| 
                    [1]
                 | 
			
				S. Dodelson, Modern Cosmology (New York:Accademic Press, 2003) | 
		
	
			| 
                    [2]
                 | 
			
				V. M. Moukhanov, Physical Foundation of Cosmology (New York:Cambridge University Press, 2005) | 
		
	
			| 
                    [3]
                 | 
			
				S. Weinberg, Cosmology (New York:Cambridge University Press, 2008) | 
		
	
			| 
                    [4]
                 | 
			
				A. H. Guth, Phys. Rev. D, 23:347(1981) | 
		
	
			| 
                    [5]
                 | 
			
				D. H. Lyth and A. R. Liddle, The primordial density pertur-bation:cosmology, in ation and the origin of structure (New York:Cambridge University Press, 2009) | 
		
	
			| 
                    [6]
                 | 
			
				D. Baumann, TASI 2009, arXiv:hep-th/0907.5424v1 | 
		
	
			| 
                    [7]
                 | 
			
				G. Hinshaw, D. Larson, E. Komatsu et al, ApJS, 208:19(2013) | 
		
	
			| 
                    [8]
                 | 
			
				P. A. R. Ade et al, Astron. Asstrophys. A, 571:22(2014); P. Ade et al[arXiv:1502.02114] | 
		
	
			| 
                    [9]
                 | 
			
				A. Kempf and J. C. Niemeyer, Phys. Rev. D, 64:103501(2001) | 
		
	
			| 
                    [10]
                 | 
			
				N. Kaloper et al, Phys. Rev. D, 66:123510(2002) | 
		
	
			| 
                    [11]
                 | 
			
				U. H. Danielsson, Phys. Rev. D, 66:023511(2002) | 
		
	
			| 
                    [12]
                 | 
			
				J. Martin and R. H. Brandenberger, Phys. Rev. D, 68:063513(2003) | 
		
	
			| 
                    [13]
                 | 
			
				A. Ashoorioon et al, JCAP, 02:025(2014) | 
		
	
			| 
                    [14]
                 | 
			
				R. Holman and A. J. Tolley, JCAP, 05:001(2008) | 
		
	
			| 
                    [15]
                 | 
			
				S. Kundu, JCAP, 02:005(2012) | 
		
	
			| 
                    [16]
                 | 
			
				S. Kundu, arXiv:1311.1575v1 | 
		
	
			| 
                    [17]
                 | 
			
				T. S. Bunch and P. C. W. Davies, Proc. Roy. Soc. Lond. A, 360:117(1978) | 
		
	
			| 
                    [18]
                 | 
			
				Y. Cai, Y. Wang, and Y. Piao, Phys. Rev D, 92:023518(2015) | 
		
	
			| 
                    [19]
                 | 
			
				Y. Cai, T. Qiu, J. Xia, and X. Zhang, Phys. Rev. D, 79:021303(2009) | 
		
	
			| 
                    [20]
                 | 
			
				Y. Cai, D. A. Easson, and R. Brandenberger, JCAP, 08:020(2012) | 
		
	
			| 
                    [21]
                 | 
			
				J. Xia, Y. Cai, H. Li, and X. Zhang, Phys. Rev. Lett., 112:251301(2014) | 
		
	
			| 
                    [22]
                 | 
			
				Y. Cai, SCIENCE CHINA, Physics, Mechanics and Astronomy, 57:1414(2014) | 
		
	
			| 
                    [23]
                 | 
			
				Y. Piao, B. Feng, and X. Zhang, Phys. Rev. D, 69:103520(2004) | 
		
	
			| 
                    [24]
                 | 
			
				Z. Liu, Z. Guo, and Y. Piao, Eur. Phys. J. C, 74:3006(2014) | 
		
	
			| 
                    [25]
                 | 
			
				Z. Liu, Z. Guo, and Y. Piao, Phys. Rev. D, 88:063539(2013) | 
		
	
			| 
                    [26]
                 | 
			
				Y. Wang and Y. Piao, arXiv:gr-qc/1409.7153v3 | 
		
	
			| 
                    [27]
                 | 
			
				R. H. Brandenberger, arXiv:hep-ph/9910410 | 
		
	
			| 
                    [28]
                 | 
			
				J. Martin and R. H. Brandenberger, Phys. Rev. D, 63:123501(2001) | 
		
	
			| 
                    [29]
                 | 
			
				Y. Cai and Y. Wang, Phys. Let. B, 735:108111(2014) | 
		
	
			| 
                    [30]
                 | 
			
				Y. Cai, F. Chen, E. G. M. Ferreira, and J. Quintin, arXiv:1412.4298[hep-th] | 
		
	
			| 
                    [31]
                 | 
			
				Y. Cai, E. G. M. Ferreira, B. Hu, and J. Quintin, Phys. Rev. D, 92:121303(2015) | 
		
	
			| 
                    [32]
                 | 
			
				E. Yusofiand M. Mohsenzadeh, Phys. Let. B, 735:261265(2014) | 
		
	
			| 
                    [33]
                 | 
			
				M. Mohsenzadeh, M. R. Tanhayi, and E. Yusofi, Eur. Phys. J. C, 74:2920(2014) | 
		
	
			| 
                    [34]
                 | 
			
				E. Yusofiand M. Mohsenzadeh, Mod. Phys. Lett. A, 30:1550041(2015) | 
		
	
			| 
                    [35]
                 | 
			
				M. Mohsenzadeh, E. Yusofi, and M. R. Tanhayi, Canadian Journal of Physics, 93:14661469(2015) | 
		
	
			| 
                    [36]
                 | 
			
				E. Yusofiand M. Mohsenzadeh, JHEP, 09:020(2014) | 
		
	
			| 
                    [37]
                 | 
			
				C. Caroll, SPACE TIME AND GEOMETRY An introduction to general relativity (Sanfrancisco:Addition Wesley, 2003) | 
		
	
			| 
                    [38]
                 | 
			
				N. D. Birrel, P.C.W. Davies, Quantum Field in Curved Space-time (Cambridge, Cambridge University Press, 1982) | 
		
	
			| 
                    [39]
                 | 
			
				L Bergstrom U. H. Danielsson, JHEP, 0212:038(2002) | 
		
	
			| 
                    [40]
                 | 
			
				I. S. Gradshteyn and I. M. Ryzhik, Table of Integrals,Series and Products (Elsevier Accademic Press, 2007) | 
		
	
			| 
                    [41]
                 | 
			
				P. A. R. Ade et al, arxiv:astro-ph/1303.5083 | 
		
	
			| 
                    [42]
                 | 
			
				Y. Cai, W. Zhao, and Y. Zhang, Phys. Rev. D, 89:023005(2014) |