Total Cross Sections Research Articles

Hint for a Minimal Interaction Length in e+e−⟶γγ Annihilation in Total Cross Section of Center-of-Mass Energies 55-207 GeV

The measurements of the total cross section of the e+e−⟶γγγ reaction from the VENUS, TOPAS, OPAL, DELPHI, ALEPH, and L3 collaborations, collected between 1989 and 2003, are used to perform a χ2 test to validate the current quantum electrodynamics (QED) theory and search for possible deviations with the direct contact term annihilation. By observing a deviation from the QED predictions on the total cross section of the e+e−⟶γγγ reaction above s=180.0 GeV, a non-QED direct contact term is introduced following the dimension 6 effective theory to explain the deviation. In the non-QED direct contact term, a threshold energy scale Λ is included and explained to the finite interaction length in direct contact term and in consequence the size of the electron involved in the annihilation area. The experimental data of the total cross section is compared to the QED cross section by a χ2 test, which gives a best fit of the Λ to be 1576±202 GeV, corresponding to a finite interaction length of re=1.25±0.16×10−17 (cm). In the direct contact term annihilation, this interaction length is a measure of the size of an electron re. By combining all the data results from the mentioned collaborations, we have at least 2 to 3 times more statistics than every single experiment at high s region. This induces the best precision on re compared to the previous measurements.

Cross section sensitivity to perturbation strengths in distorted waves for double electron capture by alpha particles from helium targets

Computer experiments are performed on total cross sections for capture of both electrons from helium targets at 100-10000 keV. Employed are four quantum-mechanical perturbative four-body distorted wave methods (one of the first and three of the second order). The goal is to determine the cross section sensitivity to the perturbation strengths in distorted waves from the second-order methods. The perturbation strength is parametrized by the Sommerfeld factor (the quotient of the nuclear charge and the relative velocity of the colliding particles). At each fixed impact energy, the sought sensitivity is monitored by gradually modifying the nuclear charges in the Sommerfeld factors. These factors reside in the Coulomb distortions of the unperturbed channels states. The focus is on the electronic distortions through the eikonal Coulomb logarithmic phases and the full Coulomb waves. The logarithmic phases are the constituents of the compound phases for the net charges of the two heavy scattering aggregates in relative motions. A striking perturbation strength sensitivity of the obtained total cross sections is recorded.

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.

Light quark mediated Higgs boson production in association with a jet at the next-to-next-to-leading order and beyond

We study the light quark effect on the Higgs boson production in association with a jet at the LHC in the intermediate transverse momentum region between the quark and the Higgs boson mass scales. Though the effect is suppressed by the small Yukawa coupling, it is enhanced by large logarithms of the quark mass ratio to the Higgs boson mass or transverse momentum. Following a remarkable success of the logarithmic expansion [40] for the prediction of the next-to-next-to-leading bottom quark contribution to the total cross section of the Higgs boson production we extend the analysis to its kinematical distributions. A new factorization formula is derived for the light quark mediated gg → Hg amplitudes and the differential cross section of the process is computed in the logarithmic approximation, which is used for an estimate of the bottom quark effect at the next-to-next-to-leading order.

Quantum scattering in a wavy circle

We study the non-relativistic quantum mechanical scattering problem of a plane-wave by a Chebyshev particle in two spatial dimensions. The Chebyshev particle is a wavy, or undulating, circle. We formulate the problem using the Lippmann–Schwinger (LS) equation and the Chebyshev particle as a boundary-wall potential. This potential is naturally symmetric as a function of the so-called undulation parameter, and we use these symmetries to solve the LS equation and calculate three important physical quantities: the differential cross-section, the total cross-section and the quantum refractive index. We analyze these quantities as functions of the wave number k, the coupling strength γ as well as the undulation and deformation parameters of the Chebyshev particle.

Enhancement of Gamma-Ray and Neutron Shielding Properties of TeO2-Li2O-ZnO-Nb2O5 Glass System with the Addition of Sm2O3

Radiation shielding glass is widely used, as it protects people from ionizing radiation while allowing for the observation of irradiated areas. However, the performance of even the best-performing tellurite glass for radiation shielding still falls short compared to traditional radiation shielding materials. The effect of Sm2O3, with a high atomic number and cross section with neutron, on the gamma-ray and neutron shielding properties of a 75TeO2-5Li2O-10ZnO-(10-x)Nb2O5-(x)Sm2O3 glass system is studied in this work. Some critical shielding parameters, including linear attenuation coefficients, half-value thickness, tenth-value layer, and mean free path (MFP), have been calculated with the software Phy-X/PSD. Two kinds of gamma-ray buildup factors, the exposure buildup factor and the energy absorption buildup factor, have been calculated in the range of 0.015 to 15 MeV for depths up to 40 MFP. What’s more, their neutron shielding ability has been evaluated by calculating the neutron total effective removal cross section. It is shown that Sm2O3 promotes the gamma-ray and neutron shielding performance of the 75TeO2-5Li2O-10ZnO-10Nb2O5 glass system. The results indicate that the addition of Sm2O3 can be helpful for the radiation shielding performance of tellurite glass, which provides a practical way for designing glass with ideal shielding properties.

Forward proton measurements with ATLAS

The ALFA subdetector is designed to measure elastic proton-proton scattering from which the total cross section and \rhoρ-parameter are determined. In 2016, special runs at a center-of-mass energy of \sqrt{s}s = 13 TeV and with \beta^\starβ⋆ = 2.5 km were recorded.

Higgs boson pair production and decay at NLO in QCD: the bb¯γγ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ b\\overline{b}\\gamma \\gamma $$\\end{document} final state

The Higgs boson pair production at the LHC provides a probe to the Higgs boson self-coupling. The higher-order QCD corrections in this process are sizable and must be taken into account in comparison with data. Due to the small cross section, it is necessary to consider at least one of the Higgs bosons decaying to bottom quarks. The QCD corrections to the decay processes would also be important in such cases. We present a full calculation of the total and differential cross sections for the bb¯γγ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ b\\overline{b}\\gamma \\gamma $$\\end{document} final state with next-to-leading order (NLO) QCD corrections. After applying typical kinematic cuts in the final state, we find that QCD NLO corrections in the decay decrease the LO result by 19% and reduce the scale uncertainties by a factor of two. The QCD corrections to the invariant mass mjjγγ distribution, the transverse momentum spectra of the leading bottom quark jet and photon are significant and can not be approximated by a constant factor.

The Astrochemistry Low-energy Electron Cross-Section (ALeCS) database

Context. Electron–molecule interaction is a fundamental process in radiation-driven chemistry in space, from the interstellar medium to comets. Therefore, knowledge of interaction cross sections is key. There have been a plethora of both theoretical and experimental studies of total ionization cross sections spanning from diatomics to complex organics. However, the data are often spread over many sources or are not public or readily available. Aims. We introduce the Astrochemistry Low-energy Electron cross-section (ALeCS) database. This is a public database for electron interaction cross sections and ionization rates for molecules of astrochemical interest. In particular, we present here the first data release, comprising total ionization cross sections and ionization rates for over 200 neutral molecules. Methods. We include optimized geometries and molecular orbital energies at various levels of quantum chemistry theory. Furthermore, for a subset of the molecules, we have calculated ionization potentials. We computed the total ionization cross sections using the binary-encounter Bethe model and screening-corrected additivity rule, and we computed ionization rates and reaction network coefficients for molecular cloud environments. Results. We present the cross sections and reaction rates for >200 neutral molecules ranging from diatomics to complex organics, with the largest being C14H10. We find that the screening-corrected additivity rule cross sections generally significantly overestimate experimental total ionization cross sections. We demonstrate that our binary-encounter Bethe cross sections agree well with experimental data. We show that the ionization rates scale roughly linearly with the number of constituent atoms in the molecule. Conclusions. We introduce and describe the public ALeCS database. For the initial release, we include total ionization cross sections for >200 neutral molecules and several cations and anions calculated with different levels of quantum chemistry theory, the chemical reaction rates for the ionization, and network files in the formats of the two most popular astrochemical networks: the Kinetic Database for Astrochemistry, and UMIST. The database will be continuously updated for more molecules and interactions.

SET sensitivity of a VCRO-based PLL for HL-LHC ATLAS HGTD

We report the characterization of the Single Effect Transient (SET) sensitivity of an analogue Phase Locked Loop (PLL) based on a Voltage Controlled Ring Oscillator (VCRO) under a proton beam. The clock generator is embedded in a front-end ASIC, namely ALTIROC designed in CMOS 130 nm, reading out Low-Gain Avalanche Diode (LGAD) matrices for the High-Luminosity Large Hadron Collider (HL-LHC). We detail the methodology developed to study such events that could degrade the targeted time resolution of 35 ps per hit. Observed SET-induced phase jumps allow the estimation of the total cross-section of the PLL. The results are extrapolated to the HL-LHC radiation conditions.

Quasinormal modes, temperatures and greybody factors of black holes in a generalized Rastall gravity theory

We introduce a modification in the energy-momentum conservation violating Rastall’s theory of gravity and obtain a Reissner-Nordström-type black hole solution in spacetime surrounded by a cloud of strings and charge fields. We examine the horizons of the black hole along with the influence of the parameters of the model on it. The scalar quasinormal modes (QNMs) of oscillations of the black hole are also computed using the 6th order WKB approximation method. It is seen that the Rastall parameter β and the newly introduced energy-momentum tensor trace parameter α as well as the charge parameter q and strings field parameter a influence the amplitude and damping of the QNMs. From the metric function, we obtain the temperature of the black hole and study the effects of the four model parameters β, α, q and a on the temperature. We then examine the greybody factors associated with the black hole and the corresponding total absorption cross-section for it. It is seen that the modification we introduced in the Rastall theory has a drastic effect on various properties of the black hole and may lead to interesting outcomes in future when better detection techniques will be available with the LISA and the Einstein Telescope.

Xenon photonuclear cross sections for the production of 123I radionuclide

A simple reliable theoretical model for the calculation of total photo-absorption cross sections by atomic nuclei has been presented and applied it to get the relevant data needed for the evaluation of the production rate of 123I radionuclide isotope. Since experimental measurements are not available, the model calculation represents the only source of information. The present results, based on an accurate model of nuclear structure, are in very good agreement with the observed photoabsorption cross sections of Te isotopes, which provide reliable cross sections for the neighboring Xe nuclei, where the usual simple estimates are clearly discordant.

Determination of Some Atomic Parameters for Aktaş, Çıldır Lake, and Kura River Water with the Help of WinXCom

In this study, elemental analyses of water samples taken from Aktaş, Çıldır Lake, and Kura River basins in Ardahan province were carried out using Inductively Coupled Plasma Mass Spectrometry. The mass attenuation coefficients, total photon interaction cross sections, effective atomic numbers, and electron densities were determined with the help of WinXCom for the main gamma-ray energies released when Ra-226, which is an important source of natural radiation, decays into Rn-222, Bi-214, and Po-214.

Generation of thermal neutron scattering data for GH3535 alloy

Recent studies related to the thermal neutron scattering (TNS) data in reactors were generally focused on fuels and moderators, while the TNS data for structural materials has received little attention. The TNS effect of the GH3535 alloy, a nickel-based alloy widely used in molten salt reactor (MSR), is studied in this work. The partial phonon densities of states (PDOS) for the main metals (Ni, Mo, Cr and Fe) in the alloy, which are required for the TNS data generation, are calculated using the density functional perturbation theory (DFPT) based on a special quasi-random structure (SQS) of the alloy. The TNS cross sections for the main metals in the alloy are generated using the modified NJOY code. To preliminarily validate the TNS data, the calculated scattering cross section, combined with the evaluated absorption cross section of the alloy, is compared with the experimental total cross section, which shows a good agreement. Moreover, an integral neutronics experiment of neutron leakage spectrum is designed to further validate the TNS data. The neutron leakage spectrum is simulated by the Monte Carlo method, which can be compared with the future experimental result. Based on the experiment geometry modeling, the TNS effects of the GH3535 alloy are analyzed at multiple incident neutron energies, sample thicknesses and temperatures, respectively. It is found that the TNS effect of the GH3535 alloy on the neutron leakage spectrum cannot be ignored, and the scattering cross section of the alloy with high precision should be included in designs of MSR.

Dichotomy of the description of the elastic and electronically inelastic scattering of electrons by methane

The interaction between electrons and methane is studied with a particular focus on describing the dynamics of elastic and electronic excitation processes under the influence of the multichannel coupling effects. Elastic and electronically inelastic integral and differential cross sections are reported. These cross sections were calculated with the Schwinger multichannel method implemented with norm-conserving pseudopotentials within the minimal orbital basis for single-configuration interaction approach with up to 181 open channels. While an excellent agreement with previously published data is found in the elastic channel, the comparisons involving electronic excitation cross sections reveal significant discrepancies. Furthermore, the lack of reliable experimental data regarding the electronically inelastic channels hampers a more detailed analysis of the theoretical results. Additionally, total ionization and total cross sections for electron collisions with methane are also presented. By highlighting the current theoretical challenges in dealing with electron-induced electronic excitation of molecules, we seek to contribute to a deeper understanding of this scattering process and, thus, pave the way for future research.

A rotary lead viscoelastic damper with force-resisting capacity: Experimental verification and parametric analysis

The seismic safety of buildings can be improved by installing energy dissipators. A rotary lead viscoelastic damper (RLVD) with force-resisting capacity is proposed in this paper. RLVD consists of laminated rubber, lead rods, a cylindrical pin, and steel plates. The RLVD will rotate around the cylindrical pin when an earthquake shakes the building, resulting in the shaking energy mainly being dissipated by the plastic deformation of lead rods. To justify the reasonability and feasibility of RLVD, a prototype of RLVD was manufactured and tested under cyclic loading. The test results showed that the working mechanism of RLVD is reasonable and effective. The hysteretic curves of RLVD were plump and characterized by a bilinear behavior. A numerical model of RLVD in Abaqus was established and calibrated by the test results. A parametric analysis was conducted to further investigate the effect of the key design parameters of RLVD on its mechanical behavior. The parameter analysis showed that the number and diameter of lead rods have little effect on the mechanical properties of RLVD under the constraint of the same total cross-section area of lead rods. The yielding moment and energy dissipation of RLVD were affected by the distance from the center of the lead rod to the center of the cylindrical pin while the post-yielding stiffness of RLVD was affected by the thickness and shear modulus of the laminated rubber. The concept of the RLVD is justified.

Ionization Cross Sections of Hydrogen Molecule by Electron and Positron Impact.

We present ionization cross sections of hydrogen molecules by electron and positron impact for impact energies between 20 and 1000 eV. A three-body Classical Trajectory Monte Carlo approximation is applied to mimic the collision system. In this approach, the H2 molecule is modeled by a hydrogen-type atom with one active electron bound to a central core of effective charge with an effective binding energy. Although this model is crude for describing a hydrogen molecule, we found that the total cross sections for positron impact agree reasonably well with the experimental data. For the electron impact, our calculated cross sections are in good agreement with the experimental data in impact energies between 80 eV and 400 eV but are smaller at higher impact energies and larger at lower impact energies. Our calculated cross sections are compared with the scaled cross sections obtained experimentally for an atomic hydrogen target. We also present single differential cross sections as a function of the energy and angle of the ejected electron and scattered projectiles for a 250 eV impact. These are shown to agree well with available data. Impact parameter distributions are also compared for several impact energies.

State-to-State Quantum Dynamics Study of Intramolecular Isotope Effects on Be(1S) + HD (v0 = 2, j0 = 0) → BeH/BeD + H/D Reaction.

The dynamic mechanisms and intramolecular isotope effects of the Be(1S) + HD (v0 = 2, j0 = 0) → BeH/BeD + H/D reaction are studied at the state-to-state level using the time-dependent wave packet method on a high-quality potential energy surface. This reaction can proceed along the indirect pathway that features a barrier and a deep well or the smooth direct pathway. The reaction probabilities, total and state-resolved integral cross sections, and differential cross sections are analyzed in detail. The calculated dynamics results show that both of the products are mainly formed by the dissociation of a collinear HBeD intermediate when the collision energy is slightly larger than the threshold. As the collision energy increases, the BeH + D channel is dominated by the direct abstraction process, whereas the BeD + H channel mainly follows the complex-forming mechanism.

Energy dependence of J/ψ production in pp collisions from the PACIAE model

In this work we investigate the J/ψ production in proton-proton collisions at the center-of-mass energy (s) equal to 2.76, 5.02, 7, 8, and 13 TeV with the parton and hadron cascade model PACIAE 2.2a. It is based on PYTHIA but extended considering the partonic and hadronic rescatterings before and after hadronization, respectively. In the PYTHIA sector the J/ψ production quantum chromodynamics processes are selected specially and a bias factor is proposed correspondingly. The calculated total cross sections, the transverse momentum differential, and the rapidity differential cross sections of J/ψ in the forward rapidity region reproduce the corresponding experimental measurements reasonably well. In the mid-rapidity region, the double-differential cross sections at s=5.02, 7, and 13 TeV are also in a good agreement with the experimental data. Moreover, we interpolate the double-differential cross section as well as the total cross section of J/ψ in the mid-rapidity region at s=8 TeV, which could be validated if the experimental data are available. Published by the American Physical Society 2024

Electron impact partial ionization cross sections: R-carvone, 2-butanol, imidazole, and 2-nitroimidazole.

We calculate electron impact partial and total ionization cross sections of R-carvone (C10H14O), 2-butanol (C4H10O), imidazole (C3H4N2), and 2-nitroimidazole (C3H3N3O2). We have used the Binary Encounter Bethe (BEB) model to obtain total electron impact ionization cross sections (TICSs). The modified BEB method in combination with mass spectrum data of the molecules is used to calculate the partial ionization cross section (PICS) of the cationic fragments dissociating from the parent molecule. Our PICS data for R-carvone and 2-butanol are in good agreement with the experimental data for all the cation fragments along with the TICS data. For imidazole and 2-nitroimidazole, the estimates of the PICS are reported for the first time in the present study. We have found that both the modified BEB method and the mass spectrum dependence method work effectively to estimate PICS if we have information about the appearance energies and relative abundance data of the target under investigation.