Bimaximal fermion mixing from the quark and leptonic mixing matrices

In this paper, we show how the mixing angles of the standard parameterization add when multiplying the quark and leptonic mixing matrices, i.e., we derive explicit sum rules for the quark and leptonic mixing angles. In this connection, we also discuss other recently proposed sum rules for the mixing angles assuming bimaximal fermion mixing. In addition, we find that the present experimental and phenomenological data of the mixing angles naturally fulfill our sum rules, and thus, give rise to bilarge or bimaximal fermion mixing.Comment: 5 pages, RevTeX4. Final version published in Phys. Lett.

Molecular Weight Dependent Kernels in Generalized Mixing Rules

In this paper, a model is proposed for the kernel in the generalized mixing rule recently formulated by Anderssen and Mead (1998). In order to derive such a model, it is necessary to take account of the rheological significance of the kernel in terms of the relaxation behaviour of the individual polymers involved. This leads naturally to consider a way how additional physical effects, which depend on the molecular weight distribution, can be included in the mixing rule. The advantage of this approach is that, without changing the generality derived by Anderssen and Mead (1998), the choice of the model proposed here for the kernel guarantees the enhanced physical and rheological significance of their mixing rule.Comment: 11 pages, 2 figures, submitted to Journal of Rheolog

Polarization-dependent optical nonlinearities of multiquantum-well laser amplifiers studied by four-wave mixing

We present a detailed study of the polarization properties of four-wave mixing in multiquantum-well (MQW) semiconductor optical amplifiers (SOA's). In particular, the polarization selection rules relevant to all processes contributing to the generation of the four-wave mixing signal are rigorously derived and discussed. We then show the importance of these results in applications where four-wave mixing is used as a spectroscopic tool to study the optical nonlinearities of semiconductor gain media. For illustration, we demonstrate two novel applications of polarization-resolved four-wave mixing. The first is a new technique for measuring the recombination lifetime in SOA's, based on mixing of a pump wave with polarized amplified spontaneous emission noise. In the second, we use the same polarization selection rules to measure the interwell transport lifetime in alternating-strain MQW amplifiers. Finally, we also discuss the possibility of studying the dynamics of the optically induced phase coherence between spin-degenerate states

Determination of the Σ\Sigma--Λ\Lambda mixing angle from QCD sum rules

The $\Sigma$--$\Lambda$ mixing angle is calculated in framework of the QCD sum rules. We find that our prediction for the mixing angle is $(1.00\pm 0.15)^0$ which is in good agreement with the quark model prediction, and approximately two times larger than the recent lattice QCD calculations.Comment: 5 pages, no figures, LaTeX formatte

Determination of f0−a00f_0 - a_0^0 mixing angle from QCD sum rules

By assuming that the $f_0$ and $a_0^0$ mesons are mixed states of the two-quark - tetraquark, the mixing angle between them is estimated within QCD sum rules method, and it is obtained that the mixing angle is $(6.03 \pm 0.08)^\circ$. Our prediction on mixing angle can be checked in further experiments which can shed light on choosing the "right" structure of $f_0$ and $a_0^0$ mesons

Alternative fuels for spark-ignition engines: mixing rules for the laminar burning velocity of gasoline-alcohol blends

Experimental measurements of the laminar burning velocity are mostly limited in pressure and temperature and can be compromised by the effects of flame stretch and instabilities. Computationally, these effects can be avoided by calculating one-dimensional, planar adiabatic flames using chemical oxidation mechanisms. Chemical kinetic models are often large, complex and take a lot of computation time, and few models exist for multi-component fuels. The aim of the present study is to investigate if simple mixing rules are able to predict the laminar burning velocity of fuel blends with a good accuracy. An overview of different mixing rules to predict the laminar burning is given and these mixing rules are tested for blends of hydrocarbons and ethanol. Experimental data of ethanol/n-heptane and ethanol/n-heptane/iso-octane mixtures and modeling data of an ethanol/n-heptane blend and blends of ethanol and a toluene reference fuel are used to test the different mixing rules. Effects of higher temperature and pressure on the performance of the mixing rules are investigated. It was found that simple mixing rules that consider only the change in composition are accurate enough to predict the laminar burning velocity of ethanol/hydrocarbon blends. For the blends used in this study, a Le Chatelier's rule based on energy fractions is preferable because of the similar accuracy in comparison to other mixing rules while being more simple to use