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Statefinder—A new geometrical diagnostic of dark energy

2002/01/31 by V. Sahni, Varun Sahni, Tarun Deep Saini +5 · 1,500 citations
Physics and Astronomy · #Classical mechanics #Computer science #Constant (computer programming) #Cosmological constant #Cosmology #Cosmology and Gravitation Theories #Dark energy #Deceleration parameter #Dimensionless quantity #Energy (signal processing) #Galaxies: Formation, Evolution, Phenomena #Hubble's law #Metric expansion of space #Physics #Quantum mechanics #Scale factor (cosmology) #Simple (philosophy) #Solar and Space Plasma Dynamics #Theoretical physics #Universe #astro-ph #gr-qc #hep-ph

paper · pdf · doi:10.1134/1.1574831

published in Journal of Experimental and Theoretical Physics Letters 77(5), 201-206 (Pleiades Publishing) · 7 pages, 3 figures. Final version to be published in JETP Lett., presentation shortened, references added and updated, consideration of brane cosmological models included, conclusions unchanged

arxiv created 2003/02/14 · openalex publication_date 2003/03/01 · arxiv updated 2011/07/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We introduce a new cosmological diagnostic pair r , s called the Statefinder. The Statefinder is a geometrical diagnostic and allows us to characterize the properties of dark energy in a model-independent manner. The Statefinder is dimensionless and is constructed from the scale factor of the Universe and its time derivatives only. The parameter r forms the next step in the hierarchy of geometrical cosmological parameters after the Hubble parameter H and the deceleration parameter q , while a is a linear combination of q and r chosen in such a way that it does not depend upon the dark energy density. The Statefinder pair r , s is algebraically related to the equation of state of dark energy and its first time derivative. The Statefinder pair is calculated for a number of existing models of dark energy having both constant and variable w . For the case of a cosmological constant, the Statefinder acquires a particularly simple form. We demonstrate that the Statefinder diagnostic can effectively differentiate between different forms of dark energy. We also show that the mean Statefinder pair can be determined to very high accuracy from a SNAP-type experiment.

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