2,309 research outputs found
Rare tau Decays in R-parity Violating Supersymmetry
We constrain, from rare tau decays, several combinations of and
type couplings coming from Supersymmetry without R-parity. The
processes that we consider are tau --> l M, tau --> l_i l_j l_k, and tau --> l
gamma, where l stands for either e or mu, and M is the generic symbol for a
meson. We update several existing bounds, and provide a few new ones too.Comment: 12 pages, no figure
Non-critical open strings beyond the semi-classical approximation
We studied the lowest order quantum corrections to the macroscopic wave
functions of non-critical string theory using the
semi-classical expansion of Liouville theory. By carefully taking the perimeter
constraint into account we obtained a new type of boundary condition for the
Liouville field which is compatible with the reparametrization invariance of
the boundary and which is not only a mixture of Dirichlet and Neumann types but
also involves an integral of an exponential of the Liouville field along the
boundary. This condition contains an unknown function of . We
determined this function by computing part of the one-loop corrections to
.Comment: 23 pages, 1 figure, LaTeX file, epsf.st
A novel experiment searching for the lepton flavour violating decay mu -> eee
Since the discovery of neutrino oscillations it is known that lepton flavour
is not conserved. Lepton flavour violating processes in the charged lepton
sector have so far however eluded detection; as they are heavily suppressed in
the standard model of particle physics, an observation would be a clear signal
for new physics and help to understand the source of neutrino masses and CP
violation. We propose a novel experiment searching for the decay mu -> eee with
the aim of ultimately reaching a sensitivity of 10^-16, an improvement by four
orders of magnitude compared to previous experiments. The technologies enabling
this step are thin high-voltage monolithic active pixel sensors for precise
tracking at high rates with a minimum of material and scintillating fibres for
high resolution time measurements.Comment: 4 pages, 3 figures, contribution to NUFACT 11, XIIIth International
Workshop on Neutrino Factories, Super beams and Beta beams, 1-6 August 2011,
CERN and University of Genev
Search for Lepton Flavor Violating Tau Decays into Three Leptons with 719 Million Produced Tau+Tau- Pairs
We present a search for lepton-flavor-violating tau decays into three leptons
(electrons or muons) using 782 fb^-1 of data collected with the Belle detector
at the KEKB asymmetric-energy e+e- collider. No evidence for these decays is
observed and we set 90% confidence level upper limits on the branching
fractions between 1.5 x 10^-8 and 2.7 x 10^-8.Comment: 13 pages, 7 figure
Deterministic cavity quantum electrodynamics with trapped ions
We have employed radio-frequency trapping to localize a single 40Ca+-ion in a high-finesse optical cavity. By means of laser Doppler cooling, the position spread of the ion's wavefunction along the cavity axis was reduced to 42 nm, a fraction of the resonance wavelength of ionized calcium (λ = 397 nm). By controlling the position of the ion in the optical field, continuous and completely deterministic coupling of ion and field was realized. The precise three-dimensional location of the ion in the cavity was measured by observing the fluorescent light emitted upon excitation in the cavity field. The single-ion system is ideally suited to implement cavity quantum electrodynamics under cw conditions. To this end we operate the cavity on the D3/2âP1/2 transition of 40Ca+ (λ = 866 nm). Applications include the controlled generation of single-photon pulses with high efficiency and two-ion quantum gates
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