UNIVERSIDADE DA BEIRA INTERIOR Ci^encias Inflaton candidates: from string theory to particle physics Sravan Kumar Korumilli Tese para obten¸c~aodo Grau de Doutor em F´ısica (3o ciclo de estudos) arXiv:1808.03701v1 [hep-th] 24 Jul 2018 Orientador: Prof. Doutor Paulo Vargas Moniz Covilh~a,Maio 2017 The research work on this dissertation was supported by the PhD scholarship from the International Doctorate Network in Particle Physics, Astrophysics and Cosmology (IDPASC) funded by Portuguese agency Funda¸c~aopara a Ci^enciae Tecnologia (FCT) through the fellowship SFRH/BD/51980/2012. I don't want to believe. I want to know - Carl Sagan The Starry Night by Vincent Van Gogh, 1889. Abstract Cosmic inflation is the cornerstone of modern cosmology. In particular, following the Planck mission reports presented in 2015 regarding cosmic microwave background (CMB), there is an increasing interest in searching for inflaton candidates within fundamental theories and to ultimately test them with future CMB data. This thesis presents in- flationary models using a methodology that can be described as venturing top-down or bottom-up along energy scales. In the top-down motivation, we study inflation- ary scenarios in string theory and supergravity (SUGRA), namely with (multiple) 3- forms, Dirac-Born-Infeld Galileon model, a string field theory setup and N = 1 SUGRA α−attractor models. In the bottom-up motivation, we construct a grand unified theory based inflationary model with an additional conformal symmetry and study not only inflation but also provide predictions related to particle physics. Our research work in- cludes various classes of inflation driven by scalar fields under a canonical, non-canonical and induced gravity frameworks. All these models are consistent with Planck data, sup- ported by key primordial cosmological parameters such as the scalar spectral index ns, the tensor to scalar ratio r, together with the primordial non-Gaussianities. Future probes aiming to detect primordial gravitational waves and CMB non-Gaussianities can further help to distinguish between them. Keywords: Inflation, String theory, Supergravity, Grand unified theories, Primordial gravitational waves, Non-gaussianities. List of publications This dissertation is based on the following publications: K. Sravan Kumar, J. Marto, N. J. Nunes, and P. V. Moniz, \Inflation in a two 3-form fields scenario," JCAP 1406 (2014) 064, arXiv:1404.0211 [gr-qc]. K. Sravan Kumar, J. C. Bueno S´anchez, C. Escamilla-Rivera, J. Marto, and P. Var- gas Moniz, \DBI Galileon inflation in the light of Planck 2015," JCAP 1602 no. 02, (2016) 063, arXiv:1504.01348 [astro-ph.CO]. K. Sravan Kumar, J. Marto, P. Vargas Moniz, and S. Das, \Non-slow-roll dynamics in α−attractors," JCAP 1604 no. 04, (2016) 005, arXiv:1506.05366 [gr-qc]. K. Sravan Kumar, J. Marto, P. Vargas Moniz, and S. Das, \Gravitational waves in α−attractors," in Proceedings, 14th Marcel Grossmann Meeting on Recent De- velopments in Theoretical and Experimental General Relativity, Astrophysics, and Relativistic Field Theories (MG14) (In 4 Volumes): Rome, Italy, July 12-18, 2015, vol. 4, pp. 4262{4267. 2017. arXiv:1512.08490 [gr-qc]. A. S. Koshelev, K. Sravan Kumar, and P. Vargas Moniz, “Inflation from string field theory," Phys.Rev. D96 (2017) no.10, 103503,arXiv:1604.01440 [hep-th]. K. Sravan Kumar, D. J. Mulryne, N. J. Nunes, J. Marto, and P. Vargas Moniz, \Non-Gaussianity in multiple three-form field inflation,” Phys. Rev. D 94, 103504 (2016),arXiv:1606.07114 [astro-ph.CO]. K. Sravan Kumar and P. Vargas Moniz, \Conformal GUT inflation, proton life time and non-thermal leptogenesis," arXiv:arXiv:1806.09032 [astro-ph.CO] Other publications during this doctoral studies: A. Burgazli, A. Zhuk, J. Morais, M. Bouhmadi-L´opez and K. Sravan Kumar, \Cou- pled scalar fields in the late Universe: The mechanical approach and the late cosmic acceleration," JCAP 1609 no. 09, (2016) 045, arXiv:1512.03819 [gr-qc]. M. Bouhmadi-L´opez, K. S. Kumar, J. Marto, J. Morais, and A. Zhuk, \K-essence model from the mechanical approach point of view: coupled scalar field and the late cosmic acceleration," JCAP 1607 no. 07, (2016) 050, arXiv:1605.03212 [gr-qc]. J. Morais, M. Bouhmadi-L´opez, K. Sravan Kumar, J. Marto, and Y. Tavakoli, \In- teracting 3-form dark energy models: distinguishing interactions and avoiding the Little Sibling of the Big Rip," Phys. Dark Univ. 15 (2017) 7{30, arXiv:1608.01679 [gr-qc]. Shreya Banerjee, Suratna Das, K. Sravan Kumar and T.P. Singh, \On signatures of spontaneous collapse dynamics modified single field inflation,”, Phys. Rev. D 95, 103518 (2017) arXiv:1612.09131 [astro-ph.CO]. 2 Alexey S. Koshelev, K. Sravan Kumar, Alexei A. Starobinsky \R inflation to probe non-perturbative quantum gravity," JHEP 1803 (2018) 071 arXiv:1711.08864 [hep-th]. Resumo A infla¸c~aoconstitui um paradigma essencial na cosmologia moderna. Em particular, e de acordo com os comunicados da misso Planck em 2015, acerca da medi¸c~aoda ra- dia¸c~aoc´osmicade fundo, h´aum interesse crescente na procura de candidatos a inflat˜ao extra´ıdos de teorias fundamentais e em testar estas propostas. Esta tese apresenta modelos inflacion´ariosque podem ser classificados numa abordagem descendente ou as- cendente nas escalas de energia. Na abordagem descendente, apresentamos estudos de cen´ariosinflacion´ariosligados `ateoria de cordas e `asupergravidade (SUGRA), seja com campos (m´ultiplos)3-formas, com o modelo Dirac-Born-Infeld Galileon, no contexto de uma teoria de campos para cordas ou ainda no modelo α−atrator SUGRA N = 1. Na abordagem ascendente, propomos a constru¸c~aode um modelo inflacion´ariobaseado numa teoria de grande unifica¸c~ao,complementada com uma simetria conforme, em que estudamos, n~aos´oa infla¸c~ao,mas tamb´emimplica¸c~oesno campo da f´ısicade part´ıculas. O nosso trabalho de investiga¸c~aoinclui diferentes classes de infla¸c~aogovernadas por campos escalares can´onicos,n~aocan´onicosou ainda em contexto de gravidade induzida. A totalidade destes modelos ´econsistente com os dados obtidos na miss~ao Planck e suportados por par^ametroscosmol´ogicoscruciais como o ´ındiceespectral escalar ns, a raz~aotensor para escalar r ou ainda a n~ao-Gaussianidade primordial. O estudo abor- dado nesta tese refor¸caa espectativa que futuras miss~oesobservacionais, cujo objectivo seja detetar ondas gravitacionais primordiais e a n~ao-Gaussianidadeda radia¸c~aoc´osmica de fundo, possam ajudar a melhor distinguir os modelos inflacion´ariosconsiderados. Palavras-chave: Infla¸c~ao,Teoria de cordas, Supergravidade, Teoria de grande unifica¸c~ao, Ondas gravitacionais primordiais, N~ao-Gaussianidades. Acknowledgements First, my sincere thanks to the Jury members of this thesis Dr. J. P. Mimoso, Dr. J. G. Rosa, Dr. N. J. Nunes, Dr. C. A. R. Herdeiro, Dr. J. P. Marto, Dr. P. A. P. Parada and Dr. P. R. L. V. Moniz. My sincere and deepest gratitude to my PhD supervisor Prof. Paulo Vargas Moniz for the guidance, patience and invaluable suggestions. I am grateful for all the efforts he has done introducing me to the exciting area of theoretical cosmology. I am greatly thankful and indebted to Dr. Jo~aoMarto for his very generous and abun- dant help in all aspects during my PhD. I always enjoyed very fruitful scientific dis- cussions with him and also heavily benefitted in learning numerical techniques such as Mathematica from him. Thanks you for invaluable help in writing this dissertation. I am specially thankful to Dr. Alexey S. Koshelev, Dr. Mariam Bouhmadi L´opez, Dr. Suratna Das, Dr. Yaser Tavakoli and Dr. Paulo Parada for reading and provid- ing valuable feedbacks during the writing of this thesis. I am very thankful to Dr. Yaser Tavakoli for helping me with LATEX program during the writing of this thesis. During my PhD I greatly benefited from invaluable discussions with many scientists. In particular, I am grateful to Dr. Nelson J. Nunes for very fruitful collaboration. I learned a lot from him during my doctoral research. My sincere gratitude to Dr. Mariam Bouhmadi L´opez for her excellent support, collaboration and for introducing me to the research on late time cosmology. I am very thankful to Prof. Alexander Zhuk for the opportunity to work with him during his visit to UBI. I am indebted to Dr. Alexey S. Koshelev with whom I have been having very delighted scientific discussions and wonderful collaboration. I am thankful to him for introducing me to the exciting area of non-local gravity. I am very grateful to Prof. Alexei A. Starobinsky for the opportunity to work with him during PhD. I am grateful to Prof. Qaisar shafi for illuminating me on particle physics and cosmology. I am thankful to Prof. Anupam Mazumdar and Prof. Leonardo Modesto for the very useful discussions and on going exciting collaborations. I thank Dr. C. Pallis and Dr. John Ward for useful comments on the drafts of my work. I thank Dr. David J. Mulryne, Dr. Suratna Das, Dr. Celia Escamilla-Rivera, Dr. Juan C. Bueno S´anchez, Prof. T.P. Singh, Shreya Banerjee, Jo~aoMorais and A. Burgazli for very interesting dicussions and collaborations during these years. I acknowledge Dr. S. M. M. Rasouli for his help during my PhD. I also thank Dr. C´esarSilva for useful discussions. I acknowledge the hospitality of Institute of astrophysics (IA) at University of Lisbon, Department of Theoretical Physics of University of Basque country (UPV/EHU) and Indian Institute of Technology (IIT) Kanpur, where part of my research during PhD has been carried out. I greatly acknowledge Center of Mathematics and Applications (CMA-UBI) for the support and encouragement to attend conferences and present my research. I am also very delighted to express my gratitude to the people in department of physics of UBI, especially grateful to Dr.