Cross Section Distribution Research Articles

Production pair of higher excited massive quarkonium at super Z factory

Abstract Sizable amounts of massive quarkonium events should be produced through $Z^0$ boson decays at a future super $Z$ factory. Such channels will provide a suitable platform to study the precisely properties of massive quarkonium. We show that sizable amounts of events for pair of the higher excited states quarkonia can also be produced at the super Z factory. Therefore, we make a further study on calculate the exclusive production of pair of the higher excited charmonium, pair of the higher excited bottomonium, and pair of the higher excited $B_c$ mesons via $e^+e^-\to Z^0 \to |(Q\bar{Q^\prime})[n]\rangle + |(Q^\prime \bar{Q})[n']\rangle$ ($Q,~Q^\prime=c$- or $b$-quarks) at the future $Z$ factory under the NRQCD, where the $[n]$/$[n^\prime]$ represents the color-singlet states $[n^1S_0], [n^3S_1],~[n^1P_1]$, and $[^3P_J]$ ($[n]=1,2,3;J=0,1,2$).
The differential angle distribution of cross sections $d\sigma/dcos\theta$ is given. For a sound estimate,
we discus the uncertainties of total cross sections caused by varying quark masses and the renormalization scale $\mu$. The numerical results show that the future super $Z$ factory should be also a good platform to study the exclusive production of pair of the higher excited massive quarkonium.

Heavy-Quark Pair Production at Lepton Colliders at NNNLO in QCD.

We compute the total cross section and invariant mass distribution for heavy-quark pair production in e^{+}e^{-} annihilation at the next-to-next-to-next-to-leading order in QCD. The obtained results are expressed as piecewise functions defined by several deeply expanded power series, facilitating a rapid numerical evaluation. Utilizing top-pair production at a collision energy of 500GeV as a benchmark, we observe a correction of approximately 0.1% for the total cross section and around 10% for the majority of the invariant mass distribution range. These results play a crucial role in significantly reducing theoretical uncertainty: the scale dependence has been diminished to 0.06% for the total cross section and to 5% for the invariant mass distribution. This reduction of uncertainty meets the stringent requirements of future lepton colliders.

Predicting optical properties of different photonic crystal fibers from 2D structural images using convolutional neural network and transfer learning

An efficient and accurate joint neural network has been established to predict the optical properties of different photonic crystal fibers using two-dimensional structural images. The input variables of this network are structural images derived from the two-dimensional material refractive index distribution of the fiber cross-section. The structural images have greater flexibility and facilitate generalization research and transfer learning testing on various types of optical fibers. The generalization properties of this neural network for other photonic crystal fibers with different lattice arrangements have been investigated, and the corresponding transfer learning method is also proposed. With this transfer learning method, only a small amount of data is required to train and update the parameter weights of the last fully connected hidden layers. As a result, efficient and accurate prediction performance can be achieved for other photonic crystal fibers with different lattice arrangements. The proposed joint neural network and the transfer learning method are flexible and efficient, which provide new approaches for more flexible optimization and reverse design of optical fiber structures in the two-dimensional parameter space.

A numerical model for calculating velocity distribution in cross-section of an open channel

Flow velocity in open channels is a fundamental hydraulic parameter with wide-ranging applications, including the development of rating curves and the study of sediment transport. While some river engineering projects may only require the calculation of average flow velocity, others, such as the design of hydraulic structures and stable channels, as well as the assessment of boundary shear stress, necessitate a more comprehensive understanding of flow dynamics, including the two-dimensional velocity distribution within open channels. To address this, various mathematical models have been proposed for estimating the two-dimensional distribution of flow velocity across transverse and depth directions. However, these models often come with complexities that hinder their practical application. In this research, we introduce a simplified numerical model that combines simplified Navier–Stokes equations with an eddy viscosity formula. This innovative approach aims to estimate velocity distribution in both rectangular and trapezoidal channels. The accuracy of our developed model hinges on the momentum transfer coefficient used in the eddy viscosity formula. Through the execution of the numerical model and the utilization of observational data, we determined the optimal value of the momentum transfer coefficient to be 0.241. To validate the effectiveness of our numerical model, we compared its predictions with laboratory data encompassing diverse hydraulic conditions. The results demonstrated a high level of accuracy, with the calculated velocity distribution and flow discharge differing by no more than 7.6% and 6.8%, respectively.

Using Thin Films of Phase-Change Material for Active Tuning of Terahertz Waves Scattering on Dielectric Cylinders.

The scattering of electromagnetic waves by isotropic dielectric cylinders can be dramatically modified by means of vanadium dioxide (VO2) thin-film coatings. Efficient dynamic control of scattering is achieved due to the variations in material parameters realizable by means of external biasing. In this paper, we study the scattering of terahertz waves in a case where the coating shells are made of VO2, a phase-change material, whose thin films may work rather as electromagnetic phase screens in the insulator material phase, but as lossy quasi-metallic components in the metallic material phase. The shells that uniformly cover the dielectric cylinders are investigated. Attention will be paid to the demonstration of the potential of VO2 in the external control of diverse scattering regimes of the dielectric-VO2 core-shell scatterer, while conductivity of VO2 corresponds to rather insignificant variations in temperature. In line with the purposes of this work, it is shown that the different resonant and nonresonant regimes have different sensitivity to the variations in VO2 conductivity. Both the total scattering cross section and field distributions inside and around the core are studied, as well as the angle-dependent scattering cross section.

The role of solvation on the conformational landscape of α-synuclein.

Native ion mobility mass spectrometry has been used extensively to characterize ensembles of intrinsically disordered protein (IDP) conformers, but the extent to which the gaseous measurements provide realistic pictures of the solution conformations for such flexible proteins remains unclear. Therefore, we systematically studied the relationship between the solution and gaseous structural ensembles by measuring electrospray charge state and collision cross section (CCS) distributions for cationic and anionic forms of α-synuclein (αSN), an anionic protein in solution, as well as directly probed gas phase residue to residue distances via ion/ion reactions between gaseous α-synuclein cations and disulfonic acid linkers that form strong electrostatic bonds. We also combined results from in-solution protein crosslinking identified from native tandem mass spectrometry (MS/MS) with an initial αSN ensemble generated computationally by IDPConformerGenerator to generate an experimentally restrained solution ensemble of αSN. CCS distributions were directly calculated for the solution ensembles determined by NMR and compared to predicted gaseous conformers. While charge state and collision cross section distributions are useful for qualitatively describing the relative structural dynamics of proteins and major conformational changes induced by changes to solution states, the predicted and measured gas phase conformers include subpopulations that are significantly different than those expected from completely "freezing" solution conformations and preserving them in the gas phase. However, insights were gained on the various roles of solvent in stabilizing various conformers for extremely dynamic proteins like α-synuclein.

Electron and positron impact differential cross sections for the (e,2e) process on water molecule

We present a theoretical study for electron and positron-impact ionization of water molecule by using the three-body formalism of distorted-wave approximation. In this approximation, the final state contains one-Coulomb, two-Coulomb, and three-Coulomb distortion due to pairwise Coulombic interactions, respectively. In the entrance channel, the initial state is a product of two wavefunctions: the first one for the incident electron/positron described by a Coulomb wave and the second one for the ten bound electrons. The molecular wavefunction for these bound electrons of H2O are described by the linear combination of atomic orbitals. We investigate the angular distribution of the triple differential cross section (TDCS) for single ionization of the outer orbitals 1b1,3a1,1b2, and 2a1. The structure with two peaks around the binary and recoil region are clearly observed for 1b1, 3a1, and 1b2 orbitals. At the same time, a single peak in the binary region with no recoil peak is found for the 2a1 orbital. The present TDCS results are compared with available experimental and theoretical findings. Fair agreement regarding the structure of angular profile of the TDCS is observed for all orbitals except 2a1. Finally, an enhanced TDCS have been found for positron impact compared to the electron impact.

A Compact Model for Unresolved Resonance Region Cross Sections

For decades, the probability table technique has been used to model the behavior of neutron cross sections in the unresolved resonance region with a stochastic approach. Early work from Hwang hinted at the possibility of a universal probability distribution to fit the URR cross section distribution. In this work we present a solution to Hwang’s problem: the normal inverse Gaussian distribution fits the probabilistic behavior of the total cross section almost perfectly for the most important nuclides, both in asymptotic behavior and around the more probable regions.

Effects of correlations in uncertainties of total cross section and elastic angular distribution for a deep penetration of 14-MeV neutrons in Cu

ABSTRACT Uncertainty in neutron reaction rates after penetrating a thick copper benchmark assembly was estimated based on two different kinds of Total Monte Carlo methods under random sampling methodology. Five hundred random nuclear data files were generated for 63Cu by Bayesian Monte Carlo method by perturbing the underlying nuclear model parameters. In the first method, these files were used directly to generate processed libraries, preserving all the correlations among different physical quantities. In the second method, the random files generated in the first method were used, but the angular distributions of elastic scattering were kept fixed to those of the non-perturbed nominal one. It was found that the two methods have the same neutron reaction rate after 608 mm penetration of copper. However, the uncertainty of the first method was smaller than that of the second method. It shows that the correlation between angular distribution of elastic scattering at 0 degrees and total cross section, which stems from Wick’s inequality, affects uncertainty of the calculated neutron reaction rate. It could be concluded that the uncertainty obtained by using the covariance files given in the ENDF-6 format may not give correct results for the uncertainty of neutron penetration calculations.

Search for the 6α condensed state in 24Mg using the 12C+12C scattering

We searched for the 6α-condensed state in 24Mg by measuring the C12+12C scattering with the SAKRA Si detector array at Ecm=17.5–25.0 MeV. By using the invariant-mass method for the detected 3α particles, the inclusive cross sections for the C12+12C→12C(02+)+X and C12(31−)+X reactions were determined. In addition, the missing-mass spectroscopy was successfully utilized to determine the excitation energy of the residual C12 nucleus and the exclusive cross sections for the C12+12C→12C(02+)+12C(01+), C12(02+)+12C(21+), and C12(02+)+12C(02+) reactions. In both the inclusive C12(02+)+X channel and the exclusive C12(02+)+12C(01+) channel, the cross section peaked at Ecm=19.4 MeV, which correspond to the excitation energy of Ex=33.3 MeV in 24Mg. This 19.4-MeV state is a candidate for the 6α-condensed state because of the agreement of the excitation energy with the theoretical value and its decay property. In the exclusive C12(02+)+12C(02+) channel, a broad state was observed at Ecm=22.5 MeV, which correspond to the excitation energy of Ex=36.4 MeV in 24Mg. From the angular distribution of the differential cross section, the spin and parity of this 22.5-MeV state was assigned to be 4+. In addition, a 2+ state was suggested at the low-energy side of the 22.5-MeV state. Because their excitation energies are higher than the theoretical value of the 6α-condensed state, these states might be excited states of the 6α-condensed state such as the 22+ and 41+ states in C12.

Electromechanical characteristic of stacked REBCO tapes under tension deformation

Stacking REBCO tapes is an effective way to increase the current-carrying capacity of the cable. Various loading conditions, including combined tension-bend, are applied to these tapes during fabrication and operation of the magnets. This paper investigates the degradation behaviors of critical current (Ic) in stacked rare earth–barium–copper–oxide (REBCO) coated conductor (CC) tapes under tension loading through experimental. Uniaxial tension experiments are conducted on single tapes and 4-tape cables with different stacking at 77 K. The critical current degrades rapidly when strain exceeds an irreversible threshold around 0.4-0.5%. A 3D finite element model analyzes the non-uniform stress distribution in the cable cross-section under tension, causing different degradation behaviors. An empirical model combining the Ekin law and Weibull distribution is proposed to relate Ic and axial strain. By fitting experimental data, the key parameters are determined. The Ic of a single tape reduces 20% at 0.4% strain. Face-to-face stacking decays at 0.45% irreversible strain, while back-to-back decays at 0.38%. The model provides an effective way to optimize the electromechanical performance of stacked REBCO cables.

Force Transfer Mechanism and Behavior Insights for a Large-Diameter CFST Column to Steel Beam Connection

Concrete-filled steel tube (CFST) columns with internal ring-plate-reinforced connections are increasingly used in high-rise buildings. However, the behavior and optimal design of such large-scale connections is not well established. This study presents a numerical investigation of the structural performance of a ring-plate-reinforced CFST column to steel beam connection. The paper begins by reviewing a previous experimental study. Subsequently, nonlinear finite element models were developed and validated using the test results. Parametric analyses were conducted to evaluate the effects of the ring plate dimensions, friction coefficient, and concrete defects on the load transfer mechanism. The results showed that the ring plate and friction force together effectively transferred the beam load to the concrete core. An optimal ring plate width of 75 mm was identified. Concrete defects significantly reduced the load carrying capacity of the ring plate. The stress distribution in the concrete cross section transitioned from nonuniform to uniform over a length approximately equal to the column diameter. The connection design was found adequate for the prototype structure analyzed. The study provides valuable guidance for improving ring-plate-reinforced connection design in future construction.

Nudging International Sustainable Practices Confirmed with Renewable Energy Consumption

The study explores the resemblance of the countries based on renewable energy consumption (% of total energy consumption). A simplistic clustering approach is applied to implement the segmentation using the gap statistic method. The paper deals with the comparability of countries from the perspective of income level and geographical distribution. The clustering-based results reveal that the values of most mean clusters representing major economies have deteriorated over the past few years. The High and Upper-middle income countries are found to be not following sustainable practices, while Low and Lower-middle income countries are relying much on renewable energy consumption. The outcome is also presented as clusters for geographical distribution and a cross-section distribution of Income level-Region for all economies sampled. The study may assist in policy-making in the wake of the global clean energy transition.

Dynamical studies for the S+ + D2(v0 = 2, j0 = 0) → SD+ + D reaction by time-dependent wave packet

Using time-dependent wave packet method, the dynamics studies of the S+ + D2(v0 = 2, j0 = 0) → SD+ + D reaction were carried out based on the potential energy surface (PES) reported by Zhu et al., (Phys. Chem. Chem. Phys.23 4757–4767 (2021)). The isotope effect is very obvious. When the H atom is replaced by the D atom, the reaction probability at total angular momentum equal to zero has a threshold of about 0.28 eV and it decreases significantly in the collision energy range studied. The total and rovibrational state-resolved integral cross section were reported and the results indicate that the distribution of integral cross section is mainly concentrated in the ground state. The forward biased differential cross sections show that the stripping mechanism due to high total angular momentum plays a dominant role in the reaction.

Effective extraction of photoneutron cross-section distribution using gamma activation and reaction yield ratio method

Effective extraction of photoneutron cross-section distribution using gamma activation and reaction yield ratio method

Laser stripe center extraction method base on Hessian matrix improved by stripe width precise calculation

The line laser measurement technology based on triangulation is widely used in the field of complex surface topography measurement. The key technology of line laser measurement is laser stripe center extraction. For high reflective surfaces, due to the low surface roughness, some areas of the laser stripe image are overexposed, resulting in uneven stripe width distribution, asymmetric light intensity distribution of the stripe cross section, and difficulty in extracting the center of the stripe. In this paper, Laser stripe center extraction method based on Hessian matrix method improved by stripe width is proposed. Firstly, the laser stripe image is preprocessed, the influence of noise in the image is alleviated by image filtering and adaptive threshold segmentation, and the region of interest of the image is extracted to reduce the amount of subsequent calculation. The laser stripe width is calculated based on BPNN and divided into different width intervals. The Gaussian kernel is calculated according to the light stripe width and the Hessian matrix is constructed. The Hessian matrix method is used to roughly extract the center coordinates of the light stripe. Based on the continuity of the light stripe, the center coordinates of the light stripe are weighted and corrected to realize the smooth optimization of the center coordinates of the light stripe. The experimental results show that the proposed light stripe center extraction method is superior to the traditional method under different surface roughness and exposure time conditions, which can effectively improve the measurement accuracy of the sensor.

Isolated photon production in association with a jet pair through next-to-next-to-leading order in QCD

In this work, we provide a comprehensive set of differential cross-section distributions for photon + di-jet production in proton-proton collisions with next-to-next-to-leading order precision in massless QCD. The event selection corresponds to recent measurements by the ATLAS collaboration. We observe an improved description of data in comparison to lower-order calculations in the case of observables that are expected to be well described by perturbation theory. The results also show better agreement with data than parton-shower-matched and multi-jet-merged predictions generated for the ATLAS analysis using the Sherpa Monte Carlo. A particular highlight of our study is the use of exact five-point two-loop virtual amplitudes. This is the first calculation of a complete two-to-three hadron-collider process at next-to-next-to-leading order in QCD that does not rely on the leading-colour approximation at two loops. We demonstrate, nevertheless, that the sub-leading-colour effects present in the infraredand ultraviolet-finite double-virtual contributions are negligible in view of the remaining scale uncertainties.

Determining the Spectrum of Eigenvalues and Eigenfunctions for the Bernoulli–Euler Equation with Variable Coefficients by the Peano Method

The paper considers the problem of determining the natural frequencies and eigenwaves of transverse vibrations for the Bernoulli–Euler equation with variable coefficients. Such problems arise both in the case of complex geometry of a vibrating solid and in the case of functionally graded materials or the accumulation of damage in a classical elastic material. Solutions of boundary value problems are constructed using the expansion in Peano series. Under broad assumptions, the uniform convergence of Peano series is shown and estimates of the residual terms are obtained. Examples of the numerical implementation of the proposed procedure are given for bending vibrations of a rod with certain parameters of a variable cross section (geometric heterogeneity) and elastic modulus distribution (physical heterogeneity). Numerical examples are focused on assessing the geometric and elastic properties of samples in an experimental study of the fatigue strength of alloys during high-frequency cyclic tests based on the general principle of point resonant loading. The method proposed for solving problems of resonant vibrations for the Bernoulli–Euler equation can be used in the design of new promising cyclic test schemes and mathematical modeling of fatigue failure processes under high-frequency resonant vibrations.

Influence of High-Order Twisting Phases on Polarization States and Optical Angular Momentum of a Vector Light Field

This study investigates the influence of high-order twisting phases on polarization states and optical angular momentum of a vector light field with locally linear polarization and a hybrid state of polarization (SoP). The twisted vector optical field (TVOF) is experimentally generated based on the orthogonal polarization bases with high-order twisting phases. The initial SoP of a TVOF modulated by the high-order twisting phase possesses various symmetric distributions. The propagation properties of a high-order TVOF with locally linear polarization and hybrid SoP are explored, including the intensity compression, expansion, and conversion between the linear and circular polarization components. In particular, orbital angular momentum (OAM) appears in a high-order TVOF during propagation where no OAM exists in the initial field. The variation of OAM distribution in cross-section becomes more frequent with the increase of the twisting phase order. In addition, a non-symmetric OAM distribution appears in a non-isotropic TVOF, leading to the rotation of the beam around the propagation axis during propagation. The optical energy flow distribution of a high-order TVOF provides a more profound understanding of the propagation dynamics of high-order TVOF. These results provide a new approach for optical field manipulation in a high-order TVOF.

Properties of water and argon clusters developed in supersonic expansions.

Using adiabatic molecular dynamics coupled with the fluid dynamics equations, we model nucleation in an expanding beam of water vapor and argon on a microsecond scale. The size distribution of clusters, their temperature, and pickup cross sections in dependence on velocity are investigated and compared to the geometric cross sections and the experiment. The clusters are warmer than the expanding gas because of the time scale of relaxation processes. We also suggest that their translational and rotational kinetic energies are modified due to evaporative cooling. The pickup cross sections determined for the final clusters using molecules of the same kind increase with decreasing velocity, still obeying the (a+bN1/3)2 law.