数学物理学报(英文版) ›› 1990, Vol. 10 ›› Issue (4): 427-431.
陆洪文
Lu Hongwen
摘要: The main result of this note is as follows:
Let M=(C A D B)∈SL(2,Z) be hyperbolic. Then the Atiyah's invariant
η(M)=-sign (trac (M))|m (M) Ψ0 (M), whore m(M) is the index of M in the stable subgroup for
α=(A-D+√(A+D)2-4)/2C of the PSL (2, Z), and
Ψ0(M)=(1)/3Ψ(α).