For a large class of repulsive interaction models, the Mayer cluster integrals can be transformed into a tridiagonal real symmetric matrix Rmn, whose elements converge to two constants with 1/n 2 correction. We find exact expressions in terms of these correction terms for the two critical exponents describing the density near the two singular termination points of the fluid phase. We apply the method to the hard-spheres model and find that the metastable fluid phase terminates at t ؍ 0.751 [5]. The density near the transition is given by t-ϳ (zt ؊ z) , where the critical exponent is predicted to be ؍ 0.0877 [25]. Interestingly, the termination density is close to the observed glass transition; thus, the above critical behavior is expected to be associated with the onset of glassy behavior in hard spheres.glass transition ͉ Mayer cluster integrals H ard-core models have long played a central role as models for structural ordering transitions. These models are purely entropy-driven, thus capturing the essential molecular mechanism that drives freezing transitions. In particular, the equation of state of classical hard spheres and their freezing transition have been extensively studied for over a century, dating back to the pioneering works of the founding fathers of statistical mechanics (1, 2). Nevertheless, there are still a lot of fundamental unresolved problems regarding this system. Early MonteCarlo works have established that in 3D the system freezes through a first-order phase transition at a density f ϭ 0.665[2] (3-6). [All densities here are scaled by the closest packing density; for hard spheres the volume fraction density ˆis given by ˆϭ /3 ͌ 2; here and throughout this paper, the numbers in square brackets represent the uncertainty in the last digit(s).] Increasing the density of the hard-sphere fluid quickly enough, crystallization can be avoided, and the system stays in a metastable supercooled fluid phase. As the density of supercooled fluid increases, its dynamics becomes slower and slower. Experimental (7,8) and computational (9-11) studies have shown that the typical relaxation times increase very fast around g ϳ 0.76. Despite its long history, the question of whether this increase is due to a true thermodynamic glass transition or a purely dynamical phenomenon is still hotly debated (12-18).The most pronounced manifestation (and, experimentally, the definition) of glassiness is through the dynamical properties. Thus, characterization of the onset of glassiness by using statistical-mechanics approaches is challenging. Several approaches have been taken to meet this challenge, including the ModeCoupling theory (19), using the replica method (16) and analysis of the virial expansion (20). In this work we suggest to use the Mayer cluster expansion for describing the metastable supercooled fluid and, in particular, the critical behavior near its termination point.It was previously shown that the Mayer cluster expansion for the fluid density can be represented by a real symmetric tridiagonal matri...