13 references, page 1 of 2 [3] C. Beasley, J.J. Heckman and C. Vafa, GUTs and exceptional branes in F-theory | I, JHEP [4] C. Beasley, J.J. Heckman and C. Vafa, GUTs and exceptional branes in F-theory | II: experimental predictions, JHEP 01 (2009) 059 [arXiv:0806.0102] [INSPIRE].

[5] R. Donagi and M. Wijnholt, Breaking GUT groups in F-theory, Adv. Theor. Math. Phys. 15 [6] C. Vafa, Evidence for F-theory, Nucl. Phys. B 469 (1996) 403 [hep-th/9602022] [INSPIRE].

[7] D.R. Morrison and C. Vafa, Compacti cations of F-theory on Calabi-Yau threefolds. 1, Nucl.

[8] D.R. Morrison and C. Vafa, Compacti cations of F-theory on Calabi-Yau threefolds. 2, Nucl.

[9] A. Sen, F theory and orientifolds, Nucl. Phys. B 475 (1996) 562 [hep-th/9605150] [11] P.S. Aspinwall and D.R. Morrison, Point-like instantons on K3 orbifolds, Nucl. Phys. B 503 [12] L.B. Anderson, J.J. Heckman and S. Katz, T-branes and geometry, JHEP 05 (2014) 080 [13] A.P. Braun, Y. Kimura and T. Watari, The Noether-Lefschetz problem and gauge-group-resolved landscapes: F-theory on K3 K3 as a test case, JHEP 04 (2014) 050 [29] K. Kodaira, On compact analytic surfaces III, Ann. Math. 78 (1963) 1.

[30] K. Becker and M. Becker, M theory on eight manifolds, Nucl. Phys. B 477 (1996) 155 [31] S. Sethi, C. Vafa and E. Witten, Constraints on low dimensional string compacti cations, Nucl. Phys. B 480 (1996) 213 [hep-th/9606122] [INSPIRE].

[32] E. Witten, On ux quantization in M-theory and the e ective action, J. Geom. Phys. 22 [33] S. Gukov, C. Vafa and E. Witten, CFT's from Calabi-Yau four folds, Nucl. Phys. B 584 [34] K. Dasgupta, G. Rajesh and S. Sethi, M theory, orientifolds and G- ux, JHEP 08 (1999) groups of open K3 surfaces, Nagoya Math. J. 161 (2001) 23 [math/0007171].

[26] T. Shioda and H. Inose, On singular K3 surfaces, in Complex analysis and algebraic geometry, in W.L. Jr. Baily and T. Shioda eds., Iwanami Shoten, Tokyo Japan (1977).

[27] M. Bershadsky et al., Geometric singularities and enhanced gauge symmetries, Nucl. Phys. B [28] M. Schutt, Elliptic brations of some extremal K3 surfaces, Rocky Mount. J. Math. 37 [45] M. Cvetic et al., F-theory vacua with Z3 gauge symmetry, Nucl. Phys. B 898 (2015) 736 [46] L. Lin, C. Mayrhofer, O. Till and T. Weigand, Fluxes in F-theory compacti cations on genus-one brations, JHEP 01 (2016) 098 [arXiv:1508.00162] [INSPIRE].

[47] Y. Kimura, Gauge groups and matter spectra in F-theory compacti cations on genus-one [48] Y. Kimura, Discrete gauge groups in F-theory models on genus-one bered Calabi-Yau 4-folds [50] S. Kondo, Type II degenerations of K3 surfaces, Nagoya Math J. 99 (1985) 11.