Observation of B_s Production at the Y(5S) Resonance

Using the CLEO detector at the Cornell Electron Storage Ring, we have observed the B_s meson in e^+e^- annihilation at the Υ(5S) resonance. We find 14 candidates consistent with B_s decays into final states with a J/ψ or a D_s^((*)-). The probability that we have observed a background fluctuation is less than 8×10^(-10). We have established that at the energy of the Υ(5S) resonance B_s production proceeds predominantly through the creation of B_s^*B̅ _s^* pairs. We find σ(e^+e^-→B^s^*B̅ ^*)=[0.11_(-0.03)^(+0.04)(stat)±0.02(syst)]  nb, and set the following limits: σ(e^+e^-→B_sB̅ _s)/σ(e^+e^-→B_s^*B̅ _s^*)<0.16 and [σ(e^+e^-→B_sB̅ _s^*)+σ(e^+e^-→B_s*B̅ _s)]/σ(e^+e^-→B_s*B̅ _s^*)<0.16 (90% C.L.). The mass of the B_s^* meson is measured to be M_(B_s^*=[5.414±0.001(stat)±0.003(syst)]  GeV/c^2

First Measurement of the Electromagnetic Form Factor of the Neutral Kaon at a Large Momentum Transfer and the Effect of SU(3)SU(3) Breaking

At large momentum transfers the photon interacts with the charges and spins of the constituent partons in a hadron. It is expected that the neutral kaon can acquire finite electromagnetic form factors because its wave function is affected by the order of magnitude difference between the mass of the strange quark and that of the down quark, or flavor $SU(3)$ breaking. We report on the first measurement of the form factor of neutral kaons at the large timelike momentum transfer of $|Q^2|=17.4$ GeV$^2$ by measuring the cross section for $e^+e^-\to K_SK_L$ at $\sqrt{s}=4.17$ GeV using CLEO-c data with an integrated luminosity of 586 pb$^{-1}$. We obtain $F_{K_SK_L}(17.4~\textrm{GeV}^2)=5.3\times10^{-3}$, with a 90% C.L. interval of $(2.9-8.2)\times10^{-3}$. This is nearly an order of magnitude smaller than $F_{K^+K^-}(17.4~\textrm{GeV}^2)=(44\pm1)\times10^{-3}$, and indicates that the effect of $SU(3)$ breaking is small. In turn, this makes it unlikely that the recently observed strong violation of the pQCD prediction, $F_{\pi^+\pi^-}(|Q^2|)/F_{K^+K^-}(|Q^2|)=f_\pi^2/f_K^2$, which is based on the assumption of similar wave functions for the pions and kaons, can be attributed to $SU(3)$ breaking alone.Comment: 4 pages, 2 figures, accepted to PL

Primitive one-factorizations and the geometry of mixed translations

AbstractWe construct an infinite family of one-factorizations of Kv admitting an automorphism group acting primitively on the set of vertices but no such group acting doubly transitively. We also give examples of one-factorizations which are live, in the sense that every one-factor induces an automorphism, but do not coincide with the affine line parallelism of AG(n,2). To this purpose we develop the notion of a “mixed translation” in AG(n,2)

Low-energy solar anti-neutrinos

If neutrino conversions within the Sun result in partial polarization of initial solar neutrino fluxes, then a new opportunity arises to observe the anti-\nu_e's in future neutrino experiments in the low energy region (such as BOREXINO or HELLAZ) and thus to probe the Majorana nature of the neutrinos. The \nu_e -> anti-\nu_e conversions may take place for low energy solar neutrinos while being unobservable at the Kamiokande and Super-Kamiokande experiments.Comment: Talk given at TAUP 97, Gran Sasso, Italy, Sep. 1997; LaTeX, 3 pages, 1 postscript figure, uses espcrc2.st

Scanning Electron Microscopy in the Study of Campylobacter Pylori Associated Gastritis

The close association between Campylobacter pylori (CP), gastritis and peptic ulcer is now well established. Moreover increasing evidence has been collected of a major etiological role of CP in type B chronic gastritis. For this reason, searching for CP is essential in all patients with upper gastrointestinal symptoms. Scanning electron microscopy (SEM) is a most reliable technique for studying the distribution of microorganisms and their relationship to the gastric mucosal surface. The aim of this paper is to compare SEM to other routine methods of detection for CP, such as Giemsa staining on histological sections and Urease Microtiter Test (MT) on fresh tissue and to investigate the surface morphology of gastric mucosa colonized by CP and to correlate it with the histopathological picture. Thirty-seven biopsies taken from the gastric body and the antrum of 22 patients were used for each type of determination. The different parameters were graded semiquantitatively. Histology showed a normal mucosa in 4 cases, chronic superficial gastritis in 12 and chronic atrophic gastritis in 21 cases. SEM was more sensitive than histology and Urease MT in detecting Campylobacter pylori. This is due to the patchy distribution of this bacterium on gastric mucosa. For this reason SEM should always be performed when routine tests are negative. The presence of CP correlated significantly (p \u3c 0.001, Spearman Rank Correlation Test) with the neutrophilic infiltrate, thus with the activity of the gastritis. The CP associated gastritis has no distinctive surface features other than the presence of the bacterium SEM morphology of surface gastric mucous cells suggests that CP does not damage the lining epithelium directly. Neutrophils and inflammatory mediators could be involved in the production of the mucosal lesions