• [1]

    C. Patrignani et al (Particle Data Group), Chin. Phys. C, 40:100001(2016)

  • [2]

    P. Minkowski, Phys. Lett. B, 67:421(1977); T. Yanagida, in Proceedings of the Workshop on Unified Theory and the Baryon Number of the Universe, edited by O. Sawada and A. Sugamoto (KEK, Tsukuba, 1979), p. 95; M. Gell-Mann, P. Ramond, and R. Slansky, in Supergravity, edited by P. van Nieuwenhuizen and D. Freedman (North Holland, Amsterdam, 1979), p. 315; S.L. Glashow, in it Quarks and Leptons, edited by M. Levy et al, (Plenum, New York, 1980), p. 707; R.N. Mohapatra and G. Senjanovic, Phys. Rev. Lett., 44:912(1980). For a brief review of other seesaw mechanisms, see:Z. Z. Xing, Prog. Theor. Phys. Suppl., 180:112(2009), arXiv:0905.3903

  • [3]

    G. Altarelli and F. Feruglio, Rev. Mod. Phys., 82:2701(2010), arXiv:1002.0211; S. F. King, Rept. Prog. Phys., 76:056201(2013), arXiv:1301.1340; A. Aranda, C. Bonilla, S. Morisi, E. Peinado, and J. W. F. Valle, Phys. Rev. D, 89:033001(2014), arXiv:1307.3553; S. Centelles Chuli, R. Srivastava, and J. W. F. Valle, Phys. Lett. B, 773:26(2017), arXiv:1706.00210

  • [4]

    Z. Z. Xing and Z. H. Zhao, Rept. Prog. Phys., 79:076201(2016), arXiv:1512.04207

  • [5]

    P. H. Chankowski and Z. Pluciennik, Phys. Lett. B, 316:312(1993),[hep-ph/9306333]; K. S. Babu, C. N. Leung, and J. T. Pantaleone, Phys. Lett. B, 319:191(1993),[hep-ph/9309223]; J. A. Casas, J. R. Espinosa, A. Ibarra, and I. Navarro, Nucl. Phys. B, 573:652(2000),[hep-ph/9910420]; S. Antusch, M. Drees, J. Kersten, M. Lindner, and M. Ratz, Phys. Lett. B, 519:238(2001),[hep-ph/0108005]; P. H. Chankowski and S. Pokorski, Int. J. Mod. Phys. A, 17:575(2002),[hep-ph/0110249]; S. Antusch, J. Kersten, M. Lindner, M. Ratz, and M. A. Schmidt, JHEP, 0503:024(2005),[hep-ph/0501272]; S. Ray, Int. J. Mod. Phys. A, 25:4339(2010), arXiv:1005.1938; For a recent review with extensive references, see:T. Ohlsson and S. Zhou, Nature Commun., 5:5153(2014), arXiv:1311.3846

  • [6]

    S. Antusch, J. Kersten, M. Lindner, and M. Ratz, Nucl. Phys. B, 674:401(2003),[hep-ph/0305273]

  • [7]

    Z. Maki, M. Nakagawa, and S. Sakata, Prog. Theor. Phys., 28:870(1962); B. Pontecorvo and Sov. Phys., JETP, 26:984(1968),[Zh. Eksp. Teor. Fiz., 53:1717(1967)]

  • [8]

    F. Capozzi, E. Lisi, A. Marrone, and A. Palazzo, arXiv:1804.09678

  • [9]

    P. F. de Salas, D. V. Forero, C. A. Ternes, M. Tortola, and J. W. F. Valle, arXiv:1708.01186(updated in April 2018); I. Esteban, M. C. Gonzalez-Garcia, M. Maltoni, I. Martinez-Soler, and T. Schwetz, JHEP, 01:087(2017), arXiv:1611.01514, and NuFIT 3.2(2018), www.nu-fit.org

  • [10]

    W. Grimus and L. Lavoura, Fortsch. Phys., 61:535(2013), arXiv:1207.1678

  • [11]

    R. N. Mohapatra and C. C. Nishi, JHEP, 1508:092(2015), arXiv:1506.06788

  • [12]

    P. F. Harrison and W. G. Scott, Phys. Lett. B, 547:219(2002),[hep-ph/0210197]; Z. z. Xing, H. Zhang, and S. Zhou, Phys. Lett. B, 641:189(2006),[hep-ph/0607091]; Z. z. Xing, Phys. Rev. D, 78:011301(2008), arXiv:0805.0416; B. Adhikary, A. Ghosal, and P. Roy, JHEP, 0910:040(2009), arXiv:0908.2686; T. Baba and M. Yasue, Prog. Theor. Phys., 123:659(2010), arXiv:1003.1438; Z. z. Xing and Y. L. Zhou, Phys. Lett. B, 693:584(2010), arXiv:1008.4906

  • [13]

    H. Zhang and S. Zhou, Phys. Lett. B, 704:296(2011), arXiv:1107.1097; S. Zhou, arXiv:1205.0761[hep-ph]; Z. z. Xing, Phys. Lett. B, 716:220(2012), arXiv:1205.6532; Z.Z. Xing and S. Zhou, Phys. Lett. B, 737:196(2014), arXiv:1404.7021; R. N. Mohapatra and C. C. Nishi, JHEP, 1508:092(2015), arXiv:1506.06788; Z. z. Xing and J. y. Zhu, Chin. Phys. C, 41:123103(2017), arXiv:1707.03676; Z.H. Zhao, arXiv:1803.04603; N. Nath, arXiv:1805.05823; S. F. King and C. C. Nishi, arXiv:1807.00023[hep-ph]

  • [14]

    S. Luo and Z. Z. Xing, Phys. Rev. D, 90:073005(2014), arXiv:1408.5005

  • [15]

    Y. L. Zhou, arXiv:1409.8600

  • [16]

    Z. H. Zhao, arXiv:1605.04498; Z. H. Zhao, JHEP, 1709:023(2017), arXiv:1703.04984; W. Rodejohann and X. J. Xu, Phys. Rev. D, 96:055039(2017), arXiv:1705.02027; Z. C. Liu, C. X. Yue, and Z. H. Zhao, JHEP, 1710:102(2017), arXiv:1707.05535; N. Nath, Z. z. Xing, and J. Zhang, Eur. Phys. J. C, 78:289(2018), arXiv:1801.09931; and references therein

  • [17]

    Z. Z. Xing, D. Zhang, and J. Y. Zhu, JHEP, 1711:135(2017), arXiv:1708.09144

  • [18]

    G. L. Fogli, E. Lisi, A. Marrone, A. Palazzo, and A. M. Rotunno, Phys. Rev. Lett., 101:141801(2008), arXiv:0806.2649

  • [19]

    F. P. An et al (Baya Bay Collaboration), Phys. Rev. Lett., 108:171803(2012), arXiv:1203.1669

  • [20]

    J. Ellis and S. Lola, Phys. Lett. B, 458:310(1999),[hep-ph/9904279]; H. Fritzsch and Z. Z. Xing, Prog. Part. Nucl. Phys., 45:1(2000),[hep-ph/9912358]

  • [21]

    F. Feroz and M. P. Hobson, Mon. Not. Roy. Astron. Soc., 384:449(2008), arXiv:0704.3704; F. Feroz, M. P. Hobson, and M. Bridges, Mon. Not. Roy. Astron. Soc., 398:1601(2009), arXiv:0809.3437; F. Feroz, M. P. Hobson, E. Cameron, and A. N. Pettitt, arXiv:1306.2144

  • [22]

    P. A. R. Ade et al (Planck Collaboration), Astron. Astrophys., 594:A13(2016), arXiv:1502.01589

  • [23]

    See, e.g., Z. Z. Xing, H. Zhang, and S. Zhou, Phys. Rev. D, 86:013013(2012), arXiv:1112.3112; J. Elias-Miro, J. R. Espinosa, G. F. Giudice, G. Isidori, A. Riotto, and A. Strumia, Phys. Lett. B, 709:222(2012), arXiv:1112.3022

  • [24]

    G. C. Branco, P. M. Ferreira, L. Lavoura, M. N. Rebelo, M. Sher, and J. P. Silva, Phys. Rept., 516:1(2012), arXiv:1106.0034