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Author Agullo, I.; Navarro-Salas, J.; Parker, L. url  doi
openurl 
  Title Enhanced local-type inflationary trispectrum from a non-vacuum initial state Type Journal Article
  Year 2012 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 05 Issue 5 Pages 019 - 13pp  
  Keywords (up) inflation; non-gaussianity; quantum field theory on curved space; cosmological perturbation theory  
  Abstract We compute the primordial trispectrum for curvature perturbations produced during cosmic inflation in models with standard kinetic terms, when the initial quantum state is not necessarily the vacuum state. The presence of initial perturbations enhances the trispectrum amplitude for configuration in which one of the momenta, say k(3), is much smaller than the others, k(3) << k(1,2,4). For those squeezed con figurations the trispectrum acquires the so-called local form, with a scale dependent amplitude that can get values of order epsilon(k(1)/k(3))(2). This amplitude could be larger than the prediction of the so-called Maldacena consistency relation by a factor as large as 10(6), and could reach the sensitivity of forthcoming observations, even for single-field inflationary models.  
  Address [Agullo, Ivan] Penn State Univ, Inst Gravitat & Cosmos, University Pk, PA 16802 USA, Email: agullo@gravity.psu.edu;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000305415200020 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1083  
Permanent link to this record
 
 
Author Kim, J.; Ko, P.; Park, W.I. url  doi
openurl 
  Title Higgs-portal assisted Higgs inflation with a sizeable tensor-to-scalar ratio Type Journal Article
  Year 2017 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 02 Issue 2 Pages 003 - 16pp  
  Keywords (up) inflation; particle physics – cosmology connection; physics of the early universe  
  Abstract We show that the Higgs portal interactions involving extra dark Higgs field can save generically the original Higgs inflation of the standard model (SM) from the problem of a deep non-SM vacuum in the SM Higgs potential. Specifically, we show that such interactions disconnect the top quark pole mass from inflationary observables and allow multi-dimensional parameter space to save the Higgs inflation, thanks to the additional parameters (the dark Higgs boson mass m(phi), the mixing angle a between the SM Higgs H and dark Higgs Phi, and the mixed quartic coupling) affecting RG-running of the Higgs quartic coupling. The effect of Higgs portal interactions may lead to a larger tensor-to-scalar ratio, 0.08 less than or similar to r less than or similar to 0.1, by adjusting relevant parameters in wide ranges of alpha and m(phi), some region of which can be probed at future colliders. Performing a numerical analysis we find an allowed region of parameters, matching the latest Planck data.  
  Address [Kim, Jinsu; Ko, Pyungwon] Korea Inst Adv Study, Quantum Universe Ctr, 85 Hoegiro Dongdaemungu, Seoul 02455, South Korea, Email: kimjinsu@kias.re.kr;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000399455000003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3080  
Permanent link to this record
 
 
Author Barenboim, G.; Park, W.I. url  doi
openurl 
  Title New- vs. chaotic- inflations Type Journal Article
  Year 2016 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 02 Issue 2 Pages 061 - 20pp  
  Keywords (up) inflation; physics of the early universe; cosmology of theories beyond the SM  
  Abstract We show that “spiralized” models of new-inflation can be experimentally identified mostly by their positive spectral running in direct contrast with most chaotic-inflation models which have negative runnings typically in the range of O(10(-4)-10(-3)).  
  Address [Barenboim, Gabriela; Park, Wan-Il] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain, Email: Gabriela.Barenboim@uv.es;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000372467600062 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 2589  
Permanent link to this record
 
 
Author Figueroa, D.G.; Raatikainen, S.; Rasanen, S.; Tomberg, E. url  doi
openurl 
  Title Implications of stochastic effects for primordial black hole production in ultra-slow-roll inflation Type Journal Article
  Year 2022 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 05 Issue 5 Pages 027 - 48pp  
  Keywords (up) inflation; primordial black holes; dark matter theory; massive black holes  
  Abstract We study the impact of stochastic noise on the generation of primordial black hole (PBH) seeds in ultra-slow-roll (USR) inflation with numerical simulations. We consider the non-linearity of the system by consistently taking into account the noise dependence on the inflaton perturbations, while evolving the perturbations on the coarse-grained background affected by the noise. We capture in this way the non-Markovian nature of the dynamics, and demonstrate that non-Markovian effects are subleading. Using the Delta N formalism, we find the probability distribution P(R) of the comoving curvature perturbation R. We consider inflationary potentials that fit the CMB and lead to PBH dark matter with i) asteroid, ii) solar, or iii) Planck mass, as well as iv) PBHs that form the seeds of supermassive black holes. We find that stochastic effects enhance the PBH abundance by a factor of O(10)-O(10(8)), depending on the PBH mass. We also show that the usual approximation, where stochastic kicks depend only on the Hubble rate, either underestimates or overestimates the abundance by orders of magnitude, depending on the potential. We evaluate the gauge dependence of the results, discuss the quantum-to-classical transition, and highlight open issues of the application of the stochastic formalism to USR inflation.  
  Address [Figueroa, Daniel G.] CSIC, Inst Fis Corpuscular IFIC, E-46980 Valencia, Spain, Email: daniel.figueoa@ific.uv.es;  
  Corporate Author Thesis  
  Publisher IOP Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000804493000010 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5239  
Permanent link to this record
 
 
Author Gariazzo, S.; Mena, O.; Ramirez, H.; Boubekeur, L. url  doi
openurl 
  Title Primordial power spectrum features in phenomenological descriptions of inflation Type Journal Article
  Year 2017 Publication Physics of the Dark Universe Abbreviated Journal Phys. Dark Universe  
  Volume 17 Issue Pages 38-45  
  Keywords (up) Inflation; Primordial power spectrum; Sound speed  
  Abstract We extend an alternative, phenomenological approach to inflation by means of an equation of state and a sound speed, both of them functions of the number of e-folds and four phenomenological parameters. This approach captures a number of possible inflationary models, including those with non-canonical kinetic terms or scale-dependent non-gaussianities. We perform Markov Chain Monte Carlo analyses using the latest cosmological publicly available measurements, which include Cosmic Microwave Background (CMB) data from the Planck satellite. Within this parameterization, we discard scale invariance with a significance of about 10 sigma, and the running of the spectral index is constrained as alpha(s) = -0.60(-0.10)(+0.08) x 10(-3) (68% CL errors). The limit on the tensor-to-scalar ratio is r < 0.005 at 95% CL from CMB data alone. We find no significant evidence for this alternative parameterization with present cosmological observations. The maximum amplitude of the equilateral non-gaussianity that we obtain, vertical bar f(NL)(equil)vertical bar < 1, is much smaller than the current Planck mission errors, strengthening the case for future high-redshift, all-sky surveys, which could reach the required accuracy on equilateral non-gaussianities.  
  Address [Gariazzo, Stefano] Univ Turin, Dept Phys, Via P Giuria 1, I-10125 Turin, Italy, Email: omena@ific.uv.es  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2212-6864 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000411869100006 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3319  
Permanent link to this record
 
 
Author Pallis, C. url  doi
openurl 
  Title Induced-gravity in inflation no-scale supergravity and beyond Type Journal Article
  Year 2014 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 08 Issue 8 Pages 057 - 20pp  
  Keywords (up) inflation; supersymmetry and cosmology  
  Abstract Supersymmetric versions of induced-gravity inflation are formulated within Supergravity (SUGRA) employing two gauge singlet chiral super fields. The proposed super-potential is uniquely determined by applying a continuous R and a discrete Z(n) symmetry. We select two types of logarithmic Kahler potentials, one associated with a no-scale-type SU(2, 1)/SU(2) x U(1)(R) x Z(n) Kahler manifold and one more generic. In both cases, imposing a lower bound on the parameter c R involved in the coupling between the inflaton and the Ricci scalar curvature – e.g. c(R) greater than or similar to 76, 105, 310 for n – 2, 3 and 6 respectively -, inflation can be attained even for subplanckian values of the inflaton while the corresponding effective theory respects the perturbative unitarity. In the case of no-scale SUGRA we show that, for every n, the inflationary observables remain unchanged and in agreement with the current data while the inflaton mass is predicted to be 3 . 10(13) GeV. Beyond no-scale SUGRA the inflationary observables depend mildly on n and crucially on the coefficient involved in the fourth order term of the Kahler potential which mixes the inflaton with the accompanying non-inflaton field.  
  Address [Pallis, C.] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, Spain, Email: kpallis@gen.auth.gr  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000341848800057 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 1944  
Permanent link to this record
 
 
Author Pallis, C.; Shafi, Q. url  doi
openurl 
  Title Gravity waves from non-minimal quadratic inflation Type Journal Article
  Year 2015 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 03 Issue 3 Pages 023 - 31pp  
  Keywords (up) inflation; supersymmetry and cosmology; cosmology of theories beyond the SM  
  Abstract We discuss non-minimal quadratic inflation in supersymmetric (SUSY) and non-SUSY models which entails a linear coupling of the inflaton to gravity. Imposing a lower bound on the parameter c(R), involved in the coupling between the inflaton and the Ricci scalar curvature, inflation can be attained even for subplanckian values of the inflaton while the corresponding effective theory respects the perturbative unitarity up to the Planck scale. Working in the non-SUSY context we also consider radiative corrections to the inflationary potential due to a possible coupling of the inflaton to bosons or fermions. We find ranges of the parameters, depending mildly on the renormalization scale, with adjustable values of the spectral index n(s), tensor-to-scalar ratio r similar or equal to (2 – 4) . 10(-3), and an inflaton mass close to 3 . 10 (13) GeV. In the SUSY framework we employ two gauge singlet chiral superfields, a logarithmic Kahler potential including all the allowed terms up to fourth order in powers of the various fields, and determine uniquely the superpotential by applying a continuous R and a global U(1) symmetry. When the Kahler manifold exhibits a no-scale-type symmetry, the model predicts n(s) similar or equal to 0.963 and r similar or equal to 0.004. Beyond no-scale SUGRA, n(s) and r depend crucially on the coefficient involved in the fourth order term, which mixes the inflaton with the accompanying non-inflaton field in the Kahler potential, and the prefactor encountered in it. Increasing slightly the latter above (-3), an efficient enhancement of the resulting r can be achieved putting it in the observable range. The inflaton mass in the last case is confined in the range (5 – 9) . 10(13) GeV.  
  Address [Pallis, Constantinos] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, Spain, Email: cpallis@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000355633800023 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2263  
Permanent link to this record
 
 
Author Beltran Jimenez, J.; Heisenberg, L.; Olmo, G.J. url  doi
openurl 
  Title Infrared lessons for ultraviolet gravity: the case of massive gravity and Born-lnfeld Type Journal Article
  Year 2014 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 11 Issue 11 Pages 004 - 26pp  
  Keywords (up) modified gravity; alternatives to inflation; gravity  
  Abstract We generalize the ultraviolet sector of gravitation via a Born-Infeld action using lessons from massive gravity. The theory contains all of the elementary symmetric polynomials and is treated in the Palatini formalism. We show how the connection can be solved algebraically to be the Levi-Civita connection of an effective metric. The non-linearity of the algebraic equations yields several branches, one of which always reduces to General Relativity at low curvatures. We explore in detail a minimal version of the theory, for which we study solutions in the presence of a perfect fluid with special attention to the cosmological evolution. In vacuum we recover Ricci-flat solutions, but also an additional physical solution corresponding to an Einstein space. The existence of two physical branches remains for non-vacuum solutions and, in addition, the branch that connects to the Einstein space in vacuum is not very sensitive to the specific value of the energy density. For the branch that connects to the General Relativity limit we generically find three behaviours for the Hubble function depending on the equation of state of the fluid, namely: either there is a maximum value for the energy density that connects continuously with vacuum, or the energy density can be arbitrarily large but the Hubble function saturates and remains constant at high energy densities, or the energy density is unbounded and the Hubble function grows faster than in General Relativity. The second case is particularly interesting because it could offer an interesting inflationary epoch even in the presence of a dust component. Finally, we discuss the possibility of avoiding certain types of singularities within the minimal model.  
  Address [Jimenez, Jose Beltran] Univ Louvain, Ctr Cosmol Particle Phys & Phenomenol, Inst Math & Phys, B-1348 Louvain La Neuve, Belgium, Email: jose.beltran@uclouvain.be;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000346105300004 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2039  
Permanent link to this record
 
 
Author Beltran Jimenez, J.; Heisenberg, L.; Olmo, G.J.; Ringeval, C. url  doi
openurl 
  Title Cascading dust inflation in Born-lnfeld gravity Type Journal Article
  Year 2015 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 11 Issue 11 Pages 046 - 30pp  
  Keywords (up) modified gravity; inflation  
  Abstract In the framework of Born-Infeld inspired gravity theories, which deviates from General Relativity (GR) in the high curvature regime, we discuss the viability of Cosmic Inflation without scalar fields. For energy densities higher than the new mass scale of the theory, a gravitating (lust component is shown to generically induce an accelerated expansion of the Universe. Within such a simple scenario, inflation gracefiffly exits when the CR regime is recovered, but the Universe would remain matter dominated. In order to implement a reheating era after inflation, we then consider inflation to be driven by a mixture of unstable dust species decaying into radiation. Because the speed of sound gravitates within the BornInfeld model under consideration, our scenario ends up being predictive on various open questions of the inflationary paradigm. The total number of e-folds of acceleration is given by the lifetime of the unstable dust components and is related to the duration of reheating. As a result, inflation does not last much longer than the number of e-folds of deceleration allowing a small spatial curvature and large scale deviations to isotropy to be observable today. Energy densities are self-regulated as inflation can only start for a total energy density less than a threshold value, again related to the species' lifetime. Above this threshold, the Universe may bc nee thereby avoiding a singularity. Another distinctive feature is that the accelerated expansion is of the superinflationary ldnd, namely the first Hubble flow function is negative. We show however that the tensor modes are never excited and the tensor-to-scalar ratio is always vanishing, independently of the energy scale of inflation.  
  Address [Jimenez, Jose Beltran] Aix Marseille Univ, Ctr Phys Theor, UMR 7332, F-13288 Marseille, France, Email: jose.beltran@cpt.univ-mrs.fr;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000365821200047 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2478  
Permanent link to this record
 
 
Author Beltran Jimenez, J.; Heisenberg, L.; Olmo, G.J. url  doi
openurl 
  Title Tensor perturbations in a general class of Palatini theories Type Journal Article
  Year 2015 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 06 Issue 6 Pages 026 - 16pp  
  Keywords (up) modified gravity; inflation; gravity; dark energy theory  
  Abstract We study a general class of gravitational theories formulated in the Palatini approach and derive the equations governing the evolution of tensor perturbations. In the absence of torsion, the connection can be solved as the Christoffel symbols of an auxiliary metric which is non-trivially related to the space-time metric. We then consider background solutions corresponding to a perfect fluid and show that the tensor perturbations equations (including anisotropic stresses) for the auxiliary metric around such a background take an Einstein-like form. This facilitates the study in a homogeneous and isotropic cosmological scenario where we explicitly establish the relation between the auxiliary metric and the spacetime metric tensor perturbations. As a general result, we show that both tensor perturbations coincide in the absence of anisotropic stresses.  
  Address [Jimenez, Jose Beltran] Univ Louvain, Inst Math & Phys, Ctr Cosmol Particle Phys & Phenomenol, B-1318 Louvain, Belgium, Email: jose.beltran@cpt.univ.mrs.fr;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000359215400027 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2368  
Permanent link to this record
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