1,654 research outputs found
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 - and -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
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 W cm
GHz at 10 km from the shower core for a vertical shower induced by a
proton of 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 Quark hiding the Top: Tevatron and LEP Implications
If and quarks are strongly mixed with a weak singlet charge
quark, could be suppressed via the mode,
thereby the top quark could still hide below , whereas the heavy quark
signal observed at the Tevatron is due to the dominantly singlet quark .
This may occur without affecting the small value. Demanding GeV and m_t \ltap M_W, we find that cannot be too
suppressed. The heavy quark decays via , and bosons. The latter
can lead to -tagged jet events, while the strong -- mixing is
reflected in sizable fraction. decay occurs at tree
level and may be at the order, leading to the signature of , all isolated and with large , at order.Comment: 10 pages + 3 Figures (not included), ReVTeX, NTUTH-94-1
Production of scalar molecules in radiative decays
The potentialities of the production of the scalar molecules in the
radiative decays are considered beyond the narrow resonance width
approximation. It is shown that $BR(\phi\rightarrow\gamma
f_0(a_0)\rightarrow\gamma\pi\pi(\pi\eta))\approx (1\div 2)\times 10^{-5}\
,\BR(\phi\rightarrow\gamma (f_0+a_0)\rightarrow\gamma K^+K^-)\alt 10^{-6}BR(\phi\rightarrow\gamma (f_0+a_0) \to \gamma K^0\bar K^0)\alt 10^{-8}\pi\pi\ ,\ \pi\eta\ ,\ K^+K^-\ ,\ K^0\bar K^0\phi\rightarrow\gamma
f_0(a_0)e^+e^-\rightarrow\gamma \pi^+\pi^-\phi$ 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
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