“…It is a well known fact (see [9], [14] or [18]) that if M is a compact flat spin manifold, the spin structures on M are in a one-to-one correspondence with group homomorphisms…”
Section: Preliminariesmentioning
confidence: 99%
“…In [18], Pfäffle computes the eta invariants of all 3-dimensional compact flat manifolds. In [21], the authors consider the case of a family of Z nmanifolds of dimension n, arriving at an expression of the eta invariant in terms of solutions of certain congruences.…”
Section: Eta Invariants and Class Numbersmentioning
Furthermore, for p = 3, we show that η is an explicit integral multiple of the class number h −p of the imaginary quadratic field Q( √ −p). We also provide alternative expressions for η as finite cotangent or cosecant sums.
“…It is a well known fact (see [9], [14] or [18]) that if M is a compact flat spin manifold, the spin structures on M are in a one-to-one correspondence with group homomorphisms…”
Section: Preliminariesmentioning
confidence: 99%
“…In [18], Pfäffle computes the eta invariants of all 3-dimensional compact flat manifolds. In [21], the authors consider the case of a family of Z nmanifolds of dimension n, arriving at an expression of the eta invariant in terms of solutions of certain congruences.…”
Section: Eta Invariants and Class Numbersmentioning
Furthermore, for p = 3, we show that η is an explicit integral multiple of the class number h −p of the imaginary quadratic field Q( √ −p). We also provide alternative expressions for η as finite cotangent or cosecant sums.
“…This obstruction, discovered by Long and Reid [25], is the integrality of the eta invariant (for the signature operator) of the oriented Bieberbach manifold modeling the cusps. The eta invariant of Dirac operators on Bieberbach 3-manifolds was computed by Pfäffle [36] and may provide additional obstructions. See also [18] and references therein for an introduction to the eta invariant.…”
Section: Betti Numbers and Cusps Of Hyperbolic Manifoldsmentioning
Abstract. We describe the spectrum of the k-form Laplacian on conformally cusp Riemannian manifolds. The essential spectrum is shown to vanish precisely when the k and k − 1 de Rham cohomology groups of the boundary vanish. We give Weyl-type asymptotics for the eigenvalue-counting function in the purely discrete case.In the other case we analyze the essential spectrum via positive commutator methods and establish a limiting absorption principle. This implies the absence of the singular spectrum for a wide class of metrics. We also exhibit a class of potentials V such that the Schrödinger operator has compact resolvent, although V tends to −∞ in most of the infinity. We correct a statement from the literature regarding the essential spectrum of the Laplacian on forms on hyperbolic manifolds of finite volume, and we propose a conjecture about the existence of such manifolds in dimension four whose cusps are rational homology spheres.
“…β = 0, the manifold M is Ricci flat hence flat, therefore it is isometric to the quotient \ R 3 where ⊂ Isom + (R 3 , can) = R 3 SO 3 is a discrete subgroup of orientation-preserving isometries acting freely on R 3 . In other words, M is one of the Bieberbach manifolds [21].…”
Section: Compact η-Einstein 3-dimensional Minimal Flows With Transvermentioning
We study a Killing spinor type equation on spin Riemannian flows. We prove integrability conditions and partially classify those flows carrying non-trivial solutions.
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