Correlation Amplitudes for the spin-1/2 XXZ chain in a magnetic field

We present accurate numerical estimates for the correlation amplitudes of leading and main subleading terms of the two- and four-spin correlation functions in the one-dimensional spin-1/2 XXZ model under a magnetic field. These data are obtained by fitting the correlation functions, computed numerically with the density-matrix renormalization-group method, to the corresponding correlation functions in the low-energy effective theory. For this purpose we have developed the Abelian bosonization approach to the spin chain under the open boundary conditions. We use the numerical data of the correlation amplitudes to quantitatively estimate spin gaps induced by a transverse staggered field and by exchange anisotropy.Comment: 18 pages, 6 figures, 1 tabl

The Height Fluctuations of an Off-Critical Dimer Model on the Square Grid

The dimer model on a planar bipartite graph can be viewed as a random surface measure. We study these fluctuations for a dimer model on the square grid with two different classes of weights and provide a condition for their equivalence. In the thermodynamic limit and scaling window, these height fluctuations are shown to be non-Gaussian. They are also rotationally invariant for a certain choice of weights. Finally, we show that the height difference between any two points is Gaussian for a specific choice of weights

T cell immunity does not age in a long-lived rodent species

In this work we have analysed TCR alpha and beta chain repertoires in Spalax of different age groups. We demonstrated that unlike mice and humans TCR repertoire in Spalax does not shrink with age