4,328 research outputs found
Nuclear Deformation Effects in the Cluster Radioactivity
We investigate the influence of the nuclear deformation on the decay rates of
some cluster emission processes. The interaction between the daughter and the
cluster is given by a double folding potential including quadrupole and
hexadecupole deformed densities of both fragments. The nuclear part of the
nucleus-nucleus interaction is density dependent and at small distances a
repulsive core in the potential will occur. In the frame of the
WKB-approximation the assault frequency of the cluster will depend on the
geometric properties of the potential pocket whereas the penetrability will be
sensitive to changes in the barrier location. The results obtained in this
paper point out that various combinations of cluster and daughter deformations
may account for the measured values of the decay rate.T he decay rather are
however more sensitive to the changes in the daughter deformation due to the
large mass asymmetry of the process.Comment: 11 pages, 6 figure
Simulating Supersymmetry with ISAJET 7.0/ ISASUSY 1.0
We review the physics assumptions and input used in ISAJET~7.0 /
ISA\-SUSY~1.0 that are relevant for simulating fundamental processes within the
framework of the Minimal Supersymmetric Standard Model (MSSM) at and
colliders. After a brief discussion of the underlying MSSM framework, we
discuss event simulation and list the sparticle production processes and decay
modes that have been incorporated into our calculations. We then describe how
to set up and run an ISAJET / ISASUSY job and the user input and output
formats. The ISAJET program is sufficiently flexible that some non-minimal
supersymmetry scenarios may be simulated as well. Finally, plans for future
upgrades which include the extension to collisions, are listed.Comment: 17 pages, FSU-HEP-930329 UH-511-764-9
Pion-Pion Phase-Shifts and the Value of Quark-Antiquark Condensate in the Chiral Limit
We use low energy pion-pion phase-shifts in order to make distinction between
the alternatives for the value of the quark-antiquark condensate in the
chiral limit. We will consider the amplitude up to and including contributions within the Standard and Generalized Chiral Perturbation
Theory frameworks. They are unitarized by means of Pad\'e approximants in order
to fit experimental phase-shifts in the resonance region. As the best fits
correspond to , we conclude that pion-pion phase-shift
analysis favors the standard ChPT scenario, which assumes just one, large
leading order parameter .Comment: 5 pages, 3 figures and 1 tabl
Sliding mode control of quantum systems
This paper proposes a new robust control method for quantum systems with
uncertainties involving sliding mode control (SMC). Sliding mode control is a
widely used approach in classical control theory and industrial applications.
We show that SMC is also a useful method for robust control of quantum systems.
In this paper, we define two specific classes of sliding modes (i.e.,
eigenstates and state subspaces) and propose two novel methods combining
unitary control and periodic projective measurements for the design of quantum
sliding mode control systems. Two examples including a two-level system and a
three-level system are presented to demonstrate the proposed SMC method. One of
main features of the proposed method is that the designed control laws can
guarantee desired control performance in the presence of uncertainties in the
system Hamiltonian. This sliding mode control approach provides a useful
control theoretic tool for robust quantum information processing with
uncertainties.Comment: 18 pages, 4 figure
Precision Measurement of the π+→e+νe Branching Ratio in the PIENU Experiment
The PIENU experiment at TRIUMF aims to measure the branching ratio of the pion decay modes Rπ=[π+→e+νe(γ)]/[π+→μ+νμ(γ)] with precision of <0.1%.
Precise measurement of RÏ€ provides a stringent test of electron-muon universality in weak interactions. The current status of the PIENU experiment and future prospects are presented
Improved Search for Heavy Neutrinos in the Decay
A search for massive neutrinos has been made in the decay . No evidence was found for extra peaks in the positron energy spectrum
indicative of pion decays involving massive neutrinos (). Upper limits (90 \% C.L.) on the neutrino mixing matrix element
in the neutrino mass region 60--135 MeV/ were set, which are
%representing an order of magnitude improvement over previous results
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