20 research outputs found
Multiple cavity experiments to detect parity nonconservation in atomic hydrogen
We develop general guidelines and criteria for designing and evaluating beam experiments which use Ramsey's method of separated oscillating fields to detect PNC (parity nonconserving) effects in atomic hydrogen. We find that variation of the relative radio-frequency phases between different field configurations may offer distinct advantages in measuring and processing expected PNC data. We evaluate several specific experiments employing such multiple region designs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23951/1/0000198.pd
Memory Effects in Spontaneous Emission Processes
We consider a quantum-mechanical analysis of spontaneous emission in terms of
an effective two-level system with a vacuum decay rate and
transition angular frequency . Our analysis is in principle exact,
even though presented as a numerical solution of the time-evolution including
memory effects. The results so obtained are confronted with previous
discussions in the literature. In terms of the {\it dimensionless} lifetime
of spontaneous emission, we obtain deviations from
exponential decay of the form for the decay amplitude as
well as the previously obtained asymptotic behaviors of the form or for . The actual
asymptotic behavior depends on the adopted regularization procedure as well as
on the physical parameters at hand. We show that for any reasonable range of
and for a sufficiently large value of the required angular frequency
cut-off of the electro-magnetic fluctuations, i.e. , one obtains either a or a
dependence. In the presence of physical boundaries, which can change the decay
rate with many orders of magnitude, the conclusions remains the same after a
suitable rescaling of parameters.Comment: 13 pages, 5 figures and 46 reference
Atoms in Flight and the Remarkable Connections between Atomic and Hadronic Physics
Atomic physics and hadron physics are both based on Yang Mills gauge theory;
in fact, quantum electrodynamics can be regarded as the zero-color limit of
quantum chromodynamics. I review a number of areas where the techniques of
atomic physics provide important insight into the theory of hadrons in QCD. For
example, the Dirac-Coulomb equation, which predicts the spectroscopy and
structure of hydrogenic atoms, has an analog in hadron physics in the form of
light-front relativistic equations of motion which give a remarkable first
approximation to the spectroscopy, dynamics, and structure of light hadrons.
The renormalization scale for the running coupling, which is unambiguously set
in QED, leads to a method for setting the renormalization scale in QCD. The
production of atoms in flight provides a method for computing the formation of
hadrons at the amplitude level. Conversely, many techniques which have been
developed for hadron physics, such as scaling laws, evolution equations, and
light-front quantization have equal utility for atomic physics, especially in
the relativistic domain. I also present a new perspective for understanding the
contributions to the cosmological constant from QED and QCD.Comment: Presented at EXA2011, the International Conference on Exotic Atoms
and Related Topics, Vienna, September 5-9, 201
DISSOCIATIVE EXCITATION OF MOLECULAR HYDROGEN.
Author Institution: Department of Physics, The University of MichiganThe velocity spectrum of metastable H(2S) atoms produced by electron bombardment of has been measured by a time-of-flight technique. Two distinct groups of metastables have been detected. The slower atoms are interpreted as arising from transitions to attractive states just above the H(1S)+H(2S) dissociation limit. The absence of very slow atoms may indicate maxima in the relevant excited state potential curves at large internuclear separation. The faster atoms probably arise from transitions to doubly excited repulsive states, such as , The fast atom spectrum shows a strong dependence on observation angle