caa a22 4500 467886679 CHVBK 20180406152736.0 cr unu---uuuuu 170328e20060101xx s 000 0 eng 10.1007/s10714-005-0208-7 doi (NATIONALLICENCE)springer-10.1007/s10714-005-0208-7 Conformal aspects of the Palatini approach in Extended Theories of Gravity [Elektronische Daten] [Gianluca Allemandi, Monica Capone, Salvatore Capozziello, Mauro Francaviglia] The debate on the physical relevance of conformal transformations can be faced by taking the Palatini approach into account gravitational theories. We show that conformal transformations are not only a mathematical tool to disentangle gravitational and matter degrees of freedom (passing from the Jordan frame to the Einstein frame) but they acquire a physical meaning considering the bi-metric structure of Palatini approach which allows to distinguish between spacetime structure and geodesic structure. These facts are relevant at least at cosmological scales, while at small scale (i.e. in the spacetime regions relevant for observations) the conformal factor is slowly varying and its effects are not relevant. Examples of higher-order and non-minimally coupled theories are worked out and relevant cosmological solutions in Einstein frame and Jordan frame are discussed showing that also the interpretation of cosmological observations can drastically change depending on the adopted frame. Springer-Verlag, 2005 Cosmology nationallicence Conformal factor nationallicence Jordan frame nationallicence Allemandi Gianluca Dipartimento di Matematica, Università di Torino, Via Carlo Alberto 10, 10123, Torino, Italy aut Capone Monica Politecnico di Torino, Via Duca degli Abbruzzi 24, 10129, Torino, Italy aut Capozziello Salvatore Dipartimento di Scienze Fisiche, Università "Federico II” di Napoli and INFN Sez. di Napoli, Complesso Universitario di Monte S. Angelo, Via Cinthia, I-80126, Napoli, Italy aut Francaviglia Mauro Dipartimento di Matematica, Università di Torino, Via Carlo Alberto 10, 10123, Torino, Italy aut General Relativity and Gravitation Springer US; http://www.springer-ny.com 38/1(2006-01-01), 33-60 0001-7701 38:1<33 2006 38 10714 https://doi.org/10.1007/s10714-005-0208-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10714-005-0208-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Allemandi Gianluca Dipartimento di Matematica, Università di Torino, Via Carlo Alberto 10, 10123, Torino, Italy aut NATIONALLICENCE 700 1- Capone Monica Politecnico di Torino, Via Duca degli Abbruzzi 24, 10129, Torino, Italy aut NATIONALLICENCE 700 1- Capozziello Salvatore Dipartimento di Scienze Fisiche, Università "Federico II” di Napoli and INFN Sez. di Napoli, Complesso Universitario di Monte S. Angelo, Via Cinthia, I-80126, Napoli, Italy aut NATIONALLICENCE 700 1- Francaviglia Mauro Dipartimento di Matematica, Università di Torino, Via Carlo Alberto 10, 10123, Torino, Italy aut NATIONALLICENCE 773 0- General Relativity and Gravitation Springer US; http://www.springer-ny.com 38/1(2006-01-01), 33-60 0001-7701 38:1<33 2006 38 10714 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer