Bost-Connes systems associated with function fields
Bost-Connes systems associated with function fields
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与功能域相关的 Bost-Connes 系统
DOI:
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发表时间:
2011
期刊:
影响因子:
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通讯作者:
Simen Rustad
中科院分区:
文献类型:
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作者:
S. Neshveyev;Simen Rustad
With a global function field K with constant field F_q, a finite set S of primes in K and an abelian extension L of K, finite or infinite, we associate a C*-dynamical system. The systems, or at least their underlying groupoids, defined earlier by Jacob using the ideal action on Drinfeld modules and by Consani-Marcolli using commensurability of K-lattices are isomorphic to particular cases of our construction. We prove a phase transition theorem for our systems and show that the unique KMS_eta-state for every 0<etale1 gives rise to an ITPFI-factor of type III_{q^{-eta n}}, where n is the degree of the algebraic closure of F_q in L. Therefore for n=+infty we get a factor of type III_0. Its flow of weights is a scaled suspension flow of the translation by the Frobenius element on Gal(ar F_q/F_q).