Now showing items 1-20 of 40

  • ANÀLISI FUNCIONAL 

    Haro Cases, Jaume (Universitat Politècnica de Catalunya, 2007-06-29)
    Exam
    Restricted access to the UPC academic community
  • An extended matter bounce scenario: current status and challenges 

    Haro Cases, Jaume; Cai, Yi-Fu (2015-08-01)
    Article
    Open Access
    As an alternative to the paradigm of slow roll inflation, we propose an extended scenario of the matter bounce cosmology in which the Universe has experienced a quasi-matter contracting phase with a variable background ...
  • Bouncing cosmologies in geometries with positively curved spatial sections 

    Haro Cases, Jaume (Elsevier, 2016-09-10)
    Article
    Open Access
    Background bouncing cosmologies, driven by a single scalar field, having a quasi-matter domination period during the contracting phase, i.e., depicting the so-called Matter Bounce Scenario, are reconstructed for cosmologies ...
  • Bouncing cosmologies via modified gravity in the ADM formalism: Application to loop quantum cosmology 

    Haro Cases, Jaume; Amorós Torrent, Jaume (American Physical Society (APS), 2018-03-15)
    Article
    Open Access
    We consider the Arnowitt-Deser-Misner formalism as a tool to build bouncing cosmologies. In this approach, the foliation of the spacetime has to be fixed in order to go beyond general relativity modifying the gravitational ...
  • Bouncing loop quantum cosmology from F(T) gravity 

    Amorós Torrent, Jaume; Haro Cases, Jaume; Odintsov, Sergei D. (2013-05)
    Article
    Open Access
    The big bang singularity could be understood as a breakdown of Einstein’s general relativity at very high energies. By adopting this viewpoint, other theories that implement Einstein cosmology at high energies might solve ...
  • Bouncing loop quantum cosmology in Gauss-Bonnet gravity 

    Haro Cases, Jaume; Makarenko, A. M.; Myagky, A. N.; Odintsov, Sergei D.; Oikonomou, V. K. (American Physical Society, 2015-12-11)
    Article
    Open Access
    We develop an effective Gauss-Bonnet extension of loop quantum cosmology, by introducing holonomy corrections in modified F(G) theories of gravity. Within the context of our formalism, we provide a perturbative expansion ...
  • Brane cosmology from observational surveys and its comparison with standard FRW cosmology 

    Astashenok, Artyom V.; Elizalde, Emilio; Haro Cases, Jaume; Odintsov, Sergei D.; Yurov, Artyom V. (2013-09)
    Article
    Restricted access - publisher's policy
    Several simple dark energy models on the brane are investigated. They are compared with corresponding models in the frame of 4d Friedmann-Robertson-Walker cosmology. For constraining the parameters of the models considered, ...
  • Bulk viscous quintessential inflation 

    Haro Cases, Jaume; Pan, Supriya (2018-04-01)
    Article
    Open Access
    In a spatially-flat Friedmann–Lemaître–Robertson–Walker universe, the incorporation of bulk viscous process in general relativity leads to an appearance of a nonsingular background of the universe that both at early and ...
  • Calculation of the renormalized two-point function by adiabatic regularization 

    Haro Cases, Jaume (2010-11)
    Article
    Restricted access - publisher's policy
    We calculate a renormalized two-point function using the adiabatic regularization method. We study the conformally and minimally coupled cases for massless and massive scalar fields in full detail. We reproduce previous ...
  • Can quantum effects due to a massless conformally coupled field avoid gravitational singularities? 

    Haro Cases, Jaume (2012-04)
    Article
    Restricted access - publisher's policy
    Using quantum corrections from massless fields conformally coupled to gravity, we study the possibility of avoiding singularities that appear in the flat Friedmann–Robertson–Walker model. We assume that the universe ...
  • Cosmological perturbations in a class of fully covariant modified theories: application to models with the same background as standard LQC 

    Haro Cases, Jaume; Aresté Saló, Llibert; Elizalde, Emilio (Springer, 2018-09-01)
    Article
    Open Access
    Bouncing cosmologies are obtained by adding to the Einstein–Hilbert action a term of the form -g---vf(¿), with ¿ a scalar depending on the Hubble parameter only, not on its derivatives, and which is here shown to arise ...
  • Different reheating mechanisms in quintessence inflation 

    Haro Cases, Jaume (American Physical Society (APS), 2019-02-11)
    Article
    Open Access
    Different well-known ways to reheat the Universe, such as instant preheating, the creation of particles nearly or conformally coupled with gravity, or from the decay of products of a curvaton field, are revisited and ...
  • Evolution and dynamics of a matter creation model 

    Pan, Supriya; Haro Cases, Jaume; Paliathanasis, A.; Slagter, R.J. (2016-05-01)
    Article
    Open Access
    In a flat Friedmann–Lemaître–Robertson–Walker (FLRW) geometry, we consider the expansion of the universe powered by the gravitationally induced ‘adiabatic’ matter creation. To demonstrate how matter creation works well ...
  • Gravitationally induced adiabatic particle production: from big bang to de Sitter 

    Haro Cases, Jaume (2016-07-27)
    Article
    Open Access
    In the background of a flat homogeneous and isotropic space–time, we consider a scenario of the Universe driven by the gravitationally induced 'adiabatic' particle production with constant creation rate. We have shown that ...
  • Gravitational particle production in bouncing cosmologies 

    Haro Cases, Jaume; Elizalde, Emilio (2015-10-13)
    Article
    Open Access
    © 2015 IOP Publishing Ltd and Sissa Medialab srl . It is argued that the Universe reheating in bouncing cosmologies could be explained via gravitational particle production, as due to a sudden phase transition in the ...
  • Gravitational Particle Production in Massive Chaotic Inflation and the Moduli Problem 

    Haro Cases, Jaume; Elizalde, Emilio (2012-02)
    Article
    Restricted access - publisher's policy
    Particle production from vacuum fluctuations during inflation is briefly revisited. The moduli problem occurring with light particles produced at the end of inflation is addressed, namely the fact that some results are in ...
  • How can holonomy corrections be introduced in f(R) gravity? 

    Haro Cases, Jaume (2014-07-08)
    Article
    Open Access
    We study the introduction of holonomy corrections in f(R) gravity. We will show that there are infinitely many ways, as many as canonical transformations, to introduce this kind of corrections, depending on the canonical ...
  • Inflation and late-time acceleration from a double-well potential with cosmological constant 

    Haro Cases, Jaume; Elizalde, Emilio (2016-06-01)
    Article
    Open Access
    A model of a universe without big bang singularity is presented, which displays an early inflationary period ending just before a phase transition to a kination epoch. The model produces enough heavy particles so as to ...
  • Nonsingular models of universes in teleparallel theories 

    Haro Cases, Jaume; Amorós Torrent, Jaume (2013-02-14)
    Article
    Open Access
    Different models of universes are considered in the context of teleparallel theories. Assuming that the universe is filled by a fluid with an equation of state P ¼ f ð Þ , for different teleparallel theories ...
  • Note on bouncing backgrounds 

    Haro Cases, Jaume; Pan, Supriya (American Physical Society (APS), 2018-05-15)
    Article
    Open Access
    The theory of inflation is one of the fundamental and revolutionary developments of modern cosmology that became able to explain many issues of the early Universe in the context of the standard cosmological model (SCM). ...