Abstract
We study the Sasaki cone of a CR structure of Sasaki type on a given closed manifold. We introduce an energy functional over the cone and use its critical points to single out the strongly extremal Reeb vector fields. Should one such vector field be a member of the extremal set, the scalar curvature of a Sasaki extremal metric representing it would have the smallest L 2-norm among all Sasakian metrics of fixed volume that can represent vector fields in the cone. We use links of isolated hypersurface singularities to produce examples of manifolds of Sasaki type, many of these in dimension five, whose Sasaki cone coincides with the extremal set, and examples where the extremal set is empty. We end up by proving that a conjecture of Orlik concerning the torsion of the homology groups of these links holds in the five-dimensional case.
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References
A. Bangaya & P. Molino, G éométric des formes de contact complètement intégrables de type toriques, Séminaire G. Darboux de Géométrie et Topologie Différentielle, 1991–1992, Montpellier.
D. Barden, Simply connected five-manifolds, Ann. Math. (2) 82 (1965), pp. 365–385. MR 32 #1714.
C.P. Boyer & K. Galicki, A note on toric contact geometry, J. Geom. Phys. 35 (2000), 4, pp. 288–298. MR 2001h:53124.
——, Einstein metrics on rational homology spheres, J. Diff. Geom. (3) 74 (2006), pp. 353– 362. MR MR2269781.
——, New Einstein metrics in dimension five, J. Diff. Geom. (3) 57 (2001), pp. 443–463. MR 2003b:53047.
——, On Sasakian-Einstein geometry, Internat. J. Math. (7) 11 (2000), pp. 873–909. MR 2001k:53081.
——, Sasakian Geometry, Oxford Mathematical Monographs, Oxford University Press, 2008, MR2382957.
——, Sasakian geometry, hypersurface singularities, and Einstein metrics, Rend. Circ. Mat. Palermo (2) Suppl. (2005), 75, suppl., pp. 57–87. MR 2152356.
C.P. Boyer, K. Galicki & J. Kollár, Einstein metrics on spheres, Ann. Math. (2) 162 (2005), no. 1, pp. 557–580. MR 2178969(2006j:53058).
C.P. Boyer, K. Galicki, J. Kollár & E. Thomas, Einstein metrics on exotic spheres in dimensions 7, 11, and 15, Experiment. Math. 14 (2005), no. 1, pp. 59–64. MR 2146519 (2006a:53042).
C.P. Boyer, K. Galicki & P. Matzeu, On eta-Einstein Sasakian geometry, Commun. Math. Phys. (1) 262 (2006), pp. 177–208. MR 2200887.
C.P. Boyer, K. Galicki & L. Ornea, Constructions in Sasakian Geometry, Math. Zeit. (4) 257 (2007), pp. 907–924. MR2342558.
C.P. Boyer, K. Galicki & S.R. Simanca, Canonical Sasakian metrics, Commun. Math. Phys. (3) 279 (2008), pp. 705–733. MR2386725.
E. Calabi, Extremal Kähler metrics II, in Differential geometry and complex analysis (I. Chavel & H.M. Farkas eds.), Springer-Verlag, Berlin, 1985, pp. 95–114.
K. Cho, A. Futaki & H. Ono, Uniqueness and examples of compact toric Sasaki–Einstein metrics, Comm. Math. Phys. (2) 277 (2008), pp. 439–458. MR2358291 (2008j:53076).
A. Futaki, An obstruction to the existence of Einstein Kähler metrics, Invent. Math., 73 (1983), pp. 437–443. MR 84j:53072.
A. Futaki, H. Ono & G. Wang, Transverse Kähler geometry of Sasaki manifolds and toric Sasaki–Einstein manifolds, preprint arXiv:math. DG/0607586, (unpublished).
J.P. Gauntlett, D. Martelli, J. Sparks & W. Waldram, Sasaki–Einstein metrics on S 2 ×S 3, Adv. Theor. Math. Phys., 8 (2004), pp. 711–734.
J.P. Gauntlett, D. Martelli, J. Sparks & S.-T. Yau, Obstructions to the existence of Sasaki– Einstein metrics, Comm. Math. Phys. (3) 273 (2007), pp. 803–827.
A. Ghigi & J. Kollár, K ähler–Einstein metrics on orbifolds and Einstein metrics on Spheres, Comment. Math. Helvetici (4) 82 (2007), pp. 877–902. MR2341843 (2008j:32027).
G. Grantcharov & L. Ornea, Reduction of Sasakian manifolds, J. Math. Phys. (8) 42 (2001), pp. 3809–3816. MR 1845220 (2002e:53060).
A.R. Iano-Fletcher, Working with weighted complete intersections, Explicit birational geometry of 3-folds, London Math. Soc. Lecture Note Ser. 281, pp. 101–173, Cambridge Univ. Press, Cambridge, (2000).
J.M. Johnson & J. Kollár, K ähler–Einstein metrics on log del Pezzo surfaces in weighted projective 3-spaces, Ann. Inst. Fourier (Grenoble) (1) 51 (2001), pp. 69–79. MR 2002b:32041.
J. Kollár, Circle actions on simply connected 5-manifolds, Topology (3) 45 (2006), pp. 643– 671. MR 2218760.
——, Einstein metrics on five-dimensional Seifert bundles, J. Geom. Anal. (3) 15 (2005), pp. 445–476. MR 2190241.
——, Positive Sasakian structures on 5-manifolds, these Proceedings, Eds. Galicki & Simanca, Birkhauser, Boston.
C. LeBrun & S.R. Simanca, On the Kähler Classes of Extremal Metrics, Geometry and Global Analysis (Sendai, Japan 1993), First Math. Soc. Japan Intern. Res. Inst. Eds. Kotake, Nishikawa & Schoen.
E. Lerman, Contact toric manifolds, J. Symp. Geom. (4) 1 (2002), pp. 785–828, MR 2 039 164.
D. Martelli, J. Sparks & S.-T. Yau, Sasaki–Einstein manifolds and volume minimisation, Comm. Math. Phys. (3) 280 (2008), pp. 611–673. MR2399609.
J.W. Milnor, Singular points of complex hypersurfaces, Annals of Mathematics Studies 61, Princeton University Press, Princeton, N.J., 1968. MR 39 #969.
J. Milnor & P. Orlik, Isolated singularities defined by weighted homogeneous polynomials, Topology 9 (1970), pp. 385–393. MR 45 #2757.
P. Orlik, On the homology of weighted homogeneous manifolds, Proceedings of the 2nd Conference on Compact Transformation Groups (Univ. of Mass., Amherst, Mass., 1971), Part I, Lect. Notes Math. 298, Springer-Verlag, Berlin, 1972, pp. 260–269. MR 55 #3312.
——, Seifert manifolds, Lect. Notes Math. 291, Springer-Verlag, Berlin, 1972, MR 54 #13950.
P. Orlik & R.C. Randell, The monodromy of weighted homogeneous singularities, Invent. Math. (3) 39 (1977), pp. 199–211. MR 57 #314.
P. Orlik & P. Wagreich, Isolated singularities of algebraic surfaces with C* action, Ann. Math. (2) 93 (1971), pp. 205–228. MR 44 #1662.
R.C. Randell, The homology of generalized Brieskorn manifolds, Topology (4) 14 (1975), pp. 347–355. MR 54 #1270.
P. Rukimbira, Chern-Hamilton’s conjecture and K-contactness, Houston J. Math. (4) 21 (1995), pp. 709–718. MR 96m:53032.
S.R. Simanca, Canonical metrics on compact almost complex manifolds, Publicacões Matemáticas do IMPA, IMPA, Rio de Janeiro (2004), 97 pp.
——, Heat Flows for Extremal Kähler Metrics, Ann. Scuola Norm. Sup. Pisa CL. Sci., 4 (2005), pp. 187–217.
——, Precompactness of the Calabi Energy, Internat. J. Math., 7 (1996) pp. 245–254.
——, Strongly Extremal Kähler Metrics, Ann. Global Anal. Geom. 18 (2000), no. 1, pp. 29–46.
S.R. Simanca & L.D. Stelling, Canonical Kähler classes. Asian J. Math. 5 (2001), no. 4, pp. 585–598.
S. Smale, On the structure of 5-manifolds, Ann. Math. (2) 75 (1962), pp. 38–46. MR 25 #4544.
T. Takahashi, Deformations of Sasakian structures and its application to the Brieskorn manifolds, Tôhoku Math. J. (2) 30 (1978), no. 1, pp. 37–43. MR 81e:53024.
M.Y. Wang & W. Ziller, Einstein metrics on principal torus bundles, J. Diff. Geom. (1) 31 (1990), pp. 215–248. MR 91f:53041.
S.S.-T. Yau and Y. Yu, Classification of 3-dimensional isolated rational hypersurface singularities with C*-action, Rocky Mountain J. Math. (5) 35 (2005), pp. 1795–1809. MR 2206037(2006j:32034).
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Boyer, C.P., Galicki, K., Simanca, S.R. (2009). The Sasaki Cone and Extremal Sasakian Metrics. In: Galicki, K., Simanca, S.R. (eds) Riemannian Topology and Geometric Structures on Manifolds. Progress in Mathematics, vol 271. Birkhäuser Boston. https://doi.org/10.1007/978-0-8176-4743-8_11
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DOI: https://doi.org/10.1007/978-0-8176-4743-8_11
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