43 research outputs found
Improved Study of the Antiprotonic Helium Hyperfine Structure
We report the initial results from a systematic study of the hyperfine (HF)
structure of antiprotonic helium (n,l) = (37,~35) carried out at the Antiproton
Decelerator (AD) at CERN. We performed a laser-microwave-laser resonance
spectroscopy using a continuous wave (cw) pulse-amplified laser system and
microwave cavity to measure the HF transition frequencies. Improvements in the
spectral linewidth and stability of our laser system have increased the
precision of these measurements by a factor of five and reduced the line width
by a factor of three compared to our previous results. A comparison of the
experimentally measured transition frequencies with three body QED calculations
can be used to determine the antiproton spin magnetic moment, leading towards a
test of CPT invariance.Comment: 14 pages 9 figure
Angular distributions of scattered excited muonic hydrogen atoms
Differential cross sections of the Coulomb deexcitation in the collisions of
excited muonic hydrogen with the hydrogen atom have been studied for the first
time. In the framework of the fully quantum-mechanical close-coupling approach
both the differential cross sections for the transitions and
-averaged differential cross sections have been calculated for exotic atom
in the initial states with the principle quantum number at relative
motion energies eV and at scattering angles
. The vacuum polarization shifts of the
-states are taken into account. The calculated in the same approach
differential cross sections of the elastic and Stark scattering are also
presented. The main features of the calculated differential cross sections are
discussed and a strong anisotropy of cross sections for the Coulomb
deexcitation is predicted.Comment: 5 pages, 9 figure
Gauge Field Formulation of Adiabatic Spin Torques
Previous calculation of spin torques for small-amplitude magnetization
dynamics around a uniformly magnetized state [J. Phys. Soc. Jpn. {\bf 75}
(2006) 113706] is extended here to the case of finite-amplitude dynamics. This
is achieved by introducing an `` adiabatic'' spin frame for conduction
electrons, and the associated SU(2) gauge field. In particular, the Gilbert
damping is shown to arise from the time variation of the spin-relaxation source
terms in this new frame, giving a new physical picture of the damping. The
present method will allow a `` first-principle'' derivation of spin torques
without any assumptions such as rotational symmetry in spin space.Comment: 4 pages, 3 figure
Variational calculations for the hydrogen-antihydrogen system with a mass-scaled Born-Oppenheimer potential
The problem of proton-antiproton motion in the --
system is investigated by means of the variational method. We introduce a
modified nuclear interaction through mass-scaling of the Born-Oppenheimer
potential. This improved treatment of the interaction includes the nondivergent
part of the otherwise divergent adiabatic correction and shows the correct
threshold behavior.
Using this potential we calculate the vibrational energy levels with angular
momentum 0 and 1 and the corresponding nuclear wave functions, as well as the
S-wave scattering length. We obtain a full set of all bound states together
with a large number of discretized continuum states that might be utilized in
variational four-body calculations. The results of our calculations gives an
indication of resonance states in the hydrogen-antihydrogen system