Design and expected performance of the ANTARES neutrino telescope

The ANTARES Collaboration is aiming at the construction and the operation of a large undersea neutrino telescope for neutrino astronomy, neutrino oscillation and indirect dark matter searches. Started 3 years ago an intensive R&D program has shown the feasibility of such a detector in the deep waters of the Mediterranean sea. We have now started the design and the construction of a 0.1 km(^{2}) detector for which the expected performance will be briefly described here.Comment: Talk given at TAUP99, the Sixth International Workshop on Topics in Astroparticle and Underground Physics, College de France, Paris, France, September 6-10, 1999 3 page

EUSO duty cycle : moon and sun light effects

The major limitation on the EUSO duty cycle comes from the fraction of the time the field of view will be exposed to the sun light or to the moon light. A further limitation could come from the fact that the telescope shutter might have to be closed also when the ISS itself is exposed to either light source. We compute the year averaged duty cycle due to the light-shadow effect under different conditions, taking into account the exact position of the ISS, the sun and the moon minute per minute. This fine time step prediction allows also computing the distribution of the shutter opening times which can be as small as 1 minute

Can new heavy gauge bosons be observed in ultra-high energy cosmic neutrino events?

A wide range of models beyond the Standard Model predict charged and neutral resonances, generically called $W'$- and $Z'$-bosons, respectively. In this paper we study the impact of such resonances on the deep inelastic scattering of ultra-high energy neutrinos as well as on the resonant charged current $\bar\nu_e e^-$ scattering (Glashow resonance). We find that the effects of such resonances can not be observed with the Pierre Auger Observatory or any foreseeable upgrade of it.Comment: 5 pages, 2 figure

Molecular Bremsstrahlung Radiation at GHz Frequencies in Air

A detection technique for ultra-high energy cosmic rays, complementary to the fluorescence technique, would be the use of the molecular Bremsstrahlung radiation emitted by low-energy ionization electrons left after the passage of the showers in the atmosphere. In this article, a detailed estimate of the spectral intensity of photons at ground level originating from this radiation is presented. The spectral intensity expected from the passage of the high-energy electrons of the cascade is also estimated. The absorption of the photons in the plasma of electrons/neutral molecules is shown to be negligible. The obtained spectral intensity is shown to be $2\times10^{-21}$W cm$^{-2}$ GHz$^{-1}$ at 10 km from the shower core for a vertical shower induced by a proton of $10^{17.5}$ eV. In addition, a recent measurement of Bremsstrahlung radiation in air at gigahertz frequencies from a beam of electrons produced at 95 keV by an electron gun is also discussed and reasonably reproduced by the model.Comment: 20 pages, 9 figures, figures (2,4,7) improved in v2, accepted by Phys. Rev.

Mixing of Xi_c and Xi_c' Baryons

The mixing angle between the Xi_c and Xi_c' baryons is shown to be small, with a negligible shift in the Xi_c masses.Comment: One missprint corrected. The numerator of Eq. (12) should read {2[(Sigma_c^{*++}-Sigma_c^{++})-(Xi_c^{*+}-Xi_c^{'+})]} The correct equation was used in the calculation so no other change is mad

Singlet Charge 2/32/3 Quark hiding the Top: Tevatron and LEP Implications

If $c$ and $t$ quarks are strongly mixed with a weak singlet charge $2/3$ quark, $BR(t\to \ell\nu + X)$ could be suppressed via the $t\to cH^0$ mode, thereby the top quark could still hide below $M_W$, whereas the heavy quark signal observed at the Tevatron is due to the dominantly singlet quark $Q$. This may occur without affecting the small $m_c$ value. Demanding $m_Q \simeq 175$ GeV and m_t \ltap M_W, we find that $BR(t\to \ell\nu + X)$ cannot be too suppressed. The heavy quark $Q$ decays via $W,\ H$, and $Z$ bosons. The latter can lead to $b$-tagged $Z + 4$ jet events, while the strong $c$--$Q$ mixing is reflected in sizable $Q\to sW$ fraction. $Z\to t\bar c$ decay occurs at tree level and may be at the $10^{-3}$ order, leading to the signature of $Z\to \ell\nu b\bar c$, all isolated and with large $p_T$, at $10^{-5}$ order.Comment: 10 pages + 3 Figures (not included), ReVTeX, NTUTH-94-1

Production of scalar KKˉK\bar K molecules in ϕ\phi radiative decays

The potentialities of the production of the scalar $K\bar K$ molecules in the $\phi$ radiative decays are considered beyond the narrow resonance width approximation. It is shown that $BR(\phi\rightarrow\gamma f_0(a_0)\rightarrow\gamma\pi\pi(\pi\eta))\approx (1\div 2)\times 10^{-5}\ ,\BR(\phi\rightarrow\gamma (f_0+a_0)\rightarrow\gamma K^+K^-)\alt 10^{-6}$and$BR(\phi\rightarrow\gamma (f_0+a_0) \to \gamma K^0\bar K^0)\alt 10^{-8}$. The mass spectra in the$\pi\pi\ ,\ \pi\eta\ ,\ K^+K^-\ ,\ K^0\bar K^0$channels are calculated. The imaginary part of the amplitude$\phi\rightarrow\gamma f_0(a_0)$is calculated analytically. It is obtained the phase of the scalar resonance production amplitude that causes the interference patterns in the reaction$e^+e^-\rightarrow\gamma \pi^+\pi^-$in the$\phi$ meson mass region.Comment: 19 pages, revtex, 4 eps files of figure

Diquark-Antidiquarks with Hidden or Open Charm and the Nature of X(3872)

Heavy-light diquarks can be the building blocks of a rich spectrum of states which can accommodate some of the newly observed charmonium-like resonances not fitting a pure c-cbar assignment. We examine this possibility for hidden and open charm diquark-antidiquark states deducing spectra from constituent quark masses and spin-spin interactions. Taking the X(3872) as input we predict the existence of a 2++ state that can be associated to the X(3940) observed by Belle and re-examine the state claimed by SELEX, X(2632). The possible assignment of the previously discovered states D_s(2317) and D_s(2457) is discussed. We predict X(3872) to be made of two components with a mass difference related to (m_u-m_d) and discuss the production of X(3872) and of its charged partner X^(+-) in the weak decays of B^(+,0).Comment: 11 pages, 2 figures, revtex, minor typos correcte