Publications (12)
Surface structure of i-Al(68)Pd(23)Mn(9): An analysis based on the T*(2F) tiling decorated by Bergman polytopes
G. Kasner, Z. Papadopolos, P. Kramer +1
A Fibonacci-like terrace structure along a 5fold axis of i-Al(68)Pd(23)Mn(9) monograins has been observed by T.M. Schaub et al. with scanning tunnelling microscopy (STM). In the pl…
Root lattices and quasicrystals
M. Baake, D. Joseph, P. Kramer +1
It is shown how root lattices and their reciprocals might serve as the right pool for the construction of quasicrystalline structure models. All non-periodic symmetries observed so…
The double torus as a 2D cosmos: groups, geometry and closed geodesics
P. Kramer, M. Lorente
The double torus provides a relativistic model for a closed 2D cosmos with topology of genus 2 and constant negative curvature. Its unfolding into an octagon extends to an octagona…
Tiles--Inflation Rules for the Class of Canonical Tilings T*(2F)
Z. Papadopolos, C. Hohneker, P. Kramer
The tiles of the canonical tilings (of the 3dimensional space) T*(2F) are six tetrahedra. We determine their inflation rules by the projection method.
Tensor and spin representations of SO(4) and discrete quantum gravity
M. Lorente, P. Kramer
Starting from the defining transformations of complex matrices for the SO(4) group, we construct the fundamental representation and the tensor and spinor representations of the gro…
Discrete Quantum Gravity: I. Zonal spherical functions of the representationsof the SO(4,R) group with respect to the SU(2) subgroup and their application to the Barrett-Crane model
P. Kramer, M. Lorente
Starting from the defining transformations of complex matrices for the group, we construct the fundamental representation and the tensor and spinor representations of the…
Induced representations of Poincare group on the lattice: spin 1/2 and 1 case
M. Lorente, P. Kramer
Following standard methods we explore the construction of the discrete Poincare group, the semidirect product of discrete translations and integral Lorentz transformations, using t…
Representations of the discrete inhomogeneous Lorentz group and Dirac wave equation on the lattice
M. Lorente, P. Kramer
We propose the fundamental and two dimensional representation of the Lorentz groups on a (3+1)-dimensional hypercubic lattice, from which representations of higher dimensions can b…
CMB radiation in an inhomogeneous spherical space
R. Aurich, P. Kramer, S. Lustig
We analyse the CMB radiation in spherical 3-spaces with non-trivial topology. The focus is put on an inhomogeneous space which possesses observer dependent CMB properties. The supp…
Discrete Quantum Gravity: II. Simplicial complexes, irreps of SL(2,C), and a Lorentz invariant weight in a state sum model
P. Kramer, M. Lorente
In part I of [1] we have developed the tensor and spin representation of SO(4) in order to apply it to the simplicial decomposition of the Barrett-Crane model. We attach to each fa…
Imaging ultrafast electronic domain fluctuations with X-ray speckle visibility
N. Hua, Y. Sun, P. Rao +22
Speckle patterns manifesting from the interaction of coherent X-rays with matter offer a glimpse into the dynamics of nanoscale domains that underpin many emergent phenomena in qua…
Surface embedding, topology and dualization for spin networks
P. Kramer, M. Lorente
Spin networks are graphs derived from 3nj symbols of angular momentum. The surface embedding, the topology and dualization of these networks are considered. Embeddings into compact…