EPJ manuscript No. (will be inserted by the editor) Reconstruction of ghost scalar fields Mustafa Salti Department of Physics, Faculty of Art and Science, Mersin University, 33342, Ciftlikkoy, Mersin-Turkey Received: date / Revised version: date Abstract. In literature, a large number of approaches have been done to reconstruct the potential and dynamics of the scalar fields by establishing a connection between holographic/Ricci/new agegraphic/ghost energy density and a scalar field model of dark energy. In most of these attempts, the analytical form of the potentials in terms of the scalar field have not been reconstructed due to the complexity of the equations involved. In the present work, we establish a correspondence between ghost dark energy and quintessence, tachyon and dilaton scalar field models in anisotropic Bianchi type-I universe to reconstruct the dynamics of these scalar fields. PACS. 95.30.Sf Relativity and gravitation – 95.35.+d Dark matter – 98.80.-k Cosmology 1 Introduction Based on the recent observational evidences: SNe-Ia[1], WMAP[2], SDS[3], X-Ray[4] and Planck-2013[5], it is accepted that the universe has a phase transition from decelerating to accelerating and expands with accelerating velocity due to the presence of an unknown mysterious component namely the dark energy. Investigating the origin and the nature of this enigmatic component has been one of the great challenges in modern cosmology. Ghost dark energy[6–12] is one of the interesting models of dark energy and was recently proposed. Among plenty of models, the so called Veneziano ghost dark energy[13] is proposed to discuss the U(1)A problem in low-energy effective theory of QCD[14–16], but it is completely decoupled from the physical sector[17–19]. The Veneziano ghost dark energy seems to be unphysical in the quantum field theory in Minkowski spacetime, but exhibits an important non-trivial physical influence in the expanding universe and this remarkable effect gives rise to a vacuum energy density ρ D ∼ HΛ 3 QCD ∼ (10 −3 eV ) 4 (with H ∼ 10 −33 eV and Λ QCD ∼ 100eV we have the right magnitude for the force accelerating the Universe today)[20]. This numerical coincidence means that the ghost dark energy model gets rid of fine-tuning problem. On the other hand, scalar fields can be regarded as an effective description of the dark Universe and naturally arise in particle physics including the String/M theory and super-symmetric field theories, hence scalar fields are expected to reveal the dynamical mechanism and the nature of the dark Universe[21]. Fundamental theories such as string/M theory provide many possible scalar field candidates, but they do not predict its potential V (φ) uniquely[21]. In the present work, we are interested in that if we consider the ghost dark energy model as the underlying theory of dark energy, how the low-energy effective scalar field model can be used to describe it. On this purpose, we reconstruct the potential and the dynamics of scalar field models including quintessence, tachyon and dilaton according to the results we obtained for the Ghost dark energy. We can establish a correspondence between the ghost dark energy and scalar field models, and describe ghost dark energy in this case effectively by making use of these scalar fields. 2 Ghost dark energy scenario The metric representation of the Bianchi type-I spacetime is given as ds 2 = −dt 2 + A 2 (t)dx 2 + B 2 (t)dy 2 + C 2 (t)dz 2 ), (1) where A, B and C are the cosmic scale factors along the x, y and z axes, respectively, and they measure the expansion of the universe[22]. For the case A = B = C , the Bianchi type-I model reduces to the flat Friedmann-Robertson-Walker spacetime.