arXiv:1302.4315v1 [math.DG] 18 Feb 2013
EMBEDDED TRIPLY PERIODIC ZERO MEAN CURVATURE SURFACES OF MIXED TYPE IN LORENTZ-MINKOWSKI 3-SPACE S. FUJIMORI, W. ROSSMAN, M. UMEHARA, K. YAMADA, AND S.-D. YANG Abstract. We construct embedded triply periodic zero mean curvature surfaces of mixed type in the Lorentz-Minkowski 3-space R31 with the same topology as the Schwarz D surface in the Euclidean 3-space R3 .
1. Introduction In any robust surface theory, it is essential to have a large collection of interesting examples. One of the interesting classes of surfaces to study are the zero mean curvature surfaces of mixed type in Lorentz-Minkowski three-space R31 , which, roughly speaking, are smooth surfaces of mixed causal type with mean curvature, wherever it is well defined, equal to zero. Several authors have found such examples [9], [5], [11], [8], [3], all of which have simple topology. The main goal of this article is to provide a concrete example of a family of such surfaces with nontrivial topology. The motivation for the method of our construction is the fact that fold singularities of spacelike maximal surfaces have real analytical extensions to timelike minimal surfaces (cf. [5], [8], [6], [3]). Main ingredients are the spacelike maximal analogues in R31 of the Schwarz P surfaces and the Schwarz D surfaces in R3 , which were remarked upon in a previous work [4] by the authors. The Schwarz P-type maximal surfaces admit cone-like singularities while the Schwarz D-type maximal surfaces admit fold singularities (cf. Figure 1.1). By extending the Schwarz D-type (spacelike) maximal surfaces to timelike minimal surfaces, we obtain the following main result of this article: Theorem A. The 1-parameter family of Schwarz D-type spacelike maximal surfaces {Xa }0 0,
−2 cos u sin v < 0.
consists of the three straight line segments
3 ˇ Lmin A := {fa (0, β) ∈ R1 ; 0 < β ≤ ca /2}, Lmin := {fˇa (τ (π/4), β) ∈ R3 ; 0 < β ≤ ca /2}, B
1
Lmin := {fˇa (α, ca /2) ∈ R31 ; 0 ≤ α ≤ τ (π/4)}, C and the singular curve γ˜a (τ ) (0 ≤ τ ≤ τ (π/4)), and all of them are contained in ∆ × Lmin C , the claim follows. References [1] L. J. Al´ıas, R. M. B. Chaves and P. Mira, Bj¨ orling problem for maximal surfaces in LorentzMinkowski space, Math. Proc. Cambridge Philos. Soc. 134 (2003), 289–316. [2] S. Fujimori, Y.W. Kim, S.-E. Koh, W. Rossman, H. Shin, H. Takahashi, M. Umehara, K. Yamada and S.-D. Yang, Zero mean curvature surfaces in L3 containing a light-like line, Comptes Rendus Math´ ematique, 2012 (on line first), DOI:10.1016/j.crma.2012.10.024
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[3] S. Fujimori, Y.W. Kim, S.-E. Koh, W. Rossman, H. Shin, M. Umehara, K. Yamada and S.-D. Yang, Zero mean curvature surfaces in Lorentz-Minkowski 3-space which change type across a light-like line, preprint. [4] S. Fujimori, W. Rossman, M. Umehara, K. Yamada and S.-D. Yang, New maximal surfaces in Minkowski 3-space with arbitrary genus and their cousins in de Sitter 3-space, Result. Math. 56 (2009), 41–82. [5] C. Gu, The extremal surfaces in the 3-dimensional Minkowski space, Acta. Math. Sinica. 1 (1985), 173–180. [6] Y. W. Kim, S.-E Koh, H. Shin and S.-D. Yang, Spacelike maximal surfaces, timelike minimal surfaces, and Bj¨ orling representation formulae, J. Korean Math. Soc. 48 (2011), 1083–1100. [7] Y. W. Kim and S.-D. Yang, Prescribing singularities of maximal surfaces via a singular Bj¨ orling representation formula, J. Geom. Phys., 57 (2007), no. 11, 2167–2177. [8] V. A. Klyachin, Zero mean curvature surfaces of mixed type in Minkowski space, Izvestiya Math. 67 (2003), 209–224. [9] O. Kobayashi, Maximal surfaces in the 3-dimensional Minkowski space L3 , Tokyo J. Math., 6 (1983), 297–309. [10] M. Ross, Schwarz’ P and D surfaces are stable, Differential Geom. Appl. 2 (1992), 179–195. [11] V. Sergienko and V.G. Tkachev, Doubly periodic maximal surfaces with singularities, Proceedings on Analysis and Geometry (Russian) (Novosibirsk Akademgorodok, 1999), 571–584, Izdat. Ross. Akad. Nauk Sib. Otd. Inst. Mat., Novosibirsk, 2000. [12] M. Umehara and K. Yamada, Maximal surfaces with singularities in Minkowski space, Hokkaido Math. J., 35 (2006), 13–40. (Shoichi Fujimori) Department of Mathematics, Okayama University, Tsushima-naka, Okayama 700-8530, Japan E-mail address:
[email protected] (Wayne Rossman) Department of Mathematics, Faculty of Science, Kobe University, Rokko, Kobe 657-8501, Japan E-mail address:
[email protected] (Masaaki Umehara) Department of Mathematical and Computing Sciences, Tokyo Institute of Technology, 2-12-1-W8-34, O-okayama, Meguro-ku, Tokyo 152-8552, Japan. E-mail address:
[email protected] (Kotaro Yamada) Department of Mathematics, Tokyo Institute of Technology, 1-121-H-7, O-okayama, Meguro, Tokyo 152-8551, Japan E-mail address:
[email protected] (Seong-Deog Yang) Department of Mathematics, Korea University, Seoul 136-701, Korea E-mail address:
[email protected]
