Zobrazeno 1 - 10
of 667
pro vyhledávání: '"Gasperini, M. A."'
Publikováno v:
JCAP12(2023)019
We first make more precise a recent "Hamiltonian" reformulation of the Hohm-Zwiebach approach to the tree-level, $O(d,d)$-invariant string cosmology equations at all orders in the $\alpha'$ expansion, and recall how it allows to give a simple charact
Externí odkaz:
http://arxiv.org/abs/2308.16076
Publikováno v:
Universe 9, 327 (2023)
In this article, we compare different formulations of the number count prescription using the convenient formalism of the Geodesic-Light-Cone gauge. We then find a simple, exact, and very general expression of such a prescription which is suitable fo
Externí odkaz:
http://arxiv.org/abs/2307.04565
Autor:
Gasperini, M., Veneziano, G.
Publikováno v:
JHEP 07 (2023) 144
We reformulate in Hamiltonian language the recent proposal by Hohm and Zwiebach of an action yielding the most general $O(d,d)$-symmetric string cosmology equations, at tree-level in the string-loop expansion, but to all orders in the $\alpha'$ expan
Externí odkaz:
http://arxiv.org/abs/2305.00222
Autor:
Gasperini, M.
Publikováno v:
Ithaca: Viaggio nella Scienza, XXI, 47 (2023)
A very short, non-technical review of the main problems which are presently open in the context of the gravitational theory and of its cosmological applications, and which are currently under investigation and deep discussion. We will talk in particu
Externí odkaz:
http://arxiv.org/abs/2302.07708
Autor:
Gasperini, M.
We present a short introduction to a non-standard cosmological scenario motivated by the duality symmetries of string theory, in which the big bang singularity is replaced with a "big bounce" at high but finite curvature. The bouncing epoch is prepar
Externí odkaz:
http://arxiv.org/abs/2106.12865
Publikováno v:
JCAP 07 (2021) 021
The linearized dynamical equation for metric perturbations in a fully general, non-vacuum, background geometry is obtained from the Hamilton variational principle applied to the action up to second order. We specialize our results to the case of trac
Externí odkaz:
http://arxiv.org/abs/2105.13041
Autor:
Gasperini, M.
Publikováno v:
Universe 7, 14 (2021)
We present a short review of possible applications of the Wheeler-De Witt equation to cosmological models based on the low-energy string effective action, and characterised by an initial regime of asymptotically flat, low energy, weak coupling evolut
Externí odkaz:
http://arxiv.org/abs/2101.01070
Autor:
Gasperini, M.
Publikováno v:
"Breakdown of the Einstein's Equivalence Principle'', ed. by A. G. Lebed (World Scientific, 2023), Cap. 3, p. 77
In this Chapter we illustrate the close connection between the violation of the weak equivalence principle typical of gravitational interactions at finite temperature, and similar violations induced by a breaking of the local Lorentz symmetry. We als
Externí odkaz:
http://arxiv.org/abs/2101.00458
Publikováno v:
Gen. Rel. Grav. 52, 111 (2020)
We compute the modified friction coefficient controlling the propagation of tensor metric perturbations in the context of a generalized cosmological scenario based on a theory of gravity with quadratic curvature corrections. In such a context we disc
Externí odkaz:
http://arxiv.org/abs/2010.06569
We discuss the possibility of producing a significant fraction of dark matter in the form of primordial black holes in the context of the pre-big bang inflationary scenario. We take into account, to this purpose, the enhancement of curvature perturba
Externí odkaz:
http://arxiv.org/abs/2004.08111