arXiv subjects

A. L. Maroto

Publications and source records attributed to A. L. Maroto.

59 records · Page 4Linked to original sources

arXiv2000

The Lame equation in parametric resonance after inflation

We show that the most general inflaton potential in Minkowski spacetime for which the differential equation for the Fourier modes of the matter fields reduces to Lamé's equation is of the form $V(ϕ)= λϕ^4/4+Kϕ^2/2+μ/(2ϕ^2)+V_0$. As an application, we study the preheating phase after inflation for the above potential with K=0 and arbitrary $λ,μ>0$. For certain values of the coupling constant between the inflaton and the matter fields, we calculate the instability intervals and the characteristic exponents in closed form.

hep-ph↗

arXiv2000

The equivalence theorem and the production of gravitinos after inflation

We study the high-energy equivalence between helicity 1/2 gravitinos and goldstinos in order to calculate the production of gravitinos in time-dependent scalar and gravitational backgrounds. We derive this equivalence for equations of motion, paying attention to some subtleties, mainly due to external sources, that are not present in the standard proofs. We also propose the Landau gauge as a simplifying alternative to the usual gauge choices, both for practical calculations and in the equivalence theorem proof.

hep-ph↗

arXiv2000

Production of high-energy gravitinos during preheating

We present a new technique for the calculation of helicity $\pm 1/2$ gravitino production during preheating. It is based on the equivalence between goldstinos and helicity $\pm 1/2$ gravitinos at high energies. The problem is thus reduced to the standard (Majorana) fermion production after inflation. Comparison with the results obtained in the unitary gauge is also presented.

hep-ph↗

arXiv1998

Non-local gravitational effective action and particle production

We study the effective action for gravity obtained after the integration of scalar matter fields, using the local momentum representation based on the Riemann normal coordinates expansion. By considering this expansion around different space-time points, we also compute the non-local terms together with the more usual divergent ones. We discuss the applicability of our results to the calculation of particle production rates in cosmological backgrounds and compare this method with the traditional Bogolyubov transformations.

gr-qc↗

arXiv1997

On the inflationary solutions in higher-derivative gravity with dilaton field

We discuss the existence of de Sitter inflationary solutions for the string-inspired fourth-derivative gravity theories with dilaton field. We consider a space-time of arbitrary dimension D and an arbitrary parametrization of the target space metric. The specific features of the theory in dimension D=4 and those of the special ghost-free parametrization of the metric are found. We also consider similar string-inspired theories with torsion and construct an inflationary solution with torsion and dilaton for D=4. The stability of the inflationary solutions is also investigated.

hep-th↗