721 research outputs found
Probing low-mass vector bosons with parity nonconservation and nuclear anapole moment measurements in atoms and molecules
In the presence of P-violating interactions, the exchange of vector bosons
between electrons and nucleons induces parity-nonconserving (PNC) effects in
atoms and molecules, while the exchange of vector bosons between nucleons
induces anapole moments of nuclei. We perform calculations of such
vector-mediated PNC effects in Cs, Ba, Yb, Tl, Fr and Ra using the same
relativistic many-body approaches as in earlier calculations of standard-model
PNC effects, but with the long-range operator of the weak interaction. We
calculate nuclear anapole moments due to vector boson exchange using a simple
nuclear model. From measured and predicted (within the standard model) values
for the PNC amplitudes in Cs, Yb and Tl, as well as the nuclear anapole moment
of Cs, we constrain the P-violating vector-pseudovector
nucleon-electron and nucleon-proton interactions mediated by a generic vector
boson of arbitrary mass. Our limits improve on existing bounds from other
experiments by many orders of magnitude over a very large range of vector-boson
masses.Comment: 5 pages, 2 figure
Probing low-mass vector bosons with parity nonconservation and nuclear anapole moment measurements in atoms and molecules
In the presence of P-violating interactions, the exchange of vector bosons
between electrons and nucleons induces parity-nonconserving (PNC) effects in
atoms and molecules, while the exchange of vector bosons between nucleons
induces anapole moments of nuclei. We perform calculations of such
vector-mediated PNC effects in Cs, Ba, Yb, Tl, Fr and Ra using the same
relativistic many-body approaches as in earlier calculations of standard-model
PNC effects, but with the long-range operator of the weak interaction. We
calculate nuclear anapole moments due to vector boson exchange using a simple
nuclear model. From measured and predicted (within the standard model) values
for the PNC amplitudes in Cs, Yb and Tl, as well as the nuclear anapole moment
of Cs, we constrain the P-violating vector-pseudovector
nucleon-electron and nucleon-proton interactions mediated by a generic vector
boson of arbitrary mass. Our limits improve on existing bounds from other
experiments by many orders of magnitude over a very large range of vector-boson
masses.Comment: 5 pages, 2 figure
Searching for Scalar Dark Matter in Atoms and Astrophysical Phenomena: Variation of Fundamental Constants
We propose to search for scalar dark matter via its effects on the
electromagnetic fine-structure constant and particle masses. Scalar dark matter
that forms an oscillating classical field produces `slow' linear-in-time drifts
and oscillating variations of the fundamental constants, while scalar dark
matter that forms topological defects produces transient-in-time variations of
the constants of Nature. These variations can be sought for with atomic clock,
laser interferometer and pulsar timing measurements. Atomic spectroscopy and
Big Bang nucleosynthesis measurements already give improved bounds on the
quadratic interaction parameters of scalar dark matter with the photon,
electron, and light quarks by up to 15 orders of magnitude, while Big Bang
nucleosynthesis measurements provide the first such constraints on the
interaction parameters of scalar dark matter with the massive vector bosons.Comment: 4 pages, 1 figure, Contributed to the 11th Patras Workshop on Axions,
WIMPs and WISPs, Zaragoza, June 22 to 26, 201
Search for the effect of massive bodies on atomic spectra and constraints on Yukawa-type interactions of scalar particles
We propose a new method to search for hypothetical scalar particles that have
feeble interactions with Standard-Model particles. In the presence of massive
bodies, these interactions produce a non-zero Yukawa-type scalar-field
magnitude. Using radio-frequency spectroscopy data of atomic dysprosium, as
well as atomic clock spectroscopy data, we constrain the Yukawa-type
interactions of a scalar field with the photon, electron, and nucleons for a
range of scalar-particle masses corresponding to length scales cm. In
the limit as the scalar-particle mass , our derived limits on the
Yukawa-type interaction parameters are: GeV, GeV, and GeV. Our measurements also constrain combinations of
interaction parameters, which cannot otherwise be probed with traditional
anomalous-force measurements. We suggest further measurements to improve on the
current level of sensitivity.Comment: 7 pages, 2 figure
Violation of the equivalence principle from light scalar fields: from Dark Matter candidates to scalarized black holes
Tensor-scalar theory is a wide class of alternative theory of gravitation
that can be motivated by higher dimensional theories, by models of dark matter
or dark ernergy. In the general case, the scalar field will couple
non-universally to matter producing a violation of the equivalence principle.
In this communication, we review a microscopic model of scalar/matter coupling
and its observable consequences in terms of universality of free fall, of
frequencies comparison and of redshifts tests. We then focus on two models: (i)
a model of ultralight scalar dark matter and (ii) a model of scalarized black
hole in our Galactic Center. For both these models, we present constraints
using recent measurements: atomic clocks comparisons, universality of free fall
measurements, measurement of the relativistic redshift with the short period
star S0-2 orbiting the supermassive black hole in our Galactic Center.Comment: 8 pages, 1 figure, contribution to the 2019 Gravitation session of
the 54th Rencontres de Morion
Dark matter scattering on electrons: Accurate calculations of atomic excitations and implications for the DAMA signal
We revisit the WIMP-type dark matter scattering on electrons that results in
atomic ionization, and can manifest itself in a variety of existing
direct-detection experiments. Unlike the WIMP-nucleon scattering, where current
experiments probe typical interaction strengths much smaller than the Fermi
constant, the scattering on electrons requires a much stronger interaction to
be detectable, which in turn requires new light force carriers. We account for
such new forces explicitly, by introducing a mediator particle with scalar or
vector couplings to dark matter and to electrons. We then perform state of the
art numerical calculations of atomic ionization relevant to the existing
experiments. Our goals are to consistently take into account the atomic physics
aspect of the problem (e.g., the relativistic effects, which can be quite
significant), and to scan the parameter space: the dark matter mass, the
mediator mass, and the effective coupling strength, to see if there is any part
of the parameter space that could potentially explain the DAMA modulation
signal. While we find that the modulation fraction of all events with energy
deposition above 2 keV in NaI can be quite significant, reaching ~50%, the
relevant parts of the parameter space are excluded by the XENON10 and XENON100
experiments
Limiting P-odd interactions of cosmic fields with electrons, protons and neutrons
We propose methods for extracting limits on the strength of P-odd
interactions of pseudoscalar and pseudovector cosmic fields with electrons,
protons and neutrons. Candidates for such fields are dark matter (including
axions) and dark energy, as well as several more exotic sources described by
standard-model extensions. Calculations of parity nonconserving amplitudes and
atomic electric dipole moments induced by these fields 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.Comment: 6 pages, 1 figur
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