String Regge trajectory in de Sitter space and implications for inflation

Abstract

We study the spectrum of semiclassical rotating strings in de Sitter space and its consistency. Even though a naive extrapolation of the linear Regge trajectory on flat space implies a violation of the Higuchi bound (a unitarity bound on the mass of higher-spin particles in de Sitter space), the curved space effects turn out to modify the trajectory to respect the bound. Interestingly, as a consequence of accelerated expansion, there exists a maximum spin for each Regge trajectory, which is helpful to make the spectrum consistent with the Higuchi bound, but at the same time, it could be an obstruction to stringy UV completion based on an infinite higher-spin tower. By pushing further this observation, we demonstrate that the vacuum energy $V$ inflating the universe has to be bounded by the string scale $M_s$ as $V\lesssim M_s^4$, if UV completion is achieved with the leading Regge trajectory of higher spin states up to the 4D Planck scale. Its application to inflation in the early universe implies an upper bound on the tensor-to-scalar ratio, $r\lesssim 0.01\times (M_s/10^{16}\text{GeV}{)}^4$, which is within the scope of the near future CMB experiments. We also discuss another possibility that UV completion is achieved by multiple Regge trajectories.

arXiv comment6 pages, 5 figures; v2: minor revisions, references added; v3: version published in PRD

References in corpus (18)

• de Sitter Vacua in String Theory
• Supergravity description of field theories on curved manifolds and a no go theorem
• A semi-classical limit of the gauge/string correspondence
• The Swampland: Introduction and Review
• Distance and de Sitter Conjectures on the Swampland
• Bounds on Slow Roll and the de Sitter Swampland
• De Sitter Space and the Swampland
• What if string theory has no de Sitter vacua?
• On three-point correlation functions in the gauge/gravity duality
• Holographic three-point functions of semiclassical states
• Planetoid String Solutions in 3 + 1 Axisymmetric Spacetimes
• Correlation functions of three heavy operators - the AdS contribution
• Three-point functions in the SU(2) sector at strong coupling
• On holographic three point functions for GKP strings from integrability
• Massive higher spin fields in the frame-like multispinor formalism
• A Note on String Excitations and the Higuchi Bound
• Classical Integrability for Three-point Functions: Cognate Structure at Weak and Strong Couplings
• The Thermal Bath of de Sitter from Holography

Cited by in corpus (17)

• Quantum de Sitter horizon entropy from quasicanonical bulk, edge, sphere and topological string partition functions
• Higher Spin Supersymmetry at the Cosmological Collider: Sculpting SUSY Rilles in the CMB
• The Gravitino and the Swampland
• Large Spin-2 Signals at the Cosmological Collider
• Finiteness and the Swampland
• Gravitational orbits, double-twist mirage, and many-body scars
• Higher Spin Dark Matter
• Inflation, Higher Spins and the Swampland
• Closed Strings and Weak Gravity from Higher-Spin Causality
• Confinement in de Sitter Space and the Swampland
• Axionic Festina Lente
• String Excitation by Initial Singularity of Inflation
• Bulk/boundary Modular Quintessence and DESI
• Spiky strings in de Sitter space
• Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the string-theoretical Swampland Programme
• Mass and spin for classical strings in $d{S}_3$
• Bounds on tower mass scales in the presence of throats of different warping