76 research outputs found
Theoretical study of ThF in the search for T,P-violation effects: Effective state of a Th atom in ThF and ThO compounds
We report the results of theoretical investigation of electronic structure of
ThF cation which is one of the most interesting systems to search for the
electron electric dipole moment (eEDM) [H. Loh, K.C. Cossel, M.C. Grau, K.-K.
Ni, E.R. Meyer, J.L. Bohn, J. Ye, E.A. Cornell, Science {\bf 342}, 1220 (2013)]
and other effects of violation of time reversal (T) and spacial parity (P)
symmetries in fundamental interactions. For the working state we
have found a quite high value of the effective electric field acting on
unpaired electrons (37.3 GV/cm). The field will be required to interpret the
experiment planed on ThF in terms of eEDM. Within the concept of atoms in
compounds [A.V. Titov, Y.V. Lomachuk, and L.V. Skripnikov, Phys. Rev. A {\bf
90}, 052522 (2014)] we have compared the ThF electronic structure with that
of ThO. Also we have calculated other parameters of T,P-odd interactions:
, which is needed for interpretation of the experiment in terms of the
dimensionless constant characterizing the strength of the T,P-odd
pseudoscalarscalar electronnucleus neutral current interaction (50 kHz);
, which is required to search for the Th nuclear magnetic quadrupole
moment in ThF (0.88 ). A
number of properties which can be measured are also calculated: hyperfine
structure constant, the molecule-frame dipole moment, and g-factor
Theoretical study of the parity and time reversal violating interaction in solids
A new theoretical approach to study the properties in solids, which are
sensitive to a change of densities of the valence electrons in atomic cores
(hyperfine structure constants, parameters of space parity (P) and time
reversal (T) violation interaction, etc.) is proposed and implemented. It uses
the two-step concept of calculation of such properties which was implemented
earlier for the case of molecules [Progr.\ Theor.\ Chem.\ Phys. B 15, 253
(2006)]. The approach is applied to evaluate the parameter describing
electronic density gradient on the Pb nucleus that is required to interpret the
proposed experiment on PbTiO crystal [PRA, 72, 034501 (2005)] to search for
the Schiff moment of the Pb nucleus because of its high sensitivity to
the corresponding P,T-violating interactions. For comparison the parameter
has also been calculated on the Pb nucleus for the state of
PbO molecule using the same density functionals as those utilized in
PbTiO studies. The relativistic coupled-clusters approach with single,
double and perturbative triple cluster amplitudes, applicable to a few atom
systems and providing high accuracy for , is also applied to the PbO case to
estimate the accuracy of density functional studies
Theoretical study of ThO for the electron electric dipole moment search
An experiment to search for the electron electric dipole moment (\eEDM) on
the metastable state of ThO molecule was proposed and now in the
final stage of preparation by the ACME collaboration
[http://www.electronedm.org]. To interpret the experiment in terms of \eEDM\
and dimensionless constant characterizing the strength of the scalar
T,P-odd electron-nucleus neutral current interaction, an accurate theoretical
study of effective electric field on electron, Eeff, and constants is
required. We report calculation of \Eeff\ (84 GV/cm) and a parameter of T,P-odd
scalar neutral currents interaction, (116 kHz), together with the
hyperfine structure constant, molecule frame dipole moment and transition energy, which can serve as a measure of reliability of
the obtained \Eeff\ and values. Besides, our results include a parity
assignment and evaluation of the electric-field dependence for the magnetic
factors for the -doublets of
Evaluation of CP-violation in HfF
CP violation effects produced by the nuclear magnetic quadrupole moment
(MQM), electron electric dipole moment (EDM) and scalarpseudoscalar
nucleuselectron neutral current (SP) interaction in HfF
and HfF are calculated. The role of the hyperfine
interaction is investigated. It is shown that the MQM shift can be
distinguished from the electron EDM and SP ones due to the implicit dependence
of MQM shift on the hyperfine sublevel. The MQM effect is expressed in terms of
the proton (EDM), QCD vacuum angle and quark chromo-EDMs
Manifestations of nuclear CP-violation in ThO molecule
Investigations of CP violation in hadron sector may be done using
measurements in the ThO molecule. Recent measurements in this molecule improved
the limit on electron EDM by an order of magnitude. Another time reversal (T)
and parity (P) violating effect in ThO is induced by the nuclear
magnetic quadrupole moment. We have performed nuclear and molecular
calculations to express this effect in terms of the strength constants of
T,P-odd nuclear forces, neutron EDM, QCD vacuum angle , quark EDM and
chromo-EDM
Centrifugal correction to hyperfine structure constants in the ground state of lead monofluoride, PbF
The sensitivity of the PbF molecule to the electron electric dipole moment
has motivated detailed microwave spectroscopy. Previous theoretical approaches
cannot fully explain the spectra. In turn, the explanation from "first
principles" is very important both for molecular theory and for confirmation of
the correctness of the interpretation of experimental data obtained with high
precision. All of these issues are decisively addressed here. We have
determined centrifugal correction parameters for hyperfine structure constants,
both on lead and fluorine nuclei, of the state of lead
monofluoride. These parameters were obtained by fitting experimentally observed
pure rotational transitions and from {\it ab initio} calculations. We show that
taking this correction into account is required to reproduce the experimental
transition energies obtained in [Phys. Rev. A 84, 022508 (2011)]
Accurate Evaluation of ,-odd Faraday Effect in Atoms of Xe and Hg
Accurate evaluation of the ,-odd Faraday effect
(rotation of the polarization plane for the light propagating through a medium
in presence of an external electric field) is presented. This effect can arise
only due to the ,-odd interactions and is different
from the ordinary Faraday effect, i.e. the light polarization plane rotation in
an external magnetic field. The rotation angle is evaluated for the ICAS
(intracavity absorption spectroscopy) type experiments with Xe and Hg atoms.
The results show that Hg atom may become a good candidate for a search for the
,-odd effects in atomic physics
TaN molecule as a candidate to search for New physics
It is demonstrated that the TaN molecule is the best candidate to search for
T,P-violating nuclear magnetic quadrupole moment (MQM), it also looks promising
to search for other T,P-odd effects. We report results of coupled-cluster
calculations of T,P-odd effects in TaN produced by the Ta nucleus MQM, electron
electric dipole moment (EDM), scalarpseudoscalar nucleuselectron
interactions, also of the molecule-axis hyperfine structure constant and dipole
moment. Nuclear calculations of Ta MQM are performed to express the
T,P-odd effect in terms of the strength constants of T,P-odd nuclear forces,
proton and neutron EDM, QCD parameter and quark chromo-EDM
Effect of nuclear magnetization distribution within the Woods-Saxon model: Hyperfine splitting in neutral Tl
Three models of the nuclear magnetization distribution are applied to predict
the hyperfine structure of the hydrogenlike heavy ions and neutral thallium
atoms: the uniformly magnetized ball model and single-particle models for the
valence nucleon with the uniform distribution and the distribution determined
by the Woods-Saxon potential. Results for the hydrogenlike ions are in
excellent agreement with previous studies. The application of the Woods-Saxon
model is now extended to the neutral systems with the explicit treatment of the
electron correlation effects within the relativistic coupled cluster theory
using the Dirac-Coulomb Hamiltonian. We estimate the uncertainty for the ratio
of magnetic anomalies and numerically confirm its near nuclear-model
independence. The ratio is used as a theoretical input to predict the nuclear
magnetic moments of short-lived thallium isotopes. We also show that the
differential magnetic anomalies are strongly model dependent. The accuracy of
the single-particle models significantly surpasses the accuracy of the simplest
uniformly magnetized ball model for the prediction of this quantity. Skripnikov
[Skripnikov, J. Chem. Phys. 153, 114114 (2020)] has shown that the
Bohr-Weisskopf contribution to the magnetic dipole hyperfine structure constant
for an atom or a molecule induced by a heavy nucleus can be factorized into the
electronic part and the universal nuclear magnetization dependent part. We
numerically confirm this factorization for the Woods-Saxon single-particle
model with an uncertainty less than 1%
,-odd Faraday rotation on atoms and molecules in intra-cavity absorption spectroscopy as an alternative way to search for the ,-odd effects in nature
Present limit on the electron electric dipole moment (EDM) is based on the
electron spin precession measurement. We propose an alternative approach -
observation of the ,-odd Faraday effect in an
external electric field on atoms and molecules using cavity-enhanced
polarimetric scheme in combination with molecular (atomic) beam crossing the
cavity. Our calculations of the effective electric fields and theoretical
simulation of the proposed experiment on Tl and Pb atoms, PbF, YbF, ThO, and
YbOH show that the present limit on the EDM can be improved by 6-7 orders of
magnitude
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