Now showing items 21-40 of 44

    • 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). ...
    • Qualitative study in loop quantum cosmology 

      Aresté Saló, Llibert; Amorós Torrent, Jaume; Haro Cases, Jaume (2017-12-07)
      Article
      Open Access
      This work contains a detailed qualitative analysis, in general relativity and in loop quantum cosmology, of the dynamics in the associated phase space of a scalar field minimally coupled with gravity, whose potential mimics ...
    • Quintessential inflation at low reheating temperatures 

      Aresté Saló, Llibert; Haro Cases, Jaume (2017-11-23)
      Article
      Open Access
      We have tested some simple quintessential inflation models, imposing the requirement that they match with the recent observational data provided by the BICEP and Planck team and leading to a reheating temperature, which ...
    • Reheating constraints in quintessential inflation 

      Haro Cases, Jaume; Aresté Saló, Llibert (2017-06-02)
      Article
      Open Access
      We study the consequences of reheating in quintessential inflation. From simple inflationary quintessential models introduced by de Haro, Amorós, and Pan in [Phys. Rev. D 93, 084018 (2016)] and [Phys. Rev. D 94, 064060 ...
    • Reheating in quintessential inflation via gravitational production of heavy massive particles: a detailed analysis 

      Haro Cases, Jaume; Yang, Weiqiang; Pan, Supriya (2019-01-01)
      Article
      Open Access
      An improved version of the well-known Peebles-Vilenkin model unifying early inflationary era to current cosmic acceleration, is introduced in order to match with the theoretical values of the spectral quantities provided ...
    • Reheating via gravitational particle production in simple models of quintessence or ¿CDM Inflation 

      Haro Cases, Jaume; Aresté Saló, Llibert (2017-11-14)
      Article
      Open Access
      We have tested some simple CDM (the same test is also valid for quintessence) inflation models, imposing that they match with the recent observational data provided by the BICEP and Planck’s team and leading to a reheating ...
    • Scaling solutions in quintessential inflation 

      Haro Cases, Jaume; Amorós Torrent, Jaume; Pan, Supriya (springer-Verlag, 2020-05)
      Article
      Open Access
      In quintessence scalar field theories, the presence of scaling solutions are important during the radiation and matter epoch due to having their attractor character. Usually, it is assumed that the initial conditions of ...
    • Simple inflationary quintessential model 

      Haro Cases, Jaume; Amorós Torrent, Jaume; Pan, Supriya (2016-04-12)
      Article
      Open Access
      In the framework of a flat Friedmann-Lemaitre-Robertson-Walker geometry, we present a nongeodesically past complete model of our Universe without the big bang singularity at finite cosmic time, describing its evolution ...
    • Simple inflationary quintessential model. II. Power law potentials 

      Haro Cases, Jaume; Amorós Torrent, Jaume; Pan, Supriya (American Physical Society, 2016-09-21)
      Article
      Open Access
      The present work is a sequel of our previous work [Phys. Rev. D 93, 084018 (2016)] which depicted a simple version of an inflationary quintessential model whose inflationary stage was described by a Higgs-type potential ...
    • Sudden singularities in semiclassical gravity 

      Haro Cases, Jaume; Amorós Torrent, Jaume; Elizalde, Emilio (2012-06-19)
      Article
      Restricted access - publisher's policy
      It has been claimed in a recent paper [J. D. Barrow, A. B. Batista, J. C. Fabris, M. J. S. Houndjo, and G. Dito, Phys. Rev. D 84, 123518 (2011).] that sudden singularities will survive in semiclassical gravity. This issue ...
    • Teleparallel loop quantum cosmology in a system of intersecting branes 

      Haro Cases, Jaume (Elsevier, 2016-09-10)
      Article
      Open Access
      Recently, some authors have removed the big bang singularity in teleparallel Loop Quantum Cosmology (LQC) and have shown that the universe may undergo a number of oscillations. We investigate the origin of this type of ...
    • The Dapor–Liegener model of loop quantum cosmology: a dynamical analysis 

      Haro Cases, Jaume (Springer, 2018-11-01)
      Article
      Open Access
      The Dapor-Liegener model of loop quantum cosmology (LQC), which depicts an emergent universe from a de Sitter regime in the contracting phase is studied from the mathematical viewpoint of dynamical systems and compared ...
    • The Lein-Gordon's field: a counter-example of the classical limit 

      Haro Cases, Jaume (2000)
      Article
      Open Access
      We will study the Klein-Gordon's field with an homogeneous external potential, which does not depend on ħ. We will construct the Fock's space corresponding to our problem and we will see that there are phenomena of creation ...
    • The matter-ekpyrotic bounce scenario in Loop Quantum Cosmology 

      Haro Cases, Jaume; Amorós Torrent, Jaume; Aresté Saló, Llibert (2017-09-01)
      Article
      Open Access
      We will perform a detailed study of the matter-ekpyrotic bouncing scenario in Loop Quantum Cosmology using the methods of the dynamical systems theory. We will show that when the background is driven by a single scalar ...
    • The Peebles–Vilenkin quintessential inflation model revisited 

      Haro Cases, Jaume; Amorós Torrent, Jaume; Pan, Supriya (springer-Verlag, 2019-06-01)
      Article
      Open Access
      We review the well-known Peebles–Vilenkin (PV) quintessential inflation model and discuss its possible improvements in agreement with the recent observations. The improved PV model depends only on two parameters: the ...
    • The Schwinger formula revisited II (a mathematical treatment). 

      Haro Cases, Jaume (2003)
      Article
      Open Access
      In this paper we study the production of pairs in no-analytic potentials. It is a well-known fact that, when the potential is analytic the average number of produced pairs is exponentially small in ?. On the other hand, when ...
    • The semiclassical theory of quantized fields in classical electromagnetic backgrounds 

      Haro Cases, Jaume (2003)
      Article
      Open Access
      We show the mathematical formulation of the process of pair production in electromagnetic fields for spinless particles. We compute the probability that ? pairs are created in the semiclassical approximation, and we prove ...
    • The spectrum of gravitational waves, their overproduction in quintessential inflation and its influence in the reheating temperature 

      Haro Cases, Jaume; Aresté Saló, Llibert (2020-06-01)
      Article
      Open Access
      One of the most important issues in an inflationary theory as standard or quintessential inflation is the mechanism to reheat the universe after the end of the inflationary period in order to match with the Hot Big Bang ...
    • Understanding the phenomenology of interacting dark energy scenarios and their theoretical bounds 

      Pan, Supriya; Haro Cases, Jaume; Yang, Weiqiang; Amorós Torrent, Jaume (American Physical Society (APS), 2020-06-15)
      Article
      Open Access
      Nongravitational interaction between dark matter and dark energy has been considered in a spatially flat Friedmann-Lemaître-Robertson-Walker (FLRW) universe. The interaction rate is assumed to be linear in the energy ...