Self-duality and the Supersymmetric KdV Hierarchy

We show how the supersymmetric KdV equation can be obtained from the self-duality condition on Yang-Mills fields in four dimension associated with the graded Lie algebra OSp(2/1). We also obtain the hierarchy of Susy KdV equations from such a condition. We formulate the Susy KdV hierarchy as a vanishing curvature condition associated with the U(1) group and show how an Abelian self-duality condition in four dimension can also lead to these equations.Comment: 10 page

Quasiadiabatic dynamics of ultracold bosonic atoms in a one-dimensional optical superlattice

We study the quasiadiabatic dynamics of a one-dimensional system of ultracold bosonic atoms loaded in an optical superlattice. Focusing on a slow linear variation in time of the superlattice potential, the system is driven from a conventional Mott insulator phase to a superlattice-induced Mott insulator, crossing in between a gapless critical superfluid region. Due to the presence of a gapless region, a number of defects depending on the velocity of the quench appear. Our findings suggest a power-law dependence similar to the Kibble-Zurek mechanism for intermediate values of the quench rate. For the temporal ranges of the quench dynamics that we considered, the scaling of defects depends nontrivially on the width of the superfluid region.Comment: 6 Pages, 4 Figure

Electronic phase separation due to magnetic polaron formation in the semimetallic ferromagnet EuB6_6 - A weakly-nonlinear-transport study

We report measurements of weakly nonlinear electronic transport, as measured by third-harmonic voltage generation $V_{3\omega}$, in the low-carrier density semimetallic ferromagnet EuB$_6$, which exhibits an unusual magnetic ordering with two consecutive transitions at $T_{c_1} = 15.6$\,K and $T_{c_2} = 12.5$\,K. Upon cooling in zero magnetic field through the ferromagnetic transition, the dramatic drop in the linear resistivity at the upper transition $T_{c_1}$ coincides with the onset of nonlinearity, and upon further cooling is followed by a pronounced peak in $V_{3 \omega}$ at the lower transition $T_{c_2}$. Likewise, in the paramagnetic regime, a drop of the material's magnetoresistance $R(H)$ precedes a magnetic-field-induced peak in nonlinear transport. A striking observation is a linear temperature dependence of $V_{3\omega}^{\rm peak}(H)$. We suggest a picture where at the upper transition $T_{c_1}$ the coalescing MP form a conducting path giving rise to a strong decrease in the resistance. The MP formation sets in at around $T^\ast \sim 35$\,K below which these entities are isolated and strongly fluctuating, while growing in number. The MP then start to form links at $T_{c_1}$, where percolative electronic transport is observed. The MP merge and start forming a continuum at the threshold $T_{c_2}$. In the paramagnetic temperature regime $T_{c_1} < T < T^\ast$, MP percolation is induced by a magnetic field, and the threshold accompanied by charge carrier delocalization occurs at a single critical magnetization.Comment: to appear in J. Kor. Phys. Soc (ICM2012 conference contribution

Annihilation Diagrams in Two-Body Nonleptonic Decays of Charmed Mesons

In the pole-dominance model for the two-body nonleptonic decays of charmed mesons $D \rightarrow PV$ and $D \rightarrow VV$, it is shown that the contributions of the intermediate pseudoscalar and the axial-vector meson poles cancel each other in the annihilation diagrams in the chiral limit. In the same limit, the annihilation diagrams for the $D \rightarrow PP$ decays vanish independently.Comment: 9 pages (+ 3 figures available upon request), UR-1316, ER-40685-766, IC/93/21

Quantization in a General Light-front Frame

In this paper, we study the question of quantization of quantum field theories in a general light-front frame. We quantize scalar, fermion as well as gauge field theories in a systematic manner carrying out the Hamiltonian analysis carefully. The decomposition of the fields into positive and negative frequency terms needs to be done carefully after which we show that the (anti) commutation relations for the quantum operators become frame independent. The frame dependence is completely contained in the functions multiplying these operators in the field decomposition. We derive the propagators from the vacuum expectation values of the time ordered products of the fields.Comment: 14 pages, revtex, version to be published in Phys. Rev. D with the discussion of Abelian field quantization replaced by the non-Abelian field and some comments added on the Mandelstam-Liebbrandt prescriptio