- Accepted Paper
Cosmographic reconstruction of the quintessence potential in scalar-tensor gravity
Phys. Rev. D - Accepted 3 November, 2026
DOI: https://doi.org/10.1103/pwq9-kn5k
Phys. Rev. D - Accepted 3 November, 2026
DOI: https://doi.org/10.1103/pwq9-kn5k
We generalise the cosmographic reconstruction programme of Chakraborty, Dunsby & Scherrer to scalar-tensor gravity. Working in the Jordan frame with a general non-minimal coupling , we derive exact closed-form expressions for the potential slope , the coupling slope , and their curvature parameters and in terms of the cosmographic parameters , the Planck-mass running and its derivatives. We express and its derivatives in terms of a set of coefficients describing the time variation of the gravitational constant , casting all four quantities in terms of the time derivatives of , which are in principle observable. We then evaluate the reconstruction against current data, including DESI DR2 baryon acoustic oscillation measurements and Solar-System tests of gravity, propagating the cosmographic uncertainties through to the reconstructed potential. All expressions reduce analytically to those of Chakraborty, Dunsby & Scherrer in the minimally-coupled limit, which we verify symbolically. We find that the potential slope is recovered at the few-tenths level while the curvature is essentially unconstrained. We further show that for minimally-coupled quintessence the positivity of the scalar kinetic term is equivalent to $w_{\rm eff,0}\geq-1$, so that the region of cosmographic parameter space closed to it is exactly the phantom region, and that the non-minimal coupling reopens this region through a single coefficient of the gravitational tower. Because Solar-System tests restrict at our benchmarks while the reconstruction is sensitive to , the framework presupposes that is passing through zero at the present epoch, as expected on the Damour–Nordtvedt least-coupling attractor.
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