9,075 research outputs found
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 SrRuO 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 SrRuO.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 Br nuclear quadrupole
resonance (NQR) and Te nuclear magnetic resonance (NMR) studies in the
weakly coupled Cu () tetrahedral system CuTeOBr.
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
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 flavor symmetry and a type-I seesaw mechanism. Our
model allows for approximate tri-bimaximal mixing and non-zero ,
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
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 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 measurable in neutrinoless double beta decay to be in
the range eV for the normal hierarchy and
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.
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