On the 3-particle scattering continuum in quasi one dimensional integer spin Heisenberg magnets

We analyse the three-particle scattering continuum in quasi one dimensional integer spin Heisenberg antiferromagnets within a low-energy effective field theory framework. We exactly determine the zero temperature dynamical structure factor in the O(3) nonlinear sigma model and in Tsvelik's Majorana fermion theory. We study the effects of interchain coupling in a Random Phase Approximation. We discuss the application of our results to recent neutron-scattering experiments on the Haldane-gap material ${\rm CsNiCl_3}$.Comment: 8 pages of revtex, 5 figures, small changes, to appear in PR

Mutant screen reveals the Piccolo's control over depression and brain-gonad crosstalk

Successful sexual reproduction involves a highly complex, genetically encoded interplay between animal physiology and behavior. Here we developed a screen to identify genes essential for rat reproduction based on an unbiased methodology involving mutagenesis via the Sleeping Beauty transposon. As expected, our screen identified genes where reproductive failure was connected to gametogenesis (Btrc, Pan3, Spaca6, Ube2k) and embryogenesis (Alk3, Exoc6b, Slc1a3, Tmx4, Zmynd8). In addition, our screen identified Atg13 (longevity) Dlg1 and Pclo (neuronal disorders), previously not associated with reproduction. Dominant Pclo traits caused epileptiform activity and affected genes supporting GABAergic synaptic transmission (Gabra6, Gabrg3), and animals exhibited a compromised crosstalk between the brain and gonads via disturbed GnRH signaling. Recessive Pclo traits disrupted conspecific recognition required for courtship/mating and were mapped to allelic markers for major depressive disorder (Grm5, Htr2a, Sorcs3, Negr1, Drd2). Thus, Pclo-deficiency in rats link neural networks controlling sexual motivation to Pclo variants that have been associated with human neurological disorders

Universality class of S=1/2 quantum spin ladder system with the four spin exchange

We study s=1/2 Heisenberg spin ladder with the four spin exchange. Combining numerical results with the conformal field theory(CFT), we find a phase transition with central charge c=3/2. Since this system has an SU(2) symmetry, we can conclude that this critical theory is described by k=2 SU(2) Wess-Zumino-Witten model with Z$_2$ symmetry breaking

Haldane-Gapped Spin Chains as Luttinger Liquids: Correlation Functions at Finite Field

We study the behavior of Heisenberg, antiferromagnetic, integer-spin chains in the presence of a magnetic field exceeding the attendant spin gap. For temperatures much smaller than the gap, the spin chains exhibit Luttinger liquid behavior. We compute exactly both the corresponding Luttinger parameter and the Fermi velocity as a function of magnetic field. This enables the computation of a number of correlators from which we derive the spin conductance, the expected form of the dynamic structure factor relevant to inelastic neutron scattering experiments, and NMR relaxation rates. We also comment upon the robustness of the magnetically induced gapless phase both to finite temperature and finite couplings between neighbouring chains.Comment: 32 pages, 8 figures; published version includes additions discussing the robustness of the magnetically induced gapless phase to ordering between chains as well as the relationship between the spin-1 chains and spin-1/2 ladders in the presence of a magnetic fiel