Double-peak Structure Research Articles

THE SHAPE OF SOLAR CYCLES DESCRIBED BY A SIMPLIFIED BINARY MIXTURE OF GAUSSIAN FUNCTIONS

ABSTRACT Sunspot cycles usually present a double-peak structure. This work is devoted to using a function to describe the shape of sunspot cycles, including bimodal cycles, and we find that the shape of sunspot cycles can be described by a binary mixture of Gaussian functions with six parameters, two amplitudes, two gradients of curve, and two rising times, and the parameters could be reduced to three. The fitting result of this binary mixture of Gaussian functions is compared with some other functions used previously in the literature, and this function works pretty well, especially at cycle peaks. It is worth mentioning that the function can describe well the shape of those sunspot cycles that show double peaks, and it is superior to the binary mixture of the Laplace functions that was once utilized. The Solar Influences Data Analysis Center, on behalf of the World Data Center, recently issued a new version (version 2) of sunspot number. The characteristics of sunspot cycles are investigated, based on the function description of the new version.

Magnetron sputtering of Fe-oxides on the top of HTS YBCO films

The possibilities for preparation of bilayers containing magnetic Fe-oxide (Fe-O) and high temperature superconducting (HTS) YBa2Cu3O7−x (YBCO) thin films were investigated. For this purpose, Fe-O films were deposited using reactive magnetron sputtering at comparatively low temperatures T≤250°C onto dielectric (for example, LaAlO3 (LAO)) substrates, covered with a HTS YBCO film. The sputtering of the Fe-O layer at such conditions did not lead to a crucial damage of the critical temperature TC of the YBCO film, but could affect the width of the superconducting transition. A decrease of the critical temperature of the (Fe-O)/YBCO/LAO bilayer kept at ambient conditions was observed, possibly due to the negative effects of the water vapour on the sample characteristics. The double peak structure of the imaginary component of the response signal to the AC harmonic magnetic field, observed in such a (Fe-O)/YBCO/LAO sample, was ascribed from two possible views: as a consequence of morphology determined inter- and intra-granular contributions and/or as transitions from dominant irreversible processes as Bean-Livingston barrier to vortex state chains formation.

Numerical analytic continuation: Answers to well-posed questions

We formulate the problem of numerical analytic continuation in a way that lets us draw meaningful conclusions about properties of the spectral function based solely on the input data. Apart from ensuring consistency with the input data (within their error bars) and the {\it a priori} and {\it a posteriori} (conditional) constraints, it is crucial to reliably characterize the accuracy---or even ambiguity---of the output. We explain how these challenges can be met with two approaches: stochastic optimization with consistent constraints and the modified maximum entropy method. We perform illustrative tests for spectra with a double-peak structure, where we critically examine which spectral properties are accessible and which ones are lost. For an important practical example, we apply our protocol to the Fermi polaron problem.

Probing the Nodal Structure of Landau Level Wave Functions in Real Space

The inversion layer of p-InSb(110) obtained by Cs adsorption of 1.8% of a monolayer is used to probe the Landau level wave functions within smooth potential valleys by scanning tunneling spectroscopy at 14T. The nodal structure becomes apparent as a double peak structure of each spin polarized first Landau level, while the zeroth Landau level exhibits a single peak per spin level only. The real space data show single rings of the valley-confined drift states for the zeroth Landau level and double rings for the first Landau level. The result is reproduced by a recursive Green function algorithm using the potential landscape obtained experimentally. We show that the result is generic by comparing the local density of states from the Green function algorithm with results from a well-controlled analytic model based on the guiding center approach.

Size and temperature dependence of the line shape of ESR spectra of the XXZ antiferromagnetic chain

The electron spin resonance spectrum of the $\mathit{XXZ}$ spin chain with finite length shows a double-peak structure at high temperatures around the electron paramagnetic resonance (EPR) frequency. This fact has been pointed out by direct numerical methods [S. El Shawish, O. C\'epas, and S. Miyashita, Phys. Rev. B 81, 224421 (2010); H. Ikeuchi, H. De Raedt, S. Bertaina, and S. Miyashita, Phys. Rev. B 92, 214431 (2015)]. The question of whether the double-peak structure survives in the thermodynamics is of particular interest. We study the size dependence of the line shape, including the even-odd effect. It is found that the peaks forming the double-peak structure are assigned to individual resonances, each of which is specified by the magnetizations of the resonating states $(M,M\ensuremath{-}1)$. To understand dependences, we decompose the spectrum into contributions from transitions specified by the magnetization, and we characterize the structure of the spectrum by individual contributions. We analyze the size dependence of each contribution individually by extending the moment method introduced by M. Brockman et al. to each component, and we find that the mean of each peak approaches the paramagnetic resonance point with $1/N$ (where $N$ is the length of the chain), which indicates that the separation of the peaks of the double-peak structure also vanishes inversely with the system size. We also study the temperature dependence of the structure. At low temperatures, the spectrum has a single peak with a finite width at a position with a finite shift from the frequency of EPR, as pointed out by the analysis of field-theoretical works [M. Oshikawa and I. Affleck, Phys. Rev. Lett. 82, 5136 (1999)]. The study of the temperature dependence of the spectrum shows how the high-temperature spectrum changes to the low-temperature one with a drastic broadening of the spectrum.

Deformation-induced splitting of the isoscalarE0giant resonance: Skyrme random-phase-approximation analysis

The deformation-induced splitting of isoscalar giant monopole resonance (ISGMR) is systematically analyzed in a wide range of masses covering medium, rare-earth, actinide, and superheavy axial deformed nuclei. The study is performed within the fully self-consistent quasiparticle random-phase-approximation (QRPA) method based on the Skyrme functional. Two Skyrme forces, one with a large (SV-bas) and one with a small (SkP) nuclear incompressibility, are considered. The calculations confirm earlier results that, due to the deformation-induced E0-E2 coupling, the isoscalar E0 resonance attains a double-peak structure and significant energy upshift. Our results are compared with available analytic estimations. Unlike earlier studies, we get a smaller energy difference between the lower and upper peaks and thus a stronger E0-E2 coupling. This in turn results in more pumping of E0 strength into the lower peak and more pronounced splitting of ISGMR. We also discuss widths of the peaks and their negligible correlation with deformation.

Comparison of the observed topside ionospheric and plasmaspheric electron content derived from the COSMIC podTEC measurements with the IRI_Plas model results

In this paper, variations of the topside ionospheric and plasmaspheric electron contents (TPEC) in the altitude range of ∼800 to 20,200km are compared with the IRI_Plas model results for the low (2008) and high (2012) solar activity years using TEC data (podTEC) derived from the upward-looking precise orbit determination antenna on board COSMIC low Earth orbit (LEO) satellites tracking the GPS signals. For each year, the dataset were divided into groups according to four seasons: M-Equinox (March, April), J-Solstice (May June, July and August), S-Equinox (September, October) and D-Solstice (January, February, November, and December). Our study showed that the IRI_Plas model is able to reproduce reasonably well the main features of the observational TPEC’s latitudinal, diurnal as well as seasonal variation tendency when no longitudinal difference is taken into account. However, there exist discrepancies between the observational TPEC and the model results. Except for the daytime hours in the Equinoctial seasons of the high solar activity year 2012 when the IRI_Plas model results showed an overestimation, in general, the IRI_Plas model results underestimate the observational ones, in particular at nighttime hours in the low-latitude region. When the longitudinal difference is taken into account, the comparison study showed that the longitudinal dependence effect shown in the observational TPEC’s seasonal variations was not captured by the IRI_Plas model result. Moreover, the IRI_Plas model results tend to show a double-peak structure in the low-latitude region, a feature not appearing in the observational results.

Two charmoniumlike charged axial resonances near 3885 MeV

It is argued that the charged $Z^+_c(3885)$ resonance, treated as a `molecular' state of charmed $D$ and $D^*$ mesons, is likely to consist of two peaks unequally coupled to the $D^{*+} \bar D^0$ and $D^+ \bar D^{*0}$ channels. The peaks should be split in mass by at least approximately 1.5 MeV. This behavior arises from an enhancement of the effect of isospin violation in the masses of the $D$ and $D^*$ mesons due to apparent suppression of forces between the mesons depending on the spins of the heavy as well as of the light quarks. The suggested double-peak structure can be studied either by direct shape measurement in the channels with heavy mesons, or by isospin-violating transitions from $Z_c^\pm(3885)$ to the states of charmonium plus a light meson.

Interplay between spin frustration and magnetism in the exactly solved two-leg mixed spin ladder**Project supported by the National Natural Science Foundation of China (Grant No. 11547236), the General Project of the Education Department of Liaoning Province, China (Grant No. L2015130), the Fundamental Research Funds for the Central Universities, China (Grant Nos. DC201501065 and DCPY2016014), and the Doctoral Starting-up Foundation of

We study a mixed spin-(3/2, 1) ladder system with antiferromagnetic rung coupling and next-nearest-neighbor interaction. The exactly solved Ising-chain model is employed to investigate the ground-state properties and thermodynamics of the low-dimensional ladder system. Our results show that the competition between different exchange couplings brings in a large variety of ground states characterized by various values of normalized magnetization equal to 0, 1/5, 2/5, 3/5, 1. Moreover, an interesting double-peak structure is also detected in the thermal dependence of magnetic susceptibility and specific heat when the frustration comes into play. It is shown that the double-peak phenomenon at zero-field for the case of AF2 ground-state arises from the very strong antiferromagnetic rung coupling, while other cases are attributed to the excitations induced by temperature and external field around the phase boundary.

Topological Domain Wall and Valley Hall Effect in Charge Ordered Phase of Molecular Dirac Fermion System α-(BEDT-TTF)2I3

The topological domain wall and valley Hall effect are theoretically investigated in the molecular conductor α-(BEDT-TTF)2I3. By using the mean-field theory in an extended Hubbard model, it is demonstrated under a cylinder boundary condition that a domain wall emerges in the charge ordered phase, and exhibits a topological nature near the phase transition to the massless Dirac Fermion phase. The topological nature is well characterized by the Berry curvature, which has opposite signs in two charge ordered phases divided by the domain wall, and gives rise to the valley Hall conductivity with opposite signs, enabling these phases to be distinguished. It is also found that the valley Hall conductivity in the tilted Dirac cones exhibits a characteristic double-peak structure as a function of chemical potential using the semi classical formalism.

Evolution of the energy-loss-spectrum profile with the projectile mass in impulsive ion-molecule collisions

Systematic analysis is made for illuminating the mechanism of rotational and vibrational excitations in an impulsive ion-molecule collision from the viewpoint of its sudden nature. Variation of the energy-loss spectrum with the projectile mass is examined in the collision system of an alkali-metal ion with a nitrogen molecule at a hyperthermal energy of 27 eV using a common interaction potential. The spectra are obtained by the classical trajectory calculation and compared with two sudden-limit models---the hard-shell model for rigid-rotor molecules and the hard-potential model for vibrating-rotor molecules [A. Ichimura and M. Nakamura, Phys. Rev. A 69, 022716 (2004)]. For a projectile much lighter than the target, the vibrational and rotational excitation occurs in such a way that the hard-potential model predicts, producing a spectral profile with double peaks. As the projectile mass increases, the vibrational suddenness is degraded so that the vibrational excitation becomes quenched, while the spectral profile still shows a double-peak structure explainable with the hard-shell model. Subsequently, as the projectile mass further increases, the rotational suddenness is also degraded so that the spectrum indicates a profile departing far from the prediction of the hard-shell model; the deeply inelastic peak is suppressed and the nearly elastic peak is enhanced. Such spectral deformation actually occurs in an experimental result reported for ${\mathrm{Na}}^{+}--{\mathrm{N}}_{2}$ collisions [M. Nakamura, S. Kita, and T. Hasegawa, J. Phys. Soc. Jpn. 56, 3161 (1987)]. Eventually, the deeply inelastic peak disappears due to temporary excitation during a collision.

Optical Evidence of Itinerant-Localized Crossover of 4fElectrons in Cerium Compounds

Cerium (Ce)-based heavy-fermion materials have a characteristic double-peak structure (mid-IR peak) in the optical conductivity [$\sigma(\omega)$] spectra originating from the strong conduction ($c$)--$f$ electron hybridization. To clarify the behavior of the mid-IR peak at a low $c$-$f$ hybridization strength, we compared the $\sigma(\omega)$ spectra of the isostructural antiferromagnetic and heavy-fermion Ce compounds with the calculated unoccupied density of states and the spectra obtained from the impurity Anderson model. With decreasing $c$-$f$ hybridization intensity, the mid-IR peak shifts to the low-energy side owing to the renormalization of the unoccupied $4f$ state, but suddenly shifts to the high-energy side owing to the $f$-$f$ on-site Coulomb interaction at a slight localized side from the quantum critical point (QCP). This finding gives us information on the change in the electronic structure across QCP.

Response function of super-resolution readout of an optical disc studied by coupled electromagnetic–thermal simulation

To fully understand the properties of the readout signal in the super-resolution state, we implemented a multi-physics simulation of the propagation of electromagnetic waves and heat conduction in an optical disc that incorporates an InSb active layer. Response functions were obtained by calculating the light intensity reflected from a single small-pit structure. It was found that a typical response function in the super-resolution state has an asymmetric double-peak structure with high-spatial-frequency components. The complex profile of the response function indicated that the position of protrusions in the readout signal does not exactly correspond to that of the refractive index profile of the pit arrangement. We demonstrated that the measured readout signals also exhibit this particular characteristic and are roughly reproduced by the signals estimated from the response functions.

Absence of Andreev bound states inβ−PdBi2probed by point-contact Andreev reflection spectroscopy

We report point-contact spectroscopic studies on high quality single crystalline $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{PdBi}}_{2}$ with a superconducting ${T}_{c}=5.2\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. Our measurements show a typical double-peak structure in the voltage-biased junction conductance at low temperatures, probably excluding the existence of topological Andreev bound states. The conductance curves can be well fitted with the standard Blonder-Tinkham-Klapwijk model for $s$-wave superconductors, yielding a superconducting gap ${\mathrm{\ensuremath{\Delta}}}_{0}\ensuremath{\simeq}0.92\phantom{\rule{0.28em}{0ex}}\mathrm{meV}$ with $2{\mathrm{\ensuremath{\Delta}}}_{0}/{k}_{B}{T}_{c}\ensuremath{\sim}4.1$. Our results strongly suggest that $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{PdBi}}_{2}$ is a conventional intermediate-coupling $s$-wave superconductor.

Resonant Phase Escape from the First Resistive State of Bi2Sr2CaCu2Oy Intrinsic Josephson Junctions under Strong Microwave Irradiation

We report a study of the phase escape in Bi2Sr2CaCu2Oy intrinsic Josephson junctions under the strong microwave irradiation, focusing on the switch from the first resistive state (2nd SW). The resonant double-peak structure is clearly observed in the switching current distributions below 10 K and is successfully explained by a quantum-mechanical model on the quantum phase escape under the strong microwave field. These results provide the first evidence for the formation of the energy level quantization for the 2nd SW, supporting that the macroscopic quantum tunneling for the 2nd SW survives up to ∼10 K.

Line shape in a free-jet hypersonic expansion investigated by cavity ring-down spectroscopy and computational fluid dynamics

Experiments are carried out for spectroscopic studies using hypersonic jet of carbon monoxide seeded in argon as a carrier gas. Probing of this jet using cavity ring-down spectroscopy revealed a double peak structure for various absorption lines. Flow field simulation using computational fluid dynamics is used to understand the shape of such lines integrated over line of sight. Absorption contribution from warmer non-isentropic part of the jet, owing to its transverse velocity variation, is found responsible for those line shapes.

INVESTIGATION ON THE SWELLING PROPERTIES AND MICROSTRUC-TURE MECHANISM OF COMPACTED GAOMIAOZI BENTONITE

Bentonite has the property of swelling when meeting water. It is a desirable buffer/backfill material in the deep geological disposal for high-level radioactive waste. The expansibility is one of the most important properties for bentonite as the buffer/backfill material, and is influenced by a number of factors. For study the expansibility of bentonite, Gaomiaozi(GMZ)bentonite was taken as the research object. Gaomiaozi(GMZ)bentonite had been proposed as the first choice of buffer/backfill material for the high-level radioactive waste disposal in China. Its expansibility was studied by the constant volume swelling test method which is one of the commonest methods for measuring the swelling pressure of bentonite. In these tests, water content and dry density were chosen as the control variable. Two types of dry density and three types of water content were adopted in the tests. Results of the swelling tests show that the shape of swelling curves and the maximum swelling pressure depend on the water content and dry density of the bentonite samples. There are conspicuous double-peak shapes of the swelling curve for the samples with low dry density. When the dry density is high, the swelling curves have different shapes with different water contents. The curve's shapes change from double-peak to smooth curve with the water content increasing. For analysis of the results of swelling tests, the mercury intrusion porosimetry(MIP)test has been carried out. MIP test results indicate that the pore size distribution curves of samples also depend on the water content and dry density, with the volume of inter-aggregate pores increasing as the water content or dry density decreases. In accordance with the relevant researches, the swelling curve of GMZ bentonite is deeply influenced by the volume of the inter-aggregate pores. When meeting water, the bentonite aggregates absorb water and swell quickly. When the inter-aggregate pores are large enough, there will be sufficient space for swelled aggregates to form a provisional structure. The provisional structure will collapse with the swelling pressure reach the limit load. Then the measured pressure fall and inner structure of bentonite recombination. The hydration is continuous so that the curve will get the second peak. Therefore, a double-peak structure can be observed when the space of inter-aggregate is great. With the volume of inter-aggregate pore decrease, the swell curve of bentonite changes from a double-peak structure to a smooth curve.

SUBSTRUCTURE WITHIN THE SSA22 PROTOCLUSTER AT z ≈ 3.09*

ABSTRACT We present the results of a densely sampled spectroscopic survey of the SSA22 protocluster at z ≈ 3.09. Our sample with Keck/LRIS spectroscopy includes 106 Lyα emitters (LAEs) and 40 Lyman break galaxies (LBGs) at z = 3.05–3.12. These galaxies are contained within the 9′ × 9′ region in which the protocluster was discovered, which also hosts the maximum galaxy overdensity in the SSA22 region. The redshift histogram of our spectroscopic sample reveals two distinct peaks, at z = 3.069 (blue; 43 galaxies) and z = 3.095 (red; 103 galaxies). Furthermore, objects in the blue and red peaks are segregated on the sky, with galaxies in the blue peak concentrating toward the western half of the field. These results suggest that the blue and red redshift peaks represent two distinct structures in physical space. Although the double-peaked redshift histogram is traced in the same manner by LBGs and LAEs, and brighter and fainter galaxies, we find that 9 out of 10 X-ray AGNs in SSA22, and all 7 spectroscopically confirmed giant Lyα “blobs,” reside in the red peak. We combine our data set with sparsely sampled spectroscopy from the literature over a significantly wider area, finding preliminary evidence that the double-peaked structure in redshift space extends beyond the region of our dense spectroscopic sampling. In order to fully characterize the three-dimensional structure, dynamics, and evolution of large-scale structure in the SSA22 overdensity, we require the measurement of large samples of LAE and LBG redshifts over a significantly wider area, as well as detailed comparisons with cosmological simulations of massive cluster formation.

Co-evolution of payoff strategy and interaction strategy in prisoner’s dilemma game

Abstract Co-evolutionary dynamical models, providing a realistic paradigm for investigating complex system, have been extensively studied. In this paper, the co-evolution of payoff strategy and interaction strategy is studied. Starting with an initial Gaussian distribution of payoff strategy r with the mean u and the variance q , we focus on the final distribution of the payoff strategy. We find that final distribution of the payoff strategy may display different structures depending on parameters. In the ranges u − 1 and u > 3 , the distribution displays a single-peak structure which is symmetric about r = u . The distribution manifests itself as a double-peak structure in the range − 1 u 3 although a fake three-peak structure shows up in range 1 u 2 . The explanations on the formation of different types of payoff strategy distributions are presented.

Nuclear effects in Drell-Yan pair production in high-energypAcollisions

The Drell-Yan (DY) process of dilepton pair production off nuclei is not affected by final state interactions, energy loss or absorption. A detailed phenomenological study of this process is thus convenient for investigation of the onset of initial-state effects in proton-nucleus ($pA$) collisions. In this paper, we present a comprehensive analysis of the DY process in $pA$ interactions at RHIC and LHC energies in the color dipole framework. We analyse several effects affecting the nuclear suppression, $R_{pA}<1$, of dilepton pairs, such as the saturation effects, restrictions imposed by energy conservation (the initial-state effective energy loss) and the gluon shadowing, as a function of the rapidity, invariant mass of dileptons and their transverse momenta $p_T$. In this analysis, we take into account besides the $\gamma^*$ also the $Z^0$ contribution to the production cross section, thus extending the predictions to large dilepton invariant masses. Besides the nuclear attenuation of produced dileptons at large energies and forward rapidities emerging due to the onset of shadowing effects, we predict a strong suppression at large $p_T$, dilepton invariant masses and Feynman $x_F$ caused by the Initial State Interaction effects in kinematic regions where no shadowing is expected. The manifestations of nuclear effects are investigated also in terms of the correlation function in azimuthal angle between the dilepton pair and a forward pion $\Delta\phi$ for different energies, dilepton rapidites and invariant dilepton masses. We predict that the characteristic double-peak structure of the correlation function around $\Delta \phi\simeq \pi$ arises for very forward pions and large-mass dilepton pairs.