39 research outputs found
An alternative derivation of the gravitomagnetic clock effect
The possibility of detecting the gravitomagnetic clock effect using
artificial Earth satellites provides the incentive to develop a more intuitive
approach to its derivation. We first consider two test electric charges moving
on the same circular orbit but in opposite directions in orthogonal electric
and magnetic fields and show that the particles take different times in
describing a full orbit. The expression for the time difference is completely
analogous to that of the general relativistic gravitomagnetic clock effect in
the weak-field and slow-motion approximation. The latter is obtained by
considering the gravitomagnetic force as a small classical non-central
perturbation of the main central Newtonian monopole force. A general expression
for the clock effect is given for a spherical orbit with an arbitrary
inclination angle. This formula differs from the result of the general
relativistic calculations by terms of order c^{-4}.Comment: LaTex2e, 11 pages, 1 figure, IOP macros. Submitted to Classical and
Quantum Gravit
Neutron reflection interferometry: physical principles of surface analysis with phase information
It is shown that the analysis of surface layers by neutron reflection interferometry is considerably enhanced by performing the reflectometry with phase information. We discuss two methods of providing such information. One method involves physically adding an extra reference layer, whose amplitude and phase are known theoretically. The other uses the Lloyd\u27s mirror configuration, in which a directly propagating ray that interferes with the reflected ray supplies the phase information. The methods have much in common with holography
Extended Gaussian wave packet dynamics
We examine an extension to the theory of Gaussian wave packet dynamics in a
one-dimensional potential by means of a sequence of time dependent displacement
and squeezing transformations. Exact expressions for the quantum dynamics are
found, and relationships are explored between the squeezed system, Gaussian
wave packet dynamics, the time dependent harmonic oscillator, and wave packet
dynamics in a Gauss-Hermite basis. Expressions are given for the matrix
elements of the potential in some simple cases. Several examples are given,
including the propagation of a non-Gaussian initial state in a Morse potential
Capture rate and neutron helicity asymmetry for ordinary muon capture on hydrogen
Applying heavy-baryon chiral perturbation theory to ordinary muon capture
(OMC) on a proton, we calculate the capture rate and neutron helicity asymmetry
up to next-to-next-to-leading order. For the singlet hyperfine state, we obtain
the capture rate Gamma_0 = 695 sec^{-1} while, for the triplet hyperfine state,
we obtain the capture rate Gamma_1 = 11.9 sec^{-1} and the neutron asymmetry
alpha_1 = 0.93. If the existing formalism is used to relate these atomic
capture rates to Gamma_{liq}, the OMC rate in liquid hydrogen, then Gamma_{liq}
corresponding to our improved values of Gamma_0 and Gamma_1 is found to be
significantly larger than the experimental value, primarily due to the updated
larger value of g_A. We argue that this apparent difficulity may be correlated
to the specious anomaly recently reported for mu^- + p to n + nu_mu + gamma,
and we suggest a possibility to remove these two "problems" simply and
simultaneously by reexamining the molecular physics input that underlies the
conventional analysis of Gamma_{liq}.Comment: 14 pages, 1 figur
Reconstruction of a cold atom cloud by magnetic focusing
No description supplie
Properties of Microelectromagnet Mirrors as Reflectors of Cold Rb Atoms
Cryogenically cooled microelectromagnet mirrors were used to reflect a cloud
of free-falling laser-cooled 85Rb atoms at normal incidence. The mirrors
consisted of microfabricated current-carrying Au wires in a periodic serpentine
pattern on a sapphire substrate. The fluorescence from the atomic cloud was
imaged after it had bounced off a mirror. The transverse width of the cloud
reached a local minimum at an optimal current corresponding to minimum mirror
roughness. A distinct increase in roughness was found for mirror configurations
with even versus odd number of lines. These observations confirm theoretical
predictions.Comment: Physical Review A, in print; 11 pages, 4 figure
Muon Physics: A Pillar of the Standard Model
Since its discovery in the 1930s, the muon has played an important role in
our quest to understand the sub-atomic theory of matter. The muon was the first
second-generation standard-model particle to be discovered, and its decay has
provided information on the (Vector -Axial Vector) structure of the weak
interaction, the strength of the weak interaction, G_F, and the conservation of
lepton number (flavor) in muon decay. The muon's anomalous magnetic moment has
played an important role in restricting theories of physics beyond the standard
standard model, where at present there is a 3.4 standard-deviation difference
between the experiment and standard-model theory. Its capture on the atomic
nucleus has provided valuable information on the modification of the weak
current by the strong interaction which is complementary to that obtained from
nuclear beta decay.Comment: 8 pages, 9 figures. Invited paper for the Journal of Physical Society
in Japan (JPSJ), Special Topics Issue "Frontiers of Elementary Particle
Physics, The Standard Model and beyond
Induced pseudoscalar coupling of the proton weak interaction
The induced pseudoscalar coupling is the least well known of the weak
coupling constants of the proton's charged--current interaction. Its size is
dictated by chiral symmetry arguments, and its measurement represents an
important test of quantum chromodynamics at low energies. During the past
decade a large body of new data relevant to the coupling has been
accumulated. This data includes measurements of radiative and non radiative
muon capture on targets ranging from hydrogen and few--nucleon systems to
complex nuclei. Herein the authors review the theoretical underpinnings of
, the experimental studies of , and the procedures and uncertainties
in extracting the coupling from data. Current puzzles are highlighted and
future opportunities are discussed.Comment: 58 pages, Latex, Revtex4, prepared for Reviews of Modern Physic