Leptogenesis origin of Dirac gaugino dark matter

The Dirac nature of the gauginos (and also the Higgsinos) can be realized in $R$-symmetric supersymmetry models. In this class of models, the Dirac bino (or wino) with a small mixture of the Dirac Higgsinos is a good dark matter candidate. When the seesaw mechanism with Higgs triplet superfields is implemented to account for the neutrino masses and mixing, the leptogenesis driven by the heavy triplet decay is shown to produce not only the matter-antimatter asymmetry but also the asymmetric relic density of the Dirac gaugino dark matter. The dark matter mass turns out to be controlled by the Yukawa couplings of the heavy Higgs triplets, and it can be naturally at the weak scale for a mild hierarchy of the Yukawa couplings.Comment: 9 pages. Restructured for clear presentation, corrected some errors and typos. No change in conclusio

Minimal Models for Axion and Neutrino

The PQ mechanism resolving the strong CP problem and the seesaw mechanism explaining the smallness of neutrino masses may be related in a way that the PQ symmetry breaking scale and the seesaw scale arise from a common origin. Depending on how the PQ symmetry and the seesaw mechanism are realized, one has different predictions on the color and electromagnetic anomalies which could be tested in the future axion dark matter search experiments. Motivated by this, we construct various PQ seesaw models which are minimally extended from the (non-) supersymmetric Standard Model and thus set up different benchmark points on the axion-photon-photon coupling in comparison with the standard KSVZ and DFSZ models.Comment: 12 pages and 2 figures, references added, matched with the published version in PL

The influence of non-neuronal cells on catecholamine and acetylcholine synthesis and accumulation in cultures of dissociated sympathetic neurons

The effects of several non-neuronal cell types on neurotransmitter synthesis in cultures of dissociated sympathetic neurons from the new-born rat were studied. Acetylcholine synthesis from radioactive choline was increased 100- to 1000-fold in the presence of non-neuronal cells from sympathetic ganglia. This increase was roughly dependent on the number of ganglionic non-neuronal cells present. The effect did not appear to be due to an increased plating efficiency of neurons, since the non-neuronal cells were capable of increasing acetylcholine synthesis after only 48-hr contact with neurons that had been previously grown without non-neuronal cells for 2 weeks. C6 rat glioma cells were also able to stimulate acetylcholine synthesis, but 3T3 mouse fibroblast cells had little or no effect. None of the non-neuronal cell types synthesized detectable acetylcholine in the absence of the neurons. The ganglionic non-neuronal cells had no significant effect on catecholamine synthesis (which occurs in the absence of non-neuronal cells)

New transformation of Wigner operator in phase space quantum mechanics for the two-mode entangled case

As a natural extension of Fan's paper (arXiv: 0903.1769vl [quant-ph]) by employing the formula of operators' Weyl ordering expansion and the bipartite entangled state representation we find new two-fold complex integration transformation about the Wigner operator (in its entangled form) in phase space quantum mechanics and its inverse transformation. In this way, some operator ordering problems can be solved and the contents of phase space quantum mechanics can be enriched.Comment: 8 pages, 0 figure

Can one identify the intrinsic structure of the yrast states in 48^{48}Cr after the backbending?

The backbending phenomenon in $^{48}$Cr has been investigated using the recently developed Projected Configuration Interaction (PCI) method, in which the deformed intrinsic states are directly associated with shell model (SM) wavefunctions. Two previous explanations, (i) $K=0$ band crossing, and (ii) $K=2$ band crossing have been reinvestigated using PCI, and it was found that both explanations can successfully reproduce the experimental backbending. The PCI wavefunctions in the pictures of $K=0$ band crossing and $K=2$ band crossing are highly overlapped. We conclude that there are no unique intrinsic states associated with the yrast states after backbending in $^{48}$Cr.Comment: 5 pages, 5 figure

Modulating the Single-Molecule Magnet, Magnetocaloric and Luminescent Behavior in Metallacrowns.

The first part of this thesis focuses on the study of single-molecule magnets (SMMs), which have potential uses in high-density magnetic data storage. A new family of [M4Ln2(shi3-)4(Hshi2-)2(H2shi-)2(C5H5N)4(CH3OH)x(H2O)x] complexes (M = GaIII, FeIII; Ln = GdIII, TbIII, DyIII, ErIII, YIII0.9DyIII0.1) were prepared in order to investigate the effect of 3d and 4f magnetic interactions on slow magnetic relaxation behavior. It was found the antiferromagnetic 3d-4f coupling had adverse effects on slow magnetic relaxation. Furthermore, the dynamic magnetic behavior in the Ga4Dy2 analogue was elucidated, with two relaxation processes being attributed to the decoupled and excited ferromagnetic states. The magnetocaloric effect (MCE) is a phenomenon which holds promise for low-temperature refrigeration applications. Iron(III), an inexpensive, isotropic S = 5/2 ion, was selected to develop efficient low-temperature magnetic refrigerants. An investigation of FeIII(X)3[9-MCFeIIIN(shi)-3] compounds (X = acetate or benzoate) revealed that inter- and intramolecular magnetic interactions could be tuned to achieve greater MCE behavior. The acetate complex exhibited a -ΔSm value of -15.4 J kg-1 K-1 (T = 3 K, ΔH = 7 T), which is comparable to higher nuclearity FeIII clusters. Extensive antiferromagnetic intermolecular interactions resulted in a smaller MCE in the benzoate derivative and an analogous FeIII2(isopthalate)3[9-MCFeIIIN(shi)-3]2 dimer compound. These studies show that rational design and control of magnetic interactions may be employed to develop high performance MCE materials. LnIII(benzoate)4[12-MCGaIIIN(shi)-4](pyridinium+) complexes (LnIII = SmIII, EuIII, GdIII, TbIII, DyIII, HoIII, ErIII, TmIII, YbIII) were found to be capable of sensitizing both visible and NIR emitting LnIII ions. Efficient energy transfer from the ligand T1 state to the emitting state on the LnIII led to the observation of remarkable luminescent behavior. In particular, solid state quantum yields for the YbIII and ErIII analogues (5.88% and 4.4·10-2%, respectively) are greater than any reported in the literature. This system presents a highly efficient and modular platform on which to develop practical bio-imaging agents. The work presented in this thesis demonstrates that physical properties can be tuned through systematic ligand and metal substitution in metallacrown coordination complexes. These results have given new insight towards the understanding of single-molecule magnets, MCE materials and luminescent lanthanide complexes.PHDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/113333/1/davidyc_1.pd

Kondo Spin Screening Cloud in Two-dimensional Electron Gas with Spin-orbit Couplings

A spin-1/2 Anderson impurity in a semiconductor quantum well with Rashba and Dresselhaus spin-orbit couplings is studied by using a variational wave function method. The local magnetic moment is found to be quenched at low temperatures. The spin-spin correlations of the impurity and the conduction electron density show anisotropy in both spatial and spin spaces, which interpolates the Kondo spin screenings of a conventional metal and of a surface of three-dimensional topological insulators.Comment: accepted by the Journal of Physics: Condensed Matte