Upper limits on dark energy-dark matter interaction from DESI DR2 in a field-theoretic analysis

Abstract One of the important issues both in particle physics and cosmology relates to whether dark energy is a cosmological constant Λ, or is dynamical in nature such as quintessence. In this work, we discuss a model of quintessence interacting with dark matter and analyze the resulting phenomenology of the dark energy equation of state. We identify two regions where the equation of state behaves differently depending on the size of the dark matter-dark energy interaction strength. We show that the strong coupling region induces a transmutation of quintessence from thawing to freezing. Using the recent data release from the Dark Energy Spectroscopic Instrument (DESI), we rule out this possibility of transmutation and investigate the weak coupling region to derive upper limits on the interaction strength. Our analysis indicates that while ΛCDM lies within the 1σ contour in the plane, the best fit points lie in the fourth quadrant and show deviations from the ΛCDM prediction.