220 research outputs found

    Geodesics of electrically and magnetically charged test particles in the Reissner-Nordstr\"om space-time: analytical solutions

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    We present the full set of analytical solutions of the geodesic equations of charged test particles in the Reissner-Nordstr\"om space-time in terms of the Weierstra{\ss} \wp, σ\sigma and ζ\zeta elliptic functions. Based on the study of the polynomials in the ϑ\vartheta and rr equations we characterize the motion of test particles and discuss their properties. The motion of charged test particles in the Reissner-Nordstr\"om space-time is compared with the motion of neutral test particles in the field of a gravitomagnetic monopole. Electrically or magnetically charged particles in the Reissner-Nordstr\"om space-time with magnetic or electric charges, respectively, move on cones similar to neutral test particles in the Taub-NUT space-times

    Acoustic Spectroscopy of the DNA in GHz range

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    We find a parametric resonance in the GHz range of the DNA dynamics, generated by pumping hypersound . There are localized phonon modes caused by the random structure of elastic modulii due to the sequence of base pairs

    Symmetry breaking in low-dimensional SU(N) antiferromagnets

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    Consequences of explicit symmetry breaking in a physically motivated model of SU(N) antiferromagnet in spatial dimensions one and two are studied. It is shown that the case N=3, which can be realized in spin-1 cold atom systems, displays special properties distinctly different from those for N>=4. Qualitative form of the phase diagram depending on the model parameters is given.Comment: 10 pages, 2 figures; added references, corrected fig.2; the final version to appear in PR

    Symmetries of Electrostatic Interaction between DNA Molecules

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    We study a model for pair interaction UU of DNA molecules generated by the discrete dipole moments of base-pairs and the charges of phosphate groups, and find noncommutative group of eighth order S{\cal S} of symmetries that leave UU invariant. We classify the minima using group S{\cal S} and employ numerical methods for finding them. The minima may correspond to several cholesteric phases, as well as phases formed by cross-like conformations of molecules at an angle close to 90o\rm{90}^{o}, "snowflake phase". The results depend on the effective charge QQ of the phosphate group which can be modified by the polycations or the ions of metals. The snowflake phase could exist for QQ above the threshold QCQ_C. Below QCQ_C there could be several cholesteric phases. Close to QCQ_C the snowflake phase could change into the cholesteric one at constant distance between adjacent molecules.Comment: 13 pages, 4 figure

    Nahm Transform and Moduli Spaces of CPn Models on the Torus

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    There is a Nahm transform for two-dimensional gauge fields which establishes a one-to-one correspondence between the orbit space of U(N) gauge fields with topological charge k defined on a torus and that of U(k) gauge fields with charge N on the dual torus. The main result of this paper is to show that a similar duality transform cannot exist for CPn instantons. This fact establishes a significative difference between 4-D gauge theories and CPn models. The result follows from the global analysis of the moduli space of instantons based on a complete and explicit parametrization of all self-dual solutions on the two-dimensional torus. The boundary of the space of regular instantons is shown to coincide with the space of singular instantons. This identification provides a new approach to analyzing the role of overlapping instantons in the infrared sector of CPn sigma models.Comment: 28 pages, 5 eps-figure

    Efficient Cluster Algorithm for CP(N-1) Models

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    Despite several attempts, no efficient cluster algorithm has been constructed for CP(N-1) models in the standard Wilson formulation of lattice field theory. In fact, there is a no-go theorem that prevents the construction of an efficient Wolff-type embedding algorithm. In this paper, we construct an efficient cluster algorithm for ferromagnetic SU(N)-symmetric quantum spin systems. Such systems provide a regularization for CP(N-1) models in the framework of D-theory. We present detailed studies of the autocorrelations and find a dynamical critical exponent that is consistent with z = 0.Comment: 14 pages, 3 figure

    The Topological Susceptibility of the Lattice CP(n-1) Model on the Torus and the Sphere

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    The topological vacuum structure of the two-dimensional  CPn1 ~CP^{n-1}~ model for  n=3,5,7 ~n = 3,5,7~ is studied on the lattice. In particular we investigate the small-volume limit on the torus as well as on the sphere and compare with continuum results. For  n5 ~n \ge 5~ , where lattice artifacts should be suppressed, the topological susceptibility shows unexpectedly strong deviations from asymptotic scaling. On the other hand there is an indication for a convergence to values obtained analytically within the limit  n ~n \rightarrow \infty~ .Comment: 20 pages, 14 figures not included, sorry, HU Berlin-IEP-92/2, Nucl. Phys. B in prin
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