Search

We theoretically investigate the intrinsic anomalous Hall effect in two magnetically ordered systems: One is the ferromagnetic dipole system, and the other is the anisotropic magnetic dipole system, the latter of which has been proposed as a microscopic indicator of the anomalous Hall effect in antiferromagnets with the negligibly small magnetization. We show their similarity and difference in the anomalous Hall effect by analyzing the fundamental tight-binding model on a two-dimensional square lattice. We find that the magnitudes of the anomalous Hall effect in the two systems are similar to each other, while the magnetization in the anisotropic magnetic dipole system is much smaller than that in the ferromagnetic dipole system; this indicates that the microscopic mechanisms are different from each other. We show that such a difference appears in the momentum-resolved Berry curvature resulting from the different types of magnetic order parameters. We also show that the anomalous Hall effect in the anisotropic magnetic dipole system is enhanced when the magnitude of the spin-orbit coupling is smaller than that of the magnetic mean field. Our results provide a possibility of the giant anomalous Hall effect in collinear and coplanar antiferromagnetic systems with the anisotropic magnetic dipole., Comment: 11 pages, 9 figures

We provided comments on the article Orbits of particles with magnetic dipole moment around magnetized Schwarzschild black holes: Applications to S2 star orbit by Uktamjon Uktamov, Mohsen Fathi, Javlon Rayimbaev, and Ahmadjon Abdujabbarov from arXiv:2406.03371v2. We derived the Hamilton-Jacobi equation used in the article from the Lagrangian utilized and found inconsistencies in the use of the interaction term which describes the magnetic dipole moment of the particle. Consequently, this results in incorrect equations of motion for the particle., Comment: 5 pages; comment on arXiv:2406.03371v2

The electromagnetic characteristics of singly-heavy baryons at low energies are responsive to their internal composition, structural configuration, and the associated chiral dynamics of light diquarks. To gain further insight, experimentalists are attempting to measure the magnetic and electric dipole moments of charm baryons at the LHC. In view of these developments, we conducted an extensive analysis of the magnetic dipole moments of both $\rm{J^P}=\frac{1}{2}^+$ and $\rm{J^P}=\frac{3}{2}^+$ singly-heavy baryons by means of the QCD light-cone sum rules. Our findings have been compared with other phenomenological estimations that could prove a valuable supplementary resource for interpreting the singly-heavy baryon sector. To shed light on the internal structure of these baryons we study the contributions of the individual quark sectors to the magnetic dipole moments. It was observed that the magnetic dipole moments of the spin-$\frac{1}{2}$ sextet singly-heavy baryons are governed by the light quarks. Conversely, the role of the heavy quark is significantly enhanced for the spin-$\frac{1}{2}$ anti-triplet and spin-$\frac{3}{2}$ sextet singly-heavy baryons. The contribution of light and heavy quarks is observed to have an inverse relationship. The signs of the magnetic dipole moments demonstrate the interaction of the spin degrees of freedom of the quarks. The opposing signs of the light and heavy-quark magnetic dipole moments imply that the spins of these quarks are anti-aligned with respect to each other in the baryon. As a byproduct, the electric quadrupole and magnetic octupole moments of spin-$\frac{3}{2}$ singly-heavy baryons are also calculated. We ascertained the existence of non-zero values for the electric quadrupole and magnetic octupole moments of these baryons, indicative of a non-spherical charge distribution., Comment: 21 pages, 5 figures, 9 Tables

We have observed the Autler-Townes effect in single- and suspected double-photon magnetic-dipole transitions in the Cesium ground-state magnetic-sublevel manifold. Experiments were performed in a Cesium vapor cell. The D$_1$ line was excited by laser radiation to create ground-state optical polarization, and transitions between the ground-state magnetic sublevels were excited by radio-frequency (RF) radiation. Two different excitation geometries were studied: in one case the electric field vector of the linearly polarized laser radiation was parallel to the static magnetic field, whereas in the other case these vectors were perpendicular. The oscillating magnetic field produced by the RF coils was in the plane perpendicular to the electric field vector of the laser radiation. The Autler-Townes effect was confirmed by its linear dependence on the RF magnetic field amplitude, which is proportional to the Rabi frequency, in the case of single-photon transitions. We also observed peaks that by their position appeared to correspond to double and even triple photon transitions, which were more pronounced when the DC magnetic field and optical electric field vectors were perpendicular. In the peak at an energy that corresponds to two photons, splitting with a quadratic dependence on the RF magnetic field amplitude could be observed. The experimental measurements are supplemented by theoretical calculations of a model $J=1 \longrightarrow J=0$ system.

We compute the magnetic dipole (M1) $\gamma$-ray strength functions ($\gamma$SF) for the odd-mass lanthanides $^{143-151}$Nd and $^{147-153}$Sm using the shell-model Monte Carlo method in combination with the static-path approximation and the maximum-entropy method. In particular, we quantify the statistical uncertainties in the calculated M1 $\gamma$SFs and show that they are under control for the excitation energies relevant to the experiments despite a Monte Carlo sign problem that originates in the projection onto an odd number of neutrons. We identify a low-energy enhancement (LEE) in the M1 $\gamma$SFs of these odd-mass lanthanides, which was recently observed experimentally in some of them. We also find a scissors mode resonance (SR) in the strongly deformed isotopes. We observe that the decrease in the LEE strength with neutron number along an isotopic chain is compensated for by an increase in the SR strength in the deformed nuclei. We compare our results with recent experiments., Comment: 15 pages, 8 figures, 1 table

One in about a few hundred thousand sub-Coulomb $d$-$t$ collisions is accompanied by the emission of a $\gamma$-photon. The $\gamma$-spectrum from these collisions is dominated by a 16.7 MeV peak, corresponding to the population of the $p$-wave $3/2^-$ $\alpha$-$n$ ground-state resonance in the E1 transition from an intermediate $d$-wave $\alpha$-$n$ state, corresponding to the $^5$He excited state around 16.7 MeV. The strength of this spectrum at the large $\gamma$-energy endpoint decreases fast both due to kinematic factors and due to centrifugal repulsion between neutron and $\alpha$-particle at near-zero relative energies. However, no centrifugal repulsion would occur if $s$-wave $\alpha$-$n$ states were populated in magnetic dipole transition. Therefore, one can expect that close to the $\gamma$-spectrum endpoint around 17.5 MeV the M1 transition could dominate, leading to additional counts in experimental spectra which could be easily misinterpreted as a background. This work presents calculations of the M1 contribution to the $d+t\rightarrow \alpha+n+\gamma$ cross section caused both by convection and magnetization currents. While the first contribution was found to be negligible, the one from magnetization depends strongly on the choice of the model for the $d$-$t$ channel scattering wave function. Using $d$-$t$ interaction models from the literature, represented either by a gaussian of by a square well, resulted in unrealistically strong M1 contribution. With constructed in the present work optical folding potential, correctly representing the sizes of deuteron and triton, the M1 contribution near the endpoint is reduced to about 2$\%$ of the 16.7-MeV E1 peak. Arguments in favor of more detailed calculations, that could potentially change this number, are put forward., Comment: Accepted in Phys Rev C

According to the Dilaton-Einstein-Maxwell theory, dilatons can be generated by electromagnetic fields with a non-zero the Maxwell tensor invariant. This research focuses on the dilaton generation while magnetic dipole radiation from a rotating neutron star propagates through a Coulomb field created by a point-charged particle. The exact solution of the dilaton field equation has been obtained, and the angular distribution of dilaton generation has been established.

This study provides a comprehensive analytical investigation of the bound and unbound motion of magnetized particles orbiting a Schwarzschild black hole immersed in an external asymptotically uniform magnetic field, which includes all conceivable types of bounded and unbounded orbits. In particular, for planetary orbits, we perform a comparative analysis of our findings with the observed position of the S2 star carrying magnetic dipole moment around Sagittarius A* (Sgr A*). We found maximum and minimum values for the parameter of magnetic interaction between the magnetic dipole of the star and the external magnetic field, as well as the energy and angular momentum of the S2 star. As a result, we obtain estimations of the magnetic dipole of the star in order of $10^6 \rm \ G\cdot cm^{3}$. Additionally, we explore deflecting trajectories akin to gravitational Rutherford scattering. In obtaining the solutions for the orbital equations, we articulate the elliptic integrals and Jacobi elliptic functions, and our study is augmented by illustrative figures and simulations., Comment: 17 pages, 10 figures, 6 tables

We calculate the magnetic dipole $\gamma$-ray strength functions in a chain of even-mass neodymium isotopes $^{144-152}$Nd in the framework of the configuration-interaction (CI) shell model. We infer the strength function by applying the maximum entropy method (MEM) to the exact imaginary-time response function calculated with the shell-model Monte Carlo (SMMC) method. The success of the MEM depends on the choice of a good strength function as a prior distribution. We investigate two choices for the prior strength function: the static path approximation (SPA) and the quasiparticle random-phase approximation (QRPA). We find that the QRPA is a better approximation at low temperatures (i.e., near the ground state), while the SPA is a better choice at finite temperatures. We identify a low-energy enhancement (LEE) in the MEM deexcitation $M1$ strength functions of the even-mass neodymium isotopes and compare with recent experimental results for the total deexcitation $\gamma$-ray strength functions. The LEE is already seen in the SPA strength function but not in the QRPA strength function, indicating the importance of large-amplitude static fluctuations around the mean field in reproducing the LEE. Our method is currently the only one which can reproduce LEE in heavy open-shell nuclei where conventional CI shell model calculations are prohibited. With the onset of deformation as number of neutrons increases along the chain of neodymium isotopes, we observe that some of the LEE strength transfers to a low-energy excitation, which we interpret as a finite-temperature "scissors" mode. We also observe a finite-temperature spin-flip mode., Comment: 11 pages, 6 figures

We obtain the value of the magnetic dipole moment of the $\rho$ meson, using data from the BaBar Collaboration for the $e^{+} e^{-} \to \pi^+ \pi^- 2 \pi^0$ process. The considered center of mass energy range is from 0.9 to 1.8 GeV. We describe the $\gamma^* \to 4\pi$ vertex using a vector meson dominance model, including the intermediate resonant contributions relevant at these energies. We find $\mu_\rho = 2.7 \pm 0.3 $ in $e/2 m_\rho$ units. We improve on the previous extracted value, where preliminary data from the same collaboration was used, by considering definite data, better grounded values of the parameters involved and explicit gauge invariant description of the process., Comment: 12 pages, 7 figures and 1 table. Accepted for publication in PRD

Sterile neutrinos that couple to the Standard Model via the neutrino magnetic dipole portals have been extensively studied at various experiments. In this work, we scrutinize these interactions for sterile neutrinos in the mass range of $\unit[0.1]{}-\unit[50]{MeV}$ through the nuclear and electron recoils at various neutrino scattering experiments. For the $e$-flavor specific dipole portal, we demonstrate that Dresden-II can provide leading constraints for $m_N \lesssim \unit[0.5]{MeV}$, setting aside currently unresolved theoretical uncertainties. For the $\mu$-flavor case, we show that the COHERENT experiment can probe a unique parameter region for $m_N$ in the range of $\unit[10]{}-\unit[40]{MeV}$ with the full dataset collected by the CsI[Na] scintillation detector, including both the energy and timing structure of the neutrino beam. We also present limits on the parameter regions of the $\tau$-flavor dipole portal using measurements of the solar neutrino flux from dark matter direct detection experiments., Comment: 8 pages, 2 figures

Many accretion-powered pulsars rotate in magnetocentrifugal disequilibrium, spinning up or down secularly over multi-year intervals. The magnetic dipole moment $\mu$ of such systems cannot be inferred uniquely from the time-averaged aperiodic X-ray flux $\langle L(t) \rangle$ and pulse period $\langle P(t) \rangle$, because the radiative efficiency of the accretion is unknown and degenerate with the mass accretion rate. Here we circumvent the degeneracy by tracking the fluctuations in the unaveraged time series $L(t)$ and $P(t)$ using an unscented Kalman filter, whereupon $\mu$ can be estimated uniquely, up to the uncertainties in the mass, radius and distance of the star. The analysis is performed on Rossi X-ray Timing Explorer observations for $24$ X-ray transients in the Small Magellanic Cloud, which have been monitored regularly for $\sim 16$ years. As well as independent estimates of $\mu$, the analysis yields time-resolved histories of the mass accretion rate and the Maxwell stress at the disk-magnetosphere boundary for each star, and hence auto- and cross-correlations involving the latter two state variables. The inferred fluctuation statistics convey important information about the complex accretion physics at the disk-magnetosphere boundary., Comment: 42 pages, 10 figures, accepted for publication in The Astrophysical Journal

A reentrant behavior of temperature dependent magnetic ac-susceptibility (or excess susceptibility(ES)) at lower temperature is observed in a composite made of superconductor $La_{1.85}Sr_{0.15}CuO_4$ (LCu) and an insulating paramagnetic salt $Gd_2O_3$ (GdO). The ES exhibits an exponential characteristic that varies with temperature ($\exp,[\frac{T_0}{T}]$), T0 is characteristics temperature. The characteristics temperature,T$_0$, decreases as the effective interface diminishes and the amplitude of the dc magnetic field increases. The creation of ferromagnetic dimers between Gd$^{+3}$ ions in GdO is observed as a result of vortex-dipole interaction, which causes the observation of this unusual ES at temperatures much lower than the superconducting onset temperature T$_{S}^{onset}$. This type of ferromagnetic dimer formation much below superconducting transition temperature is found comparable with the formation of Yu-Shiba-Rusinov (YSR) state and interaction between these YSR state., Comment: 12 pages, 8 figures

This study is devoted to dilaton generation in propagation of magnetic dipole waves of pulsar in a galactic magnetic field. It is shown that in this process it's necessary to take into account the presence of a reflective index of matter distributed in the galaxy. According to obtained estimates influence of the gravitational field of pulsars and magnetars on radiation of magnetic dipole waves is negligible and tends to a small change of their amplitude, near about 1 per cent. That's why in this study one can neglect the impact of gravitational field on process of dilaton generation. Exact solution of the dilaton equation is found and angular distribution of dilaton radiation is obtained in propagation of magnetic dipole waves of pulsar in galactic magnetic field.

In this contribution, the classical tests of general relativity using the Gutsunaev-Manko metric with slow rotation are obtained. This metric represents the spacetime of an object endowed with mass, magnetic dipole moment and angular moment. These tests are the deflection of light, time delay, precession of the periastron and gravitational redshift. We also provide numerical estimations for real magnetars and magnetar candidates from the McGill magnetar catalogue, and for the Sun in the cycles of low activity. Our results find that the magnetic dipole contribution to the deflection of light is significant when compared to the rotation contribution. The magnetic dipole contributions to the periastron precession and the time delay are 3 and 6 orders of magnitude lower than the rotation contribution respectively. For the gravitational redshift, the contribution is negligible within the approximation presented.

The $pd$ radiative capture reaction plays a vital role in Big Bang nucleosynthesis and stellar proton-proton chain. The study of the low-energy reaction is challenging in both experiments and theories. Using the framework of potential model, we analyze $pd$ radiative capture below 1 MeV for both electric dipole ($E1$) and magnetic dipole ($M1$) transitions. The obtained astrophysical $S$ factors agree well with recent results, especially at energies relevant to sensitive deuterium abundance. The calculated reaction rate shows good agreement, with less than a 5\% difference compared to recent works. The extrapolated value for $S(0)$ including both transitions is determined to be $0.211 \pm 0.016$ eV b. A comparison with experimental data using the $\chi^2$ test reveals the sensitivity of the $M1$ cross section at low energies to the scattering potential depth., Comment: 17 pages, 6 figures, 2 tables, accepted for publication in Physica Scripta

We consider the bending of light around a compact astrophysical object with both the electric field and the magnetic field in Einstein-Born-Infeld theory. From the null geodesic of a light ray passing a massive object with electric charge and magnetic dipole, the effective metric was obtained from the light cone condition reflecting the nonlinear electromagnetic effects. We found the asymptotic form of the effective metric up to the first order in gravitational constant $G$ and Born-Infeld parameter $1/\beta^2$ on the equatorial plane. Then we compute the bending angle of light from the geodesic equation. The result includes particular cases where only one type of field is present taking the appropriate limits., Comment: 13 pages, 1 figure, published version in Eur. Phys. J. C

The aim of the present work is a state-by-state analysis of possible E1 and M1 transitions in $^{58}$Ni with a high-resolution (p,p') experiment at 295 MeV and very forward angles including 0{\deg} and a comparison to results from studies of the dipole strength with the $(\gamma,\gamma')$ and (e,e') reactions. The E1 and M1 cross sections of individual peaks in the spectra are deduced with a multipole decomposition analysis and converted to reduced E1 and spin-M1 transition strengths using the virtual photon and the unit cross-section method, respectively. Despite the high level density good agreement is obtained for the deduced excitation energies of J = 1 states in the three types of experiments indicating that the same states are excited. The B(E1) and B(M1) strengths from the $(\gamma,\gamma^\prime)$ experiments are systematically smaller than in the present work because of the lack of information on branching ratios to lower-lying excited states and the competition of particle emission. Fair agreement with the B(M1) strengths extracted from the (e,e') data is obtained after removal of E1 transitions uniquely assigned in the present work, which belong to a low-energy toroidal mode with unusual properties mimicking M1 excitations in electron scattering. The experimental M1 strength distribution is compared to large-scale shell-model calculations with the effective GXPF1A and KB3G interactions. They provide a good description of the isospin splitting and the running sum of the M1 strength. A quenching factor 0.74 for the spin-isospin part of the M1 operator is needed to attain quantitative agreement with the data., Comment: 16 pages, 15 figures

A low-energy enhancement (LEE) has been observed in the deexcitation $\gamma$-ray strength function ($\gamma$SF) of compound nuclei. The LEE has been a subject of intense experimental and theoretical interest since its discovery, and, if the LEE persists in heavy neutron-rich nuclei, it would have significant effects on calculations of r-process nucleosynthesis. Standard configuration-interaction (CI) shell-model calculations in medium-mass nuclei have attributed the LEE to the magnetic dipole $\gamma$SF but such calculations are computationally intractable in heavy nuclei. We review a combination of beyond-mean-field many-body methods within the framework of the CI shell model that enables the calculation of $\gamma$SF in heavy nuclei, and discuss the recent theoretical identification of a LEE in the magnetic dipole $\gamma$SF of lanthanide isotopes., Comment: 8 pages, 5 figures

The low-energy enhancement observed recently in the deexcitation gamma-ray strength functions, suggested to arise due to the magnetic dipole radiation, motivates theoretical efforts to improve the description of M1 strength in available nuclear structure models. Reliable theoretical predictions of nuclear dipole excitations are of interest for different nuclear applications and in particular for nuclear astrophysics, where the calculations of radiative capture cross sections often resort to theoretical strength functions. We aim to benchmark many-body methods in their description of the M1 strength functions, with a special emphasis on the low-energy effects observed in the deexcitation strength. We investigate the zero-temperature and finite-temperature magnetic dipole strength functions computed within the quasiparticle random-phase approximation and compare them to those from exact diagonalizations of the same Hamiltonian in restricted orbital spaces. The study is carried out for a sample of 25 spherical and deformed nuclei which can be described by diagonalization of the respective effective Hamiltonian in three different valence spaces. A reasonable agreement is found for the total photoabsorption strengths while the QRPA distributions are shown to be systematically shifted down in energy with respect to exact results. Photoemission strengths obtained within the FT-QRPA appear insufficient to explain the low-energy enhancement of the M1 strength functions. The problems encountered in QRPA calculations are ascribed to the lack of correlations in the nuclear ground state and to the truncation of the many-body space. In particular, the latter prevents obtaining the sufficiently high level density to produce the low-energy enhancement of the strength function, making the (FT-)QRPA approach unsuitable for predictions of such effects across the nuclear chart., Comment: 15 pages, 9 figures

The magnetic dipole moment $\mu$ of an accretion-powered pulsar in magnetocentrifugal equilibrium cannot be inferred uniquely from time-averaged pulse period and aperiodic X-ray flux data, because the radiative efficiency $\eta_0$ of the accretion is unknown, as are the mass, radius, and distance of the star. The degeneracy associated with the radiative efficiency is circumvented, if fluctuations of the pulse period and aperiodic X-ray flux are tracked with a Kalman filter, whereupon $\mu$ can be measured uniquely up to the uncertainties in the mass, radius, and distance. Here the Kalman filter analysis is demonstrated successfully in practice for the first time on Rossi X-ray Timing Explorer observations of the X-ray transient SXP 18.3 in the Small Magellanic Cloud, which is monitored regularly. The analysis yields $\mu = 8.0^{+1.3}_{-1.2} \, \times \, 10^{30} \, {\rm G \, cm^3}$ and $\eta_0 = 0.04^{+0.02}_{-0.01}$, compared to $\mu = 5.0^{+1.0}_{-1.0} \times 10^{30} \, {\rm G \, cm^3}$ as inferred traditionally from time-averaged data assuming $\eta_0=1$. The analysis also yields time-resolved estimates of two hidden state variables, the mass accretion rate and the Maxwell stress at the disk-magnetosphere boundary. The success of the demonstration confirms that the Kalman filter analysis can be applied in the future to study the magnetic moments and disk-magnetosphere physics of accretion-powered pulsar populations in the Small Magellanic Cloud and elsewhere., Comment: 34 pages, 5 figures, accepted for publication in The Astrophysical Journal

In this paper we study the magnetic dipole moments of the newly discovered $\Omega_{c}(3185)^0$ and $\Omega_c(3327)^0$, assuming that $\Omega_{c}(3185)^0$ and $\Omega_c(3327)^0$ are $S$-wave $D \Xi$ and $D^* \Xi$ molecular pentaquark states, respectively. Together with these states, the magnetic dipole moments of possible $D_s \Xi$, $D_s^* \Xi$, $D \Xi^*$, and $D_s \Xi^*$ pentaquark states are also studied. The magnetic dipole moments of these singly-charmed pentaquarks are estimated within the framework of the QCD light cone sum rules utilizing the photon distribution amplitudes. In the search for the properties of singly-charmed molecular pentaquark states, the results obtained for the magnetic dipole moments can be useful., Comment: 11 pages, 2 tables and 1 figure, version accepted by Physics Letters B. arXiv admin note: text overlap with arXiv:2309.00959

Investigations of electromagnetic interactions between test-charged and magnetized particles are important in the dynamics of the particles in strong gravitational fields around black holes. Here, we study the dynamics of a particle having an electric charge and a magnetic dipole moment in the spacetime of a Schwarzschild black hole in modified gravity (MOG), called Schwarzschild-MOG black hole. First, we provide a solution of Maxwell equations for the angular component of electromagnetic four potentials in the Schwarzschild-MOG spacetime. Then, we derive equations of motion and effective potential for circular motion of such particles using a hybrid form of the Hamilton-Jacobi equation which includes both interactions of electric charge and magnetic dipole moment with the external magnetic field assumed as asymptotically uniform, and interaction between the particles and the MOG field. Also, we investigate the effects of the three types of interactions on the radius of innermost stable circular orbits (ISCOs) and the energy \& angular momentum of the particles at their corresponding ISCOs. Finally, we provide detailed analyses of the effects of the three interactions mentioned above on the center of mass energy in the collisions between neutral, electrically charged, and magnetized particles.

We investigate the effects of two-body currents on magnetic dipole moments of medium-mass and heavy nuclei using the valence-space in-medium similarity renormalization group with chiral effective field theory interactions and currents. Focusing on near doubly magic nuclei from oxygen to bismuth, we have found that the leading two-body currents globally improve the agreement with experimental magnetic moments. Moreover, our results show the importance of multi-shell effects for $^{41}$Ca, which suggest that the $Z=N=20$ gap in $^{40}$Ca is not as robust as in $^{48}$Ca. The increasing contribution of two-body currents in heavier systems is explained by the operator structure of the center-of-mass dependent Sachs term., Comment: 6 pages, 4 figures, supplemental material included

The magnetic dipole transition strength $B(M1)$ of $^{48}$Ca is dominated by a single resonant state at an excitation energy of 10.23 MeV. Experiments disagree about $B(M1)$ and this impacts our understanding of spin flips in nuclei. We performed ab initio computations based on chiral effective field theory and found that $B(M1:0^+\rightarrow1^+)$ lies in the range from $7.0$ to $10.2~\mu_N^2$. This is consistent with a $(\gamma,n)$ experiment but larger than results from $(e,e^\prime)$ and $(p,p')$ scattering. Two-body currents yield no quenching of the $B(M1)$ strength and continuum effects reduce it by about 10%. For a validation of our approach, we computed magnetic moments in $^{47,49}$Ca and performed benchmark calculations in light nuclei., Comment: Published version

We revisited the electronic structure parameters used to interpret the hyperfine structure of neutral polonium. We used a computational scheme that treats relativistic and high-order electronic correlation effects within the coupled cluster with single, double, triple and perturbative quadruple excitations CCSDT(Q) method, as well as estimate the contribution of quantum electrodynamics and finite nuclear size effects. A systematic study of the uncertainty is carried out. This allowed us to obtain significantly refined values for the nuclear magnetic dipole and electric quadrupole moments of a wide range of odd-mass polonium isotopes. For $^{205}$Po and $^{207}$Po we extracted both the magnetic moment and the nuclear magnetization distribution parameter in a nuclear model-independent way. To assess the accuracy of the calculations, we also computed the ionization potential (IP), excitation energies (EE) of the $6p^4~{}^1D_2$ and $6p^3 7s^1~{}^5S_2$ electronic states and the electronic $g_J$ factor in the same theoretical framework. A good agreement of the theory and experiment for IP, EEs and $g_J$ confirms the reliability of the computational scheme and uncertainty estimation for the Po electromagnetic moments. We identify the $6p^4~{}^1D_2$ electronic level as a potentially promising state for further studies of the nuclear moments of polonium isotopes.

We present an exact, time-dependent solution for the Einstein field equations that models the coupling between an anisotropic fluid and a magnetic field in an axially symmetric space-time. By carefully selecting the metric components, we achieve a convenient separation of variables that enables us to solve Einstein's field equations and obtain a solution that evolves into the Gutsunaev-Manko massive magnetic dipole. The analysis of the thermodynamic quantities suggests that this solution may represent a pulse of radiation emitted by a massive object with magnetic properties as for example pulsars or neutron stars.

The noncommutativity concept has wide range of applications in physical and mathematical theories. Noncommutativity in the position-time coordinates concerns the microscale structure of space-time. the noncommutativity is an intrinsic property of the space-time and it could be different from usual properties when one encounters the high energy phenomena. on the other hand, the space-time is assumed to be as a background for the occurrence of physical events. therefore, it is not far-fetched to expect the emergence of new physics or dynamics when the fine geometric structure of space-time is deformed. In this work, we consider a common form of this deformation and try to answer the question as: a physical (or dynamical) model can be described by the noncommutative effects?. This can also be asked this way: dose the noncommutativity could have a physical manifestations in the nature?. Our model here is a magnetic dipole., Comment: 17 pages, 4 figures

Finite temperature effects in electromagnetic transitions in nuclei contribute to many aspects of nuclear structure and astrophysically relevant nuclear reactions. While electric dipole transitions have already been extensively studied, the temperature sensitivity of magnetic transitions remains largely unknown. This work comprises the study of isovector magnetic dipole excitations (M1) occurring between spin-orbit (SO) partner states using the recently developed self-consistent finite temperature relativistic quasiparticle random phase approximation (FT-RQRPA) in the temperature range from $T=$ 0 to 2 MeV. The M1 strength distributions of $^{40-60}$Ca and $^{100-140}$Sn isotopic chains exhibit a strong temperature dependence. The M1 strength peaks shift significantly towards the lower energies due to the decrease in SO splitting energies and weakening of the residual interaction, especially above the critical temperatures ($T_\textrm{c}$) where the pairing correlations vanish. By exploring the relevant two-quasiparticle ($2qp$) configurations contributing to the M1 strength of closed- and open-shell nuclei, new proton and neutron excitation channels between SO partners are observed in low- and high-energy regions due to the thermal unblocking effects around the Fermi level. At higher temperatures, we have noticed an interesting result in $^{40,60}$Ca nuclei, the appearance of M1 excitations, which are forbidden at zero temperature due to fully occupied (or fully vacant) spin-orbit partner states.