Some Applications of AdS/QCD Sanjay Siwach and Shobhit Sachan Department of Physics, Banaras Hindu University, Varanasi-221005, INDIA. Abstract We consider the holographic models of Quantum Chromo Dynamics (QCD) inspired by AdS/CFT correspondence. The hard wall model of AdS/QCD captures the essential features of QCD like chiral symmetry breaking, confinement- decofinement transition and spectrum of mesons and baryons. The refinement of model so called soft wall model includes dilaton field and is successful to capture the linear Regge trajectories. We review both the models and discuss the hadronic spectra, meson baryon couplings and finite temperature thermodynamics including the chemical potential. Keywords: Holographic QCD Models, Meson Baryon couplings, Phase Diagram 1. Introduction The strongly coupled domain of theories like Quan- tum Chromo Dynamics (QCD) is still not well under- stood and many approaches are available like lattice QCD and use of AdS/CFT correspondence [1]. The lattice QCD is considered an ab initio approach where many results have become available and are thought to be very reliable. A complementary approach using anti- de-Sitter/boundary theory correspondence is also avail- able for last few years and is named as AdS/QCD or holographic QCD. The later approach using AdS/CFT correspondence is considered very useful particularly for the strongly coupled gauge theories, where one can make use of su- pergravity approximation in the bulk theory. The corre- spondence is holographic in nature and a weakly cou- pled gravity theory in five dimensional spacetime cap- tures essential features of QCD on the boundary of the spacetime. An example of this approach is the use of D-brane models e.g. Sakai-Sugimoto model in string theory. A bottom up approach can also be used where one tries to capture the low energy dynamics of QCD by a minimal set of fields in five dimensional anti-de-Sitter spacetime [2, 3, 4]. The model consists of the bulk scalar field dual to quark condensate in order to cap- ture the features of chiral symmetry breaking and gauge fields which couple to boundary currents. In addition to UV cut-off at infinity, one has to impose IR boundary conditions to the fields. The IR cut-off in the model is introduced to realize confinement-deconfinement tran- sition [2]. The results from this model are 10-15 percent off the experimental results. A modified version of the above model is known as soft wall model [5]. In this model the IR cut off is pushed to infinity and a dilation field is introduced in the bulk. The presence of dilaton field replaces the hard wall (IR cut off) with the soft wall. The model is par- ticularly useful as it gives the linear Regge trajectories. Also the overall predictions of the model are better than the hard wall model. The available results from these models indicate that they are successful phenomenolog- ical models of low energy QCD. In this article I shall discuss these models and some applications like hadronic spectra, meson baryon couplings and deconfinement transition from hadronic phase to quark gluon plasma phase. Available online at www.sciencedirect.com Nuclear Physics B (Proc. Suppl.) 251–252 (2014) 150–153 0920-5632/© 2014 Elsevier B.V. All rights reserved. www.elsevier.com/locate/npbps http://dx.doi.org/10.1016/j.nuclphysbps.2014.05.002