### Abstract

The notion of a (uni)versal building associated with a point in the Hitchin base is introduced. The universal building is a building equipped with a harmonic map from the universal cover of the given Riemann surface that is initial among harmonic maps which induce the given cameral cover of the Riemann surface. The notion of a versal building is obtained by relaxing the uniqueness condition in the definition of an initial object. In the rank one case, the universal building is the leaf space of the quadratic differential defining the point in the Hitchin base. The main conjectures of this paper are: (1) a versal building always exists; (2) the asymptotics of the Riemann–Hilbert correspondence and the non-abelian Hodge correspondence are controlled by the harmonic map associated to any versal building; (3) spectral networks arise as inverse images of singularities of the versal building; and (4) versal buildings encode the data of a 3d Calabi-Yau category whose space of stability conditions has a connected component that contains the Hitchin base. The main theorem establishes the existence of the universal building, conjecture (3), as well as the Riemann–Hilbert part of conjecture (2), in the case of the rank two example introduced in the seminal work of Berk–Nevins–Roberts on higher order Stokes phenomena. It is also shown that the asymptotics of the Riemann–Hilbert correspondence are always controlled by a harmonic map to a certain building, which is constructed as the asymptotic cone of a symmetric space.

Original language | English (US) |
---|---|

Pages (from-to) | 853-903 |

Number of pages | 51 |

Journal | Communications in Mathematical Physics |

Volume | 336 |

Issue number | 2 |

DOIs | |

State | Published - 2015 |

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### ASJC Scopus subject areas

- Statistical and Nonlinear Physics
- Mathematical Physics

### Cite this

*Communications in Mathematical Physics*,

*336*(2), 853-903. https://doi.org/10.1007/s00220-014-2276-6

**Harmonic Maps to Buildings and Singular Perturbation Theory.** / Katzarkov, Ludmil; Noll, Alexander; Pandit, Pranav; Simpson, Carlos.

Research output: Contribution to journal › Article

*Communications in Mathematical Physics*, vol. 336, no. 2, pp. 853-903. https://doi.org/10.1007/s00220-014-2276-6

}

TY - JOUR

T1 - Harmonic Maps to Buildings and Singular Perturbation Theory

AU - Katzarkov, Ludmil

AU - Noll, Alexander

AU - Pandit, Pranav

AU - Simpson, Carlos

PY - 2015

Y1 - 2015

N2 - The notion of a (uni)versal building associated with a point in the Hitchin base is introduced. The universal building is a building equipped with a harmonic map from the universal cover of the given Riemann surface that is initial among harmonic maps which induce the given cameral cover of the Riemann surface. The notion of a versal building is obtained by relaxing the uniqueness condition in the definition of an initial object. In the rank one case, the universal building is the leaf space of the quadratic differential defining the point in the Hitchin base. The main conjectures of this paper are: (1) a versal building always exists; (2) the asymptotics of the Riemann–Hilbert correspondence and the non-abelian Hodge correspondence are controlled by the harmonic map associated to any versal building; (3) spectral networks arise as inverse images of singularities of the versal building; and (4) versal buildings encode the data of a 3d Calabi-Yau category whose space of stability conditions has a connected component that contains the Hitchin base. The main theorem establishes the existence of the universal building, conjecture (3), as well as the Riemann–Hilbert part of conjecture (2), in the case of the rank two example introduced in the seminal work of Berk–Nevins–Roberts on higher order Stokes phenomena. It is also shown that the asymptotics of the Riemann–Hilbert correspondence are always controlled by a harmonic map to a certain building, which is constructed as the asymptotic cone of a symmetric space.

AB - The notion of a (uni)versal building associated with a point in the Hitchin base is introduced. The universal building is a building equipped with a harmonic map from the universal cover of the given Riemann surface that is initial among harmonic maps which induce the given cameral cover of the Riemann surface. The notion of a versal building is obtained by relaxing the uniqueness condition in the definition of an initial object. In the rank one case, the universal building is the leaf space of the quadratic differential defining the point in the Hitchin base. The main conjectures of this paper are: (1) a versal building always exists; (2) the asymptotics of the Riemann–Hilbert correspondence and the non-abelian Hodge correspondence are controlled by the harmonic map associated to any versal building; (3) spectral networks arise as inverse images of singularities of the versal building; and (4) versal buildings encode the data of a 3d Calabi-Yau category whose space of stability conditions has a connected component that contains the Hitchin base. The main theorem establishes the existence of the universal building, conjecture (3), as well as the Riemann–Hilbert part of conjecture (2), in the case of the rank two example introduced in the seminal work of Berk–Nevins–Roberts on higher order Stokes phenomena. It is also shown that the asymptotics of the Riemann–Hilbert correspondence are always controlled by a harmonic map to a certain building, which is constructed as the asymptotic cone of a symmetric space.

UR - http://www.scopus.com/inward/record.url?scp=84925500300&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84925500300&partnerID=8YFLogxK

U2 - 10.1007/s00220-014-2276-6

DO - 10.1007/s00220-014-2276-6

M3 - Article

AN - SCOPUS:84925500300

VL - 336

SP - 853

EP - 903

JO - Communications in Mathematical Physics

JF - Communications in Mathematical Physics

SN - 0010-3616

IS - 2

ER -