Scalar f0(980) and sigma(500) meson exchange in phi decays into pi0pi0gamma

The complementarity between Chiral Perturbation Theory and the Linear Sigma Model is exploited to study $\pi^0\pi^0$ production in $\phi$ radiative decays, where the effects of the $f_0(980)$ scalar resonance, and those of its more controversial $\sigma(500)$ partner, should become manifest via the $\phi\to K^+ K^- (\gamma)\to\pi^0\pi^0\gamma$ decay chain. The recently reported data on $\phi\to\pi^0\pi^0\gamma$ coming from the VEPP-2M $e^+ e^-$ collider in Novosibirsk and the DA$\Phi$NE $\phi$-factory in Frascati can be reasonably described in our approach, which we propose as a promising first step towards more detailed analyses. The $f_0(980)$ contribution, which appears as a moderately narrow peak at the high part of the dipion mass spectrum, can be interpreted as the isoscalar member of the scalar nonet with a large $f_0 K\bar{K}$ coupling and an $f_0\pi\pi$ coupling suppressed by almost ideal $\sigma$-$f_0$ mixing. Indeed, the mixing angle in the flavour basis is found to be $\phi_{S}\approx -6^\circ$, if the $f_0$-propagator is approximated by a simple Breit-Wigner, or $\phi_{S}\approx -9^\circ$, if an improved two-channel analysis is performed. The $\sigma(500)$ resonance, which is then strongly coupled to pion pairs, yields a tiny contribution because, in our approach, its coupling to kaon pairs is proportional to $m^2_\sigma-m^2_K$ and thus quite small.Comment: 18 pages, 4 figures; new treatment of the f0 propagator added and Comments on previous work correcte

Real-time moving object segmentation in H.264 compressed domain based on approximate reasoning

AbstractThis paper presents a real-time segmentation algorithm to obtain moving objects from the H.264 compressed domain. The proposed segmentation works with very little information and is based on two features of the H.264 compressed video: motion vectors associated to the macroblocks and decision modes. The algorithm uses fuzzy logic and allows to describe position, velocity and size of the detected regions in a comprehensive way, so the proposed approach works with low level information but manages highly comprehensive linguistic concepts. The performance of the algorithm is improved using dynamic design of fuzzy sets that avoids merge and split problems. Experimental results for several traffic scenes demonstrate the real-time performance and the encouraging results in diverse situations

Searching for Anomalous Weak Couplings of Heavy Flavors at the SLC and LEP

The existence of anomalous electric($\tilde \kappa$) and/or magnetic($\kappa$) dipole moment couplings between the heavy flavor fermions ($c,b,\tau$) and the $Z$ boson can cause significant shifts in the values of several electroweak observables currently being probed at both the SLC and LEP. Using the good agreement between existing data and the predictions of the Standard Model we obtain strict bounds on the possible strength of these new interactions for all of the heavy flavors. The decay $Z\rightarrow b\bar b$, however, provides some possible hint of new physics. The corresponding anomalous couplings of $\tau$'s to photons is briefly examined.Comment: 21 pages, 14 figs(available on request), LaTex, SLAC-PUB-667

Limits on the Dipole Moments of the τ\tau-Lepton via the Process $e^{+}e^{-}\to \tau^+ \tau^- \gamma in a Left-Right Symmetric Model

Limits on the anomalous magnetic moment and the electric dipole moment of the $\tau$ lepton are calculated through the reaction $e^{+}e^{-}\to \tau^+ \tau^- \gamma$ at the $Z_1$-pole and in the framework of a left-right symmetric model. The results are based on the recent data reported by the L3 Collaboration at CERN LEP. Due to the stringent limit of the model mixing angle $\phi$, the effect of this angle on the dipole moments is quite small.Comment: 15 pages, 3 figure

Quark-hadron duality, axial anomaly and mixing

Interplay between axial anomaly and quark-hadron duality in the presence of strong mixing is considered. The anomaly sum rule for meson transition form factors based on the dispersive representation of axial anomaly and quark-hadron duality in octet channel is analyzed. The comparison of this sum rule to the experimental data on $\eta$ and $\eta'$ mesons transition form factors shows that the interval of duality in this channel is rather small, contradicting the usual understanding of quark-hadron duality. The same values of interval of duality are supported by considering the two-point correlator in the local duality limit. This contradiction may be resolved by introducing of some nonperturbative non-OPE correction to the relevant spectral density. The form and value of this correction are discussed.Comment: 9 pages, 1 figure, reference adde

Three-flavor MSW solutions of the solar neutrino problem

We perform an updated phenomenological analysis of the Mikheyev-Smirnov-Wolfenstein (MSW) solutions of the solar neutrino problem, assuming oscillations between two and three neutrino families. The analysis includes the total rates of the Homestake, SAGE, GALLEX, Kamiokande and Super-Kamiokande experiments, as well as the day-night asymmetry and the 18-bin energy spectrum of Super-Kamiokande. Solutions are found at several values of the theta_{13} mixing angle. Among the most interesting features, we find that solar neutrino data alone put the constraint theta_{13} < 55--59 deg at 95% C.L., and that a fraction of the MSW solutions extends at and beyond maximal (nu_1,nu_2) mixing (theta_{12} > pi/4), especially if the neutrino square mass splitting is in its lower range (m^2_2-m^2_1 ~ 10^{-7} eV^2) and if theta_{13} is nonzero. In particular, bimaximal (or nearly bimaximal) mixing is possible for atmospheric and MSW solar neutrino oscillations within the stringent reactor bounds on theta_{13}.Comment: 19 pages (RevTeX) + 14 figures (PostScript

Mirror matter admixtures in K_L \to \gamma\gamma

Based on possible albeit tiny, admixtures of mirror matter in ordinary mesons we study the K_L \to \gamma\gamma transition. We find that this process can be described with a small SU(3) symmetry breaking of only 3%. We also determine the eta-eta' mixing angle and the pseudoscalar decay constants. The results for these parameters are consistent with some obtained in the literature. They favor two recent determinations; one based on two analytical constraints, and another one based on next-to-leading order power corrections

Can We Observe Weak Anomalous Couplings of Heavy Quarks Through Three Jet Events?

The rates and corresponding jet distributions for the decay $Z\to b\bar bg$ and the process $e^+e^-\to t\bar tg$ may be sensitive to anomalous dipole-like couplings of heavy quarks to the photon and $Z$. In the $b$-quark case, after updating our previous analysis on the constraints imposed by current experiments on $Zb\bar b$ anomalous couplings, we show that the variation of these couplings within their presently allowed ranges leads to rather minor modifications to the Standard Model expectations for $Z\to b\bar bg$ observables. In the $t$-quark case, significant deviations from the Standard Model predictions for $t\bar tg$ production at the Next Linear Collider are possible.Comment: 26 pages with 9 embedded figures; gzipped, uuencoded postscript file. To obtain a copy of this paper send e-mail to [email protected]

Entrapment of citrus limon var. Pompia essential oil or pure citral in liposomes tailored as mouthwash for the treatment of oral cavity diseases

This work aimed at developing a mouthwash based on liposomes loading Citrus limon var. pompia essential oil or citral to treat oropharyngeal diseases. Vesicles were prepared by dispersing phosphatidylcholine and pompia essential oil or citral at increasing amounts (12, 25 and 50 mg/mL) in water. Transparent vesicle dispersions were obtained by direct sonication avoiding the use of organic solvents. Cryogenic transmission electron microscopy (cryo-TEM) confirmed the formation of unilamellar, spherical and regularly shaped vesicles. Essential oil and citral loaded liposomes were small in size (~110 and ~100 nm, respectively) and negatively charged. Liposomes, especially those loading citral, were highly stable as their physico-chemical properties did not change during storage. The formulations were highly biocompatible against keratinocytes, were able to counteract the damages induced in cells by using hydrogen peroxide, and able to increase the rate of skin repair. In addition, liposomes loading citral at higher concentrations inhibited the proliferation of cariogenic bacterium