arXiv subjects
Publications and source records attributed to C. H. Lam.
The W_3 algebra of central charge 6/5 is realized as a subalgebra of the vertex operator algebra V_{\sqrt{2}A_2} associated with a lattice of type \sqrt{2}A_2 by using both coset construction and orbifold theory. It is proved that W_3 is rational. Its irreducible modules are classified and constructed explicitly. The characters of those irreducible modules are also computed.
Positron lifetime, Photoluminescence and Hall measurements were performed to study undoped p-type gallium antimonide materials. A 314ps lifetime component, attributed to $V_{Ga}$ related defect, was identified in the positron lifetime measurement. In the PL measurement, a $778meV$ and a $797meV$ peaks were observed. Isochronal annealing studies were performed and at the temperature of $300^{o}C$, both the 314ps positron lifetime component and the two PL signals disappeared, which gives a clear and strong evidence for their correlation. However, the hole concentration ($\sim 2\times 10^{17}cm^{-3}$) was observed to be constant throughout the whole annealing temperature range up to $500^{o}C$. Contradictory to general belief, this implies, at least for samples with annealing temperatures above $300^{o}C$, the Ga vacancy is not the acceptor responsible for the p-type conduction.
We present a numerical study on the dynamics of imbibition fronts in porous media using a pipe network model. This model quantitatively reproduces the anomalous scaling behavior found in imbibition experiments [Phys. Rev. E {\bf 52}, 5166 (1995)]. Using simple scaling arguments, we derive a new identity among the scaling exponents in agreement with the experimental results.
We determine the decomposition of V_{\sqrt{2}D_l} into a sum of irreducible T-modules for general l where D_l is the root lattice of type D_l and T is the tensor product of l+1 Virasoro vertex operator algebras with central charges c_{1}=1/2, c_{2}=7/10, c_{3}=4/5, and c_{i}=1 for 4\le i\le l+1.