Charges Of Opposite Sign Research Articles

Search for singly produced vectorlike top partners in multilepton final states with 139 fb−1 of pp collision data at s=13 TeV with the ATLAS detector

A search for the single production of a vectorlike top partner (T) with mass greater than 1 TeV decaying into a Z boson and a top quark is presented, using the full Run 2 dataset corresponding to 139 fb−1 of pp collisions at s=13 TeV, collected in 2015–2018 with the ATLAS detector at the Large Hadron Collider. The targeted final state is characterized by the presence of a pair of electrons or muons with opposite-sign charges which form a Z-boson candidate, as well as by the presence of b-tagged jets and forward jets. Events with exactly two or at least three leptons are categorized into two independently optimized analysis channels. No significant excess above the background expectation is observed and the results from the two channels are statistically combined to set exclusion limits at 95% confidence level on the masses and couplings of T. The results are interpreted in several benchmark scenarios to set limits on the mass and universal coupling strength (κ) of the vectorlike quark. For singlet T quarks, κ values between 0.22 and 0.64 are excluded for masses between 1000 and 1975 GeV. For T quarks in the doublet scenario, where the production cross section is much lower, κ values between 0.54 and 0.88 are excluded for masses between 1000 and 1425 GeV. © 2024 CERN, for the ATLAS Collaboration 2024 CERN

Azimuthal Angle Correlations of Muons Produced via Heavy-Flavor Decays in 5.02TeV Pb+Pb and pp Collisions with the ATLAS Detector.

Angular correlations between heavy quarks provide a unique probe of the quark-gluon plasma created in ultrarelativistic heavy-ion collisions. Results are presented of a measurement of the azimuthal angle correlations between muons originating from semileptonic decays of heavy quarks produced in 5.02TeV Pb+Pb and pp collisions at the LHC. The muons are measured with transverse momenta and pseudorapidities satisfying p_{T}^{μ}>4 GeV and |η^{μ}|<2.4, respectively. The distributions of azimuthal angle separation Δϕ for muon pairs having pseudorapidity separation |Δη|>0.8, are measured in different Pb+Pb centrality intervals and compared to the same distribution measured in pp collisions at the same center-of-mass energy. Results are presented separately for muon pairs with opposite-sign charges, same-sign charges, and all pairs. A clear peak is observed in all Δϕ distributions at Δϕ∼π, consistent with the parent heavy-quark pairs being produced via hard-scattering processes. The widths of that peak, characterized using Cauchy-Lorentz fits to the Δϕ distributions, are found to not vary significantly as a function of Pb+Pb collision centrality and are similar for pp and Pb+Pb collisions. This observation will provide important constraints on theoretical descriptions of heavy-quark interactions with the quark-gluon plasma.

The electric charge of black holes within galaxies

We present improved estimates of the electric charge that black holes could hold when these are embedded in the ionised plasma within galaxies. We have implemented the spontaneous emission of charges of opposite sign to that of the black hole via athermal Hawking evaporation, including its dependence on black hole spin, and we have estimated the equilibrium charge that arises as this charge loss is balanced by the continuous accretion of charges from the surrounding plasma. The resulting charge can be several orders of magnitude lower than previously estimated upper limits, but it can surpass the pair production limit noted by Gibbons (1974) by a margin that increases with the amplitude of the black hole spin and the density of the plasma. We also implement a calculation for the net charge of galaxies due to their stellar black holes and to primordial black holes in the case these make up a fraction of the dark matter. We find that these charges lie within the range that would produce adequate magnetic field seeds at the onset of galaxy formation.

Ferroelectric Polarization‐Mediated Modulation of Optical Properties in 2D van der Waals Architectures

AbstractThe integration of 2D ferroelectric materials with 2D photoelectric materials presents a promising avenue for addressing issues related to controlled doping and device integration in layered semiconductors. The reversible and non‐volatile residual polarization inherent to ferroelectrics can provide stable n‐ or p‐type doping for 2D semiconductors. Despite advances in doping strategies for 2D materials, existing techniques, and post‐doping characterization methodologies exhibit limitations, including the challenge of achieving high‐resolution graphical depictions of doped structures. Here, a WS2/CuInP2S6 heterostructure is demonstarted whereby the residual polarization of ferroelectric CuInP2S6 regions with anti‐parallel directions supplies screening charges of opposite signs to WS2 monolayers. This notably alters the ratio of neutral excitons and negatively charged trions within the recombination luminescence of the direct‐gap semiconductor, thereby offering a viable approach for controllable, non‐volatile modulation in 2D systems. Beyond proposing a feasible strategy for patterned doping and effective regulation in 2D semiconductors through interface engineering, this work enhances the understanding of the interplay between ferroelectrics and semiconductors.

Precise QCD predictions for W-boson production in association with a charm jet

The production of a W-boson with a charm quark jet provides a highly sensitive probe of the strange quark distribution in the proton. Employing a novel flavour dressing procedure to define charm quark jets, we compute W+charm-jet production up to next-to-next-to-leading order (NNLO) in QCD. We study the perturbative stability of production cross sections with same-sign and opposite-sign charge combinations for the W boson and the charm jet. A detailed breakdown according to different partonic initial states allows us to identify particularly suitable observables for the study of the quark parton distributions of different flavours.

Trifurcated Splitting of Water Droplets on Engineered Lithium Niobate Surfaces.

Controlled splitting of liquid droplets is a key function in many microfluidic applications. In recent years, various methodologies have been used to accomplish this task. Here, we present an optofluidic technique based on an engineered surface formed by coating a z-cut iron-doped lithium niobate crystal with a lubricant-infused layer, which provides a very slippery surface. Illuminating the crystal with a light spot induces surface charges of opposite signs on the two crystal faces because of the photovoltaic effect. If the light spot is sufficiently intense, millimetric water droplets placed near the illuminated spot split into two charged fragments, one fragment being trapped by the bright spot and the other moving away from it. The latter fragment does not move randomly but rather follows one of three well-defined trajectories separated by 120°, which reflect the anisotropic crystalline structure of Fe:LiNbO3. Numerical simulations explain the behavior of water droplets in the framework of the forces induced by the interplay of pyroelectric, piezoelectric, and photovoltaic effects, which originate simultaneously inside the illuminated crystal. Such a synergetic effect can provide a valuable feature in applications that require splitting and coalescence of droplets, such as chemical microreactors and biological encapsulation and screening.

Anion⋯anion self-assembly under the control of σ- and π-hole bonds.

The electrostatic attraction between charges of opposite signs and the repulsion between charges of the same sign are ubiquitous and influential phenomena in recognition and self-assembly processes. However, it has been recently revealed that specific attractive forces between ions with the same sign are relatively common. These forces can be strong enough to overcome the Coulomb repulsion between ions with the same sign, leading to the formation of stable anion⋯anion and cation⋯cation adducts. Hydroden bonds (HBs) are probably the best-known interaction that can effectively direct these counterintuitive assembly processes. In this review we discuss how σ-hole and π-hole bonds can break the paradigm of electrostatic repulsion between like-charges and effectively drive the self-assembly of anions into discrete as well as one-, two-, or three-dimensional adducts. σ-Hole and π-hole bonds are the attractive forces between regions of excess electron density in molecular entities (e.g., lone pairs or π bond orbitals) and regions of depleted electron density that are localized at the outer surface of bonded atoms opposite to the σ covalent bonds formed by atoms (σ-holes) and above and below the planar portions of molecular entities (π-holes). σ- and π-holes can be present on many different elements of the p and d block of the periodic table and the self-assembly processes driven by their presence can thus involve a wide diversity of mono- and di-anions. The formed homomeric and heteromeric adducts are typically stable in the solid phase and in polar solvents but metastable or unstable in the gas phase. The pivotal role of σ- and π-hole bonds in controlling anion⋯anion self-assembly is described in key biopharmacological systems and in molecular materials endowed with useful functional properties.

Interaction of magnesium ions with semiquinone radicals of tiron used as an indicator of reactive oxygen species

Electron paramagnetic resonance spectroscopy (EPR) and quantum chemical calculations based on density functional theory were used to demonstrate that the earlier observed changes in the EPR spectra of Tiron semiquinone radical dissolved in sea water solution occur due to interaction of Mg2+ ions with Tiron radical. This interaction is caused by electrostatic attraction between Mg2+ ions and Tiron radicals, which bears great charges of opposite sign (+2 and -3), on the one hand, and due to the ability of Mg2+ ion to bind to bidentate oxygen-containing ligands efficiently, on the other hand. The formation of tight contact ion pairs leads to electron and spin density redistribution in the Tiron radical, as can been seen by the observed changes in the EPR spectra of the radical.

On the problem of the classical limit for statistical characteristics of a quantum Coulomb plasma

The general structure of the perturbation theory series for the thermodynamic potential of a system of electrons and point ions is discussed. In the classical limit, when Planck’s constant ℏ → 0, the particular terms of the perturbation theory series diverge due to the impossibility of maintaining of stability of a purely classical system of the opposite sign charges attracted to each other. At the same time, it is known that in a certain range of parameters, a thermodynamic potential that does not contain Planck’s constant is a good approximation. Such thermodynamic functions describes the experimental data well and corresponds to the molecular dynamics calculations of model quasi-Coulomb systems. It is shown that the transition to a purely classical description, which implies the limit ℏ → 0, is impossible, but the terms of the series containing ℏ are small for certain plasma parameters and can be discarded. This is the rationale explanation of using classical models and approximations to describe plasma in certain parameter ranges. On this basis, a hypothesis is formulated about the absence of a classical limit for all measurable physical properties (including kinetic characteristics) of the Coulomb model of plasma, in which point particles interact according to the Coulomb law and, therefore, there are no adjustable parameters.

Conformal order and Poincaré-Klein mapping underlying electrostatics-driven inhomogeneity in tethered membranes.

Understanding the organization of matter under the long-range electrostatic force is a fundamental problem in multiple fields. In this work, based on the electrically charged tethered membrane model, we reveal regular structures underlying the lowest-energy states of inhomogeneously stretched planar lattices by a combination of numerical simulation and analytical geometric analysis. Specifically we show the conformal order characterized by the preserved bond angle in the lattice deformation and reveal the Poincaré-Klein mapping underlying the electrostatics-driven inhomogeneity. The discovery of the Poincaré-Klein mapping, which connects the Poincaré disk and the Klein disk for the hyperbolic plane, implies the connection of long-range electrostatic force and hyperbolic geometry. We also discuss lattices with patterned charges of opposite signs for modulating in-plane inhomogeneity and even creating 3D shapes, which may have a connection to metamaterials design. This work suggests the geometric analysis as a promising approach for elucidating the organization of matter under the long-range force.

Search for pair-production of vector-like quarks in pp collision events at [formula omitted] TeV with at least one leptonically decaying Z boson and a third-generation quark with the ATLAS detector

A search for the pair-production of vector-like quarks optimized for decays into a Z boson and a third-generation Standard Model quark is presented, using the full Run 2 dataset corresponding to 139fb−1 of pp collisions at s=13TeV, collected in 2015–2018 with the ATLAS detector at the Large Hadron Collider. The targeted final state is characterized by the presence of a Z boson with high transverse momentum, reconstructed from a pair of same-flavour leptons with opposite-sign charges, as well as by the presence of b-tagged jets and high-transverse-momentum large-radius jets reconstructed from calibrated smaller-radius jets. Events with exactly two or at least three leptons are used, which are further categorized by the presence of boosted W, Z, and Higgs bosons and top quarks. The categorization is performed using a neural-network-based boosted object tagger to enhance the sensitivity to signal relative to the background. No significant excess above the background expectation is observed and exclusion limits at 95% confidence level are set on the masses of the vector-like partners T and B of the top and bottom quarks, respectively. The limits depend on the branching ratio configurations and, in the case of 100% branching ratio for T→Zt and 100% branching ratio for B→Zb, this search sets the most stringent limits to date, allowing mT>1.60TeV and mB>1.42TeV, respectively.

Lysozyme–Mineral Clay Systems: Comparison of Interaction for Controlled Release in Feed Application

A synthetic approach to bond lysozyme (LY) to commercial natural carriers, namely clay minerals (bentonite, BN; and sepiolite, SP) and commercial zeolite (Phil 75®, PH), already in use in feed formulation, is proposed. The synthetic route, which implies solid–liquid adsorption, is a simple and effective way for preparing hybrid materials characterized by LY loadings up to 37 mgLY/gcarrier. By operating at pH 4.3, initial LY content of 37.5 mgLY/gcarrier, and reaction time of 90 min, hybrid materials with LY loadings of 37, 35, and 12 mgLY/gcarrier for LY-SP, LY-BN, and LY-PH, respectively were obtained. The LY initial concentration and pH, as well as the physico-chemical properties of the carries were found to be the parameters that govern the synthesis of the materials. The driving force for an effective LY adsorption and interaction is the combined Zero Point Charge (ZPC) of the carriers, always negative (in the range between −4 and −170 mV) and the positive ZPC of LY, as well as the carrier morphology, characterized by mesoporosity (pore dimensions in the range of 5–12 nm). However, it is the interaction of charges of opposite sign that mainly affects LY loadings and bond strength. Based on SEM-EDX analysis, LY molecules are quite homogeneously spread onto the carriers’ surface. TG-DTG analyses showed that the LY–carrier interaction in the hybrid materials is stronger than that in a simple mechanical mixture of the components. Specifically, in the hybrid materials, the phenomenon at 300 °C, associated to LY decomposition, is broadened and slightly shifted towards higher temperatures (320–350 °C), whereas in a mechanical mixture of the same composition, it occurs at temperatures closer to those of free LY, as if there were no or very weak interactions. At pH 3, a very little LY release, 0.03 and 0.01 mgLY/gcarrier, was found for LY-BN and LY-PH, respectively. The latter became larger at pH 7, 0.06 mgLY/gcarrier for both BN and PH carriers, suggesting that BN and PH are better modulators of LY release. The paper provides insights for the study and the development of new optimized feed formulations for the targeted delivery of natural compounds with antimicrobial activity, alternatives to antibiotics, and vaccinal antigens.

On the Electromagnetic Radiation Associated with Zero and First Modes of a Droplet Oscillating in an External Electrostatic Field

The paper deals with electromagnetic radiation generated by capillary oscillations of the zero and first modes of oscillations of a droplet in an external electrostatic field. It is assumed that the droplet of an ideal incompressible electrically conductive liquid has a zero total electric charge and that it is charged in an external uniform electrostatic field by induced charges of opposite signs. The radiation under discussion is detected via analytical asymptotic calculations of the second order infinitesimal by the dimensionless amplitude of the droplet oscillations in an external electrostatic field. An analytical expression was found for the intensity of the electromagnetic radiation associated with oscillations of the zero and first modes, and the dependence of the intensity of radiation on the value of the field strength, the droplet size, and the value of the surface tension coefficient.

Unveiling the capabilities of bipolar conical channels in neuromorphic iontronics.

Conical channels filled with an aqueous electrolyte have been proposed as promising candidates for iontronic neuromorphic circuits. This is facilitated by a novel analytical model for the internal channel dynamics [T. M. Kamsma, W. Q. Boon, T. ter Rele, C. Spitoni and R. van Roij, Phys. Rev. Lett., 2023, 130(26), 268401], the relative ease of fabrication of conical channels, and the wide range of achievable memory retention times by varying the channel lengths. In this work, we demonstrate that the analytical model for conical channels can be generalized to channels with an inhomogeneous surface charge distribution, which we predict to exhibit significantly stronger current rectification and more pronounced memristive properties in the case of bipolar channels, i.e. channels where the tip and base carry a surface charge of opposite sign. Additionally, we show that the use of bipolar conical channels in a previously proposed iontronic circuit features hallmarks of neuronal communication, such as all-or-none action potentials and spike train generation. Bipolar channels allow, however, for circuit parameters in the range of their biological analogues, and exhibit membrane potentials that match well with biological mammalian action potentials, further supporting their potential biocompatibility.

Non-parallel currents and the Newton’s third law of motion

We provide an explicit calculation to check that Newtown’s third law holds for non-parallel currents if the field momentum is accounted for. In textbooks of electrodynamics, it is usually noted that in the interaction of non-parallel current elements, the action force is not balanced by the reaction force, though these forces are balanced in the interaction of two closed current-carrying loops. In the case of non-closed current segments the change in the momentum stored in the field should be taken into account. Using a simple model of two non-parallel straight current segments we show how it works. As such a model, two straight orthogonal to each other conductors are considered, with equal charges of opposite signs at the ends of each conductor. For some interval of time, a direct current is supported in the conductors. We show that the total momentum of the system is conserved.

Relaxation electrodynamics of superinsulators

Superinsulators offer a unique laboratory realizing strong interaction phenomena like confinement and asymptotic freedom in quantum materials. Recent experiments evidenced that superinsulators are the mirror-twins of superconductors with reversed electric and magnetic field effects. Cooper pairs and Cooper holes in the superinsulator are confined into neutral electric pions by electric strings, with the Cooper pairs playing the role of quarks. Here we report the non-equilibrium relaxation of the electric pions in superinsulating films. We find that the time delay t_{mathrm {sh}} of the current passage in the superinsulator is related to the applied voltage V via the power law, t_{mathrm {sh}}propto (V-V_{mathrm p})^{-mu }, where V_{mathrm p} is the effective threshold voltage. Two distinct critical exponents, mu =1/2 and mu =3/4, correspond to jumps from the electric Meissner state to the mixed state and to the superinsulating resistive state with broken charge confinement, respectively. The mu =1/2 value establishes a direct experimental evidence for the electric strings’ linear potential confining the charges of opposite signs in the electric Meissner state and effectively rules out disorder-induced localization as a mechanism for superinsulation. We further report the memory effects and their corresponding dynamic critical exponents arising upon the sudden reversal of the applied voltage. Our observations open routes for exploring fundamental strong interaction charge confinement via desktop experiments.

Choice of DLVO approximation method for quantifying the affinity between latex particles and membranes

The Derjaguin-Landau-Verwey-Overbeek (DLVO) model, as well as the extended model (XDLVO), is popularly employed to quantify the interfacial interactions underlying membrane fouling. However, disagreements between membrane fouling extent and the interaction energies derived from DLVO or XDLVO models have been reported, which suggests gaps in the understanding. This study demonstrates that the DLVO approximation methods for predicting the interfacial foulant-membrane interaction are sensitive to the boundary condition assumptions (e.g., constant charge versus constant potential). In particular, while both the Poisson-Boltzmann (P–B) and linear superposition approximation (LSA) equations can quantify the electrostatics (EL) interaction energy component, the former assumes constant potential, while the latter additionally considers constant charge scenarios. The relative accuracy of these two equations were evaluated here. For dead-end filtration tests, flux decline trends, OCT analysis results and fouling model parameters were obtained. Regarding fouling of pristine PCTE membrane by latex particles of opposite charge signs, both the P–B and LSA equations contribute to predict relative fouling extents correctly. However, for the case of the BPEI-coated membrane, the P–B equation failed whereas the LSA equation gave good agreements. For cross-flow filtration tests in organic solvents, LSA also out-performed the P–B equation in providing more accurate predictions of membrane fouling. The results here highlight the shortcomings in the commonly used P–B equation and are expected to be potentially valuable in the development of better approximations for quantifying interfacial interaction energies.

Optofluidic Platform for the Manipulation of Water Droplets on Engineered LiNbO3 Surfaces

AbstractThe actuation and control of liquid droplets on a surface have important implications in many industrial applications and microfluidics. In recent years, various strategies have been used. Here, an optofluidic platform that performs the basic droplet handling operations required in a common microfluidic device is presented. It is based on z‐cut, iron‐doped lithium niobate crystals that, when illuminated, generate surface charges of opposite sign at the two crystal faces because of the photovoltaic effect. The face of the crystal in contact with the droplets is coated with a lubricant‐infused layer, which guarantees hydrophobicity and, more importantly, a very slippery and robust surface for prolonged use. In this way, sessile water droplets having volumes of microliters, corresponding to millimeters in size, can be easily actuated, guided, merged, and split by projection on the crystal of suitable static or dynamic light patterns. The actuated droplets can cover distances of centimeters on a timescale of a few seconds. The resulting platform is highly flexible and reconfigurable and does not require moving parts.

Distortion of electric field homogeneity between two thin toroidal electrodes by a dielectric sphere

We assess the influence of a radius and a relative permittivity of an isotropic dielectric sphere on electric field homogeneity. The homogenous electric field is generated using two thin toroidal electrodes, charged by equal charges of opposite signs. The Poisson equation is solved by a method of separation of variables. Increase in a relative permittivity of the sphere and in its radius, produces more distortions of the electric field homogeneity.

Brownian dynamics of cylindrical capsule-like particles in a nanopore in an electrically biased solid-state membrane.

We use Brownian dynamics simulations to study the motion of cylindrical capsule-like particles (capsules) as they translocate through nanopores of various radii in an electrically biased silicon membrane. We find that for all pore sizes the electrostatic interaction between the particle and the pore results in the particle localization towards the pore 's center when the membrane and the particle have charges of the same sign (case 1) while in case of the opposite sign charges, the capsule prefers to stay near and along the nanopore wall (case 2). The preferential localization leads to all capsules rotating less while inside the pore compared to the bulk solution, with a larger net charge and/or particle length resulting in a smaller range of rotational movement. It also strongly affects the whole translocation process: in the first case, the translocation is due to the free diffusion along the pore axis and is weakly dependent on the particle charge and the nanopore radius while in the second case, the translocation time dramatically increases with the particle size and charge as the capsule gets "stuck" to the nanopore surface.