Real Part Research Articles

A further generalization of sums of higher derivatives of the Riemann zeta function

We obtain a full asymptotic for the sum of [Formula: see text], where [Formula: see text] denotes the [Formula: see text]th derivative of the Riemann zeta function, [Formula: see text] is a positive real number, and [Formula: see text] denotes a nontrivial zero of the Riemann zeta function. The sum is over the zeros with imaginary parts up to a height [Formula: see text], as [Formula: see text]. We also specify what the asymptotic formula becomes when [Formula: see text] is a positive integer, highlighting the differences in the asymptotic expansions as [Formula: see text] changes its arithmetic nature.

Cutkosky rules and 1-loop κ -deformed amplitudes

In this paper, we show that the Cutkosky cutting rules are still valid term by term in the expansion in powers of κ of the κ-deformed 1-loop correction to the propagator of the κ-deformed complex scalar field. We first present a general argument which relates each term in the expansion to a nondeformed amplitude containing additional propagators with mass M>κ. We then show the same thing more pragmatically, by reducing the singularity structure of the coefficients in the expansion of the κ-deformed amplitude, to the singularity structure of nondeformed loop amplitudes, by using algebraic and analytic identities. We will explicitly show this up to second order in 1/κ, but the technique can be generalized to higher orders in 1/κ. Both the abstract and the more direct approach easily generalize to different deformed theories. We will then compute the full imaginary part of the κ-deformed 1-loop correction to the propagator in a specific model, up to second order in the expansion in 1/κ, highlighting the usefulness of the approach for the phenomenology of deformed models. This explicitly confirms previous qualitative arguments concerning the behavior of the decay width of unstable particles in the considered model. Published by the American Physical Society 2024

Electromagnetic Debye mass within Gribov–Zwanziger action

Abstract In the present study we have investigated the electromagnetic Debye mass by computing the static limit of the temporal component of the one-loop photon polarization tensor involving effective quarks in the loop. These effective quarks have been considered within the Gribov–Zwanziger action, thereby incorporating the necessary non-perturbative effects. As an academic exercise, we have also shown one of the applications of this Gribov modified Debye mass by using it to evaluate the real and imaginary parts of the heavy quark potential in a Quantum Electrodynamics (QED) system. This computation of the electromagnetic Debye mass and the corresponding estimations of the heavy quark potential can be seen as stepping stones in the direction of further practical Quantum Chromodynamics (QCD) calculations in the non perturbative domain.

Vibration characteristics of piezoelectric pipe conveying fluid subjected to fluid-structure-electrical interaction

This paper mainly investigates the vibration characteristics of piezoelectric pipe conveying fluid subjected to fluid-structure-electrical interaction. Based on the Hamilton’s principle, the dynamic equations of the cantilever piezoelectric pipe subjected to the weight and fluid-structure-electrical interaction are established and solved by using the Galerkin method. Ultimately, complex frequency and critical flow velocity are obtained. The main discussion focused on the influence of electromechanical coupling, resistive load, and dimensionless capacitance on the critical flow velocity under different lengths of piezoelectric materials. It also examined the dynamic trajectories of the real and imaginary parts of the complex frequency under various mass ratios and resistive loads. Furthermore, it explored the impact of parameters representing voltage on the stability of the system. The results indicate various stability evolutions under different lengths of piezoelectric materials, flow velocities, and parameters representing voltage. The stability of the system pipe is influenced by factors such as the length of the piezoelectric material and resistive load.

Tracking microbial movement in saturated media with spectral induced polarization

Pathogenic microorganisms in the subsurface can contaminate soil and water supplies, potentially posing great danger to human health. Early contamination detection routines rely on sparse direct sampling which is spatiotemporally limited. Thus, the path of microorganisms in the subsurface remains ambiguous and this can cause delays in detection of biohazardous threats. The geophysical spectral induced polarization (SIP) technique, sensitive to microbes' presence and activity in porous media, is a promising method to monitor microbial transport pathways. Here we evaluated the efficiency of SIP in monitoring the chemotactic movement of Sporosarcina pasteurii in saturated porous media. A cylindrical sample holder was packed with Ottawa sand and saturated with sterile KCl solution. The sample holder was oriented vertically and S. pasteurii was introduced at the bottom, forcing the movement of the microbes against gravity, towards a carbon source available at the top of the column. Temporal SIP measurements were collected at 3 regions of the sample holder: bottom (microbial injection point), middle and top (carbon source). Both the real (σ′) and imaginary (σ″) conductivity parts of the SIP signal increased over time with the σ″ showing a peak signal magnitude following the upward movement of the microbes. We repeated the experiment excluding the carbon source in experiment 2 and omitting microbial injection in experiment 3. However, we did not observe any significant SIP signal changes in these two experiments. This is the first study to indicate the strong SIP signal correlation with microbial chemotaxis.

New method for graphing impedance values as an analytical tool suitable for electrochemical impedance spectroscopy

A new method for graphing electrical impedance values named a “differentiation-based Bode plot” is proposed. This method facilitates the analysis procedure and reduces the arbitrariness of the interpretation of electrochemical impedance spectroscopy (EIS) data. Among the various methods for graphing impedance values, Nyquist plots are commonly adopted (primarily in the field of EIS) because of the apparent correlation between their shape and the corresponding equivalent circuit. However, because Nyquist plots do not contain frequency information, Bode phase and magnitude plots are frequently utilized. Although such plots are suitable for determining the absolute magnitude and phase of the impedance, they are not always useful for selecting the structure of an equivalent circuit, which is a hypothetical model for electrochemical cells. In the proposed method, instead of the real (Z’) and imaginary (Z’’) parts, two functions of the impedance derivatives with respect to frequency, i.e., dZ’/d(log f) and dZ’’/d(log f), are plotted. As substitutions for the Bode phase and magnitude plots, arctan{dZ’’/d(log f) ÷ dZ’/d(log f)} and log[sqrt{(dZ’/d(log f))2 + (dZ’’/d(log f))2}] are plotted against log f. Unlike the classical Bode plot, the differentiation-based Bode plot is independent of the lateral shift in the Nyquist plot, which is advantageous for determining an equivalent circuit. To demonstrate this advantage, the impedance values of typical equivalent circuits used in electrochemistry are calculated and plotted to compare differentiation-based Bode plots with Nyquist and classical Bode plots.

Exploring new lead-free halide perovskites RbSnM3 (M = I, Br, Cl) and achieving power conversion efficiency > 32%

Lead-free ABX3 inorganic perovskites, where A = Cs, Rb; B = Sn, Ge; and X = I, Br, Cl, have recently gained significant attention due to their remarkable optical, structural, and electronic properties, as well as their potential for solar cell applications. In this study, we thoroughly examined the optical, structural, and electronic properties of RbSnM3 (M = I, Br, Cl) perovskites through first-principles calculations and explored their application in a HTL-free solar cell structure using SCAPS-1D. Our analysis revealed that RbSnI3, RbSnBr3, and RbSnCl3 have direct band gaps of 0.828, 0.988, and 1.242 eV, respectively, using the HSE functional. The electron charge distribution indicates a strong ionic bond between Rb and the halides, as well as a significant covalent bond between Sn and the halides. Additionally, we calculated optical properties such as electron loss function, absorption coefficients, and the real and imaginary parts of the dielectric functions. We also explored the photovoltaic performance of RbSnM3 absorbers paired with a SnS2 ETL layer, investigating different thicknesses, defect densities, doping concentrations, and interface defect densities. The highest power conversion efficiencies (PCE) achieved were 26.38%, 29.79%, and 32.53% for RbSnI3, RbSnBr3, and RbSnCl3 absorber layers, respectively, when paired with a SnS2 ETL. Overall, RbSnCl3 stands out as a highly promising absorber material for future photovoltaic devices, especially when combined with the SnS2 ETL layer.

Optoelectronic and thermodynamic properties of the Yttrium filled skutterudite YFe4P12

In this work, we sought to understand the structural, electronic, optical, and thermodynamic properties of the compound YFe4P12 using the full-potential and linear augmented plane-wave method (FP-LAPW) based on density functional theory (DFT), our calculation of the lattice parameter of this compound YFe4P12 is reasonably in good agreement with the experimental results. Calculations carried out on the electronic band structure showed that the YFe4P12 compound is classified as a direct-gap Half- half-metallic in the minority spins. Moreover, optical properties, such as the optical absorption coefficient, real and imaginary parts of the dielectric function, optical conductivity, refractive index, and optical reflectivity have been studied. The effects of pressure and temperature on the lattice parameter, heat capacities, coefficients of thermal expansion, entropy, and Debye temperature were explored using the quasi-harmonic Debye model.

Quantifying Heterogeneous Interface Effect of Fe3O4(111)/C for Enhanced Low-Frequency Electromagnetic Wave Absorption

How to tailor electromagnetic parameters of multi-component materials is the fundamental issues for low-frequency electromagnetic wave absorbers (EMA). However, there remains a challenge to accurately elucidate the impact of respective components at heterogeneous interfaces on the EMAs, not to mentioning the further quantitative contribution of the interfacial effect to the electromagnetic loss. In this paper, we for the first time separated the Fe3O4(111)/C heterogeneous interface of Fe3O4@C via a controllable interfacial separation strategy, meanwhile ensuring the consistent microstructure and the ratio of each component, as well as the unchanged macroscopic structure of the particles. Once all potential influences on electromagnetic parameters have been independently studied, the unique difference in heterogeneous interfaces enabled us to quantitatively evaluate the effect of them on electromagnetic parameters. Both experimental and density functional theory (DFT) calculation results consistently demonstrate that the Fe3O4(111)/C heterointerface increases carrier concentration and conductivity, thereby enhancing the imaginary part of the dielectric constant. Very distinguished from traditional interfacial polarisation mechanism presented in previous publications, this study introduces a novel interfacial loss mechanism primarily characterized by conductivity loss, which is rigorously investigated in a quantitative way. This discovery offers a novel approach for designing controllable heterogeneous interfaces and manipulating electromagnetic parameters in multicomponent EMAs.

Core temperature estimation of lithium-ion battery based on numerical model fusion deep learning

Temperature has a critical impact on the lifespan and safety of lithium batteries. This paper proposes a battery core temperature estimation method based on numerical model fused with long short-term memory (LSTM) neural network. The proposed technique extracts features from the numerical model, estimates the volume-averaged temperature by electrochemical impedance spectroscopy (EIS), uses an LSTM neural network to learn thermodynamic parameters and complex calculations, which takes advantage of the strengths of each method, and achieves accurate core temperature estimation. The effects of state of charge (SOC) and temperature on EIS are explored, impedance properties are selected on the criteria of robustness and rapidity, and the estimation of the volume-averaged temperature is achieved using the imaginary part of the impedance. The proposed method can achieve root mean squared error (RMSE) of less than 0.28 °C and mean absolute error (MAE) of less than 0.23 °C. The proposed method has advantages of high estimation accuracy and does not require an electrothermal model. It also considers the effect of ambient temperature and has a good generalization capability.

A model of light pseudoscalar dark matter

The EW-νR model was constructed in order to provide a seesaw scenario operating at the Electroweak scale ΛEW∼246 GeV, keeping the same SM gauge structure. In this model, right-handed neutrinos are non-sterile and have masses of the order ΛEW. They can be searched for at the LHC along with heavy mirror quarks and leptons, the lightest of which has large decay lengths. The model also incorporates a rich scalar sector, consistent with various experimental constraints, predicts a ∼125 GeV scalar with the SM Higgs characteristics satisfying the current LHC Higgs boson data. The seesaw mechanism requires the existence of a complex scalar which is singlet under the SM gauge group. The imaginary part of this complex scalar denoted by As0 is proposed to be the sub-MeV dark matter candidate in this manuscript. We find that the sub-MeV scalar can serve as a viable non-thermal feebly interacting massive particle (FIMP)-DM candidate. This As0 can be a naturally light sub-MeV DM candidate due to its nature as a pseudo-Nambu-Goldstone (PNG) boson in the model. We show that the well-studied freeze out mechanism falls short in this particular framework producing DM overabundance. We identify that the freeze in mechanism produce the correct order of relic density for the sub-MeV DM candidate satisfying all applicable constraints. We also discuss the allowed parameter space arising from the current indirect search bounds for this sub-MeV DM.

A constant self-consistent scattering lifetime in superconducting strontium ruthenate

In this numerical work, we find a self-consistent constant scattering superconducting lifetime for two different values of the disorder parameters, the inverse atomic strength, and the stoichiometric impurity in the triplet paired unconventional super-conductor strontium ruthenate. This finding is relevant for experimentalists given that the expressions for the ultrasound attenuation and the electronic thermal conductivity depend on the superconducting scattering lifetime, and a constant lifetime fits well nonequilibrium experimental data. Henceforth, this work helps experimentalists in their interpretation of the acquired data. Additionally, we encountered tiny imaginary parts of the self-energy that resembles the Miyake-Narikiyo tiny gap out-side the unitary elastic scattering limit, and below the threshold zero gap value of 1.0 meV.

Terahertz Emission Modeling of Lunar Regolith

We investigate the terahertz (THz) scattering and emission properties of lunar regolith by modeling it as a random medium with rough top and bottom boundaries and a host medium situated beneath. The total scattering and emission arise from three sources: the rough boundaries, the volume, and the interactions between the boundaries and the volume. To account for these sources, we model their respective phase matrices and apply the matrix doubling approach to couple these phase matrices to compute the total emission. The model is then used to explore insights into lunar regolith scattering and emission processes. The simulations reveal that surface roughness is the primary contributor to total scattering, while dielectric contrasts between the volume and the boundaries dominate total emission. The THz emissivity is highly sensitive to the regolith dielectric constant, particularly its imaginary part, making it a promising alternative for identifying previously undetected water ice in the lunar polar regions. The THz emissivity model developed in this study can be readily applied to invert the surface parameters of lunar regolith using THz observations.

Simultaneous path weak-measurements in neutron interferometry

The statistical properties of the detection events constituting the interference fringes at the output of an interferometer are well-known. Nevertheless, there is still no unified view of what is happening to a quantum system inside an interferometer. Strong measurements of path operators destroy the interference effect. In weak measurements, an observable is weakly coupled to a pointer system and the resulting weak values quantify the observable by minimally disturbing the system. Previous which-way experiments with weak measurements could extract either the real or imaginary part of a single weak value with each ensemble. Here, we present the simultaneous full complex quantification of two path weak values with a single ensemble in a Mach–Zehnder neutron interferometer. Magnetic fields, oscillating with different frequencies, change the energy state in each interferometer path. The time-dependent phase between the energy states distinctly marks each path. The resulting beating intensity modulation at the interferometer output gives both path weak values. For the present experiment, the weak values’ absolute value and phase directly describe the observed amplitude and phase of the intensity modulation.

Inductor-capacitor passive wireless sensors using nonlinear parity-time symmetric configurations

An inductor–capacitor passive wireless sensor is essential to physical, chemical, and biological sensing for scenarios where physical access is difficult. Exceptional points of parity-time symmetric inductor–capacitor systems featuring the linear loss and gain have been utilized for enhancing sensing. However, the exceptional point sensing scheme might bring about fundamental resolution limits and noise enhancement. Here we show, employing a nonlinear saturable gain, the responsivity has a cube-root singularity distinct from a square-root singularity of the linear exceptional point scheme. The saturable gain eliminates the imaginary part of the eigenfrequencies and significantly suppresses the noise. Through an example of inductor–capacitor wireless wearable temperature sensors, we demonstrate the high figure of merit for the nonlinear PT-symmetric configuration. Our results resolve a debate on the effectiveness of the exceptional point sensing scheme for inductor–capacitor sensors and provide a way of enhancing precision for these types of sensors.

Simple zeros of $\operatorname{GL}(2)$ $L$-functions

Let f \in S_{k}(\Gamma_{1}(N)) be a primitive holomorphic form of arbitrary weight k and level N . We show that the completed L -function of f has \Omega(T^{\delta}) simple zeros with imaginary part in [-T, T] , for any \delta <{2/27} . This is the first power bound in this problem for f of non-trivial level, where previously the best results were \Omega(\log\log\log{T}) for N odd, due to Booker, Milinovich, and Ng, and infinitely many simple zeros for N even, due to Booker. In addition, for f of trivial level ( N=1 ), we also improve an old result of Conrey and Ghosh on the number of simple zeros.

Structural, electronic and optical properties of CdTiX2 (X = N and P): A first principles density functional theory investigation

In the present paper, we have proposed new ternary materials CdTiN2 and CdTiP2 with body centered tetragonal structure. We have studied the structural, electronic, and optical properties of the proposed compounds with the help of the first principles density functional theory. The calculated electronic band structure shows that these compounds show indirect band gap of 1.089 eV and 0.359 eV for the compounds CdTiN2 and CdTiP2 respectively and hence it is concluded that these compounds are semiconducting nature. The optical properties such as the reflectivity, absorption, refractive index, real and imaginary part of dielectric function, optical conductivity, electronic energy loss function shows that studied compounds CdTiN2 and CdTiP2 may be promising materials for optoelectronic devices and the photoelectric solar cells.

Theoretical aspects of structure, electronic, optical and elastic properties of Ca(1-x)CxSe mixed alloys in binary and ternary phases

The structural, optoelectronic, and elastic properties of Carbon doped Calcium Selenide binary and ternary semiconductor alloys with the general form of Ca(1-x)CxSe, 0 ≤ x ≤ 1 in B1 and B3 phases have been scrutinized adopting augmented plane wave plus local orbital methods within density functional theory applying different approximations like the Local density approximation (LDA), Wu-Cohen-Generalized Gradients Approximation (WC-GGA) and modified Becke-Johnson (mBJ). Structural properties summarize the crystal structure, relevant atomic positions, lattice constant, Bulk modulus B0, minimum energy E0, and minimum volume V0. Elastic constants confirm the structure stability of the B1 and B3 phases. The band gap was modified from a wider for appropriate optoelectronic devices application to narrow that enhanced the range of applicability of these binary and ternary semiconductor compounds for optoelectronic device applications. Whereas optical properties which include the study of zero frequency limit of static dielectric constant ε0(ω) with its real and imaginary parts, static refractive index n(0), optical reflectivity R(ω), optical absorption coefficient α(ω), optical conductivity σ(ω), and loss function L(ω) studied comprehensively to get real electrical and optical properties of these materials and give semiconductor market best alternative candidate which shows its effectiveness in the visible, ultraviolet and infrared region of the electromagnetic spectrum. Obtained results compared together and with the available experimental along with theoretical work on these binary and ternary Carbon-doped Alkaline earth Selenide.

Understanding the pressure effect on the physical properties of half-Heusler semiconductor LiCaX (X = As, Sb, N) compounds from Ab-initio calculations

The study delves into the structural, elastic, electronic, thermodynamic, and lattice dynamical and optic properties of LiCaX (X = As, Sb, N) ternary half-Heusler compounds under varying pressure and temperature conditions. Employing density functional theory with the generalized gradient approximation (GGA) in VASP codes, the initial steps involve optimizing the structure of the compound (cubic MgAgAs-type, space group F43m, C1b), determining elastic constants (C11, C12, and C44), and calculating elastic moduli (bulk modulus, shear modulus, Young's modulus). Other mechanical parameters such as Pugh's ratio, Poisson's ratio, and Zener anisotropy factor are also derived, providing insights into the brittle/ductile characteristics and isotropic/anisotropic behavior. The study further explores different vibrational modes in the compounds, and the effects of pressure on elastic anisotropy, vibrational, and optical properties are thoroughly investigated. Utilizing the quasi-harmonic Debye model, the research successfully reports V/Vo, bulk modulus, thermal expansion coefficient, and heat capacity at constant volume over a temperature range from 0 to 1000 K. The variation of photon energy is analyzed concerning the real and imaginary parts of the dielectric constant, refractive indices, extinction coefficient, reflectivity, and energy loss function up to 20 eV. The findings encapsulate the fundamental physical properties of all considered compounds, concluding with suggestions for potential future research avenues.

Nonleptonic B-meson decays to next-to-next-to-leading order

We compute next-to-next-to-leading order QCD corrections to the partonic processes b → cu¯d\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ c\\overline{u}d $$\\end{document} and b → cc¯s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ c\\overline{c}s $$\\end{document}, which constitute the dominant decay channels in standard model predictions for B-meson lifetimes within the heavy quark expansion. We consider the contribution from the four-quark operators O1 and O2 in the ∆B = 1 effective Hamiltonian. The decay rates are obtained from the imaginary parts of four-loop propagator-type diagrams. We compute the corresponding master integrals using the “expand and match” approach which provides semi-analytic results for the physical charm and bottom quark masses. We show that the dependence of the decay rate on the renormalization scale is significantly reduced after including the next-to-next-to-leading order corrections. Furthermore, we compute next-to-next-to-leading order corrections to the Cabibbo-Kobayashi-Maskawa-suppressed decay channels b → uc¯s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ u\\overline{c}s $$\\end{document} and b → uu¯d\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ u\\overline{u}d $$\\end{document}.