N=2 supersymmetric extension of l-conformal Galilei algebra

N=2 supersymmetric extension of the l-conformal Galilei algebra is constructed. A relation between its representations in flat spacetime and in Newton-Hooke spacetime is discussed. An infinite-dimensional generalization of the superalgebra is given.Comment: V4: 8 pages, references and acknowledgements adde

Dynamical realizations of N=1 l-conformal Galilei superalgebra

Dynamical systems which are invariant under N=1 supersymmetric extension of the l-conformal Galilei algebra are constructed. These include a free N=1 superparticle which is governed by higher derivative equations of motion and an N=1 supersymmetric Pais-Uhlenbeck oscillator for a particular choice of its frequencies. A Niederer-like transformation which links the models is proposed.Comment: 12 pages. New material and references added. Published versio

Canonical Coherent States for the Relativistic Harmonic Oscillator

In this paper we construct manifestly covariant relativistic coherent states on the entire complex plane which reproduce others previously introduced on a given $SL(2,R)$ representation, once a change of variables $z\in C\rightarrow z_D \in$ unit disk is performed. We also introduce higher-order, relativistic creation and annihilation operators, \C,\Cc, with canonical commutation relation [\C,\Cc]=1 rather than the covariant one [\Z,\Zc]\approx Energy and naturally associated with the $SL(2,R)$ group. The canonical (relativistic) coherent states are then defined as eigenstates of \C. Finally, we construct a canonical, minimal representation in configuration space by mean of eigenstates of a canonical position operator.Comment: 11 LaTeX pages, final version, shortened and corrected, to appear in J. Math. Phy

Modular Invariance on the Torus and Abelian Chern-Simons Theory

The implementation of modular invariance on the torus as a phase space at the quantum level is discussed in a group-theoretical framework. Unlike the classical case, at the quantum level some restrictions on the parameters of the theory should be imposed to ensure modular invariance. Two cases must be considered, depending on the cohomology class of the symplectic form on the torus. If it is of integer cohomology class $n$, then full modular invariance is achieved at the quantum level only for those wave functions on the torus which are periodic if $n$ is even, or antiperiodic if $n$ is odd. If the symplectic form is of rational cohomology class $\frac{n}{r}$, a similar result holds --the wave functions must be either periodic or antiperiodic on a torus $r$ times larger in both direccions, depending on the parity of $nr$. Application of these results to the Abelian Chern-Simons is discussed.Comment: 24 pages, latex, no figures; title changed; last version published in JM

Development of a high altitude Stokes flow decelerator Final report

Drag generation theory, design, and drop tests for high altitude Stokes flow decelerato

Thermally activated conductance of a silicon inversion layer by electrons excited above the mobility edge

The thermally activated conductivity sigma of an n-type inversion layer on a (100) oriented silicon surface and its derivative d sigma /dT were measured in the temperature range 1.4K-4.2K. Above T approximately=2.5K both the temperature dependence of (T/ sigma ) (d sigma /dT) and the relation between this quantity and sigma cannot be reconciled with a universal pre-exponential factor, i.e. the minimum metallic conductivity, but are shown to be satisfactorily described by a prefactor which is proportional to the temperature. The experimental results presented are consistent with activation of the number of mobile electrons above a mobility edge in the lowest sub-band, and indicate a mobility which is independent of both temperature and electron density

Temperature dependent metallic conductance above the mobility edge of a silicon inversion layer

The temperature dependence of the conductance of an n-type inversion layer on a (100) silicon surface has been examined between 1.4K and 4.2K at electron densities at which the Fermi level is close above the mobility edge of the lowest sub-band. It can be explained by assuming a separate band of localised bound states from which electrons are thermally excited into the extended states of the sub-band. The absence of any noticeable change in the conductivity mobility demonstrates that the nature of the electron transport is preserved when the conductivity is lowered from 8*10-5mho to 2*10-5mho

Deformed Schrodinger symmetry on noncommutative space

We construct the deformed generators of Schroedinger symmetry consistent with noncommutative space. The examples of the free particle and the harmonic oscillator, both of which admit Schroedinger symmetry, are discussed in detail. We construct a generalised Galilean algebra where the second central extension exists in all dimensions. This algebra also follows from the Inonu--Wigner contraction of a generalised Poincare algebra in noncommuting space.Comment: 9 pages, LaTeX, abstract modified, new section include

Logarithmic Correlators in Non-relativistic Conformal Field Theory

We show how logarithmic terms may arise in the correlators of fields which belong to the representation of the Schrodinger-Virasoro algebra (SV) or the affine Galilean Conformal Algebra (GCA). We show that in GCA, only scaling operator can have a Jordanian form and rapidity can not. We observe that in both algebras logarithmic dependence appears along the time direction alone.Comment: 18 pages, no figures,some errors correcte