Entanglement entropy and Hyperscaling violation

At first we will discuss some holographic techniques to compute entanglement entropy of field theories with a gravity dual and dwell on some of its interesting properties. Using these tools we shall argue that the entanglement entropy for a very small subsystem, obeys a property which is analogous to the first law of thermodynamics, when we excite the system. We will further use these holographic methods to indicate the presence of hidden fermi surfaces, in field theories dual to certain hyperscaling violating geometries, which has potential applications in condensed matter physics. We will finally discuss certain interesting construction of these hyperscaling violating geometries inside the framework of supergravity.