Browsing by Author "Partouche, Hervé"

Now showing items 1-14 of 14

    • Article  

      Bridging the static patches: de Sitter holography and entanglement 

      Franken, Victor; Partouche, Hervé; Rondeau, François; Toumbas, Nicolaos K. (Springer, 2023-08-14)
      In the context of de Sitter static-patch holography, two prescriptions have been put forward for holographic entanglement entropy computations, the monolayer and bilayer proposals. In this paper, we reformulate both ...
    • Article  

      Cosmological perturbations across an S-brane 

      Brandenberger, R. H.; Kounnas, Costas; Partouche, Hervé; Patil, S. P.; Toumbas, Nicolaos K. (2014)
      Space-filling S-branes can mediate a transition between a contracting and an expanding universe in the Einstein frame. Following up on previous work that uncovered such bouncing solutions in the context of weakly coupled ...
    • Article  

      Gauge Fixing and Field Redefinitions of the Hartle-Hawking Wavefunction Path Integral 

      Partouche, Hervé; Toumbas, Nicolaos K.; de Vaulchier, Balthazar (Andromeda Proceedings, 2021)
      We review some recent results concerning the Hartle-Hawking wavefunction of the universe. We focus on pure Einstein theory of gravity in the presence of a positive cosmological constant. We carefully implement the gauge-fixing ...
    • Article  

      Induced superstring cosmologies and moduli stabilization 

      Catelin-Jullien, T.; Kounnas, Costas; Partouche, Hervé; Toumbas, Nicolaos K. (2009)
      We extend the analysis of the recently obtained stringy cosmological solutions induced by thermal and quantum effects, once space-time supersymmetry is spontaneously broken by geometrical fluxes. Cases in which more than ...
    • Article  

      Non-singular string cosmology in a 2d hybrid model 

      Florakis, Ioannis G.; Kounnas, Costas; Partouche, Hervé; Toumbas, Nicolaos K. (2011)
      The existence of non-singular string cosmologies is established in a class of two-dimensional supersymmetric Hybrid models at finite temperature. The left-moving sector of the Hybrid models gives rise to 16 real (N4=4) ...
    • Article  

      Probability distribution for the quantum universe 

      Kehagias, Alex; Partouche, Hervé; Toumbas, Nicolaos K. (Springer, 2021-12-22)
      We determine the inner product on the Hilbert space of wavefunctions of the universe by imposing the Hermiticity of the quantum Hamiltonian in the context of the minisuperspace model. The corresponding quantum probability ...
    • Article  

      Resolution of Hagedorn singularity in superstrings with gravito-magnetic fluxes 

      Angelantonj, Carlo; Kounnas, Costas; Partouche, Hervé; Toumbas, Nicolaos K. (2009)
      We consider closed type II and orientifold backgrounds where supersymmetry is spontaneously broken by asymmetric geometrical fluxes. We show that these can be used to describe thermal ensembles with chemical potentials ...
    • Article  

      S-brane to thermal non-singular string cosmology 

      Kounnas, Costas; Partouche, Hervé; Toumbas, Nicolaos K. (2012)
      We present a new class of non-singular string cosmologies in d spacetime dimensions. At very early times, τ τ c, the Universe is described by a flat σ-model metric, a constant maximal temperature T c and super-weak string ...
    • Article  

      Thermal and quantum superstring cosmologies 

      Catelin-Jullien, T.; Kounnas, Costas; Partouche, Hervé; Toumbas, Nicolaos K. (2008)
      We consider four dimensional heterotic string backgrounds for which supersymmetry is spontaneously broken via the Scherk-Schwarz mechanism on an internal spatial cycle and by finite temperature effects. We concentrate on ...
    • Article  

      Thermal duality and non-singular cosmology in d-dimensional superstrings 

      Kounnas, Costas; Partouche, Hervé; Toumbas, Nicolaos K. (2012)
      We are presenting the basic ingredients of a stringy mechanism able to resolve both the Hagedorn instabilities of finite temperature superstrings as well as the initial singularity of the induced cosmology in arbitrary ...
    • Article  

      Thermal/quantum effects and induced superstring cosmologies 

      Catelin-Jullien, T.; Kounnas, Costas; Partouche, Hervé; Toumbas, Nicolaos K. (2008)
      We consider classical superstring theories on flat four-dimensional space-times, and where N = 4 or N = 2 supersymmetry is spontaneously broken. We obtain the thermal and quantum corrections at the string one-loop level ...
    • Article  

      A unimodular-like string effective description 

      Kehagias, Alex; Partouche, Hervé; Toumbas, Nicolaos K. (Elsevier, 2023-04-14)
      We show that vanishing of the sigma-model beta-functions for the metric gμν , antisymmetric tensor Bμν and dilaton Phi of any string-theory model in D dimensions at tree level can be obtained from a universal effective ...
    • Article  

      Wavefunction of the universe: Diffeomeorphism invariance and field redefinitions 

      Partouche, Hervé; Toumbas, Nicolaos K.; de Vaulchier, Balthazar (Proceedings of Science (SISSA), 2022-11-23)
      We review some recent results concerning the Hartle-Hawking wavefunction of the universe. We focus on pure Einstein theory of gravity in the presence of a positive cosmological constant. We carefully implement the gauge-fixing ...
    • Article  

      Wavefunction of the universe: Reparametrization invariance and field redefinitions of the minisuperspace path integral 

      Partouche, Hervé; Toumbas, Nicolaos K.; de Vaulchier, Balthazar (Elsevier, 2021-11-03)
      We consider the Hartle–Hawking wavefunction of the universe defined as a Euclidean path integral that satisfies the “no-boundary proposal.” We focus on the simplest minisuperspace model that comprises a single scale factor ...