Absence Of Symmetry Research Articles

Multiple optical spin-orbit Hall effect at the tight focus

We reveal that a multiple optical spin-orbit Hall effect occurs at the tight focus of light fields with hybrid m-th order polarization thanks to spin-orbit coupling and angular momentum conservation, or symmetry violation (e.g. at non-integer m). The effect manifests itself through the formation of multiple, spatially separated subwavelength regions such that circular and elliptical polarization vectors in adjacent regions are oppositely directed, with the corresponding on-axis components of the spin angular momenta being opposite in sign. Besides, subwavelength regions are formed where transverse energy flows rotate along closed paths, being oppositely directed in the adjacent regions. The optical spin-orbit Hall effect occurs at the tight focus of a cylindrical m-th order vector field if cylindrical symmetry is violated by one way or another.

Magnetoelectric‐Field Electrodynamics: Search for Magnetoelectric Point Scatterers

AbstractResonant scattering of electromagnetic (EM) waves by small particles is considered as one of the basic problems in metamaterial science. At present, special subwavelength resonators are considered as structural elements in chiral and bianisotropic metamaterials. There is a general consensus that these small scatterers behave like “artificial atoms” with strong electrical and magnetic responses and an interconnection between these responses. However, the observed effect of magnetoelectric (ME) coupling in these meta‐atoms is not associated with the near‐field manipulation properties caused by intrinsic magnetoelectricity. This arises the question whether ME point scatterers of EM radiation really exist. In this paper, we show that there are mesoscopic structures with electric and magnetic dipole‐carrying excitations that behave like point scatterers with their inherent magnetoelectricity. In such subwavelength resonators, coherent oscillations of the electric polarization and magnetization can be considered as quasistatic oscillations described by electrostatic (ES) and magnetostatic (MS) scalar wave functions. The ME resonance effect arises from the coupling of two, ES and MS, oscillations. The near fields of these resonators, called the ME near fields, are characterized by simultaneous violation of time reversal and inversion symmetry. In study of ME fields and EM problems associated with these fields, we put forward the concept of ME‐field electrodynamics.

Effects of Lorentz symmetry breaking environment on generalized relativistic quantum oscillator field

In this paper, we study the generalized Klein–Gordon oscillator under the effects of the violation of Lorentz symmetry defined by a tensor field ( KF) μναβ out of the standard model extension. We consider a possible scenario of Lorentz-violating with a Cornell-type potential form electric field and a linear magnetic field that contributes a harmonic-type central potential effects in the quantum motions of oscillator fields. The bound-state solutions of the wave equation using the parametric Nikiforov–Uvarov method by considering Coulomb- and Cornell-type potential form functions are obtained. We see that the eigenvalue solutions get modified by the Lorentz symmetry breaking effects in comparison to the Landau levels (without Lorentz-violation effects in flat space).

Microscopic calculation of the electromagnetic dipole strength for 239,243Pu isotopes

This work investigates the electric and magnetic dipole (E1 and M1) responses for 239,243Pu isotopes based on the quasiparticle phonon nuclear model, which was complemented by adding, for the first time, residual interactions for addressing the violations of rotational, translational, and Galilean symmetries caused by the mean-field approach. We focus on the E1 and M1 dipole strengths and photoabsorption cross sections up to 20 MeV, with the results revealing that the giant dipole resonance best describes the experimental trend with a ratio of 95%. It appears that most of the E1 strength is found at Ex = 8–20 MeV, but the total B(E1)↑ strength for the pygmy dipole resonance at Ex = 4–8 MeV accounts for some 1.83 e2fm2, which in turn corresponds to 2% of the Thomas–Reiche–Kuhn sum rule. Furthermore, the resultant total B(M1)↑ value for the scissors mode strength below 4 MeV is 5.65 which is below that of the Oslo data (10.1(15) ). However, the theoretically predicted scissors resonance structure has two peaks in the 1–3.5 MeV energy range, so it exhibits a similar trend to that found in the Oslo data.

Direct observation of the Yb(4f136s2)F states and accurate determination of the YbF ionization energy

YbF has been identified as a molecule that can be used to investigate charge-parity symmetry violations that are beyond the Standard Model of particle physics. Cooling to sub-milli-Kelvin is advantageous for experiments that probe manifestations of these symmetry violations. One approach involves laser cooling of YbF via the A2P1/2-X2S+ transition. However, it appears that cooling by means of this transition may be limited by the radiative loss of population from the cooling cycle. YbF has low-energy states that arise from the Yb+(4f136s2)F- configuration. Recent theoretical calculations predict (Zhang et al J. Mol. Spectrsc. 386 11625 (2022)) that radiative decay from A2{\Pi}1/2 to the 4f136s2 states occurs with a branching fraction of approximately 10-3. In the present study we have used dispersed laser induced fluorescence spectroscopy to the observe the lowest energy 4f136s2 states. These measurements were carried out using excitation of previously unobserved YbF transitions in the near UV spectral range. An accurate ionization energy (IE) for YbF is also reported. A two-color photoionization technique was used to determine the IE and observe the v+=0-3 vibrational levels of YbF+ X1S+.

EIT for tactile sensing:considerations regarding the injection-measurement pattern

Bipolar current injection and voltage measurement (I–M) patterns are frequently used in electrical impedance tomography (EIT) for tactile sensing. In this work, the total set of 36 unique combinations for 16-electrode systems is investigated using simulations. Performance is evaluated on a circular sensor as a function of hyperparameter and target position with respect to critical performance measures for tactile sensing; these include not only peak amplitude and resolution, but also susceptibility to noise and, importantly, the uniformity of performance over the sensor area. The determination of which pattern to employ can therefore be based on the needs of the particular application. The relative performance of the I–M patterns is determined at small hyperparameters by electrode placement symmetry, but at large hyperparameters by sensitivity at the center of the sensor. Patterns with high spatial symmetry should be avoided; these include electrode pairs on opposite sides of the sensor. Patterns with electrodes in adjacent positions, which have been the norm for tactile sensing, should also not generally be used. If performance on all metrics across a wide range of hyperparameters is needed, then placing both the injection and measurement electrodes 3 spaces apart (the 3–3 pattern) can be a good strategy for the Gauss-Newton 1-step algorithm with the Laplacian prior. The use of 13 electrodes instead of 16 is also examined. The absence of symmetry provides greater flexibility in the choice of I–M pattern, and the loss in performance may be small; furthermore, the reduction in data collection time may be advantageous. Beyond avoiding the worst I–M patterns, the most important measure to take is decreasing noise on the signal to permit the use of a smaller hyperparameter; this is of greater importance than selecting from among the remaining I–M patterns.

On the Higgs spectra of the 3-3-1 model

The minimal scalar sector of the 3-3-1 model is composed by the SU(3)L triplet scalars η, ρ, χ and its potential allows the trilinear term f2χηρ. Since f is an energy scale associated to the explicit violation of Peccei-Quinn global symmetry, it is natural to wonder about its value and influence in the spectrum of scalars of the model. Here, we show that f determines the spectrum of scalars of the model. Hence, we develop the scalar sector considering f belonging to four energy regimes, namely f≪〈η〉0, 〈ρ〉0; f=〈η〉0, 〈ρ〉0; f=〈χ〉0 and f≫〈χ〉0 and obtain the spectrum of scalars for each case. In the first and second cases the spectrum of scalars presents a set of new scalars belonging to the electroweak scale, while in the third case all new scalars belong to the 3-3-1 scale and the fourth case all the new scalars have masses lying at f scale. All cases have a neutral CP-even scalar mimicking the standard Higgs.

Molecular enhancement factors for the P,T -violating electric dipole moment of the electron in BaCH3 and YbCH3 symmetric top molecules

High-precision tests of fundamental symmetries are looking for the parity- ($\mathcal{P}$), time-reversal- ($\mathcal{T}$) violating electric dipole moment of the electron (eEDM) as proof of physics beyond the Standard Model. Particularly, in polyatomic molecules, the complex vibrational and rotational structure gives the possibility to reach high enhancement of the $\mathcal{P},\mathcal{T}$-odd effects in moderate electric fields, and with the possibility of increasing the statistical sensitivity by using laser cooling. In this work, we calculate the $\mathcal{P},\mathcal{T}$-odd molecular enhancement factor of the eEDM (${W}_{\mathrm{d}}$) and of the scalar-pseudoscalar interaction (${W}_{\mathrm{s}}$) necessary for the interpretation of future experiments on the promising candidates ${\mathrm{BaCH}}_{3}$ and ${\mathrm{YbCH}}_{3}$. We employ high-accuracy relativistic coupled cluster methods and systematically evaluate the uncertainties of our computational approach. Compared to other Ba- and Yb-containing molecules, ${\mathrm{BaCH}}_{3}$ and ${\mathrm{YbCH}}_{3}$ exhibit larger ${W}_{\mathrm{d}}$ and ${W}_{\mathrm{s}}$ associated to the increased covalent character of the $M$--C bond. The calculated values are $3.22\ifmmode\pm\else\textpm\fi{}0.12\ifmmode\times\else\texttimes\fi{}{10}^{24}\frac{h\text{Hz}}{e\text{cm}}$ and $13.80\ifmmode\pm\else\textpm\fi{}0.35\ifmmode\times\else\texttimes\fi{}{10}^{24}\frac{h\text{Hz}}{e\text{cm}}$ for ${W}_{\mathrm{d}}$, and $8.42\ifmmode\pm\else\textpm\fi{}0.29\phantom{\rule{4pt}{0ex}}h\mathrm{kHz}$ and $50.16\ifmmode\pm\else\textpm\fi{}1.27\phantom{\rule{4pt}{0ex}}h\mathrm{kHz}$ for ${W}_{\mathrm{s}}$, in ${\mathrm{BaCH}}_{3}$ and ${\mathrm{YbCH}}_{3}$, respectively. The robust, accurate, and cost-effective computational scheme reported in this work makes our results suitable for extracting the relevant fundamental properties from future measurements and also can be used to explore other polyatomic molecules sensitive to various violations of fundamental symmetries.

Probing Lorentz symmetry violation using the first image of Sagittarius A*: Constraints on standard-model extension coefficients

Thanks to unparalleled near-horizon images of the shadows of Messier 87* (M87*) and Sagittarius A* (Sgr A*) delivered by the Event Horizon Telescope (EHT), two amazing windows opened up to us for the strong-field test of the gravity theories as well as fundamental physics. Information recently published from EHT about the Sgr A*'s shadow lets us have a novel possibility of exploration of Lorentz symmetry violation (LSV) within the Standard-Model Extension (SME) framework. Despite the agreement between the shadow image of Sgr A* and the prediction of the general theory of relativity, there is still a slight difference which is expected to be fixed by taking some fundamental corrections into account. We bring up the idea that the recent inferred shadow image of Sgr A* is explicable by a minimal SME-inspired Schwarzschild metric containing the Lorentz violating (LV) terms obtained from the post-Newtonian approximation. The LV terms embedded in Schwarzschild metric are dimensionless spatial coefficients ${\bar s}^{jk}$ associated with the field responsible for LSV in the gravitational sector of the minimal SME theory. In this way, one can control Lorentz invariance violation in the allowed sensitivity level of the first shadow image of Sgr A*. Actually, using the bounds released within $1\sigma$ uncertainty for the shadow size of Sgr A* and whose fractional deviation from standard Schwarzschild, we set upper limits for the two different combinations of spatial diagonal coefficients and the time-time coefficient of the SME, as well. The best upper bound is at the $10^{-2}$ level, which should be interpreted differently from those constraints previously extracted from well-known frameworks since unlike standard SME studies it is not obtained from a Sun-centered celestial frame but comes from probing the black hole horizon scale.

Impact of Lorentz violation on anomalous magnetic moments of charged leptons

We address the question whether a violation of Lorentz symmetry can explain the tension between the measurement and the Standard-Model prediction of the anomalous magnetic moment of the muon, (g − 2)μ, and whether it can significantly impact the one of the electron, (g — 2)e. While anisotropic Lorentz-violating effects are, in general, expected to produce sidereal oscillations in observables, isotropic Lorentz violation (LV) in the charged-lepton sector could also feed into (g — 2)e,μ. However, we find that this type of Lorentz violation, parametrised via a dim-4 field operator of the Standard-Model Extension (SME), is already strongly constrained by the absence of vacuum Čerenkov radiation and photon decay. In particular, the observations of very-high-energetic astrophysical photons at LHAASO and of high-energetic electrons (muons) by the LHC (IceCube) place the most stringent two-sided bounds on the relevant SME coefficients overset{circ }{c} (e) ( overset{circ }{c} (μ)). Therefore, any explanation of the tension in (g − 2)μ via isotropic Lorentz violation of the minimal spin-degenerate SME is excluded, and the possible size of its impact on (g − 2)e is very limited.

An interesting case of symmetry breaking in the absence of symmetry: the bicarbonate radical (HCO3)

As part of a computational study of the thermochemical properties of systems related to carbonic acid (HCO), an interesting phenomenon was observed in the bicarbonate radical (HCO). This species belongs to the class of formoxyl radicals, but lacks the geometric symmetry of the more heavily-studied and prototypical HCO and FCO molecules. However, it is not immune from the problems that those molecules present to electronic structure calculations. Specifically, at geometries in the vicinity of the equilibrium structure, three solutions to the unrestricted Hartree-Fock equations can be found: two in which the unpaired spin is largely localized onto one of the (inequivalent) carbonyl oxygen atoms, and one in which the spin is delocalized. While all three of these reference functions comprise orbitals that transform as pure irreducible representations of the point group, the two localized choices qualitatively correspond to the symmetry-broken solution of the formoxyl species and the delocalized solution qualitatively corresponds to the symmetry-preserving (but orbitally unstable) solution. The three solutions are described in this work, as well as the corresponding ambiguities that result in the thermochemical characterization of this species.

Loop correction to the scalar Casimir energy density and generation of topological mass due to a helix boundary condition in a scenario with Lorentz violation

In this paper, the effective potential approach in quantum field theory is used in order to investigate self-interaction loop correction to the Casimir energy density and generation of topological mass for both massless and massive real scalar fields. It is assumed that the scalar field obeys a helix boundary condition. In addition, it is also considered a CPT-even aether-type violation of the Lorentz symmetry. In the absence of the Lorentz violation, we obtain analytical expressions for the loop correction to the Casimir energy density and to the mass of the scalar field. The same expressions are also obtained assuming the Lorentz violation in each of the spacetime directions. We also show some graphs that exhibit how the loop correction and the Lorentz violation affect the Casimir energy density and the mass of the scalar field.

Scaling solution for field-dependent gauge couplings in quantum gravity

Quantum gravity can determine the dependence of gauge couplings in a scalar field, which is related to possible fifth forces and time varying fundamental “constants”. This prediction is based on the scaling solution of functional flow equations. For momenta below the field-dependent Planck mass the quantum scale invariant standard model emerges as an effective low energy theory. For a small non-zero value of the infrared cutoff scale the time-variation of couplings or apparent violations of the equivalence principle turn out to be negligibly small for the present cosmological epoch, unless some further quantum scale symmetry violation beyond the standard model comes into play. More sizable effects of quantum scale symmetry violation are expected during nucleosynthesis or before. Scaling solutions relate field dependence and dependence on the renormalization scale. We find asymptotically free gauge couplings for the standard model coupled to gravity, while for grand unified models the gauge couplings are asymptotically safe with non-zero values at the ultraviolet fixed point. The scaling solution of asymptotically safe metric quantum gravity yields restrictions for model building, as limiting the number of scalars in grand unified theories.

Lorentz- and CPT-violating neutrinos from string/D-brane model

We show that the space-time foam model from string/D-brane theory predicts a scenario in which neutrinos can possess linearly energy dependent speed variation, together with an asymmetry between neutrinos and antineutrinos, indicating the possibility of Lorentz and CPT symmetry violation for neutrinos. Such a scenario is supported by a phenomenological conjecture from the possible associations of IceCube ultrahigh-energy neutrino events with the gamma-ray bursts. It is also consistent with the constraints set by the energy-losing decay channels (e.g., e+e− pair emission, or neutrino splitting) upon superluminal neutrino velocities. We argue that the plausible violations of energy-momentum conservation during decay may be responsible for the stable propagation of these neutrinos, and hence for the evasion of relevant constraints.

Are the Zcs(3985) and Zcs(4000) the same state?

In this work, we focus on the great breakthroughs in BESIII and LHCb collaborations, the strange hidden charm tetraquarks Zcs(3985) and Zcs(4000). We aim to clarify the first and foremost question, whether they are the same state. The calculation is performed with a solvable nonrelativistic effective field theory which incorporates heavy quark spin symmetry, SU(3)F symmetry and possible violations comprehensively. Two experimentally accessible consequences with Zcs(3985) and Zcs(4000) as different states are presented, the existence of a tensor D¯s⁎D⁎ resonance and suppression of decay Zcs(3985) → J/ψK. The two predictions can be used to distinguish the two-state scheme from the one-state interpretation.

Constraining GUP models using limits on SME coefficients

Generalized uncertainty principles (GUP) and, independently, Lorentz symmetry violations are two common features in many candidate theories of quantum gravity. Despite that, the overlap between both has received limited attention so far. In this brief paper, we carry out further investigations on this topic. At the nonrelativistic level and in the realm of commutative spacetime coordinates, a large class of both isotropic and anisotropic GUP models is shown to produce signals experimentally indistinguishable from those predicted by the standard model extension (SME), the common framework for studying Lorentz-violating phenomena beyond the standard model. This identification is used to constrain GUP models using current limits on SME coefficients. In particular, bounds on isotropic GUP models are improved by a factor of 107 compared to current spectroscopic bounds and anisotropic models are constrained for the first time.

Momentum-inversion symmetry breaking on the Fermi surface of magnetic topological insulators

Magnetic topological insulators (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_n$ were anticipated to exhibit magnetic energy gaps while recent spectroscopic studies did not observe them. Thus, magnetism on the surface is under debate. In this work, we propose another symmetry criterion to probe the surface magnetism. Because of both time-reversal symmetry-breaking and inversion symmetry-breaking, we demonstrate that the surface band structure violates momentum-inversion symmetry and leads to a three-fold rather than six-fold rotational symmetry on the Fermi surface if corresponding surface states couple strongly to the surface magnetism. Such a momentum-inversion symmetry violation is significant along the $\Gamma-K$ direction for surface bands on the (0001) plane.

Non-Abelian Aether-Like Term and Applications at Finite Temperature

The Yang-Mills-aether theory is considered. Implications of the non-Abelian aether-like term, which introduces violation of the Lorentz symmetry, are investigated in a thermal quantum field theory. The thermofield dynamics formalism is used to introduce the temperature effects and spatial compactification. As a consequence, corrections due to the non-Abelian aether term are calculated for the non-Abelian Stefan-Boltzmann law and for the non-Abelian Casimir energy and pressure at zero and finite temperature.

Quantum gravitational decoherence in the three neutrino flavor scheme

In many theories of quantum gravity quantum fluctuations of spacetime may serve as an environment for decoherence. Here we study quantum-gravitational decoherence of high-energy astrophysical neutrinos in the presence of fermionic dark sectors and for a realistic three neutrino scenario. We show how violation of global symmetries expected to arise in quantum gravitational interactions provides a possibility to pin down the number of dark matter fermions in the Universe. Furthermore, we predict the expected total neutrino flux and flavor ratios at experiments depending on the flavor composition at the source.

Heavy + heavy and heavy + light pseudoscalar to vector semileptonic transitions

Using a symmetry-preserving regularisation of a vector times vector contact interaction (SCI), we complete a systematic treatment of twelve semileptonic transitions with vector meson final states: Drightarrow rho , D_{(s)}rightarrow K^*, D_srightarrow phi , Brightarrow rho , B_srightarrow K^*, B_{(s)}rightarrow D_{(s)}^*, B_c rightarrow B_{(s)}^*, J/psi , D^*; and thereby finalise a unified analysis of semileptonic decays of heavy + heavy and heavy + light pseudoscalar mesons to both pseudoscalar and vector meson final states. The analysis is marked by algebraic simplicity, few parameters, and the ability to consistently describe systems from Nambu-Goldstone modes to heavy + heavy mesons. Regarding the behaviour of the transition form factors, the SCI results compare well wherever sound experimental or independent theory analyses are available; hence, the SCI branching fraction predictions should be a reasonable guide. Considering the ratios R(D_{(s)}^{(*)}), R(J/psi ), R(eta _c), whose values are key tests of lepton universality in weak interactions, the SCI values agree with Standard Model predictions. The B_{(s)}rightarrow D_{(s)}^* transitions are used to predict the precursor functions that evolve into the universal Isgur–Wise function in the heavy-quark limit, with results that conform with those from other sources where such are available. The study also exposes effects on the transition form factors that flow from interference between emergent hadron mass from the strong interaction and Higgs boson couplings via current-quark masses, including flavour symmetry violation.