Motivated by application of current superalgebras in the study of disordered systems such as the random XY and Dirac models, we investigate gl(2|2) current superalgebra at general level k. We construct its free field representation and corresponding Sugawara energy-momentum tensor in the non-standard basis. Three screen currents of the first kind are also presented.

Shaw, Keefer, Refsdsl and others (1) have shown that goopotential height is represented on the tcphigrani by an area, and that an isentropic at'mosphere XY (figure l), equal in geopotential height to a given atmosphe,re AB, may be const8ruct8ed by so placing the line XY on the tepliigram t,hat the area XAZ is equal to the area YBZ. The effect of moistmure is normally negligible, but may be allo...

In this note we demonstrate the occurrence of first-order transitions in temperature for some recently introduced generalized XY models, and also

Let Mn be the collection of n×n complex matrices equipped with operator norm. Suppose U, V ∈ Mn are two unitary matrices, each possessing a gap larger than ∆ in their spectrum, which satisfy ‖UV −V U‖ ≤ ǫ. Then it is shown that there are two unitary operators X and Y satisfying XY −Y X = 0 and ‖U−X‖+‖V −Y ‖ ≤ E(∆/ǫ) “ ǫ ∆2 ” 1 6 , where E(x) is a function growing slower than x 1 k for any posit...

Heisenberg-like spins lying on the pseudosphere (a 2-dimensional infinite space with constant negative curvature) cannot give rise to stable soliton solutions. Only fractional solutions can be stabilized on this surface provided that at least a hole is incorporated. We also address the issue of 'in-plane' vortices, in the XY regime. Interestingly, the energy of a single vortex no longer blows u...

 We consider a generalization of the classical quadratic assignment problem, where coordinates of locations are uncertain and only upper and lower bounds are known for each coordinate. We develop a mixed integer linear programming model as a robust counterpart of the proposed uncertain model. A key challenge is that, since the uncertain model involves nonlinear objective function of the ...

The thermodynamical property of a small cluster including M Hubbard dimers, each of which is described by the two-site Hubbard model, has been discussed within the nonex-tensive statistics (NES). The temperature dependence of the energy, entropy, specific heat and susceptibility has been calculated for M = 1, 2, 3 and ∞ (corresponding to q = 1) with the use of the relation between the entropic ...

today, stock investment has become an important mean of national finance. apparently, it is significant for investors to estimate the stock price and select the trading chance accurately in advance, which will bring high return to stockholders. in the past, long-term trading processes and many technical analysis methods for stock market were put forward. however, stock market is a nonlinear sys...