Anomalous Correlation Research Articles

Anomalous Hall effect and electronic correlation in a spin-reoriented kagome antiferromagnet LuFe6Sn6

Abstract The kagome lattice system has been identified as a fertile ground for the emergence of a number of new quantum states, including superconductivity, quantum spin liquids, and topological electronic states. This has attracted significant interest within the field of condensed matter physics. Here, we present the observation of an anomalous Hall effect in an iron-based kagome antiferromagnet LuFe6Sn6, which implies a non-zero Berry curvature in this compound. By means of extensive magnetic measurements, a high Neel temperature, T N = 552 K, and a spin reorientation behavior were identified and a simple temperature-field phase diagram was constructed. Furthermore, this compound was found to exhibit a large Sommerfeld coefficient of γ = 87 mJ⋅mol−1⋅K−2, suggesting the presence of a strong electronic correlation effect. Our research indicates that LuFe6Sn6 is an intriguing compound that may exhibit magnetism, strong correlation, and topological states.

Anomalous Correlation between Thermal Conductivity and Elastic Modulus in Two-Dimensional Hybrid Metal Halide Perovskites.

Device-level implementation of soft materials for energy conversion and thermal management demands a comprehensive understanding of their thermal conductivity and elastic modulus to mitigate thermo-mechanical challenges and ensure long-term stability. Thermal conductivity and elastic modulus are usually positively correlated in soft materials, such as amorphous macromolecules, which poses a challenge to discover materials that are either soft and thermally conductive or hard and thermally insulative. Here, we show anomalous correlations of thermal conductivity and elastic modulus in two-dimensional (2D) hybrid organic-inorganic perovskites (HOIP) by engineering the molecular interactions between organic cations. By replacing conventional alkyl-alkyl and aryl-aryl type organic interactions with mixed alkyl-aryl interactions, we observe an enhancement in elastic modulus with a reduction in thermal conductivity. This anomalous dependence provides a route to engineer thermal conductivity and elastic modulus independently and a guideline to search for better thermal management materials. Further, introducing chirality into the organic cation induces a molecular packing that leads to the same thermal conductivity and elastic modulus regardless of the composition across all half-chiral 2D HOIPs. This finding provides substantial leeway for further investigations in chiral 2D HOIPs to tune optoelectronic properties without compromising thermal and mechanical stability.

Prediction of Diverse Boreal Summer Intraseasonal Oscillation in the GFDL SPEAR Model

Abstract Boreal summer intraseasonal oscillation (BSISO) is a primary source of predictability for summertime weather and climate on the subseasonal-to-seasonal (S2S) time scale. Using the GFDL SPEAR S2S prediction system, we evaluate the BSISO prediction skills based on 20-yr (2000–19) hindcast experiments with initializations from May to October. It is revealed that the overall BSISO prediction skill using all hindcasts reaches out to 22 days as measured by BSISO indices before the bivariate anomalous correlation coefficient (ACC) drops below 0.5. Results also show that the northeastward-propagating canonical BSISO (CB) event has a higher prediction skill than the northward dipole BSISO (DB) event (28 vs 23 days). This is attributed to CB’s more periodic nature, resulting in its longer persistence, while DB events are more episodic accompanied by a rapid demise after reaching maximum enhanced convection over the equatorial Indian Ocean. From a forecaster’s perspective, a precursory strong Kelvin wave component in the equatorial western Pacific signifies the subsequent development of a CB event, which is likely more predictable. Investigation of individual CB events shows a large interevent spread in terms of their prediction skills. For CB, the events with weaker and fluctuating amplitude during their lifetime have relatively lower prediction skills likely linked to their weaker convection–circulation coupling. Interestingly, the prediction skills of individual CB events tend to be relatively higher and less scattered during late summer (August–October) than those in early summer (May–July), suggestive of the seasonal modulation on the evolution and predictability of BSISO. Significance Statement The advance of subseasonal-to-seasonal (S2S) prediction largely depends on dynamical models’ ability to predict some major intrinsic modes in the climate system, including the boreal summer intraseasonal oscillation (BSISO). Using a newly developed S2S prediction system, we thoroughly evaluated its performance in predicting BSISO, and revealed the skill dependence on the BSISO propagation diversity. Here we provide physical explanations of what influences the BSISO predictions and identify different precursory signals for two types of BSISO, which have important implications for operational forecasts.

Proposal for an Electromagnetic Mass Formula for the X17 Particle

Recent observations of anomalous angular correlations of electron–positron pairs in several nuclear reactions have indicated the existence of a hypothetical neutral boson of rest mass ~17 MeV/c2, called the X17 particle. Similarly, one has interpreted an independent set of experiments on photon pair spectra around the invariant mass ~38 MeV/c2, by assuming the existence of the so-called E38 particle. In the present paper, we derive analytical mass formulas for the X17 particle and the E38 particle, on the basis of quantum electrodynamics. We shall use the exact solutions of the Dirac equation of the joint system of a charged particle and plane waves of the quantized electromagnetic radiation. When these solutions are applied to a proton, they lead to dressed radiation quanta with a rest mass of 17.0087 MeV/c2, which may be identified with the X17 vector bosons. A similar consideration, applied to the udd quarks of the neutron, yields dressed quanta, whose mass equals 37.9938 MeV/c2, corresponding to the E38 particle. These formulas, besides the Sommerfeld fine structure constant and the masses of the nucleons, do not contain any adjustable parameters. The present analysis also delivers the value 0.846299 fm for the proton radius.

Anomalous kaon correlations measured in Pb-Pb collisions at the LHC as evidence for the melting and refreezing of the QCD vacuum

Measurements of the dynamical correlations between neutral and charged kaons in central Pb-Pb collisions at √SNN = 2.76 TeV by the ALICE Collaboration display anomalous behavior relative to conventional heavy-ion collision simulators. We consider other conventional statistical models, none of which can reproduce the magnitude and centrality dependence of the correlations. The data can be reproduced by coherent emission from domains which grow in number and volume with increasing centrality. We study the dynamical evolution of the strange quark condensate and show that the energy released during the expansion and cooling of the system may be sufficient to explain the anomaly.

Sequential unsharp measurement of photon polarization

We propose a general experimental scheme based on binary trees of partially polarizing beam splitters (PPBSs) for realizing sequential unsharp measurements of photon polarization. The sharpnesses and the bases of the particular photon polarization measurements can be chosen arbitrarily by using corresponding PPBSs and phase plates in the setup. In the limit of low sharpnesses the scheme can realize sequential weak measurements, too. We develop a general formalism for describing sequential unsharp measurements of photon polarization in which the particular unsharp measurements are characterized by appropriate measurement operators. We show that a straightforward experimental realization of this model is the proposed scheme. In this formalism the output polarization states after the sequential measurement and any correlation functions characterizing the measurement results can be easily calculated. Our model can be used for analyzing the consequences of applying postselection and reselection in the measurement. We derive the anomalous mean value for an unsharp polarization measurement with postselection and the anomalous second-order correlation function for the sequential unsharp measurement of photon polarization with reselection. We show that these anomalies can be easily measured using the proposed scheme.

Detecting anomalous sea-level states in North Sea tide gauge data using an autoassociative neural network

Abstract. The sea level in the North Sea is densely monitored by tide gauges. The data they provide can be used to solve different scientific and practical problems, including the validation of numerical models and the detection of extreme events. This study focuses on the detection of sea-level states with anomalous spatial correlations using autoassociative neural networks (AANNs), trained with different sets of observation- and model-based data. Such sea-level configurations are related to nonlinear ocean dynamics; therefore, neural networks appear to be the right candidate for their identification. The proposed network can be used to accurately detect such anomalies and localize them. We demonstrate that the atmospheric conditions under which anomalous sea-level states occur are characterized by high wind tendencies and pressure anomalies. The results show the potential of AANNs for accurately detecting the occurrence of such events. We show that the method works with AANNs trained on tide gauge records as well as with AANN trained with model-based sea surface height outputs. The latter can be used to enhance the representation of anomalous sea-level events in ocean models. Quantitative analysis of such states may help assess and improve numerical model quality in the future as well as provide new insights into the nonlinear processes involved. This method has the advantage of being easily applicable to any tide gauge array without preprocessing the data or acquiring any additional information.

MSCA: An Unsupervised Anomaly Detection System for Network Security in Backbone Network

Anomaly detection is a crucial topic in network security which refers to automatically mining known and unknown attacks or threats. Many detectors have been proposed in the last decade. Nonetheless, a practical solution, which is able to provide a high True Positive Rate (TPR) with an acceptable False Positive Rate (FPR) without any prior information, is still challenging due to the complexity and variability of anomaly pattern. In this article, we propose a novel unsupervised detection system called MSCA which applies multiple sketches, K-means++ unsupervised clustering, and association rule mining to detect traffic anomalies and analyze anomalous features and correlations. It can blindly identify known and unknown traffic anomalies without any labeled traffic or prior signatures about data distribution. Rich traffic data is first aggregated and compacted to traffic flows by sketches, and further detected by the combination of clustering algorithm and voting strategy. Then association rule mining is finally utilized to find the anomalous frequent item-sets and association rules. Numerical experiments on MAWILAB datasets demonstrate that the proposed detection method outperforms other reference unsupervised detection methods. It achieves an accuracy of 99.86%, 99.97%, 97.08%, and 95.19% in overall four detection types including IP and port of source and destination.

A new light particle is being born

A few years ago we observed anomalous electron-positron angular correlations for the 18.15 MeV M1 transition of 8Be. This was interpreted as the creation and decay of an intermediate bosonic particle with a mass of m 0 c 2=16.70±0.35(stat )±0.5(sys) MeV, which is now called X17. The possible relation of the X17 boson to the dark matter problem triggered an enormous interest in the wider physics community. We also observed a similar anomaly in 4He, which could be described also by the creation and subsequent decay of the same X17 particle. Very recently, the 11B proton capture reaction was used for exciting the 17.2 MeV broad (Γ=1.15 MeV) resonance in 12C and studying their internal pair creation decay. Anomalies were observed in the angular correlation of the electron-positron pairs, which together with the 8Be and 4He data provides kinematic evidence for the X17 particle and supports their vector boson and fifth force explanation.

Anomaly detection of time series correlations via a novel Lie group structure

We investigate a natural Lie group structure that correlations possess, interpreted as a special case of the quotient manifold structure for correlation matrices. The one‐dimensional setting of the general theory gives rise to additional structure in the form of a natural associative multiplication of correlations making the space of correlations into a Lie group. We explicitly compute left‐invariant vector fields, exponential and logarithmic mappings, and ultimately, a closed‐form distance formula between correlations. The Lie group formalism is then applied to an application in anomalous correlation detection. The advantage of the Lie group method illustrated with time series data of stock prices.

Mechanism of oscillation of aqueous electrical double layer capacitance: Role of solvent

The present classical density functional theory (CDFT) study is focused on role of solvent in differential capacitance (Cd) behavior of aqueous electrolyte electric double-layer capacitor (EDLC). In the CDFT, water molecule is described by a solvent primitive model, which is constructed to give two experimentally measured aandb parameters in the van der Waals equation of state of water; Lennard-Jones parameters of both cation and anion are chosen to be reminiscent of properties of K+ andCl-1; a structureless and soft wall comprised of carbon atoms is considered to represent a graphene electrode. Main findings are summarized as follows. (i) The CdH (H is separation between two graphene electrodes) curve is always shifted up (at lower electrode voltage) or down (at higher electrode voltage) by increasing the electrolyte bulk concentrationc. The anomalous negative correlation between c and Cd at high voltage originates from the so-called charge inversion and one additional weak co-ion peak located closer to the electrode surface at higher voltage. (ii) Oscillation periods of CdH curves are basically fixed at 3 Å regardless of molecular characteristics of counter- and co-ions, c value, and electrode voltage; explicit consideration of the solvent granularity and polarity greatly reduces the attenuation rate of the oscillation with pore size. Increase of CdH with pore size reducing towards the ion size, does occur but only with moderate magnitude; a main CdH extreme value occurs approximately around H being two times ion diameter, which can be either a maximum or a minimum, depending on electrolyte bulk concentration, polarity and strength of the electrode. These oscillation features differ greatly from those observed in solvent-free ionic liquids and continuum solvent model. (iii) Potential of zero charge ψpzc for the case of small size of cation and weaker LJ interaction of the cation with solvent molecule in large number, is necessarily positive and its value is positively correlated with the c value; minimum point ψMin of the Cdψs curve is always larger than theψpzc, not consistent with the Gouy-Chapman theory, and both the ψpzcH curve and ψMinH curve change quasi periodically with the pore size H also in 3 Å cycle. (iv) Theoretical analysis shows that the capacitance behavior is mainly controlled by the number and position of solvent peaks and their changes with pore size, while distribution of ions is largely controlled by their LJ interaction with solvent. This shows the importance of the solvent in modulating the capacitance behavior.

Angular correlations in the e+e− decay of excited states in Be8

Motivated by the recent observation of anomalous electron-positron angular correlations in the decay of the 18.15 MeV 1+ excited states in 8Be, we reexamine in detail the Standard Model expectations for these angular correlations. The 18.15 MeV state is above particle threshold, and several multipoles can contribute to its $e^+e^-$ decay. We present the general theoretical expressions for $e^+e^-$ angular distributions for nuclear decay by C0, C1, C2 M1, E1, and E2 multipoles, and we examine their relative contribution to the $e^+e^-$ decay of 8Be at 18.15 MeV. We find that this resonance is dominated by M1 and E1 decay, and that the ratio of M1 to E1 strength is a strong function of energy. This is in contract to the original analysis of the $e^+e^-$ angular distributions, where the M1/E1 ratio was assumed to be a constant over the energy region Ep = 0:8-1:2 MeV. We find that the existence of a `bump' in the measured angular distribution is strongly dependent on the assumed M1/E1 ratio, with the present analysis finding the measured large-angle contributions to the $e^+e^-$ angular distribution to be lower than expectation. Thus, in the current analysis we find no evidence for axion decay in the 18.15 MeV resonance region of 8Be.

Anomalous correlation between quantum efficiency and transverse momentum spread in semiconductor cathode photoemission

The next generation of accelerator based scientific facilities, such as the megahertz repetition rate free electron laser and electron-ion collider, relies on photoelectron sources of high peak and high average brightness. Therefore, photocathodes with both low transverse momentum spread (TMS) and high quantum efficiency (QE) are required. The conventional positive correlation between QE and TMS leads to a tradeoff between peak and average brightness. In this study, a negative correlation between QE and TMS is experimentally observed for the first time on a semiconductor photocathode (${\mathrm{Cs}}_{2}\mathrm{Te}$). Two models are proposed to explain such an anomalous correlation. One model considers the junction between the semiconductor cathode and the metal substrate in the case of slightly excessive cesium deposition, and the other model considers different Cs-Te composites. Our studies inspire a new way to break the conventional correlation between QE and TMS, and open a new perspective to advance the beam brightness frontiers.

Stratospheric Temperature and Ozone Anomalies Associated With the 2020 Australian New Year Fires

AbstractStratospheric aerosol, temperature, and ozone anomalies after the 2020 Australian bushfires are documented from satellite observations. Aerosol extinction is enhanced in the Southern Hemisphere (SH) lower stratosphere (LS) in early 2020, comparable in magnitude to the Calbuco eruption in 2015. Warm temperature anomalies of 1–2 K occur in the SH LS during January‐April 2020 and are coincident with enhanced aerosols. Radiative heating is indicated through anomalous temperature correlations between lower and higher latitudes. LS ozone shows midlatitude decreases several months after the aerosol maximum and before the polar vortex breakup, reaching extreme minima over the available OMPS record since 2011. Antarctic ozone depletion in the LS in 2020 reached a decadal low for both magnitude and persistence during November‐December, along with record low polar temperatures and a strong polar vortex. Overall, the polar ozone depletion, temperature, and polar vortex evolution broadly resembled the effects of the Calbuco eruption in 2015.

Unraveling the Rate‐Dependent Stability of Metal Anodes and Its Implication in Designing Cycling Protocol

AbstractIt is widely recognized that a high current rate (J) speeds up dendrite formation and thus shortens the cycle life of metal anodes. Here, an anomalous correlation is reported between elevated J and deposition/stripping stability (decrease–increase–decrease), leading to the relative maximum stability at a moderate J. Complementary theoretical and experimental analyses suggest that such a complex relationship lies in high J's dual and contradictory roles in kinetics and thermodynamics. The well‐known former renders decreased Sand's time (τ) and deteriorative cyclic stability, while the commonly overlooked latter provides larger extra energy that accelerates nucleation rate (νn). Using Zn metal anode as a model system, the νn and τ controlled nucleation‐growth process is unambiguously revealed, both of which are closely related to J. Based on these findings, an initial high J discharge strategy is developed to produce abundant nuclei for uniform metal growth at standard J in the subsequent process. The protocol increases the Zn deposition/stripping lifetime from 303 to 2500 h under a cycling capacity of 1 mAh cm−2 without resorting to electrode/electrolyte modification. Furthermore, such a concept can be readily extended to Li/K metal anodes with significantly enhanced cycle life, demonstrating its universality for developing high‐performance metal batteries.

Kepatuhan Minum Obat pada Pasien Diabetes Melitus Tipe 2 di Beberapa Puskesmas Kabupaten Banyumas

Diabetes mellitus (DM) is considered as ”the mother of all diseases" because it causes many complications. Knowing and measuring medication adherence may have a greater effect on DM patients. Several studies in Indonesia used a questionnaire scale to measure adherence, however they do not validate the study population, so it could still be found anomalous correlation analysis between adherence and clinical data even though it measured in the same country and scale. This study measure the adherence level of type 2 diabetes patients, evaluates the validity of the medication adherence scale, and analyze the correlation with the clinical outcome of type 2 diabetes patients in four health centers in Banyumas district. The study uses a cross-sectional design in Prolanis type 2 DM patients of January -April 2020. The adherence is measured by MARS-10, backward-forward translation method followed by content and internal validation. Clinical outcome is evaluated based on fasting blood glucose measurement. The results of the MARS-10 Gregory index analysis showed content validity in the high category (IG ≥ 0.8). The content validity showed the results of 9 questions with the value of r count> r table (n = 30, r table = 0.361). Reliability analysis showed Cronbach's Alpha 0.747> 0.6. The measurement showed 80.3% was adherent patients and 19.3% was non-adherent patients. Correlation analysis showed that there was no significant relationship (p> 0.05) between patient adherence and clinical outcome. Those results showed that type 2 diabetes mellitus patients in 4 health centers were categorized as adherent but not correlated with the clinical outcome. This was enable due to the clinical outcome was simultaneously influenced by several factors: general factors, individual factors, and unpredictable factors.

Dynamical and Machine Learning Hybrid Seasonal Prediction of Summer Rainfall in China

The seasonal prediction of summer rainfall is crucial for regional disasters reduction, but currently has a low prediction skill. We developed a dynamical and machine learning hybrid (MLD) seasonal prediction method for summer rainfall in China based on circulation fields from the CAS FGOALS-f2(无全称) operational dynamical prediction model. By selecting the optimum hyperparameters for three machine learning methods to obtain the best fit and least overfitting, an ensemble mean of the random forest and gradient boosting regression tree methodswas shown to have the highest prediction skill measured by the anomalous correlation coefficient. The skill had anaverage value of 0.34 in the historical cross-validation period (1981–2010) and 0.20 in a 10-yr period (2011–2020) of independent prediction, which significantly improves the dynamical prediction skill by 400%. Both reducing overfitting and using the best dynamical prediction are important in applications of the dynamical and MLD method and thisrequires further investigation.

Understanding the Anomalous Short-Range Spatial Correlation Of Fe and Sn in Neutron-Irradiated Zr Alloys

Understanding the Anomalous Short-Range Spatial Correlation Of Fe and Sn in Neutron-Irradiated Zr Alloys

Stress correlations in frictional granular media

This paper investigates whether in frictional granular packings, like in Hamiltonian amorphous elastic solids, the stress autocorrelation matrix presents long range anisotropic contributions just as elastic Green's functions. We find that in a standard model of frictional granular packing this is not the case. We prove quite generally that mechanical balance and material isotropy constrain the stress auto-correlation matrix to be fully determined by two spatially isotropic functions: the pressure and torque auto-correlations. The pressure and torque fluctuations being respectively normal and hyperuniform force the stress autocorrelation to decay as the elastic Green's function. Since we find the torque fluctuations to be hyper-uniform, the culprit is the pressure whose fluctuations decay slower than normally as a function of the system's size. Investigating the reason for these abnormal pressure fluctuations we discover that anomalous correlations build up already during the compression of the dilute system before jamming. Once jammed these correlations remain frozen. Whether this is true for frictional matter in general or is it the consequence of the model properties is a question that must await experimental scrutiny and possible alternative models.

Disorder-Induced Long-Ranged Correlations in Scalar Active Matter.

We study the impact of quenched random potentials and torques on scalar active matter. Microscopic simulations reveal that motility-induced phase separation is replaced in two dimensions by an asymptotically homogeneous phase with anomalous long-ranged correlations and nonvanishing steady-state currents. Using a combination of phenomenological models and a field-theoretical treatment, we show the existence of a lower-critical dimension d_{c}=4, below which phase separation is only observed for systems smaller than an Imry-Ma length scale. We identify a weak-disorder regime in which the structure factor scales as S(q)∼1/q^{2}, which accounts for our numerics. In d=2, we predict that, at larger scales, the behavior should cross over to a strong-disorder regime. In d>2, these two regimes exist separately, depending on the strength of the potential.