95 research outputs found
Collective T- and P- Odd Electromagnetic Moments in Nuclei with Octupole Deformations
Parity and time invariance violating forces produce collective P- and T- odd
moments in nuclei with static octupole deformation. Collective Schiff moment,
electric octupole and dipole and also magnetic quadrupole appear due to the
mixing of rotational levels of opposite parity and can exceed single-particle
moments by more than a factor of 100. This enhancement is due to two factors,
the collective nature of the intrinsic moments and the small energy separation
between members of parity doublets. The above moments induce T- and P- odd
effects in atoms and molecules. Experiments with such systems may improve
substantially the limits on time reversal violation.Comment: 9 pages, Revte
Time invariance violating nuclear electric octupole moments
The existence of a nuclear electric octupole moment (EOM) requires both
parity and time invariance violation. The EOMs of odd nuclei that are
induced by a particular T- and P-odd interaction are calculated. We compare
such octupole moments with the collective EOMs that can occur in nuclei having
a static octupole deformation. A nuclear EOM can induce a parity and time
invariance violating atomic electric dipole moment, and the magnitude of this
effect is calculated. The contribution of a nuclear EOM to such a dipole moment
is found, in most cases, to be smaller than that of other mechanisms of atomic
electric dipole moment production.Comment: Uses RevTex, 25 page
Calculation of parity and time invariance violation in the radium atom
Parity (P) and time (T) invariance violating effects in the Ra atom are
strongly enhanced due to close states of opposite parity, the large nuclear
charge Z and the collective nature of P,T-odd nuclear moments. We have
performed calculations of the atomic electric dipole moments (EDM) produced by
the electron EDM and the nuclear magnetic quadrupole and Schiff moments. We
have also calculated the effects of parity non-conservation produced by the
nuclear anapole moment and the weak charge. Our results show that as a rule the
values of these effects are much larger than those considered so far in other
atoms (enhancement is up to 10^5 times).Comment: 18 pages; LaTeX; Submitted to Phys. Rev.
Nuclear Octupole Correlations and the Enhancement of Atomic Time-Reversal Violation
We examine the time-reversal-violating nuclear ``Schiff moment'' that induces
electric dipole moments in atoms. After presenting a self-contained derivation
of the form of the Schiff operator, we show that the distribution of Schiff
strength, an important ingredient in the ground-state Schiff moment, is very
different from the electric-dipole-strength distribution, with the Schiff
moment receiving no strength from the giant dipole resonance in the
Goldhaber-Teller model. We then present shell-model calculations in light
nuclei that confirm the negligible role of the dipole resonance and show the
Schiff strength to be strongly correlated with low-lying octupole strength.
Next, we turn to heavy nuclei, examining recent arguments for the strong
enhancement of Schiff moments in octupole-deformed nuclei over that of 199Hg,
for example. We concur that there is a significant enhancement while pointing
to effects neglected in previous work (both in the octupole-deformed nuclides
and 199Hg) that may reduce it somewhat, and emphasizing the need for
microscopic calculations to resolve the issue. Finally, we show that static
octupole deformation is not essential for the development of collective Schiff
moments; nuclei with strong octupole vibrations have them as well, and some
could be exploited by experiment.Comment: 25 pages, 4 figures embedded in tex
Nearby Doorways, Parity Doublets and Parity Mixing in Compound Nuclear States
We discuss the implications of a doorway state model for parity mixing in
compound nuclear states. We argue that in order to explain the tendency of
parity violating asymmetries measured in Th to have a common sign,
doorways that contribute to parity mixing must be found in the same energy
neighbourhood of the measured resonance. The mechanism of parity mixing in this
case of nearby doorways is closely related to the intermediate structure
observed in nuclear reactions in which compound states are excited. We note
that in the region of interest (Th) nuclei exhibit octupole
deformations which leads to the existence of nearby parity doublets. These
parity doublets are then used as doorways in a model for parity mixing. The
contribution of such mechanism is estimated in a simple model.Comment: 11 pages, REVTE
Electric dipole moments of Hg, Xe, Rn, Ra, Pu, and TlF induced by the nuclear Schiff moment and limits on time-reversal violating interactions
We have calculated the atomic electric dipole moments (EDMs) induced in
^{199}Hg, ^{129}Xe, ^{223}Rn, ^{225}Ra, and ^{239}Pu by their respective
nuclear Schiff moments S. The results are (in units 10^{-17}S(e {fm}^{3})^{-1}e
cm): d(^{199}Hg)=-2.8, d(^{129}Xe)=0.38, d(^{223}Rn)=3.3, d(^{225}Ra)=-8.5,
d(^{239}Pu)=-11. We have also calculated corrections to the parity- and
time-invariance-violating (P,T-odd) spin-axis interaction constant in TlF.
These results are important for the interpretation of atomic and molecular
experiments on EDMs in terms of fundamental P,T-odd parameters.Comment: 16 page
A Novel Mutation in the Upstream Open Reading Frame of the CDKN1B Gene Causes a MEN4 Phenotype
PubMed ID: 23555276This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation
The current status of electric dipole moments of diamagnetic atoms which
involves the synergy between atomic experiments and three different theoretical
areas -- particle, nuclear and atomic is reviewed. Various models of particle
physics that predict CP violation, which is necessary for the existence of such
electric dipole moments, are presented. These include the standard model of
particle physics and various extensions of it. Effective hadron level combined
charge conjugation (C) and parity (P) symmetry violating interactions are
derived taking into consideration different ways in which a nucleon interacts
with other nucleons as well as with electrons. Nuclear structure calculations
of the CP-odd nuclear Schiff moment are discussed using the shell model and
other theoretical approaches. Results of the calculations of atomic electric
dipole moments due to the interaction of the nuclear Schiff moment with the
electrons and the P and time-reversal (T) symmetry violating
tensor-pseudotensor electron-nucleus are elucidated using different
relativistic many-body theories. The principles of the measurement of the
electric dipole moments of diamagnetic atoms are outlined. Upper limits for the
nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained
combining the results of atomic experiments and relativistic many-body
theories. The coefficients for the different sources of CP violation have been
estimated at the elementary particle level for all the diamagnetic atoms of
current experimental interest and their implications for physics beyond the
standard model is discussed. Possible improvements of the current results of
the measurements as well as quantum chromodynamics, nuclear and atomic
calculations are suggested.Comment: 46 pages, 19 tables and 16 figures. A review article accepted for
EPJ
A neurally-inspired musical instrument classification system based upon the sound onset
Physiological evidence suggests that sound onset detection in the auditory system may be performed by specialized neurons as early as the cochlear nucleus. Psychoacoustic evidence shows that the sound onset can be important for the recognition of musical sounds. Here the sound onset is used in isolation to form tone descriptors for a musical instrument classification task. The task involves 2085 isolated musical tones from the McGill dataset across five instrument categories. A neurally inspired tone descriptor is created using a model of the auditory system's response to sound onset. A gammatone filterbank and spiking onset detectors, built from dynamic synapses and leaky integrate-and-fire neurons, create parallel spike trains that emphasize the sound onset. These are coded as a descriptor called the onset fingerprint. Classification uses a time-domain neural network, the echo state network. Reference strategies, based upon mel-frequency cepstral coefficients, evaluated either over the whole tone or only during the sound onset, provide context to the method. Classification success rates for the neurally-inspired method are around 75%. The cepstral methods perform between 73% and 76%. Further testing with tones from the Iowa MIS collection shows that the neurally inspired method is considerably more robust when tested with data from an unrelated dataset
- …