Muon anomalous magnetic moment from effective supersymmetry

We present a detailed analysis on the possible maximal value of the muon (g-2) (= 2 a_mu) within the context of effective SUSY models with R parity conservation. First of all, the mixing among the second and the third family sleptons can contribute at one loop level to the a_mu(SUSY) and tau -> mu gamma simultaneously. One finds that the a_mu(SUSY) can be as large as (10-20)*10^-10 for any tan beta, imposing the upper limit on the tau -> mu gamma branching ratio. Furthermore, the two-loop Barr-Zee type contributions to a_mu(SUSY) can be significant for large tan beta, if a stop is light and mu and A_t are large enough (O(1) TeV). In this case, it is possible to have a_mu(SUSY) upto O(10)*10^-10 without conflicting with tau -> l gamma. We conclude that the possible maximal value for a_mu(SUSY) is about 20*10^-10 for any tan beta. Therefore the BNL experiment on the muon a_mu can exclude the effective SUSY models only if the measured deviation is larger than \sim 30*10^-10.Comment: 10 pages, 3 figure

Nematic domains and resistivity in an itinerant metamagnet coupled to a lattice

The nature of the emergent phase near a putative quantum critical point in the bilayer ruthenate Sr$_3$Ru$_2$O$_7$ has been a recent subject of intensive research. It has been suggested that this phase may possess electronic nematic order(ENO). In this work, we investigate the possibility of nematic domain formation in the emergent phase, using a phenomenological model of electrons with ENO and its coupling to lattice degrees of freedom. The resistivity due to the scattering off the domain walls is shown to closely follow the ENO parameter. Our results provide qualitative explanations for the dependence of the resistivity on external magnetic fields in Sr$_3$Ru$_2$O$_7$.Comment: 4 pages, 4 figures, published versio

Bifurcation analysis of a predator-prey system with self- and cross-diffusion and constant harvesting rate

In this paper, we focus on a ratio dependent predator-prey system with self- and cross-diffusion and constant harvesting rate. By making use of a brief stability and bifurcation analysis, we derive the symbolic conditions for Hopf, Turing and wave bifurcations of the system in a spatial domain. Additionally, we illustrate spatial pattern formations caused by these bifurcations via numerical examples. A series of numerical examples reveal that one can observe several typical spatiotemporal patterns such as spotted, spot-stripelike mixtures due to Turing bifurcation and an oscillatory wave pattern due to the wave bifurcation. Thus the obtained results disclose that the spatially extended system with self-and cross-diffusion and constant harvesting rate plays an important role in the spatiotemporal pattern formations in the two dimensional space

Dynamic analysis of an impulsively controlled predator-prey system

In this paper, we study an impulsively controlled predator-prey model with Monod-Haldane functional response. By using the Floquet theory, we prove that there exists a stable prey-free solution when the impulsive period is less than some critical value, and give the condition for the permanence of the system. In addition, we show the existence and stability of a positive periodic solution by using bifurcation theory

Persistence of singlet fluctuations in the coupled spin tetrahedra system Cu2Te2O5Br2 revealed by high-field magnetization and 79Br NQR - 125Te NMR

We present high-field magnetization and $^{79}$Br nuclear quadrupole resonance (NQR) and $^{125}$Te nuclear magnetic resonance (NMR) studies in the weakly coupled Cu$^{2+}$ ($S=1/2$) tetrahedral system Cu$_2$Te$_2$O$_5$Br$_2$. The field-induced level crossing effects were observed by the magnetization measurements in a long-ranged magnetically ordered state which was confirmed by a strong divergence of the spin-lattice relaxation rate 1/T1 at T0=13.5 K. In the paramagnetic state, 1/T1 reveals an effective singlet-triplet spin gap much larger than that observed by static bulk measurements. Our results imply that the inter- and the intra-tetrahedral interactions compete, but at the same time they cooperate strengthening effectively the local intratetrahedral exchange couplings. We discuss that the unusual feature originates from the frustrated intertetrahedral interactions.Comment: 5 pages, 4 figures, accepted in Phys. Rev. B as a Rapid Communication

Simple renormalizable flavor symmetry for neutrino oscillations

The recent measurement of a non-zero neutrino mixing angle $\theta_{13}$ requires a modification of the tri-bimaximal mixing pattern that predicts a zero value for it. We propose a new neutrino mixing pattern based on a spontaneously-broken $A_{4}$ flavor symmetry and a type-I seesaw mechanism. Our model allows for approximate tri-bimaximal mixing and non-zero $\theta_{13}$, and contains a natural way to implement low and high energy CP violation in neutrino oscillations, and leptogenesis with a renormalizable Lagrangian. Both normal and inverted mass hierarchies are permitted within $3\sigma$ experimental bounds, with the prediction of small (large) deviations from maximality in the atmospheric mixing angle for the normal (inverted) case. Interestingly, we show that the inverted case is excluded by the global analysis in $1\sigma$ experimental bounds, while the most recent MINOS data seem to favor the inverted case. Our model make predictions for the Dirac CP phase in the normal and inverted hierarchies, which can be tested in near-future neutrino oscillation experiments. Our model also predicts the effective mass $|m_{ee}|$ measurable in neutrinoless double beta decay to be in the range $0.04\lesssim |m_{ee}| \lesssim 0.15$ eV for the normal hierarchy and $0.06\lesssim |m_{ee}| \lesssim 0.11$ eV for the inverted hierarchy, both of which are within the sensitivity of the next generation experiments.Comment: 29 pages and 10 figures. No corrections. Version for Phys. Rev.