Out of the swampland with multifield quintessence?
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Springer
Received: August Revised: September Accepted: September Published: October
4, 4, 9, 6,
2020 2020 2020 2020
Out of the swampland with multifield quintessence?
a
Dipartimento di Fisica e Astronomia, Universit` a di Bologna, via Irnerio 46, 40126 Bologna, Italy b INFN, Sezione di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy c Dipartimento di Fisica e Astronomia, Universit` a di Padova, via Marzolo 8, 35131 Padova, Italy d INFN, Sezione di Padova, via Marzolo 8, 35131 Padova, Italy
E-mail: [email protected], [email protected], [email protected] Abstract: Multifield models with a curved field space have already been shown to be able to provide viable quintessence models for steep potentials that satisfy swampland bounds. The simplest dynamical systems of this type are obtained by coupling Einstein gravity to two scalar fields with a curved field space. In this paper we study the stability properties of the non-trivial fixed points of this dynamical system for a general functional dependence of the kinetic coupling function and the scalar potential. We find the existence of non-geodesic trajectories with a sharp turning rate in field space which can give rise to late-time cosmic acceleration with no need for flat potentials. In particular, we discuss the properties of the phase diagram of the system and the corresponding time evolution when varying the functional dependence of the kinetic coupling. Interestingly, upon properly tuning the initial conditions of the field values, we find trajectories that can describe the current state of the universe. This could represent a promising avenue to build viable quintessence models out of the swampland if they could be consistently embedded in explicit string constructions. Keywords: Cosmology of Theories beyond the SM, Superstring Vacua ArXiv ePrint: 2007.11011
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP10(2020)035
JHEP10(2020)035
Michele Cicoli,a,b Giuseppe Dibitettoc,d and Francisco G. Pedroa,b
Contents 1
2 Overview of two-field dynamics with curved field space
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3 Non-geodesic dynamics and the swampland bound
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4 Growing kinetic coupling
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5 Decaying kinetic coupling
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6 Non-exponential potentials
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7 Conclusions and outlook
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1
Introduction
Shortly before the turn of the millennium we learned that the universe is currently undergoing a phase of accelerated expansion [1–3], which reveals the existence of what is usually referred to as dark energy. The simplest cosmological model successfully accounting for this late-time dynamics is the so-called ΛCDM concordance model, in which a positive cosmological constant is responsible for dark energy. Despite its compelling experimental evidence though, this conclusion raises a number of theoretical issues which are still open after more than two decades. The aforementioned issues are all mainly connected with the fact that a spacetime with positive cosmological constant turns out to possess a cosmological horizon when des
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