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Assuming that the Universe at higher redshifts ($z \sim 4$ and beyond) is consistent with \lcdm model as constrained by Planck satellite data, we reanalyze the low redshift cosmological data to reconstruct the Hubble parameter as a function of redshift in a model independent way. This enables us to address the $H_0$ and other tensions between low $z$ observations and high $z$ Planck measurement from CMB. From $H(z)$, we reconstruct the energy density and pressure for the ``dark energy'' sector of the Universe as a function of redshift and find that the dark energy density has a minimum for certain redshift range and that this $\rho_{DE}^{min}$ is negative. This behavior is most simply described by a {\it negative cosmological constant} plus a dark energy sector which has a phantom crossing. We discuss possible theoretical and observational implications of such a scenario.
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