scholarly journals On the dimension of totally geodesic submanifolds in the Prym loci

2021 ◽  
Author(s):  
Elisabetta Colombo ◽  
Paola Frediani
Keyword(s):  
Moduli Space ◽  
Abelian Varieties ◽  
Double Cover ◽  
Totally Geodesic Submanifold ◽  
Totally Geodesic ◽  
Geodesic Submanifolds ◽  
Geodesic Submanifold ◽  
Totally Geodesic Submanifolds ◽  
Double Covers

AbstractIn this paper we give a bound on the dimension of a totally geodesic submanifold of the moduli space of polarised abelian varieties of a given dimension, which is contained in the Prym locus of a (possibly) ramified double cover. This improves the already known bounds. The idea is to adapt the techniques introduced by the authors in collaboration with A. Ghigi and G. P. Pirola for the Torelli map to the case of the Prym maps of (ramified) double covers.

scholarly journals The index conjecture for symmetric spaces

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Jürgen Berndt ◽  
Carlos Olmos
Keyword(s):  
Symmetric Spaces ◽  
Systematic Approach ◽  
Riemannian Symmetric Space ◽  
Totally Geodesic Submanifold ◽  
Totally Geodesic ◽  
Geodesic Submanifolds ◽  
Geodesic Submanifold ◽  
Totally Geodesic Submanifolds ◽  
Higher Rank ◽  
Differential Geom

AbstractIn 1980, Oniščik [A. L. Oniščik, Totally geodesic submanifolds of symmetric spaces, Geometric methods in problems of algebra and analysis. Vol. 2, Yaroslav. Gos. Univ., Yaroslavl’ 1980, 64–85, 161] introduced the index of a Riemannian symmetric space as the minimal codimension of a (proper) totally geodesic submanifold. He calculated the index for symmetric spaces of rank {\leq 2}, but for higher rank it was unclear how to tackle the problem. In [J. Berndt, S. Console and C. E. Olmos, Submanifolds and holonomy, 2nd ed., Monogr. Res. Notes Math., CRC Press, Boca Raton 2016], [J. Berndt and C. Olmos, Maximal totally geodesic submanifolds and index of symmetric spaces, J. Differential Geom. 104 2016, 2, 187–217], [J. Berndt and C. Olmos, The index of compact simple Lie groups, Bull. Lond. Math. Soc. 49 2017, 5, 903–907], [J. Berndt and C. Olmos, On the index of symmetric spaces, J. reine angew. Math. 737 2018, 33–48], [J. Berndt, C. Olmos and J. S. Rodríguez, The index of exceptional symmetric spaces, Rev. Mat. Iberoam., to appear] we developed several approaches to this problem, which allowed us to calculate the index for many symmetric spaces. Our systematic approach led to a conjecture, formulated first in [J. Berndt and C. Olmos, Maximal totally geodesic submanifolds and index of symmetric spaces, J. Differential Geom. 104 2016, 2, 187–217], for how to calculate the index. The purpose of this paper is to verify the conjecture.

scholarly journals Totally geodesic submanifolds in tangent bundle with g-natural metric

2014 ◽  
Vol 11 (09) ◽  
pp. 1460033 ◽  
Author(s):  
Stanisław Ewert-Krzemieniewski
Keyword(s):  
Vector Field ◽  
Tangent Bundle ◽  
Sufficient Condition ◽  
Totally Geodesic Submanifold ◽  
Totally Geodesic ◽  
Base Manifold ◽  
Geodesic Submanifolds ◽  
Geodesic Submanifold ◽  
Totally Geodesic Submanifolds

In a tangent bundle endowed with g-natural metric G we investigate submanifolds defined by a vector field given on a base manifold. We give a sufficient condition for a vector field on M to define totally geodesic submanifold in (TM, G). The parallel vector field is discussed in more detail.

scholarly journals On totally geodesic submanifolds in the Jacobian locus

2015 ◽  
Vol 26 (01) ◽  
pp. 1550005 ◽  
Author(s):  
Elisabetta Colombo ◽  
Paola Frediani ◽  
Alessandro Ghigi
Keyword(s):  
Upper Bound ◽  
Positive Characteristic ◽  
Second Fundamental Form ◽  
Shimura Varieties ◽  
Totally Geodesic Submanifold ◽  
Totally Geodesic ◽  
Geodesic Submanifold ◽  
The Second Fundamental Form ◽  
Totally Geodesic Submanifolds ◽  
Cyclic Covers

We study submanifolds of Ag that are totally geodesic for the locally symmetric metric and which are contained in the closure of the Jacobian locus but not in its boundary. In the first section we recall a formula for the second fundamental form of the period map Mg ↪ Ag due to Pirola, Tortora and the first author. We show that this result can be stated quite neatly using a line bundle over the product of the curve with itself. We give an upper bound for the dimension of a germ of a totally geodesic submanifold passing through [C] ∈ Mg in terms of the gonality of C. This yields an upper bound for the dimension of a germ of a totally geodesic submanifold contained in the Jacobian locus, which only depends on the genus. We also study the submanifolds of Ag obtained from cyclic covers of ℙ1. These have been studied by various authors. Moonen determined which of them are Shimura varieties using deep results in positive characteristic. Using our methods we show that many of the submanifolds which are not Shimura varieties are not even totally geodesic.

Dynamics of SU (3) monopoles

1993 ◽  
Vol 440 (1909) ◽  
pp. 421-430 ◽  
Keyword(s):  
Symmetry Breaking ◽  
Moduli Space ◽  
Geodesic Flow ◽  
Totally Geodesic Submanifold ◽  
Totally Geodesic ◽  
Geodesic Submanifold

We study geodesic flow on a totally geodesic submanifold of a moduli space of solutions to Nahm’s equations, and draw conclusions about the dynamics of SU (3) monopoles with minimal symmetry breaking.

scholarly journals Axisymmetric Diffeomorphisms and Ideal Fluids on Riemannian 3-Manifolds

2020 ◽  
Author(s):  
Leandro Lichtenfelz ◽  
Gerard Misiołek ◽  
Stephen C Preston
Keyword(s):  
Euler Equations ◽  
Riemannian Geometry ◽  
Exponential Map ◽  
Totally Geodesic Submanifold ◽  
Totally Geodesic ◽  
Geodesic Submanifold ◽  
Ideal Fluids ◽  
Volume Preserving ◽  
The Way

Abstract We study the Riemannian geometry of 3D axisymmetric ideal fluids. We prove that the $L^2$ exponential map on the group of volume-preserving diffeomorphisms of a $3$-manifold is Fredholm along axisymmetric flows with sufficiently small swirl. Along the way, we define the notions of axisymmetric and swirl-free diffeomorphisms of any manifold with suitable symmetries and show that such diffeomorphisms form a totally geodesic submanifold of infinite $L^2$ diameter inside the space of volume-preserving diffeomorphisms whose diameter is known to be finite. As examples, we derive the axisymmetric Euler equations on $3$-manifolds equipped with each of Thurston’s eight model geometries.

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