2024-03-28T09:47:04Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/623832022-11-17T02:08:08Zhdl_2115_20039hdl_2115_116Beginning of Universe through large field hybrid inflationKobayashi, TatsuoSeto, OsamuInflationary Universe420Recent detection of B-mode polarization induced from tensor perturbations by the BICEP2 experiment implies the so-called large field inflation, where an inflaton field takes super-Planckian expectation value during inflation, at a high energy scale. We show however, if another inflation follows hybrid inflation, the hybrid inflation can generate a large tensor perturbation with not super-Planckian but Planckian field value. This scenario would relax the tension between BICEP2 and Planck concerning the tensor-to-scalar ratio, because a negative large running can also be obtained for a certain number of e-fold of the hybrid inflation. A natural interpretation of a large gravitational wave mode with or without the scalar spectral running might be multiple inflation in the early Universe.World Scientific PublishingJournal Articleapplication/pdfhttp://hdl.handle.net/2115/62383https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/62383/1/MPLA_30_1550106%20.pdf0217-73231793-6632Modern Physics Letters A302115501062015-07-10enginfo:doi/10.1142/S0217732315501060Electronic version of an article published as Modern Physics Letters A, Volume 30, Issue 21, 2015, 1550106 (11 pages) DOI: 10.1142/S0217732315501060 © copyright World Scientific Publishing Company http://www.worldscientific.com/worldscinet/mplaauthor