We make a detailed study of the infinite dimensional Galilean Conformal Algebra (GCA) in the case of two spacetime dimensions. Classically, this algebra is precisely obtained from a contraction of the generators of the relativistic conformal symmetry in 2d. Here we find quantum mechanical realisations of the (centrally extended) GCA by considering scaling limits of certain 2d CFTs. These parent CFTs are non-unitary and have their left and right central charges become large in magnitude and opposite in sign. We therefore develop, in parallel to the usual machinery for 2d CFT, many of the tools for the analysis of the quantum mechanical GCA. These include the representation theory based on GCA primaries, Ward identities for their correlation functions and a nonrelativistic Kac table. In particular, the null vectors of the GCA lead to differential equations for the four point function. The solution to these equations in the simplest case is explicitly obtained and checked to be consistent with various requirements.

In the string-gauge duality it is important to understand how the space-time geometry is encoded in gauge theory observables. We address this issue in the case of the D0-brane system at finite temperature T. Based on the duality, the temporal Wilson loop W in gauge theory is expected to contain the information of the Schwarzschild radius RSch of the dual black hole geometry as log(W)=RSch/(2pialpha'T). This translates to the power-law behavior log(W)=1.89(T/lambda 1/3)-3/5, where lambda is the 't Hooft coupling constant. We calculate the Wilson loop on the gauge theory side in the strongly coupled regime by performing Monte Carlo simulations of supersymmetric matrix quantum mechanics with 16 supercharges. The results reproduce the expected power-law behavior up to a constant shift, which is explainable as alpha' corrections on the gravity side. Our conclusion also demonstrates manifestly the fuzzball picture of black holes.

We study the expectation values of Wilson-loop operators with the insertions of local operators Z J and Z J for large J from the bulk viewpoint of AdS/CFT correspondence. This also requires to use the Euclideanized AdS background and Euclidean super YangMills

We show that the BMN operators arise from the expansion of the Wilson loop in four-dimensional N = 4 super Yang-Mills theory. The Wilson loop we consider is obtained from "dimensional reduction" of ten-dimensional N = 1 super Yang-Mills theory, and it contains six scalar fields as well as the gauge field. We expand the Wilson loop twice. First we expand it in powers of the fluctuations around a BPS loop configuration. Then we further expand each term in the result of the first step in powers of the scalar field Z associated with the BPS configuration. We find that each operator in this expansion with large number of Z is the BMN operator. The number of fluctuations corresponds to the number of impurities, and the phase factor of each BMN operator is supplied correctly. We have to impose the locally supersymmetric condition on the loop for obtaining the complete form of the BMN operators including the correction terms withZ. Our observation suggests the correspondence between the Wilson loop and the string field.