Exploració per autor "Haro Cases, Jaume"Més informacióMés informació

Ara es mostren els items 44-63 de 64

    • Scaling solutions in quintessential inflation 

      Haro Cases, Jaume; Amorós Torrent, Jaume; Pan, Supriya (springer-Verlag, 2020-05)
      Article
      Accés obert
      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
      Accés obert
      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
      Accés obert
      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
      Accés restringit per política de l'editorial
      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
      Accés obert
      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
      Accés obert
      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
      Accés obert
      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
      Accés obert
      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
      Accés obert
      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
      Accés obert
      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
      Accés obert
      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
      Accés obert
      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 ...

    • Theoretical and observational bounds on some interacting vacuum energy scenarios 

      Yang, Weiqiang; Pan, Supriya; Aresté Saló, Llibert; Haro Cases, Jaume (American Physical Society, 2021-04-15)
      Article
      Accés obert
      The dynamics of interacting dark matter-dark energy models is characterized through an interaction rate function quantifying the energy flow between these dark sectors. In most of the interaction functions, the expansion ...

    • Topics in cosmology — clearly explained by means of simple examples 

      Haro Cases, Jaume; Elizalde Rius, Emilio (2022-03)
      Article
      Accés obert
      This is a very comprehensible review of some key issues in modern cosmology. Simple mathematical examples and analogies are used, whenever available. The starting point is the well-known Big Bang cosmology (BBC). We deal ...

    • Understanding gravitational particle production in quintessential inflation 

      Haro Cases, Jaume; Pan, Supriya; Aresté Saló, Llibert (2019-06-01)
      Article
      Accés obert
      The diagonalization method, introduced by a group of Russian scientists at the beginning of seventies, is used to compute the energy density of superheavy massive particles produced due to a sudden phase transition from ...

    • 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
      Accés obert
      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 ...

    • Viability of the Matter Bounce Scenario 

      Haro Cases, Jaume; Amorós Torrent, Jaume (Institute of Physics (IOP), 2015)
      Article
      Accés obert
      It is shown that teleparallel F(T) theories of gravity combined with Loop Quantum Cosmology support a Matter Bounce Scenario which is an alternative to the inflation scenario in the Big Bang paradigm. It is checked that ...

    • Viability of the matter bounce scenario in Loop Quantum Cosmology from BICEP2 last data 

      Haro Cases, Jaume; Amorós Torrent, Jaume (2014-08-12)
      Article
      Accés obert
      The CMB map provided by the Planck project constrains the value of the ratio of tensor-to-scalar perturbations, namely r, to be smaller than 0.11 (95 % CL). This bound rules out the simplest models of inflation. However, ...

    • Viability of the matter bounce scenario in F(T) gravity and Loop Quantum Cosmology forgeneral potentials 

      Haro Cases, Jaume; Amorós Torrent, Jaume (2014-12-01)
      Article
      Accés obert
      We consider the matter bounce scenario in F (T) gravity and Loop Quantum Cosmology (LQC) for phenomenological potentials that at early times provide a nearly matter dominated Universe in the contracting phase, having a ...

    • Viable inflationary evolution from Einstein frame loop quantum cosmology 

      Haro Cases, Jaume; Odintsov, Sergei D.; Oikonomou, V. K. (American Physical Society (APS), 2018-04-27)
      Article
      Accés obert
      In this work we construct a bottom-up reconstruction technique for loop quantum cosmology scalar-tensor theories, from the observational indices. Particularly, the reconstruction technique is based on fixing the functional ...