-dual quintessence, the Swampland, and the DESI DR2 results

We propose a dark energy model in which a quintessence field ϕ rolls near the vicinity of a local maximum of its potential characterized by the simplest S self-dual form V ( ϕ ) = Λ sech ( 2 ϕ / M p ) , where M p is the reduced Planck mass and Λ ∼ 10 − 120 M p 4 is the cosmological constant. We confront the model with Swampland ideas and show that the S -dual potential is consistent with the distance conjecture, the de Sitter conjecture, and the trans-Planckian censorship conjecture. We also examine the compatibility of this phenomenological model with the intriguing DESI DR2 results and show that the shape of the S -dual potential is almost indistinguishable from the axion-like potential, V ( ϕ ) = m a 2 f a 2 [ 1 + cos ⁡ ( ϕ / f a ) ] , with m a and f a parameters fitted by the DESI Collaboration to accommodate the DR2 data. The self-dual potential has the advantage that one starts at the self-dual point and this is a theoretical motivation, because as the universe cools off the Z 2 symmetry gets broken leading to a natural rolling away from the symmetric point.