597 research outputs found
`St\"uckelberg interferometry' with ultracold molecules
We report on the realization of a time-domain `St\"uckelberg interferometer',
which is based on the internal state structure of ultracold Feshbach molecules.
Two subsequent passages through a weak avoided crossing between two different
orbital angular momentum states in combination with a variable hold time lead
to high-contrast population oscillations. This allows for a precise
determination of the energy difference between the two molecular states. We
demonstrate a high degree of control over the interferometer dynamics. The
interferometric scheme provides new possibilities for precision measurements
with ultracold molecules.Comment: 4 pages, 5 figure
Electric dipole moment enhancement factor of thallium
The goal of this work is to resolve the present controversy in the value of
the EDM enhancement factor of Tl. We have carried out several calculations by
different high-precision methods, studied previously omitted corrections, as
well as tested our methodology on other parity conserving quantities. We find
the EDM enhancement factor of Tl to be equal to -573(20). This value is 20%
larger than the recently published result of Nataraj et al. [Phys. Rev. Lett.
106, 200403 (2011)], but agrees very well with several earlier results.Comment: 5 pages; v2: link to supplemental material adde
Hyperfine and Zeeman interactions of the state of PbO
The role of the interaction with the nearest electronic state
on the hyperfine structure and magnetic properties of the
state of PbO is assessed. The accounting for this
contribution leads to difference between -factors of the
-doublet levels, , that is in a good
agreement with the experimental datum . The
contribution of this interaction rapidly grows with . For the
difference of -factors of -doublet states reaches 100%; for
hyperfine constants it is 18%. These differences also depend on the electric
field and for V/cm for PbO the difference in -factors turn to
zero. The latter is important for suppressing systematic effects in the
electron electric dipole moment search experiment
The Constraints on CP Violating Phases in models with a dynamical gluino phase
We have analyzed the electric dipole moment and the Higgs mass constraints on
the supersymmetric model which offers dynamical solutions to the \mu and strong
CP problems. The trilinear coupling phases, and \tan\beta-|\mu| are strongly
correlated, particularly in the low-\tan\beta regime. Certain values of the
phases of the trilinear couplings are forbidden, whereas the CP violating phase
from the chargino sector is imprisoned to lie near a CP conserving point, by
the Higgs mass and electric dipole moment constraints.Comment: 19 pages, 11 eps fig
Towards the electron EDM search. Theoretical study of PbF
We report ab initio relativistic correlation calculations of potential curves
and spectroscopic constants for four lowest-lying electronic states of the lead
monofluoride. We also calculated parameters of the spin-rotational Hamiltonian
for the ground and the first excited states including P,T-odd and P-odd terms.
In particular, we have obtained hyperfine constants of the Pb nucleus.
For the state MHz, MHz and for
the A MHz, MHz. Our values of
the ground state hyperfine constants are in good agreement with the previous
theoretical studies. We discuss and explain seeming disagreement in the sign of
the constant with the recent experimental data. The effective
electric field on the electron , which is important for the planned
experiment to search for the electric dipole moment of the electron, is found
to be 3.3 * 10^{10} V/cm
CP violation in charged Higgs boson decays in the MSSM with complex parameters
Supersymmetric loop contributions can lead to different decay rates of H+\to
t\bar b and H-\to b\bar t. We calculate the decay rate asymmetry \delta^CP =
\frac{\Gamma(H+\to t\bar b)-\Gamma(H-\to b\bar t)}{{\Gamma(H+\to t\bar
b)+\Gamma(H-\to b\bar t)} at next-to-leading order in the MSSM with complex
parameters. We analyse the parameter dependence of \delta^CP with emphasis on
the phases of A_t and A_b. It turns out that the most important contribution
comes from the loop with stop, sbottom, and gluino. If this contribution is
present, \delta^CP can go up to 10-15% for tan(beta)~10, and to ~5% for large
values of tan(beta).Comment: Eqs. (9) and (25) corrected and numerical analysis modified
accordingl
Shell-Model Effective Operators for Muon Capture in ^{20}Ne
It has been proposed that the discrepancy between the partially-conserved
axial-current prediction and the nuclear shell-model calculations of the ratio
in the muon-capture reactions can be solved in the case of ^{28}Si by
introducing effective transition operators. Recently there has been
experimental interest in measuring the needed angular correlations also in
^{20}Ne. Inspired by this, we have performed a shell-model analysis employing
effective transition operators in the shell-model formalism for the transition
. Comparison of
the calculated capture rates with existing data supports the use of effective
transition operators. Based on our calculations, as soon as the experimental
anisotropy data becomes available, the limits for the ratio can be
extracted.Comment: 9 pages, 3 figures include
Measurement of the electron electric dipole moment using GdIG
A new method for the detection of the electron edm using a solid is
described. The method involves the measurement of a voltage induced across the
solid by the alignment of the samples magnetic dipoles in an applied magnetic
field, H. A first application of the method to GdIG has resulted in a limit on
the electron edm of 5E-24 e-cm, which is a factor of 40 below the limit
obtained from the only previous solid-state edm experiment. The result is
limited by the imperfect discrimination of an unexpectedly large voltage that
is even upon the reversal of the sample magnetization.Comment: 10 pages, 5 figures, v2:references corrected, submitted to PRL,
v3:added labels to figure
An exploration of EEG features during recovery following stroke – implications for BCI-mediated neurorehabilitation therapy
Background: Brain-Computer Interfaces (BCI) can potentially be used to aid in the recovery of lost motor control in a
limb following stroke. BCIs are typically used by subjects with no damage to the brain therefore relatively little is
known about the technical requirements for the design of a rehabilitative BCI for stroke.
Methods: 32-channel electroencephalogram (EEG) was recorded during a finger-tapping task from 10 healthy
subjects for one session and 5 stroke patients for two sessions approximately 6 months apart. An off-line BCI design
based on Filter Bank Common Spatial Patterns (FBCSP) was implemented to test and compare the efficacy and
accuracy of training a rehabilitative BCI with both stroke-affected and healthy data.
Results: Stroke-affected EEG datasets have lower 10-fold cross validation results than healthy EEG datasets. When
training a BCI with healthy EEG, average classification accuracy of stroke-affected EEG is lower than the average for
healthy EEG. Classification accuracy of the late session stroke EEG is improved by training the BCI on the
corresponding early stroke EEG dataset.
Conclusions: This exploratory study illustrates that stroke and the accompanying neuroplastic changes associated
with the recovery process can cause significant inter-subject changes in the EEG features suitable for mapping as part
of a neurofeedback therapy, even when individuals have scored largely similar with conventional behavioural
measures. It appears such measures can mask this individual variability in cortical reorganization. Consequently we
believe motor retraining BCI should initially be tailored to individual patients
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