Computing the spectral action for fuzzy geometries: from random noncommutative geometry to bi-tracial multimatrix models
A fuzzy geometry is a certain type of spectral triple whose Dirac operator crucially turns out to be a finite matrix. This notion incorporates familiar examples like fuzzy spheres and fuzzy tori. In the framework of random noncommutative geometry, we use Barrett’s characterization of Dirac operators...
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| Main Author: | |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
30 December 2022
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| In: |
Journal of noncommutative geometry
Year: 2022, Volume: 16, Issue: 4, Pages: 1137-1178 |
| ISSN: | 1661-6960 |
| DOI: | 10.4171/jncg/482 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.4171/jncg/482 Verlag, lizenzpflichtig, Volltext: https://ems.press/journals/jncg/articles/8830438 
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| Author Notes: | Carlos I. Pérez-Sánchez |
| Summary: | A fuzzy geometry is a certain type of spectral triple whose Dirac operator crucially turns out to be a finite matrix. This notion incorporates familiar examples like fuzzy spheres and fuzzy tori. In the framework of random noncommutative geometry, we use Barrett’s characterization of Dirac operators of fuzzy geometries in order to systematically compute the spectral action S(D)=Trf(D)S(D)=Trf(D) for 2n2n-dimensional fuzzy geometries. In contrast to the original Chamseddine–Connes spectral action, we take a polynomial ff with f(x)→∞f(x)→∞ as ∣x∣→∞∣x∣→∞ in order to obtain a well-defined path integral that can be stated as a random matrix model with action of the type S(D)=N⋅trF+∑itrAi⋅trBiS(D)=N⋅trF+∑itrAi⋅trBi, being FF, AiAi and BiBi noncommutative polynomials in 22n−122n−1 complex N×NN×N matrices that parametrize the Dirac operator DD. For arbitrary signature—thus for any admissible \textscko\textscko-dimension—formulas for 22-dimensional fuzzy geometries are given up to a sextic polynomial, and up to a quartic polynomial for 44-dimensional ones, with focus on the octo-matrix models for Lorentzian and Riemannian signatures. The noncommutative polynomials FF, AiAi and BiBi are obtained via chord diagrams and satisfy: independence of NN; self-adjointness of the main polynomial FF (modulo cyclic reordering of each monomial); also up to cyclicity, either self-adjointness or anti-self-adjointness of AiAi and BiBi simultaneously, for fixed ii. Collectively, this favors a free probabilistic perspective for the large-NN limit we elaborate on. |
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| Item Description: | Gesehen am 15.03.2023 |
| Physical Description: | Online Resource |
| ISSN: | 1661-6960 |
| DOI: | 10.4171/jncg/482 |