38,698 research outputs found
A theoretical study of the propagation and attenuation of acoustic waves in the lunar surface Interim report
Acoustic wave propagation and attenuation in lunar space environmen
Lorentz Violation and Short-Baseline Neutrino Experiments
A general discussion is given of signals for broken Lorentz symmetry in
short-baseline neutrino experiments. Among the effects that Lorentz violation
can introduce are a dependence on energy differing from that of the usual
massive-neutrino solution and a dependence on the direction of neutrino
propagation. Using the results of the LSND experiment, explicit analysis of the
effects of broken Lorentz symmetry yields a nonzero value (3+/-1) x 10^{-19}
GeV for a combination of coefficients for Lorentz violation. This lies in the
range expected for effects originating from the Planck scale in an underlying
unified theory.Comment: 4 pages REVTe
Role of phi decays for K- yields in relativistic heavy-ion collisions
The production of strange mesons in collisions of Ar+KCl at a kinetic beam
energy of 1.756 AGeV is studied within a transport model of
Boltzmann-\"Uhling-Uhlenbeck (BUU) type. In particular, and
yields and spectra are compared to the data mesured recently by the HADES
collaboration and the yield measured previously by the FOPI
collaboration. Our results are in agreement with these data thus presenting an
interpretation of the subleading role of decays into 's and
confirming the importance of the strangeness-exchange channels for
production.Comment: 24 pages, 19 figure
Quantum Weakly Nondeterministic Communication Complexity
We study the weakest model of quantum nondeterminism in which a classical
proof has to be checked with probability one by a quantum protocol. We show the
first separation between classical nondeterministic communication complexity
and this model of quantum nondeterministic communication complexity for a total
function. This separation is quadratic.Comment: 12 pages. v3: minor correction
Momentum-Resolved Ultrafast Electron Dynamics in Superconducting Bi2Sr2CaCu2O8+delta
The non-equilibrium state of the high-Tc superconductor Bi2Sr2CaCu2O8+delta
and its ultrafast dynamics have been investigated by femtosecond time- and
angle-resolved photoemission spectroscopy well below the critical temperature.
We probe optically excited quasiparticles at different electron momenta along
the Fermi surface and detect metastable quasiparticles near the antinode. Their
decay through e-e scattering is blocked by a phase space restricted to the
nodal region. The lack of momentum dependence in the decay rates is in
agreement with relaxation dominated by Cooper pair recombination in a boson
bottleneck limit
Field Errors Decay and "Snap-Back" in LHC Model Dipoles
The magnetic field in accelerator magnets decays when the current is kept constant during the particles injection phase, and returns quickly (snaps back) to the original values as soon as ramping is restarted. Here we show results of measurements of the decay of the field errors in 10 m long LHC model dipole magnets. In accordance with previous findings, precycles and stops at intermediate current levels influence the decay. We discuss a possible mechanism causing the decay and snap-back, based on the internal field change in the cable
Photon Bunching at TeV Energies
Harwit, Protheroe, and Biermann (1999) recently proposed that Bose-Einstein
photon bunching might significantly affect the interpretation of Cerenkov
counts of TeV gamma photons. Here, we show that a combination of two recent
results of Aharonian et al. (2000) and Aharonian et al. (2001) permits us to
set new, more stringent upper limits of on the fractional amount
of photon bunching in the 7-10 TeV radiation from Markarian 501. Potential
bunching at even higher energies should nevertheless continue to be
investigated for this and other TeV sources, since a clear understanding of TeV
energy spectra is required to unambiguously determine the spectral energy
density of the mid-infrared extragalactic background
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