Experiments searching for the electric dipole moment (EDM) of the electron d e utilize atomic/molecular states with one or more uncompensated electron spins, and these paramagnetic systems have ...recently achieved remarkable sensitivity to d e . If the source of CP violation resides entirely in the hadronic sector, the two-photon exchange processes between electrons and the nucleus induce CP -odd semileptonic interactions, parametrized by the Wilson coefficient CSP, and provide the dominant source of EDMs in paramagnetic systems instead of de. We evaluate the CSP coefficients induced by the leading hadronic sources of CP violation, namely, nucleon EDMs and CP-odd pion-nucleon couplings, by calculating the nucleon-number-enhanced CP-odd nuclear scalar polarizability, employing chiral perturbation theory at the nucleon level and the Fermi-gas model for the nucleus. This allows us to translate the ACME EDM limits from paramagnetic ThO into novel-independent constraints on the QCD theta term |θ| < 3 × 10−8, proton EDM |dp| < 2 × 10−23 e cm , isoscalar CP-odd pion-nucleon coupling |g(1)πNN| < 4 × 10−10, and color EDMs of quarks |du − dd| < 2 × 10−24 cm. We note that further experimental progress with EDM experiments in paramagnetic systems may allow them to rival the sensitivity of EDM experiments with neutrons and diamagnetic atoms to these quantities.
The exchange of an axionlike particle between atomic electrons and the nucleus may induce electric dipole moments (EDMs) of atoms and molecules. This interaction is described by a parity- and ...time-reversal-invariance-violating potential which depends on the product of a scalar gs and a pseudoscalar gp coupling constant. We consider the interaction with the specific combination of these constants, gesgNp, which gives significant contributions to the EDMs of diamagnetic atoms. In this paper, we calculate these contributions to the EDMs of Hg199, Xe129, Rn211, and Ra225 for a wide range of axion masses. Comparing these results with recent experimental EDM measurements, we place new constraints on gesgNp. The most stringent atomic EDM limits come from Hg199 and improve on existing laboratory limits from other experiments for axion masses exceeding 10−2 eV.
Light (pseudo-)scalar fields are promising candidates to be the dark matter in the Universe. Under certain initial conditions in the early Universe and/or with certain types of self-interactions, ...they can form compact dark-matter objects such as axion stars or Q-balls. Direct encounters with such objects can be searched for by using a global network of atomic magnetometers. It is shown that for a range of masses and radii not ruled out by existing observations, the terrestrial encounter rate with axion stars or Q-balls can be sufficiently high (at least once per year) for a detection. Furthermore, it is shown that a global network of atomic magnetometers is sufficiently sensitive to pseudoscalar couplings to atomic spins so that a transit through an axion star or Q-ball could be detected over a broad range of unexplored parameter space.
We calculate the proton and neutron spin contributions for nuclei using semi-empirical methods, as well as a novel hybrid ab initio/semi-empirical method, for interpretation of experimental data. We ...demonstrate that core-polarisation corrections to ab initio nuclear shell model calculations generally reduce discrepancies in proton and neutron spin expectation values from different calculations. We derive constraints on the spin-dependent P,T-violating interaction of a bound proton with nucleons, which for certain ranges of exchanged pseudoscalar boson masses improve on the most stringent laboratory limits by several orders of magnitude. We derive a limit on the CPT and Lorentz-invariance-violating parameter
|
b
~
⊥
p
|
<
7.6
×
10
-
33
GeV, which improves on the most stringent existing limit by a factor of 8, and we demonstrate sensitivities to the parameters
d
~
⊥
p
and
g
~
D
⊥
p
at the level
∼
10
-
29
–
10
-
28
GeV, which is a one order of magnitude improvement compared to the corresponding existing sensitivities. We extend previous analysis of nuclear anapole moment data for Cs to obtain new limits on several other CPT and Lorentz-invariance-violating parameters:
|
b
0
p
|
<
7
×
10
-
8
GeV,
|
d
00
p
|
<
8
×
10
-
8
,
|
b
0
n
|
<
3
×
10
-
7
GeV and
|
d
00
n
|
<
3
×
10
-
7
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We propose methods for extracting limits on the strength of P-odd interactions of pseudoscalar and pseudovector cosmic fields with electrons, protons, and neutrons, by exploiting the static and ...dynamic parity-nonconserving amplitudes and electric dipole moments they induce in atoms. Candidates for such fields are dark matter (including axions) and dark energy, as well as several more exotic sources described by Lorentz-violating standard model extensions. Atomic calculations are performed for H, Li, Na, K, Rb, Cs, Ba(+), Tl, Dy, Fr, and Ra(+). From these calculations and existing measurements in Dy, Cs, and Tl, we constrain the interaction strengths of the parity-violating static pseudovector cosmic field to be 7 × 10(-15) GeV with an electron, and 3 × 10(-8) GeV with a proton.
In the recent work C. T. Hill, Phys. Rev. D 91, 111702(R) (2015)., C. Hill concludes that the axion electromagnetic anomaly induces an oscillating electron electric dipole moment of frequency ma and ...strength ∼10−32 e cm, in the limit v/c→0 for the axion field. Here, we demonstrate that a proper treatment of this problem in the lowest order yields no electric dipole moment of the electron in the same limit. Instead, oscillating electric dipole moments of atoms and molecules are produced by different mechanisms.
PDF
