Lower and upper bounds for the Lyapunov exponents of twisting dynamics: a relationship between the exponents and the angle of the Oseledet's splitting

We consider locally minimizing measures for the conservative twist maps of the $d$-dimensional annulus or for the Tonelli Hamiltonian flows defined on a cotangent bundle $T^*M$. For weakly hyperbolic such measures (i.e. measures with no zero Lyapunov exponents), we prove that the mean distance/angle between the stable and the unstable Oseledet's bundles gives an upper bound of the sum of the positive Lyapunov exponents and a lower bound of the smallest positive Lyapunov exponent. Some more precise results are proved too

Four-quark flux distribution and binding in lattice SU(2)

The full spatial distribution of the color fields of two and four static quarks is measured in lattice SU(2) field theory at separations up to 1 fm at beta=2.4. The four-quark case is equivalent to a qbar q qbar q system in SU(2) and is relevant to meson-meson interactions. By subtracting two-body flux tubes from the four-quark distribution we isolate the flux contribution connected with the four-body binding energy. This contribution is further studied using a model for the binding energies. Lattice sum rules for two and four quarks are used to verify the results.Comment: 46 pages including 71 eps figures. 3D color figures are available at www.physics.helsinki.fi/~ppennane/pics

A Classical Manifestation of the Pauli Exclusion Principle

The occupied and unoccupied fermionic BPS quantum states of a type-IIA string stretched between a D6-brane and an orthogonal D2-brane are described in M-theory by two particular holomorphic curves embedded in a Kaluza-Klein monopole. The absence of multiply-occupied fermionic states --- the Pauli exclusion principle --- is manifested in M-theory by the absence of any other holomorphic curves satisfying the necessary boundary conditions. Stable, non-BPS states with multiple strings joining the D6-brane and D2-brane are described M-theoretically by non-holomorphic curves.Comment: harvmac 6 pages. Final version as published in JHE

Cosmic microwave background constraints on coupled dark matter

We study CMB constraints on a model with a cosmological constant and a fraction of dark matter non-minimally coupled to a massless scalar field. In this scenario, there is an extra gravity-like fifth force which can affect the evolution of the Universe enough to have a discernible effect on measurements of cosmological parameters. Using Planck and WMAP polarisation data, we find that up to half of the dark matter can be coupled. The coupling can also be several times larger than in models with a single species of cold dark matter coupled to a quintessence scalar field, as the scalar field does not play the role of dark energy and is therefore less constrained by the data.Comment: 5 pages, 4 figure

Space shuttle low pressure auxiliary propulsion subsystem design definition Subtask B report

Space shuttle low pressure, hydrogen oxygen auxiliary propulsion subsystem preliminary desig