Double-Lepton Polarization Asymmetries in B_s \rar \phi \ell^+ \ell^- Decay in the Fourth-Generation Standard Model

In this paper, we investigate the effects of the fourth generation of quarks on the double-lepton polarization asymmetries in the B_s \rar \phi \ell^+ \ell^- decay. It is shown that these asymmetries in B_s \rar \phi \ell^+ \ell^- decay compared with those of B \rar K \ell^+ \ell^- decay are more sensitive to the fourth-generation parameters. We conclude that an efficient way to establish the existence of the fourth generation of quarks could be the study of these asymmetries in the B_s \rar \phi \ell^+ \ell^- decay.Comment: 25 pages and 7 figure

A Method to Determine the Tau Neutrino Helicity Using Polarized Taus

A method is presented to extract the tau neutrino helicity, or equivalently, the chirality parameter $\gamma_{\mathrm{VA}}$, independent of any tau polarization which may be present. The method is thus well-suited to measurements using taus produced from the $Z^0$ and is complementary to analyses using tau correlations since it provides the sign of the chirality parameter which is otherwise unavailable without recourse to lower energy experiments where taus are unpolarized. Results of Monte Carlo studies and comments regarding the use of the technique in experiments are also included.Comment: 13 pages, uuencoded postscript fil

Isospin Violation in tau -> 3 pi nu_tau

Isospin violating signals in the tau -> 3 pi nu_tau decay mode are discussed. For the tau -> pi^- pi^- pi^+ nu_tau decay mode, isospin violation arises from the vector current contribution in the tau -> omega pi nu_tau decay with the subsequent isospin violating omega decay into pi^+ pi^-. We demonstrate that such effects may be observed in presently available data through the measurement of the interference effects of these vector current contributions with the dominating axial vector current, i.e. through a measurement of the structure functions W_F,W_G,W_H and W_I. In the case of the tau -> pi^0 pi^0 pi^- nu_tau decay mode, a vector current contribution is generated by eta pi mixing in the decay chain tau -> eta rho nu_tau -> pi^0 pi^0 pi^- nu_tau. We find that this effect is rather small, the magnitude of the associated interference terms being too low for present statistics.Comment: LaTex, 16 pages, 5 figures. The complete paper is also available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ , or via www at http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints

Diffusion in Model Networks as Studied by NMR and Fluorescence Correlation Spectroscopy

We have studied the diffusion of small solvent molecules (octane) and larger hydrophobic dye probes in octane-swollen poly(dimethyl siloxane) linear-chain solutions and end-linked model networks, using pulsed-gradient nuclear magnetic resonance (NMR) and fluorescence correlation spectroscopy (FCS), respectively, focusing on diffusion in the bulk polymer up to the equilibrium degree of swelling of the networks, that is, 4.8 at most. The combination of these results allows for new conclusions on the feasibility of different theories describing probe diffusion in concentrated polymer systems. While octane diffusion shows no cross-link dependence, the larger dyes are increasingly restricted by fixed chemical meshes. The simple Fujita free-volume theory proved most feasible to describe probe diffusion in linear long-chain solutions with realistic parameters, while better fits were obtained assuming a stretched exponential dependence on concentration. Importantly, we have analyzed the cross-link specific effect on probe diffusion independently of any specific model by comparing the best-fit interpolation of the solution data with the diffusion in the networks. The most reasonable description is obtained by assuming that the cross-link effect is additive in the effective friction coefficient of the probes. The concentration dependences as well as the data compared at the equilibrium degrees of swelling indicate that swelling heterogeneities and diffusant shape have a substantial influence on small-molecule diffusion in networks.

Infrastructure for Detector Research and Development towards the International Linear Collider

The EUDET-project was launched to create an infrastructure for developing and testing new and advanced detector technologies to be used at a future linear collider. The aim was to make possible experimentation and analysis of data for institutes, which otherwise could not be realized due to lack of resources. The infrastructure comprised an analysis and software network, and instrumentation infrastructures for tracking detectors as well as for calorimetry.Comment: 54 pages, 48 picture

Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV

A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LQDbar coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This result is translated into lower limits on the masses of charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81 GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the 95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure

The Effects of Fourth Generation on the double Lepton Polarization in B \rar K \ell^+ \ell^- decay

This study investigates the influence of the fourth generation quarks on the double lepton polarizations in B \rar K \ell^+ \ell^- decay. Taking |V_{t's}V_{t'b}|\sim \{0.01-0.03\} with phase about 100^\circ, which is consistent with the b\to s\ell^+\ell^- rate and the B_s mixing parameter Delta m_{B_s}$, we obtain that the double lepton(muon and tau) polarizations are quite sensitive to the existence of fourth generation. It can serve as a good tool to search for new physics effects, precisely, to indirect search for the fourth generation quarks(t', b').Comment: 30 pages, 27 figure

Programme evaluation training for health professionals in francophone Africa: process, competence acquisition and use

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