Related papers: The $1/N$ Expansion and Spin Correlations in Const…
The $1/N$ expansion is an asymptotic series expansion for certain quantities in large-$N$ lattice gauge theories. This article gives a rigorous formulation and proof of the $1/N$ expansion for Wilson loop expectations in SO(N) lattice gauge…
We present a detailed study of the topological Schwinger model [Phys. Rev. D 99, 014503 (2019)], which describes (1+1) quantum electrodynamics of an Abelian $U(1)$ gauge field coupled to a symmetry-protected topological matter sector, by…
We develop a generalization of the Schwinger boson and Holstein-Primakoff transformations that is applicable to ensembles of $N$ spin $1/2$'s with weak permutational symmetry. These generalized mappings are constructed by introducing two…
We study possible quantum ground states of the Sp(N) generalized Heisenberg model on a cubic lattice with nearest-neighbor and next-nearest-neighbor exchange interactions. The phase diagram is obtained in the large-N limit and fluctuation…
Large-$S$ and large-$N$ theories (spin value $S$ and spinor component number $N$) are complementary, and sometimes conflicting, approaches to quantum magnetism. While large-$S$ spin-wave theory captures the correct semiclassical behavior,…
We study a variational wave function for the ground state of the two-dimensional S=1/2 Heisenberg antiferromagnet in the valence bond basis. The expansion coefficients are products of amplitudes h(x,y) for valence bonds connecting spins…
The staggered magnetization of the Heisenberg antiferromagnet in two dimensions can be systematically approximated by a 1/N expansion. Cancellation between self energy diagrams leads to a Luttinger-like theorem for the ground state. We…
We use the $1/M$ expansion for the $CP^{M-1}$ model to study the long-distance behaviour of the staggered spin susceptibility in the commensurate, two-dimensional quantum antiferromagnet at finite temperature. At $M=\infty$ this model…
We calculate density-density correlations of an expanding gas of strongly attractive ultra-cold spin-1/2 fermions in an optical lattice. The phase diagram of the tightly bound fermion pairs exhibits a Bose-Einstein condensed state and a…
A general two-dimensional spin model with U$(N)$ invariance, interpolating between $\CPN$ and ${\rm O}(2N)$ models, is studied in detail in order to illustrate both the general features of the $1/N$ expansion on the lattice and the specific…
We study the 1/N expansion of a generic, strongly correlated electron model (SU(N) symmetric Hubbard model with $U=\infty$ and N degrees of freedom per lattice site) in terms of X operators. The leading order of the expansion describes a…
The large $N$ expansion of giant graviton correlators is considered. Giant gravitons are described using operators with a bare dimension of order $N$. In this case the usual $1/N$ expansion is not applicable and there are contributions to…
We study a system of fermions interacting with a gauge field which can be used to describe either spin liquid or $\nu=1/2$ Quantum Hall state. We propose a generalized model with a dimensionless parameter $N$. We evaluate the properties of…
The magnetization of a two-dimensional ferromagnetic Heisenberg model, which represents a quantum Hall system at filling factor nu=1, is calculated employing a large N Schwinger boson approach. Corrections of order 1/N to the mean field…
We analyze strongly interacting Fermi gases in the unitary regime by considering the generalization to an arbitrary number N of spin-1/2 fermion flavors with Sp(2N) symmetry. For N=\infty this problem is exactly solved by the BCS-BEC…
We study a model of strongly-correlated systems that incorporates phases such as Fermi liquids, non-Fermi liquids, and superconductivity, in addition to potential intertwined orders. The model describes Fermi surfaces of spinful electron…
We compute, within the Schwinger-boson scheme, the Gaussian-fluctuation corrections to the order-parameter stiffness of two frustrated quantum spin systems: the triangular-lattice Heisenberg antiferromagnet and the J1-J2 model on the square…
We develop a generalization of the singlet sector valence bond basis projection algorithm of Sandvik, Beach, and Evertz (A. W. Sandvik, Phys. Rev. Lett. 95, 207203 (2005); K. S. D. Beach and A. W. Sandvik, Nucl. Phys. B750, 142 (2006); A.…
We develop the modification of the top - quark condensation scenario, in which the Higgs boson is composed of all Standard Model fermions. Within this scenario we suggest the phenomenological model with non - local four - fermion…
For special coupling ratios, the one-dimensional (1D) s=1/2 Heisenberg model with antiferromagnetic nearest and next-nearest neighbor interactions has a pure dimer ground state, and the 1D s=1 Heisenberg model with antiferromagnetic…