Total Cross Sections Research Articles

QCD corrections of e+e−→J/ψ+c+c¯ using the principle of maximum conformality

In this paper, we compute the total and differential cross sections for e+e−→J/ψ+c+c¯ at the B factories up to next-to-leading order (NLO) corrections within the framework of nonrelativistic quantum chromodynamics (QCD) factorization theory. We then obtain improved perturbative QCD (pQCD) series of those cross sections by using the principle of maximum conformality (PMC). We show that the PMC can be applied for any pQCD calculable observable at the total and differential levels via a self-consistent way in perturbation theory. We observe that a more precise prompt total cross section at the NLO level can be achieved after applying the PMC, e.g., σ|promptPMC=0.565−0.125+0.144 pb. Here the uncertainty is the squared average of those from the αs fixed-point uncertainty Δαs(MZ), the uncertainty of charm quark mass Δmc, and an estimated contribution of the uncalculated NNLO-terms as predicted by the Padé approximation approach. The differential cross sections dσ/dPJ/ψ, dσ/d|cosθ|, and dσ/dz for e+e−→J/ψ+c+c¯ are further examined. Those results show that by further considering the feed-down contributions, the PMC predictions show better agreement with the Belle measurements. Published by the American Physical Society 2024

Evaluation of the Mechanical and Electrical Properties of Multistage Drawn Copper-Clad Aluminum Wire After Annealing Process

This study evaluates the mechanical and electrical properties of copper-clad aluminum (CCA) wire prepared with a total cross-section reduction of 89% through a multistage cold drawing process and subjected to annealing at various temperatures. In addition to the CCA wire, individual samples of oxygen-free copper and aluminum, drawn with a cross-sectional reduction of 50%, were annealed under the same temperature conditions to enable a comparative analysis. Tensile tests for strength and elongation measurements were conducted, while electrical conductivity was assessed through resistivity tests. SEM and EDS analyses were performed to examine the diffusion thickness and the composition of intermetallic compounds generated at the Al/Cu interface of CCA wire. The tensile strength of the CCA wire decreased and its elongation increased up to 250 °C, after which were maintained. As the annealing temperature increased, intermetallic compound layers of Al2Cu, AlCu, and Al4Cu9 were formed at the Al/Cu interface of the CCA wire, and their thickness increased. Electrical conductivity reaches a maximum at 200 °C and then continuously decreases, showing a negative linear correlation with an increase in the diffusion layer thickness of intermetallic compounds. The study confirmed that cold-drawn CCA wire achieves stable mechanical properties and maximum electrical conductivity at the optimal annealing temperature.

Cross-Sections for Projectile Ionization, Electron Capture, and System Breakdown of C5+ and Li2+ Ions with Atomic Hydrogen

For many disciplines of science, all conceivable collisional cross-sections and reactions must be precisely known. Although recent decades have seen a trial of large-scale research to obtain such data, many essential atomic and molecular cross-section data are still missing, and the reliability of the existing cross-sections has to be validated. In this paper, we present projectile ionization, electron capture, and system breakdown cross-sections in carbon (C5+) ions and lithium (Li2+) ion collisions with atomic hydrogen based on the Monte Carlo models of classical and quasi-classical trajectories. According to our expectation, the QCTMC results show higher results in comparison to standard CTMC data, emphasizing the role of the Heisenberg correction constraint, especially in the low-energy regime. On the other hand, at high energy, the Heisenberg correction term has less influence as the projectile momentum increases. We present the total cross-sections of projectile ionization, electron capture, and system breakdown in C5+ ions and Li2+ ion collisions with atomic hydrogen in the impact energy range from 10 keV to 160 keV, which is of interest in astrophysical plasmas, atmospheric sciences, plasma laboratories, and fusion research.

Single-quantum annihilation of positrons at low energies

We discuss the low-energy single-quantum positron annihilation with a bound electron. The angular distribution and the total cross section are considered. We obtain a simple analytical expression for the Coulomb potential and for the screened potential. It is worth noting that the obtained results for the screened potential are universal and independent of the explicit form of the atomic potential. It is shown that screening significantly increases the cross section. We also obtain the analogous results for near-threshold bound-free e+e− photoproduction.

Dispersive optical-model potential parameters for neutron scattering on 197Au up to 200 MeV

In this study, dispersive optical model (DOM) potential parameters were derived for the 197Au target nucleus up to an incident neutron energy of 200 MeV. The procedure involved fitting the theoretical total cross sections σtot with the experimental ones and thereby determining the valid free potential parameters at the lowest value of χ2/M. The contribution of compound nuclei mechanism at low energies was also incorporated in the calculations. The theoretical results obtained using the derived potential were compared to the experimental data for both the angular differential cross-section and the elastic cross-section. While there was a good agreement with the experimental values for the total cross section, a satisfactory agreement was achieved for the angular cross section. The obtained potential is useful for describing the n+197Au scattering system and its outputs over an extensive energy spectrum.

Effect of BaO on some radiation shielding parameters of recycling waste soda lime silica glasses system

This study investigates the impact of BaO as an additive on various radiation shielding parameters for recycled waste soda-lime silica glass (WSLSG) composites. Experimental gamma-ray attenuation measurements were performed using 137Cs and 60Co sources and BaO(x) [0.2Bi2O3-0.3ZnO-0.2B2O3-0.3SLS](1-x) glass composites (x = 0, 0.01, 0.02, 0.03, 0.04, and 0.05 mole%) with a NaI(Tl) detector. Additionally, theoretical validation of gamma-ray shielding effectiveness was carried out using the EpiXS and Phy-X/PSD programs over a wide gamma-ray energy range (0.015 – 15 MeV). Key parameters such as mass attenuation coefficient (MAC), half-value layer (HVL), tenth-value layer (TVL), effective atomic number (Zeff), effective electron density (Neff), transmission factor (TF), and gamma-ray dose rate (Dr) were calculated. For a fixed sample thickness and incident gamma-ray energy, the descending order of TF for the glass samples was determined as: . Furthermore, the fast neutron removal cross section (FNRCS) at 4.5 MeV and the macroscopic removal cross section (MRCS) for fast neutrons were evaluated using Phy-X/PSD and MRCScal software, respectively. The total macroscopic cross section for thermal neutrons (Σth) and TF for fast/thermal neutrons (4 MeV/25.4 meV) were also computed using NGcal and transmission/scatter power software. Results indicated that both FNRCS and MRCS increased with BaO mole %. Additionally, the range (R) and total stopping power (TSP) for selected ions were simulated using SRIM Monte Carlo software over a broad energy range (0.01 - 20 MeV). The TSP and continuous slowing down approximation (CSDA) range for electron interactions were deduced using the ESTAR NIST program across an electron energy range of 0.01 - 1000 MeV.

Theoretical studies on the scattering of e± off the C2H2 molecule

Abstract By employing previous models [15,18], we report the differential, integrated elastic, inelastic, total (elastic+inelastic), viscosity and momentum transfer cross sections of e±- C2H2 collision dynamics, for the energy range of 1 eV-1 MeV. This report also incorporates Sherman spin polarization function and total ionization cross section. This work provides the first comprehensive study of electron/positron scattering from C2H2 over such a wide energy range. A complex optical model potential (OMP) has been used to represent the projectile-atom interaction. Relativistic Dirac equation has been solved, to get phase-shifts, needed for the calculations of scattering observables, using OMP. Our results are compared with the existing experimental data and theoretical calculations.

Mutual Neutralization in Collisions of Li+ with O−

The total and differential cross-sections and final state distribution for mutual neutralization in collisions of Li+ with O− were calculated using an ab initio quantum mechanical approach based on potential energy curves and non-adiabatic coupling elements computed with the multi-reference configuration interaction method. The final state distributions favored channels with excited oxygen states, indicating a strong effect of electron correlation, and the electron transfer could not be described by a simple one-electron exchange process.

NLO corrections to J/ψ+c+c¯ photoproduction

Based on the factorization framework of nonrelativistic quantum chromodynamics, we study the associated J/ψ+c+c¯ photoproduction process at next-to-leading order (NLO) in αs and leading order (LO) in the velocity expansion. The NLO (LO) total cross section for HERA is σtotHERA=0.118(0.074) nb and for EIC is σtotEIC=0.046(0.027) nb. The differential cross sections in pT2, W, and z are presented. The results indicate that the next-to-leading order corrections are substantial, and testable in experiment. Published by the American Physical Society 2024

Scattering effects of bumblebee gravity in metric-affine formalism

In this work, we explore a Schwarzschild-like black hole within the framework of metric-affine bumblebee gravity. First, we investigate the behavior of the Kretschmann scalar and singularities in this modified gravity approach. Next, we introduce a newly defined time coordinate related to a stationary asymptotically flat spacetime. We also analyze the scattering effects and numerically calculate and comprehensively examine the partial and total absorption cross sections. At the high-frequency approximation, we find that the absorption cross section tends to the geodesic capture cross section. The continued fraction method is applied to investigate the quasinormal modes, and we explore the deviations of both the real and imaginary terms of the quasinormal modes from the Schwarzschild case in detail. We verify the relation between the shadow radius and the real part of the quasinormal frequencies at the eikonal limit within this modified gravity framework. Finally, we examine the energy emission rate.

Microscopic description of the pygmy and giant dipole resonances in even–even nuclei. Application to the isotopes 150,152,154,156,158,160Gd

This paper deals with a microscopic approach for the description of the pygmy dipole resonance (PDR) as well as of the giant dipole resonance (GDR). The formalism is based on a Hamiltonian which is summing a mean field term, the pairing for alike nucleons and the dipole–dipole interaction. Two features are specific for our description: (a) The use of a projected spherical single particle basis and (b) the involved dipole operator is a Schif-like operator including a corrective term which is cubic in the radial coordinate. The dipole strength distribution with energy is plotted for the PDR region, i.e., [0,10] MeV. The dominant transitions have an isovector character for three isotopes and isoscalar for another three. The PDR states carry only 0.4–1.8[Formula: see text] of the total EWSR. The dependence of the dipole strength on nuclear deformation is evidenced. For the whole interval of [0,20] MeV the dipole strength was first folded by Lorentzian of 1[Formula: see text]MeV width and then plotted as function of the QRPA energies. The peaks belonging to each of the two ranges are analyzed in detail and their nature, isovector/isoscalar, was pointed out. The r-cubic term and the nuclear deformation have opposite effects on the dipole strength. The famous Thomas–Reiche–Kuhn sum rule formula is generalized to the case of the Schiff dipole momentum. The new EWSR is very well satisfied. The photoabsorbtion cross-section is calculated and compared with experimental data in a figure showing its dependence on energy. The total cross-section, [Formula: see text], the moments of the integrated cross-sections, [Formula: see text], [Formula: see text], the dipole polarizability and the thickness of the neutron crust are also calculated. The main features of PDR and GDR are realistically described.

Differential Cross-Sections for the Vibrationally Excited H + HOD(vOH = 1-4) → H2 + OD Reactions.

Using the time-dependent wave-packet approach, we calculate the first fully converged state-to-state differential cross-sections for the H + HOD(vOH = 1-4) → H2 + OD reactions on a highly accurate neural network PES. It is found that, unlike the loss of memory effect observed in the product distributions for low vibrational excitation reactions, high initial OH vibrational excitation significantly influences not only the product vibrational distribution but also the angular distribution. Furthermore, for the H + HOD(vOH = 3,4) reactions, the total integral cross-sections maintain the pronounced oscillatory structures in the J = 0 probabilities at low collision energies, which originate from the prereactive van der Waals resonances. Notably, the product angular distributions exhibit forward-backward peaked behavior at these energies, akin to those observed in the complex-forming system with deep potential wells. This is attributed to the much longer lifetimes of these resonances compared to those of conventional transition state resonances.

Probing anomalous Zγγγ couplings at a future muon collider

Abstract The sensitivity to anomalous quartic gauge couplings (AQGCs) of the
$\gamma\gamma\gamma Z$ interaction is studied in the $\mu^+\mu^-
\rightarrow \mu^+\gamma\gamma \mu^-$ scattering at a future muon
collider with unpolarized beams. The anomalous $\gamma\gamma\gamma
Z$ vertex is described by two couplings, $\zeta_1$ and $\zeta_2$.
The differential and total cross sections are calculated for the
center-of-mass energies of 3 TeV, 14 TeV, and 100 TeV. For these
values of the collision energy the $95\%$ C.L. exclusion regions for
AQGCs are obtained depending on the systematic error. In particular,
for the 14 TeV muon collider with the integrated luminosity $L = 20$
ab$^{-1}$ the best sensitivities are derived to be $\zeta_1 = 3.1
\times 10^{-5}$ TeV$^{-4}$ and $\zeta_2 = 6.5 \times 10^{-5}$
TeV$^{-4}$. These constraints are three orders of magnitude stronger
than the bounds obtained for the 27 TeV HE-LHC with $L = 15$
ab$^{-1}$. At the 100 TeV muon collider with $L = 1000$ ab$^{-1}$
AQGCs can be probed up to $1.64 \times 10^{-8}$ TeV$^{-4}$ and $3.4
\times 10^{-8}$ TeV$^{-4}$ for $\zeta_1$ and $\zeta_2$,
respectively. The partial-wave unitarity constraints on couplings
$\zeta_1$, $\zeta_2$ are evaluated. It is shown that the unitarity
is not violated in the region of the AQGCs examined in the present
paper.

Inclusive J/ψ production in forward proton-proton and proton-lead collisions at high energy

We calculate the cross section for forward J/ψ production in proton-proton and minimum bias proton-lead collisions using the color glass condensate (CGC) and nonrelativistic QCD (NRQCD) formalism consistently with deep inelastic scattering data. The cross section for color singlet states is sensitive to a four-point correlator of Wilson lines for which we describe in the Gaussian approximation in the large-Nc limit. Furthermore, we quantify the importance of finite-Nc corrections to have a small ∼12% effect. In contrast with the generic NRQCD expectation, we show that the color singlet contribution is only 15% to the total cross section. We also compare our predictions for J/ψ production as well as for the nuclear modification ratio RpPb to LHCb and ALICE data. We find a good agreement at forward rapidities, except at low transverse momenta where the cross sections are overestimated. Published by the American Physical Society 2024

First measurement of the total inelastic cross section of positively charged kaons on argon at energies between 5.0 and 7.5 GeV

First measurement of the total inelastic cross section of positively charged kaons on argon at energies between 5.0 and 7.5 GeV

NNLL-fast 2.0: Coloured sparticle production at the LHC run 3 with $\sqrt{S}$ = 13.6 TeV

We report on updated precision predictions for total cross sections of coloured supersymmetric particle production at the LHC with a centre-of-mass energy of \sqrt{S} = 13.6S=13.6 TeV, computed with the modern PDF4LHC21 set. The cross sections are calculated at an approximated NNLO accuracy in QCD and contain corrections from the threshold resummation of soft-gluon emission up to NNLL accuracy as well as Coulomb-gluon contributions including bound-state terms. The corrections are found to increase the cross sections and reduce the theoretical uncertainty as compared to the best available fixed-order calculations. These predictions constitute the state-of-the-art calculations and update the existing results for \sqrt{S} = 13S=13 TeV. We make our new results publicly available in the version 2.0 update to the code package .

Statistical theory of neutron-induced nuclear fission and of heavy-ion fusion

For both reactions I use an approach similar to that of compound-nucleus reaction theory. For neutron-induced fission, the compound system generated by absorption of the neutron and the nuclear system near the scission point are described as two statistically independent systems governed by random-matrix theory. The systems are connected either by a barrier penetration factor or by a set of transition states above the barrier. Each system is coupled to a different set of channels. An analogous model is used for heavy-ion fusion. Under the assumption that (seen from the entrance channel) the system on the other side of the barrier is in the regime of strongly overlapping resonances, closed-form analytical expressions for the total probability for fission and for fusion are obtained for each value of spin and parity. Parts of these expressions can be calculated reliably within existing compound-nucleus reaction theory. The remaining parts are the probabilities for passage through or over the barrier. These may be determined theoretically from the liquid-drop model or experimentally from total fission or fusion cross sections. Published by the American Physical Society 2024

The effect of lumbar multifidus muscle degeneration on upper lumbar disc herniation.

This study aimed to investigate the effect of lumbar multifidus muscle (MF) degeneration on upper lumbar disc herniation (ULDH). This study used 3.0T magnetic resonance imaging (MRI) T2 axial weighted images to retrospectively analyze 93 ULDH patients and 111 healthy participants. Sixty-five pairs of participants were included in this study using propensity score matching (PSM). Cross-sectional area, fat infiltration area, anteroposterior diameter (APD), lateral diameter (LD), cross-sectional area of the bilateral multifidus muscles at the corresponding level, intervertebral disc area at the corresponding section, and visual analog scale (VAS) score for low back pain (LBP). For inter-group comparisons, we used the t-test, analysis of variance (ANOVA), Mann-Whitney U test, Kruskal-Wallis test, chi-square test, or Fisher's exact test, according to the type of data. We used Pearson correlation analysis to study the correlation between the VAS score and related indicators, and established a predictive model for upper lumbar disc herniation using the receive operative characteristic (ROC) curve analysis method. Finally, univariate and multivariate logistic regression analyses were performed to establish a predictive model for the risk of high lumbar disc herniation. We compared the fat areas at the lumbar vertebral levels L1/2, L2/3, and L3/4, as well as the left lateral diameter (LD) (MF), L1/2 left lumbar multifidus muscle index (LMFI), and L1/2 total fat infiltration cross-section area (TFCSA), and found significant differences between the case and control groups (P < 0.001). Furthermore, we observed a significant positive correlation (P < 0.05) between the VAS scores and multiple muscle indicators. Additionally, we developed ROC prediction models to assess the risk of lumbar intervertebral disc protrusion at the L1/2, L2/3, and L3/4 levels, with the results identifying L1/2 TFCSA, L2/3 TFCSA, and L3/4 relative psoas major muscle cross-section area (rPMCSA) as the most predictive indicators. Finally, univariate and multivariate logistic regression analyses showed that the L1/2 rPMCSA, L2/3 TFCSA were significantly associated with the risk of lumbar intervertebral disc protrusion in both models. Degeneration of the MF is significantly correlated with the occurrence of ULDH, and the larger the area of fat infiltration in the MF, the more obvious the lower back pain in ULDH patients. In addition, TFCSA can serve as an indicator of the occurrence of ULDH.

Positron interactions with vinyl acetate from 0.1 eV to 5 keV

Abstract Scattering cross sections from positron impact on vinyl acetate are explored in the energy region 0.1 eV to a 5 keV, employing a cc-pVTZ basis set. The optimized molecular wavefunction of the target was obtained through a multi-center expansion of Gaussian-type orbitals in the Hartree–Fock self-consistent field framework. The elastic cross sections are computed using the single-centre-expansion formalism. Two distinct models were employed to address the long-range effects associated with the target's polar nature and yielded almost identical corrections. The Born-corrected elastic cross sections align more strongly with the existing experimental corrected data than the results reported from the independent-atom-model approximation. The differential and momentum transfer cross sections after applying Born-correction are also reported. The direct ionization cross sections are obtained using the binary-encounter-Bethe model for positrons. The cross sections obtained by summing elastic and ionization cross sections align closely with ‘forward angle corrected’ experimental total cross sections across a significant energy range. The agreement significantly improves beyond 30 eV, suggesting that the omission of excitation and positronium formation cross sections becomes less significant. A brief analysis of the electron interaction with the target is also made.

Bound States and Scattering of Magnons on a Superconducting Vortex in Ferromagnet-superconductor Heterostructures

We study the magnon spectrum in a thin ferromagnetic-superconductor heterostructure in the presence of a single superconducting vortex. We employ the Bogolubov–de Gennes Hamiltonian which describes the magnons in the presence of the stray magnetic field and the non-uniform magnetic texture induced by the vortex. We find that the vortex localizes magnon states approximately in the same way as a charge center produces electron bound states due to screened Coulomb interaction in the two-dimensional electron gas. The number of these localized states is substantially determined by the material parameters of the ferromagnetic film only. We solve the scattering problem for an incident plane spin wave and compute the total and transport cross sections. We demonstrate that the vortex-induced non-uniform magnetic texture in chiral ferromagnetic film produces a skew scattering of magnons. We explore the peculiarities of the quantum scattering problem that correspond to orbiting in the classical limit.