- 
								[1]
								R. Aaij et al., Phys. Rev. Lett., 122: 152002 (2019) 
- 
								[2]
								Z. G. Wang, Int. J. Mod. Phys. A, 34: 1950110 (2019) 
- 
								[3]
								H. X. Chen and W. Chen, Phys. Rev. D, 99: 074022 (2019) 
- 
								[4]
								M. Ablikim et al., Phys. Rev. Lett., 110: 252001 (2013) 
- 
								[5]
								Z. Q. Liu et al., Phys. Rev. Lett., 110: 252002 (2013) 
- 
								[6]
								T. Xiao, S. Dobbs, A. Tomaradze et al., Phys. Lett. B, 727: 366 (2013) 
- 
								[7]
								M. Ablikim et al., Phys. Rev. Lett., 112: 132001 (2014) 
- 
								[8]
								M. Ablikim et al., Phys. Rev. Lett., 111: 242001 (2013) 
- 
								[9]
								M. Tanabashi et al., Phys. Rev. D, 98: 030001 (2018) 
- 
								[10]
								R. Aaij et al., Phys. Rev. Lett., 112: 222002 (2014) 
- 
								[11]
								M. Ablikim et al., Phys. Rev. Lett., 119: 072001 (2017) 
- 
								[12]
								Q. Wang, C. Hanhart, and Q. Zhao, Phys. Rev. Lett., 111: 132003 (2013) 
- 
								[13]
								F. K. Guo, C. Hidalgo-Duque, J. Nieves et al., Phys. Rev. D, 88: 054007 (2013) 
- 
								[14]
								C. Y. Cui, Y. L. Liu, W. B. Chen et al., J. Phys. G, 41: 075003 (2014); J. R. Zhang, Phys. Rev. D, 87: 116004 (2013) 
- 
								[15]
								Z. G. Wang and T. Huang, Eur. Phys. J. C, 74: 2891 (2014); Z. G. Wang, Eur. Phys. J. C, 74: 2963 (2014) 
- 
								[16]
								H. W. Ke, Z. T. Wei, and X. Q. Li, Eur. Phys. J. C, 73: 2561 (2013) 
- 
								[17]
								J. He, X. Liu, Z. F. Sun et al., Eur. Phys. J. C, 73: 2635 (2013) 
- 
								[18]
								Y. B. Dong, A. Faessler, T. Gutsche et al., Phys. Rev. D, 88: 014030 (2013) 
- 
								[19]
								L. Maiani, V. Riquer, R. Faccini et al., Phys. Rev. D, 87: 111102 (2013) 
- 
								[20]
								Z. G. Wang and T. Huang, Phys. Rev. D, 89: 054019 (2014) 
- 
								[21]
								C. F. Qiao and L. Tang, Eur. Phys. J. C, 74: 3122 (2014); C. F. Qiao and L. Tang, Eur. Phys. J. C, 74: 2810 (2014) 
- 
								[22]
								Z. G. Wang, Commun. Theor. Phys., 63: 466 (2015) 
- 
								[23]
								Z. G. Wang, Eur. Phys. J. C, 76: 387 (2016) 
- 
								[24]
								C. Deng, J. Ping, and F. Wang, Phys. Rev. D, 90: 054009 (2014) 
- 
								[25]
								X. H. Liu and G. Li, Phys. Rev. D, 88: 014013 (2013) 
- 
								[26]
								D. Y. Chen, X. Liu, and T. Matsuki, Phys. Rev. D, 88: 036008 (2013); E. S. Swanson, Phys. Rev. D, 91: 034009 (2015) 
- 
								[27]
								L. Maiani, F. Piccinini, A. D. Polosa et al., Phys. Rev. D, 89: 114010 (2014) 
- 
								[28]
								M. Nielsen and F. S. Navarra, Mod. Phys. Lett. A, 29: 1430005 (2014) 
- 
								[29]
								Z. G. Wang, Commun. Theor. Phys., 63: 325 (2015) 
- 
								[30]
								M. S. Maior de Sousa and R. Rodrigues da Silva, Braz. J. Phys., 46: 730 (2016) 
- 
								[31]
								Z. G. Wang, Eur. Phys. J. C, 74: 2874 (2014); Z. G. Wang and T. Huang, Nucl. Phys. A, 930: 63 (2014) 
- 
								[32]
								S. S. Agaev, K. Azizi, and H. Sundu, Phys. Rev. D, 96: 034026 (2017) 
- 
								[33]
								Z. G. Wang, Eur. Phys. J. C, 71: 1524 (2011); R. T. Kleiv, T. G. Steele, and A. Zhang, Phys. Rev. D, 87: 125018 (2013) 
- 
								[34]
								Z. G. Wang and J. X. Zhang, Eur. Phys. J. C, 76: 650 (2016); Z. G. Wang and Z. Y. Di, Eur. Phys. J. C, 79: 72 (2019) 
- 
								[35]
								M. A. Shifman, A. I. Vainshtein, and V. I. Zakharov, Nucl. Phys. B, 147: 385 (1979); Nucl. Phys. B, 147: 448 (1979) 
- 
								[36]
								L. J. Reinders, H. Rubinstein, and S. Yazaki, Phys. Rept., 127: 1 (1985) 
- 
								[37]
								A. Selem and F. Wilczek, hep-ph/0602128. 
- 
								[38]
								L. Maiani, A. D. Polosa, and V. Riquer, Phys. Lett. B, 778: 247 (2018) 
- 
								[39]
								S. J. Brodsky, D. S. Hwang, and R. F. Lebed, Phys. Rev. Lett., 113: 112001 (2014) 
- 
								[40]
								W. Lucha, D. Melikhov, and H. Sazdjian, Phys. Rev. D, 100: 014010 (2019) 
- 
								[41]
								Z. G. Wang, Int. J. Mod. Phys. A, 30: 1550168 (2015) 
- 
								[42]
								P. Colangelo and A. Khodjamirian, hep-ph/0010175. 
- 
								[43]
								S. Narison and R. Tarrach, Phys. Lett. B, 125: 217 (1983) 
- 
								[44]
								Z. G. Wang, Eur. Phys. J. C, 76: 70 (2016); Z. G. Wang and T. Huang, Eur. Phys. J. C, 76: 43 (2016) 
- 
								[45]
								Z. G. Wang and J. X. Zhang, Eur. Phys. J. C, 78: 14 (2018) 
- 
								[46]
								Z. G. Wang, Eur. Phys. J. C, 78: 518 (2018)