English

The special unitary groups $SU(2n)$ as framed manifolds

Algebraic Topology 2025-02-20 v4

Abstract

Let [SU(2n),L][SU(2n), \mathscr{L}] denote the bordism class of SU(2n)SU(2n) (n2)(n\ge 2) equipped with its left invariant framing L\mathscr{L}. Then it is well known that eC([SU(2n),L])=0e_\mathbb{C}([SU(2n), \mathscr{L}])=0 where eCe_\mathbb{C} denotes the complex Adams ee-invariant. In this note we show that replacing L\mathscr{L} by the framing obtained by twisting it by a specific map the zero value of eC([SU(2n),L])e_\mathbb{C}([SU(2n), \mathscr{L}]) can be transformed into a generator of ImeC\mathrm{Im} \, e_\mathbb{C} which is isomorphic to a cyclic group. In addition we show that the same procedure affords an analogous result for a quotient of SU(2n+1)SU(2n+1) by a circle subgroup which inherits a canonical framing from SU(2n+1)SU(2n+1) in the usual way. .

Keywords

Cite

@article{arxiv.2406.11878,
  title  = {The special unitary groups $SU(2n)$ as framed manifolds},
  author = {Haruo Minami},
  journal= {arXiv preprint arXiv:2406.11878},
  year   = {2025}
}

Comments

8 pages; corrects Lemmas 1 and 3, and along with that, modifies the proofs of Theorem and Proposition; adds a remark in the last page