Cylindrically symmetric, static strings with a cosmological constant in Brans-Dicke theory

The static, cylindrically symmetric vacuum solutions with a cosmological constant in the framework of the Brans-Dicke theory are investigated. Some of these solutions admitting Lorentz boost invariance along the symmetry axis correspond to local, straight cosmic strings with a cosmological constant. Some physical properties of such solutions are studied. These strings apply attractive or repulsive forces on the test particles. A smooth matching is also performed with a recently introduced interior thick string solution with a cosmological constant.Comment: 8 pages, Revtex; Published versio

Finite temperature properties of the two-dimensional SU(2) Kondo-necklace

We analyse several thermodynamic properties of the two-dimensional Kondo necklace using finite-temperature stochastic series expansion. In agreement with previous zero-temperature findings the model is shown to exhibit a quantum critical point (QCP), separating an antiferromagnetic from a paramagnetic dimerized state at a critical Kondo exchange-coupling strength $J_{c}\approx 1.4$. We evaluate the temperature dependent uniform and staggered structure factors as well as the uniform and staggered susceptibilities and the local 'impurity' susceptibility close to the QCP as well as in the ordered and quantum disordered phase. The crossover between the classical, renormalized classical, and quantum critical regime is analyzed as a function of temperature and Kondo coupling.Comment: 4.2 pages, 6 figure