The local equivariant Tamagawa number conjecture for Tate motives

Let pp be an odd prime, let K/kK/k be a finite abelian extension of number fields with Galois group GG, and let SS contain SpSSram(K/k)S_p\cup S_\infty\cup S_{\operatorname{ram}}(K/k), with Sf=SSS_f=S\setminus S_\infty. For jZ1j\in\mathbb{Z}_{\geq 1}, let ΞK/k,Sloc(j)\Xi_{K/k,S}^{\operatorname{loc}}(j) and ϑK/k,Sloc,j\vartheta_{K/k,S}^{\operatorname{loc},j} be the determinant module and its specified isomorphism to Cp[G]\mathbb{C}_p[G]. For each finite prime vv of kk, let δv(K/k)\delta_v(K/k) be the element defined from the Euler factor, and let δK/k,1\delta_{K/k,{\bf{1}}} be the element whose value under the trivial character is 1-1 and under every nontrivial character is 11. Also write ΘK/k,S(j)\Theta_{K/k,S}^\ast(j) for the leading-term element and rkr_k for the number of real places of kk. The local equivariant Tamagawa number conjecture. For any jZ1j\in\mathbb{Z}_{\geq 1}, there is a unique Zp[G]\mathbb{Z}_p[G]-basis zK/k,Sloc,jΞK/k,Sloc(j)z_{K/k,S}^{\operatorname{loc},j}\in\Xi_{K/k,S}^{\operatorname{loc}}(j) such that

ϑK/k,Sloc,j(zK/k,Sloc,j)=(1)rk(j1)×{ΘK/k,S(1j)#ΘK/k,S(j)if j2,δK/k,1(vSfδv(K/k)#)ΘK/k(0)#ΘK/k,S(1)if j=1.\vartheta_{K/k,S}^{\operatorname{loc},j}(z_{K/k,S}^{\operatorname{loc},j})=(-1)^{r_k(j-1)}\times\begin{cases}\displaystyle\frac{\Theta_{K/k,S}^\ast(1-j)^\#}{\Theta_{K/k,S}^\ast(j)}&\text{if }j\geq2,\\[6pt]\displaystyle\delta_{K/k,{\bf{1}}}\cdot\left(\prod_{v\in S_f}\delta_v(K/k)^\#\right)\frac{\Theta_{K/k}^\ast(0)^\#}{\Theta_{K/k,S}^\ast(1)}&\text{if }j=1.\end{cases}

This is the equivariant refinement of the local Tamagawa number conjecture for the Tate motives Zp(j)\mathbb{Z}_p(j), incorporating the delicate sign and Euler-factor corrections. The paper proves this assertion under the stated unramified-at-pp hypotheses, so the conjecture is treated as solved here.

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Primary source

Mahiro Atsuta, Naoto Dainobu and Takenori Kataoka, “On the local equivariant Tamagawa number conjecture for Tate motives”, arXiv:2512.14247 (2025).

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