Model by constraining the Wilson coefficients C₇⁽⁾. We perform a fit to the B→ K^* e⁺ e⁻ differential decay rate and measure the imaginary component of the transversality amplitude to be ATIm = -1.27 ± 0.52 ± 0.12, and the K^* transverse asymmetry to be AT⁽²⁾ = 0.52 ± 0.53 ± 0.11. The resulting constraints on the value of C₇^ are consistent with the Standard Model within a 2σ confidence interval.