Browsing by Author "Haro Cases, Jaume"

An extended matter bounce scenario: current status and challenges
Haro Cases, Jaume; Cai, YiFu (20150801)
Article
Open AccessAs 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 quasimatter contracting phase with a variable background ... 
Bouncing cosmologies in geometries with positively curved spatial sections
Haro Cases, Jaume (Elsevier, 20160910)
Article
Open AccessBackground bouncing cosmologies, driven by a single scalar field, having a quasimatter domination period during the contracting phase, i.e., depicting the socalled 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), 20180315)
Article
Open AccessWe consider the ArnowittDeserMisner 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. (201305)
Article
Open AccessThe 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 GaussBonnet gravity
Haro Cases, Jaume; Makarenko, A. M.; Myagky, A. N.; Odintsov, Sergei D.; Oikonomou, V. K. (American Physical Society, 20151211)
Article
Open AccessWe develop an effective GaussBonnet 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. (201309)
Article
Restricted access  publisher's policySeveral simple dark energy models on the brane are investigated. They are compared with corresponding models in the frame of 4d FriedmannRobertsonWalker cosmology. For constraining the parameters of the models considered, ... 
Bulk viscous quintessential inflation
Haro Cases, Jaume; Pan, Supriya (20180401)
Article
Open AccessIn a spatiallyflat 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 twopoint function by adiabatic regularization
Haro Cases, Jaume (201011)
Article
Restricted access  publisher's policyWe calculate a renormalized twopoint 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 (201204)
Article
Restricted access  publisher's policyUsing 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, 20180901)
Article
Open AccessBouncing cosmologies are obtained by adding to the Einstein–Hilbert action a term of the form gvf(¿), 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), 20190211)
Article
Open AccessDifferent wellknown 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. (20160501)
Article
Open AccessIn 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 (20160727)
Article
Open AccessIn 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 (20151013)
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 (201202)
Article
Restricted access  publisher's policyParticle 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 (20140708)
Article
Open AccessWe 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 latetime acceleration from a doublewell potential with cosmological constant
Haro Cases, Jaume; Elizalde, Emilio (20160601)
Article
Open AccessA 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 (20130214)
Article
Open AccessDifferent 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), 20180515)
Article
Open AccessThe 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 (20171207)
Article
Restricted access  publisher's policyThis 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 ...