Masses Of External Particles Research Articles

Tau rightarrow mu mu mu at a rate of one out of 10^{14} tau decays?

We present in a full analytic form the partial widths for the lepton flavour violating decays mu ^{pm } rightarrow e^{pm } e^+ e^- and tau ^{pm } rightarrow ell ^{pm } ell '^{+} ell '^{-}, with ell ,ell '=mu ,e, mediated by neutrino oscillations in the one-loop diagrams. Compared to the first result by Petcov (Sov J Nucl Phys 25:340, 1977), obtained in the zero momentum limit {mathcal {P}}ll m_{nu } ll M_W, we retain full dependence on {mathcal {P}}, the momenta and masses of external particles, and we determine the branching ratios in the physical limit m_nu ll {mathcal {P}} ll M_W. We show that the claim presented in Pham (Eur Phys J C8:513, 1999) that the tau rightarrow ell ell ' ell ' branching ratios could be as large as 10^{-14}, as a consequence of keeping the {mathcal {P}} dependence, is flawed. We find rates of order 10^{-55}, even smaller than those obtained in the zero momentum limit, as the latter prediction contains an unphysical logarithmic enhancement.

Ultrasensitive mass sensing with nonlinear optics in a doubly clamped suspended carbon nanotube resonator

Nanomechanical resonator makes itself as an ideal system for ultrasensitive mass sensing due to its ultralow mass and high vibrational frequency. The mass sensing principle is due to the linear relationship of the frequency-shift and mass-variation. In this work, we will propose a nonlinear optical mass sensor based on a doubly clamped suspended carbon nanotube resonator in all-optical domain. The masses of external particles (such as nitric oxide molecules) landing onto the surface of carbon nanotube can be determined directly and accurately via using the nonlinear optical spectroscopy. This mass sensing proposed here may provide a nonlinear optical measurement technique in quantum measurements and environmental science.

Numerical Simulation of Multicomponent Isobaric Adsorption in Fixed Bed Columns

A model has been formulated for multicomponent isobaric adsorption in fixed bed columns. The following mass transfer mechanisms were used: convective flow, axial dispersion, external particle mass transfer and intraparticle diffusion. Analysis was applied on the system of governing equations to obtain controlling dimensionless criteria for the fixed bed adsorber. The derived criteria can be divided into three groups, namely: main dynamic criteria, equilibrium criteria and multicomponent dynamic criteria, their physical meaning has been discussed. The system of equations has been numerically solved using a finite difference method with an implicit conservative scheme. On the basis of this model a numerical simulation has been made to determine the influence of external particle mass transfer, axial dispersion, intraparticle diffusion and adsorption equilibrium on adsorber dynamics.

KINETIC CHARACTERISTICS OF A BATCH ADSORBER OR AN ION EXCHANGE DEVICE OPERATED UNDER NONISOTHERMAL CONDITIONS

Abstract A model was formulated for a batch adsorber or ion exchange device with heat generation inside the bulk liquid due to mixing or electrical heating and due to heat of adsorption. Internal and external particle mass and heat transfer gradients and heat transfer through the vessel wall were included. The effective diffusion coefficient was taken to be temperature dependent. Numerical calculations (by orthogonal collocation) give conditions for the existence of intra particle nonisothermity and show the effect of mixing and process temperature on adsorption kinetics.

Are dual models able to describe large-angle scattering?

The fixed-angle limit of the Mandelstam dual model is proved to behave asdσ/dt≃f(θ)s−n. The powern is a function of the masses of external particles and the slope and intercepts of Regge trajectories coupled to direct and crossed channels. The predicted energy dependence is consistent with experimental data at 90° for fifteen two-body reactions with meson trajectories exchanged in thet-channel. However the angular dependencef(θ) predicted by the Mandelstam model is not in agreement with the experimental dependence. We thus propose generalized Mandelstam amplitudes, giving a very good description of differential cross-sections forpp andpp elastic scattering at high energies and large momentum transfers, and with good theoretical properties: crossing, Regge behaviour, duality and polynomial residues. Differential cross-sections forpp scattering at all angles, the ratio (dσ/dt) pp /(dσ/dt) pp and effective trajectories and residues (in the limitt→−∞) have been successfully compared with experimental data.