arXiv subjects

I. B. Samsonov

Publications and source records attributed to I. B. Samsonov.

At least 37 records · Page 2Linked to original sources

arXiv2020

Limits on $CP$-violating hadronic interactions and proton EDM from paramagnetic molecules

Experiments with paramagnetic ground or metastable excited states of molecules (ThO, HfF$^+$, YbF, YbOH, BaF, PbO, etc.) provide strong constraints on electron electric dipole moment (EDM) and coupling constant $C_{SP}$ of contact semileptonic interaction. We compute new contributions to $C_{SP}$ arising from the nucleon EDMs due to combined electric and magnetic electron-nucleon interaction. This allows us to improve limits from the experiments with paramagnetic molecules on the $CP$-violating parameters, such as the proton EDM, $|d_p|< 1.1\times 10^{-23} e\cdot $cm, the QCD vacuum angle, $|\bar θ|<1.4\times 10^{-8}$, as well as the quark chromo-EDMs and $π$-meson-nucleon couplings. Our results may also be used to search for the axion dark matter which produces oscillating $\barθ$.

hep-ph↗

arXiv2020

Effects of $CP$-violating internucleon interactions in paramagnetic molecules

We demonstrate that electron electric dipole moment experiments with molecules in paramagnetic state are sensitive to $P,T$-violating nuclear forces and other $CP$-violating parameters in the hadronic sector. These experiments, in particular, measure the coupling constant $C_{SP}$ of the $CP$-odd contact semileptonic interaction. We establish relations between $C_{SP}$ and different $CP$-violating hadronic parameters including strength constants of the $CP$-odd nuclear potentials, $CP$-odd pion-nucleon interactions, quark-chromo EDM and QCD vacuum angle. These relations allow us to find limits on various $CP$-odd hadronic parameters.

hep-ph↗

arXiv2019

Electric field on nucleus due to phonon lattice oscillations in solid states

In atoms and molecules, the electrons screen the nucleus from the external electric field. However, if the frequency of the electric field reaches the energy of atomic or molecular transition, the electric field at the nucleus may be resonantly enhanced by many orders in magnitude. In this paper, we study the mechanisms of screening or enhancement of electric field acting on the nuclei in solid states. We show that in dielectric crystals the phonon oscillations of the lattice play crucial role for determining the electric field on nuclei in the MHz-THz region. As an application, we propose an experimental scheme for measuring nuclear electric dipole moment in a solid state based on the coherent excitation of acoustic phonons.

cond-mat.mes-hall↗

arXiv2019

Ultralight dark photon as a model for early universe dark matter

Dark photon is a massive vector field which interacts only with the physical photon through the kinetic mixing. This coupling is assumed to be weak so that the dark photon becomes almost unobservable in processes with elementary particles, but can serve as a dark matter particle. We argue that in very early Universe ($z>3000$) this vector field may have the equation of state of radiation ($w=1/3$) but later behaves as cold dark matter ($w=0$). This may slightly change the expansion rate of the Universe at early time and reduce the value of the sound horizon of baryon acoustic oscillations (standard ruler). As a result, in this model the value of the Hubble constant appears to be larger than that in the standard $Λ$CDM model. In particular, it is sufficient to have the dark photon mass of order $m\sim 10^{-27}-10^{-25}$ eV to fit the value of the Hubble constant to $H_0 = 73$ km$\cdot$s$^{-1}$Mpc$^{-1}$ thus resolving the Hubble tension.

astro-ph.CO↗

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↗

arXiv2019

Low-energy effective action in 5D, N=2 supersymmetric gauge theory

We construct ${\cal N}=2$ supersymmetric low-energy effective action of $5D, {\cal N}=2$ supersymmetric Yang-Mills theory in $5D, {\cal N}=1$ harmonic superspace. It is obtained as a hypermultiplet completion of the leading $W \ln W$-term in the ${\cal N}=1$ SYM low-energy effective action by invoking the second implicit on-shell ${\cal N}=1$ supersymmetry. After passing to components, the ${\cal N}=2$ effective action constructed displays, along with other terms, the $SO(5)$-invariant $F^4/X^3$ term. Though we specialize to the case of $SU(2)$ gauge group spontaneously broken to $U(1)$, our consideration is applicable to any gauge symmetry broken to some abelian subgroup.

hep-th↗

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

Resonant enhancement of oscillating electric field in atom

When an atom is placed into an oscillating electric field with frequency far from atomic resonances, the atomic electrons partly shield this field at the nucleus. It is conjectured that when the frequency of electric field reaches an atomic resonance, the electric field at the nucleus may be significantly enhanced. In this paper, we systematically study the mechanisms of this enhancement and show that it may reach five orders in magnitude in particular cases. As an application, we consider laser-assisted neutron capture in 139-Lanthanum nucleus and screening and resonance enhancement of nuclear electromagnetic transitions by electrons.

physics.atom-ph↗

arXiv2018

New constraints on axion-mediated P,T-violating interaction from electric dipole moments of diamagnetic atoms

The exchange of an axion-like 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 $g^s$ and a pseudoscalar $g^p$ coupling constant. We consider the interaction with the specific combination of these constants, $g_e^s g_N^p$, which gives significant contributions to the EDMs of diamagnetic atoms. In this paper, we calculate these contributions to the EDMs of $^{199}$Hg, $^{129}$Xe, $^{211}$Rn and $^{225}$Ra for a wide range of axion masses. Comparing these results with recent experimental EDM measurements, we place new constraints on $g_e^s g_N^p$. The most stringent atomic EDM limits come from $^{199}$Hg and improve on existing laboratory limits from other experiments for axion masses exceeding $10^{-2}$ eV.

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

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↗

arXiv2017

Low-energy effective action in two-dimensional SQED: A two-loop analysis

We study two-loop quantum corrections to the low-energy effective actions in N=(2,2) and N=(4,4) SQED in the Coulomb branch. In the latter model, the low-energy effective action is described by a generalized Kahler potential which depends on both chiral and twisted chiral superfields. We demonstrate that this generalized Kahler potential is one-loop exact and corresponds to the N=(4,4) sigma-model with torsion presented by Rocek, Schoutens and Sevrin. In the N=(2,2) SQED, the effective Kahler potential is not protected against higher-loop quantum corrections. The two-loop quantum corrections to this potential and the corresponding sigma-model metric are explicitly found.

hep-th↗

arXiv2016

The low-energy N=4 SYM effective action in diverse harmonic superspaces

We review various superspace approaches to the description of the low-energy effective action in N=4 super Yang-Mills (SYM) theory. We consider the four-derivative part of the low-energy effective action in the Coulomb branch. The typical components of this effective action are the gauge field F^4/X^4 and the scalar field Wess-Zumino terms. We construct N=4 supersymmetric completions of these terms in the framework of different harmonic superspaces supporting N=2,3,4 supersymmetries. These approaches are complementary to each other in the sense that they make manifest different subgroups of the total SU(4) R-symmetry group. We show that the effective action acquires an extremely simple form in those superspaces which manifest the non-anomalous maximal subgroups of SU(4). The common characteristic feature of our construction is that we restore the superfield effective actions exclusively by employing the N=4 supersymmetry and/or superconformal PSU(2,2|4) symmetry.

hep-th↗

arXiv2014

Gauge and matter superfield theories on $S^2$

We develop a superfield formulation of gauge and matter field theories on a two-dimensional sphere with rigid N=(2,2) as well as extended supersymmetry. The construction is based on a supercoset SU(2|1)/[U(1) x U(1)] containing $S^2$ as the bosonic subspace. We derive an explicit form of supervielbein and covariant derivatives on this coset, and use them to construct classical superfield actions for gauge and matter supermultiplets in this superbackground. We then apply superfield methods for computing one-loop partition functions of these theories and demonstrate how the localization technique works directly in the superspace.

hep-th↗

arXiv2014

Superfield theories on $S^3$ and their localization

We consider the superfield formulation of supersymmetric gauge and matter field theories on a three-dimensional sphere with rigid ${\cal N}=2$ supersymmetry, as well as with ${\cal N}> 2$. The construction is based on a supercoset $SU(2|1)/U(1)$ containing $S^3$ as the bosonic subspace. We derive an explicit form of $SU(2|1)/U(1)$ supervielbein and covariant derivatives, and use them to construct classical superfield actions for gauge and matter supermultiplets in this superbackground. We then apply superfield methods for computing one-loop partition functions of these theories and demonstrate how the localization technique works directly in the superspace.

hep-th↗

arXiv2014

Two-loop low-energy effective action in Abelian supersymmetric Chern-Simons matter models

We compute two-loop low-energy effective actions in Abelian Chern-Simons matter models with N=2 and N=3 supersymmetry up to four-derivative order. Calculations are performed with a slowly-varying gauge superfield background. Though the gauge superfield propagator depends on the gauge fixing parameter, it is shown that the obtained results are independent of this parameter. In the massless case the considered models are superconformal. We demonstrate that the superconformal symmetry strongly restricts the form of two-loop quantum corrections to the effective actions such that the obtained terms have simpler structure than the analogous ones in the effective action of three-dimensional supersymmetric electrodynamics (SQED) with vanishing topological mass.

hep-th↗

arXiv2013

Two-loop low-energy effective actions in N=2 and N=4 three-dimensional SQED

We study two-loop Euler-Heisenberg effective actions in three-dimensional N=2 and N=4 supersymmetric quantum electrodynamics (SQED) without Chern-Simons term. We find exact expressions for propagators of chiral superfields interacting with slowly-varying N=2 gauge superfield. Using these propagators we compute two-loop effective actions in the N=2 and N=4 SQED as the functionals of superfield strengths and their covariant spinor derivatives. The obtained effective actions contain new terms having no four-dimensional analogs. As an application, we find two-loop quantum corrections to the moduli space metric in the N=2 SQED.

hep-th↗

arXiv2012

Background field formalism and construction of effective action for N=2, d=3 supersymmetric gauge theories

We review the background field method for three-dimensional Yang-Mills and Chern-Simons models in N=2 superspace. Superfield proper time (heat kernel) techniques are developed and exact expressions of heat kernels for constant backgrounds are presented. The background field method and heat kernel techniques are applied for evaluating the low-energy effective actions in N=2 supersymmetric Yang-Mills and Chern-Simons models as well as in N=4 and N=8 SYM theories.

hep-th↗