Half angle formulas can be derived from the double angle formulas, particularly, the cosine of double angle. For easy reference, the cosines of double angle are listed below: cos 2θ = 1 - 2sin2 θ → Equation (1) cos 2θ = 2cos2 θ - 1 → Equa
2.3 Topological structure constants Correlators of half-BPS operators on the line have a topological sector that does not depend on the positions of the operators [39, 40], and whose existence follows directly from the superconformal Ward identities (2.10).3 The restriction to this subsector in ...