Top quark production cross-section at the Tevatron Run 2

The top quark pair production cross-section ${\sigma}_{t\bar{t}}$ has been measured in $p\bar{p}$ collisions at center of mass energies of 1.96 TeV using Tevatron Run 2 data. In the begining of Run 2 both CDF and D\O\ $\sigma_{t\bar{t}}$ measurements in the {\it dilepton} channel $t\bar{t}{\to}WbW\bar{b}{\to}\bar{\ell}{\nu}_{\ell}b{\ell}^{'}\ bar{\nu}_{{\ell}^{'}}\bar{b}$and in the {\it lepton plus jets} channel$t\bar{t}{\to}WbW\bar{b}{\to}q\bar{q}^{'}b{\ell}\bar{\nu}_{\ell }\bar{b}+\bar{\ell}{\nu}_{\ell}bq\bar{q}^{'}\bar{b}$ agree with the NLO (Next-to-Leading-Order) theoretical predictions. The presence of a top signal in Tevatron data has been reestablished.Comment: 4 pages, 3 figure

On a static charged fluid around a magnetized mass

We show that any magnetostatic axially symmetric solution of the Einstein-Maxwell equations can be endowed with a specific charged fluid source of the Polanco et al type via a simple procedure requiring the knowledge of exclusively the magnetostatic seed spacetime. Using this procedure we construct yet another exact solution for a massive magnetic dipole surrounded by a static charged fluid which is different from the Polanco et al metric.Comment: 5 pages, no figures, submitted to Physical Review

A combined Majumdar-Papapetrou-Bonnor field as extreme limit of the double-Reissner-Nordstrom solution

The general extreme limit of the double-Reissner-Nordstrom solution is worked out in explicit analytical form involving prolate spheroidal coordinates. We name it the combined Majumdar-Papapetrou-Bonnor field to underline the fact that it contains as particular cases the two-body specialization of the well-known Majumdar-Papapetrou solution and Bonnor's three-parameter electrostatic field. To the latter we give a precise physical interpretation as describing a pair of non-rotating extremal black holes with unequal masses and unequal opposite charges kept apart by a strut, the absolute values of charges exceeding the respective (positive) values of masses.Comment: 10 pages, 3 figures, title changed, the result extended, matching the published versio

Utility analysis : current trends and future directions.

Utility analysis procedures offer organizational decision-makers useful information regarding the relative values of different interventions. Years of research have resulted in a number of practically viable utility models and extensions. There is a continued need for research to examine the accuracy of utility estimates and to further compare the different models. A more recent research concern is that of low levels of acceptance of utility analysis results by practitioners. Many researchers are turning their attention to ways in which this acceptance may be increased. This article reviews different utility models as well as a number of important extensions. It then discusses current utility analysis issues, such as the aforementioned acceptance problem and the introduction of a multi-attribute utility model. The article concludes with suggestions for future utility analysis researchUtility theory; Mathematical models; Decision making;

Talbot effect for dispersion in linear optical fibers and a wavelet approach

We shortly recall the mathematical and physical aspects of Talbot's self-imaging effect occurring in near-field diffraction. In the rational paraxial approximation, the Talbot images are formed at distances z=p/q, where p and q are coprimes, and are superpositions of q equally spaced images of the original binary transmission (Ronchi) grating. This interpretation offers the possibility to express the Talbot effect through Gauss sums. Here, we pay attention to the Talbot effect in the case of dispersion in optical fibers presenting our considerations based on the close relationships of the mathematical representations of diffraction and dispersion. Although dispersion deals with continuous functions, such as gaussian and supergaussian pulses, whereas in diffraction one frequently deals with discontinuous functions, the mathematical correspondence enables one to characterize the Talbot effect in the two cases with minor differences. In addition, we apply, for the first time to our knowledge, the wavelet transform to the fractal Talbot effect in both diffraction and fiber dispersion. In the first case, the self similar character of the transverse paraxial field at irrational multiples of the Talbot distance is confirmed, whereas in the second case it is shown that the field is not self similar for supergaussian pulses. Finally, a high-precision measurement of irrational distances employing the fractal index determined with the wavelet transform is pointed outComment: 15 text pages + 7 gif figs, accepted at Int. J. Mod. Phys. B, final version of a contribution at ICSSUR-Besancon (May/05). Color figs available from the first autho

Formation of ϕ\phi mesic nuclei

We study the structure and formation of the $\phi$ mesic nuclei to investigate the in-medium modification of the $\phi$-meson spectral function at finite density. We consider (${\bar p},\phi$), ($\gamma,p$) and ($\pi^-,n$) reactions to produce a $\phi$-meson inside the nucleus and evaluate the effects of its medium modifications to the reaction cross sections. We also estimate the consequences of the uncertainties of the ${\bar K}$ selfenergy in medium to the $\phi$-nucleus interaction. We find that it may be possible to see a peak structure in the reaction spectra for the strong attractive potential cases. On the other hand, for strong absorptive interaction cases with relatively weak attractions, it is very difficult to observe clear peaks and we may need to know the spectrum shape in a wide energy region to deduce the properties of $\phi$.Comment: 11 pages, 8 figure