caa a22 4500 445386282 CHVBK 20180317143033.0 cr unu---uuuuu 170323e20111201xx s 000 0 eng 10.1007/s10714-011-1246-y doi (NATIONALLICENCE)springer-10.1007/s10714-011-1246-y Probability of inflation in loop quantum cosmology [Elektronische Daten] [Abhay Ashtekar, David Sloan] Inflationary models of the early universe provide a natural mechanism for the formation of large scale structure. This success brings to forefront the question of naturalness: Does a sufficiently long slow roll inflation occur generically or does it require a careful fine tuning of initial parameters? In recent years there has been considerable controversy on this issue (Hollands and Wald in Gen Relativ Gravit, 34:2043, 2002; Kofman etal. in J High Energy Phys 10:057, 2002); (Gibbons and Turok in Phys Rev D 77:063516, 2008). In particular, for a quadratic potential, Kofman etal. (J High Energy Phys 10:057, 2002) have argued that the probability of inflation with at least 65 e-foldings is close to one, while Gibbons and Turok (Phys Rev D 77:063516, 2008) have argued that this probability is suppressed by a factor of ~10−85. We first clarify that such dramatically different predictions can arise because the required measure on the space of solutions is intrinsically ambiguous in general relativity. We then show that this ambiguity can be naturally resolved in loop quantum cosmology (LQC) because the big bang is replaced by a big bounce and the bounce surface can be used to introduce the structure necessary to specify a satisfactory measure. The second goal of the paper is to present a detailed analysis of the inflationary dynamics of LQC using analytical and numerical methods. By combining this information with the measure on the space of solutions, we address a sharper question than those investigated in Kofman etal. (J High Energy Phys 10:057, 2002), Gibbons and Turok (Phys Rev D 77:063516, 2008), Ashtekar and Sloan (Phys Lett B 694:108, 2010): What is the probability of a sufficiently long slow roll inflation which is compatible with the seven year WMAP data? We show that the probability is very close to 1. The material is so organized that cosmologists who may be more interested in the inflationary dynamics in LQC than in the subtleties associated with measures can skip that material without loss of continuity. Springer Science+Business Media, LLC, 2011 Loop quantum gravity nationallicence Cosmology nationallicence Inflation nationallicence Measures nationallicence Probability nationallicence WMAP 7year data nationallicence Ashtekar Abhay Institute for Gravitation and the Cosmos, Physics Department, Penn State, 16802, University Park, PA, USA aut Sloan David Institute for Gravitation and the Cosmos, Physics Department, Penn State, 16802, University Park, PA, USA aut General Relativity and Gravitation Springer US; http://www.springer-ny.com 43/12(2011-12-01), 3619-3655 0001-7701 43:12<3619 2011 43 10714 https://doi.org/10.1007/s10714-011-1246-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10714-011-1246-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ashtekar Abhay Institute for Gravitation and the Cosmos, Physics Department, Penn State, 16802, University Park, PA, USA aut NATIONALLICENCE 700 1- Sloan David Institute for Gravitation and the Cosmos, Physics Department, Penn State, 16802, University Park, PA, USA aut NATIONALLICENCE 773 0- General Relativity and Gravitation Springer US; http://www.springer-ny.com 43/12(2011-12-01), 3619-3655 0001-7701 43:12<3619 2011 43 10714 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer