arXiv subjects

H. B. Tran Tan

Publications and source records attributed to H. B. Tran Tan.

26 records · Page 2Linked to original sources

arXiv2020

Atomic and molecular transitions induced by axions via oscillating nuclear moments

The interaction of standard model's particles with the axionic Dark Matter field may generate oscillating nuclear electric dipole moments (EDMs), oscillating nuclear Schiff moments and oscillating nuclear magnetic quadrupole moments (MQMs) with a frequency corresponding to the axion's Compton frequency. Within an atom or a molecule an oscillating EDM, Schiff moment or MQM can drive transitions between atomic or molecular states. The excitation events can be detected, for example, via subsequent fluorescence or photoionization. Here we calculate the rates of such transitions. If the nucleus has octupole deformation or quadrupole deformation then the transition rate due to Schiff moment and MQM can be up to $10^{-16}$ transition per molecule per year. In addition, an MQM-induced transition may be of M2-type, which is useful for the elimination of background noise since M2-type transitions are suppressed for photons.

hep-ph↗

arXiv2019

Time- and parity-violating effects of nuclear Schiff moment in molecules and solids

We show that existing calculations of the interaction between nuclear Schiff moments and electrons in molecules use an inaccurate operator which gives rise to significant errors. By comparing the matrix elements of the accurate and imprecise Schiff moment operators, we calculated the correction factor as a function of the nuclear charge Z and presented corrected results for the T,P-violating interaction of the nuclear spin with the molecular axis in the TlF, RaO, PbO, TlCN, ThO, AcF molecules and in the ferroelectric solid PbTiO$_3$.

physics.atom-ph↗

arXiv2019

Oscillating nuclear electric dipole moment induced by axion dark matter produces atomic and molecular EDM

According to the Schiff theorem nuclear electric dipole moment (EDM) is completely shielded in a neutral atom by electrons. This makes a static nuclear electric dipole moment (EDM) unobservable. Interaction with the axion dark matter field generates nuclear EDM $d=d_0 \cos (ωt)$ oscillating with the frequency $ω= m_a c^2/\hbar$ . This EDM generates atomic EDM proportional to $ω^2$. This effect is strongly enhanced in molecules since nuclei move slowly and do not produce as efficient screening of oscillating nuclear EDM as electrons do. An additional strong enhancement comes due to a small energy interval between rotational molecular levels. Finally, if the nuclear EDM oscillation frequency is in resonance with a molecular transition, there may be a significant resonance enhancement.

hep-ph↗

arXiv2019

Interference-assisted detection of dark photon using atomic transitions

Dark photon is a massive vector particle which couples to the physical photon through the kinetic mixing term. Such particles, if exist, are produced in photon beams and, in particular, in laser radiation. Due to the oscillations between the physical photon and the dark photon, the latter may be, in principle, detected in the light-shining-through-a-wall experiment. We propose a variant of this experiment where the detection of dark photons is based on the atomic transitions. The key feature of this scheme is that the detection probability is first order in the coupling constant due to the interference term in the photon and dark photon absorption amplitudes. We expect that such experiment may give new constraints on dark photon coupling constant in the mass region $10^{-3}< m < 10^{-2}$ eV.

hep-ph↗

arXiv2018

Screening and enhancement of oscillating electric field in molecules

According to the Schiff theorem, the atomic electrons completely screen the atomic nucleus from an external static electric field. However, this is not the case if the field is time-dependent. Electronic orbitals in atoms either shield the nucleus from an oscillating electric field when the frequency of the field is off the atomic resonances or enhance this field when its frequency approaches an atomic transition energy. In molecules, not only electronic, but also rotational and vibrational states are responsible for the screening of oscillating electric fields. As will be shown in this paper, the screening of a low-frequency field inside molecules is much weaker than it appears in atoms owing to the molecular ro-vibrational states. We systematically study the screening of oscillating electric fields inside diatomic molecules in different frequency regimes,i.e., when the field's frequency is either of order of ro-vibrational or electronic transition frequencies. In the resonance case, we demonstrate that the microwave-frequency electric field may be enhanced up to six orders in magnitude due to ro-vibrational states. We also derive the general formulae for the screening and resonance enhancement of oscillating electric field in polyatomic molecules. Possible applications of these results include nuclear electric dipole moment measurements and stimulation of nuclear reactions by laser light.

physics.atom-ph↗

arXiv2018

Coherent axion-photon transformations in the forward scattering on atoms

In certain laboratory experiments the production and/or detection of axions is due to the photon-axion transformations in a strong magnetic field. This process is coherent, and the rate of the transformation is proportional to the length $l$ and magnitude $B$ of the magnetic field squared, $\sim l^2B^2$. In the present paper, we consider coherent production of axions due to the forward scattering of photons on atoms or molecules. This process may be represented as being due to an effective electromagnetic field which converts photons to axions. We present analytical expressions for such effective magnetic and electric fields induced by resonant atomic M0 and M1 transitions, as well as give some numerical estimates for these fields. The corresponding experiments would allow one to measure the electron-axion coupling constant $g_{ae}$ in the same way as the photon-axion coupling $g_{aγ}$ is studied.

hep-ph↗

arXiv2018

Dark Matter near gravitating bodies

In this paper, we show that in the vicinity of certain astronomical bodies, e.g., a Neutron Star, a Black Hole, there exist significant enhancements of Dark Matter's density and current, due to its interaction with the gravitational field of the bodies. This enhancement implies that the effects of Dark Matter - Normal Matter interactions are enhanced and hence might be observable.

hep-ph↗

arXiv2018

Interference-assisted resonant detection of axions

Detection schemes for the quantum chromodynamics axions and other axion-like particles in light-shining-through-a-wall (LSW) experiments are based on the conversion of these particles into photons in a magnetic field. An alternative scheme may involve the detection via a resonant atomic or molecular transition induced by resonant axion absorption. The signal obtained in this process is second order in the axion-electron interaction constant but may become first order if we allow interference between the axion-induced transition amplitude and the transition amplitude induced by the electromagnetic radiation that produces the axions.

hep-ph↗