Total Differential Cross Sections Research Articles

Next-to-next-to-leading-order QCD corrections to double J/ψ production at the B factories

In this paper, we study the next-to-next-to-leading-order (NNLO) QCD corrections for the process e+e− → J/ψ + J/ψ at the B factories. By including the NNLO corrections, the cross section turns negative due to the poor convergence of perturbative expansion. Consequently, to obtain a reasonable estimation for the cross section, the square of the amplitude up to NNLO is used. In addition, the contributions from the bottom quark and the light-by-light part, which are usually neglected, are also included. The final cross section is obtained as 1.76−1.66+2.42\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {1.76}_{-1.66}^{+2.42} $$\\end{document} fb at a center-of-mass energy of s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 10.58 GeV. Our result for total cross section and differential cross section could be compared with precise experimental measurement in future at the B factories.

Unveiling Quantum Interference in the D+ + H2 Nonadiabatic Reaction Dynamics at Low Collision Energies.

Fully converged nonadiabatic dynamics calculations of the D+ + H2 → H+ + HD reaction are performed at low temperatures using the time-dependent wave packet approach based on a set of precise 3 × 3 diabatic potential energy surfaces (PESs) ( Phys. Chem. Chem. Phys., 2021, 23, 7735-7747, DOI: 10.1039/D0CP04100A). The D+ + H2 reaction is mediated by a dense manifold of resonances associated with the deep potential well on the ground-state PES. The calculated results show that the nonadiabatic coupling can affect the resonance positions, deviating from the expectation based solely on adiabatic considerations. Furthermore, significant forward-backward asymmetry in total differential cross sections (DCSs) is revealed, which is markedly influenced by nonadiabatic effects. The nonadiabatic effects not only affect the contribution of partial waves in the reaction but also make the interference patterns in the DCSs change significantly.

Scattering and conversion of electromagnetic and gravitational waves by Reissner-Nordström black holes: The Regge pole description

We investigate the problem of scattering and conversion of monochromatic planar gravitational and electromagnetic waves impinging upon a Reissner-Nordstr\"om black hole using a Regge pole description, i.e., a complex angular momentum approach. For this purpose, we first compute numerically the Regge pole spectrum for various charge-to-mass ratio configurations. We then derive an asymptotic expressions for the lowest Regge poles, and by considering Bohr-Sommerfeld-type quantization conditions, obtain the spectrum of weakly damped quasinormal frequencies from the Regge trajectories. Next, we construct the scattering and conversion amplitudes as well as the total differential cross sections for different processes using both a complex angular momentum representation and a partial wave expansion method. Finally, we provide an analytical approximation of the scattering and conversion cross sections of different processes from asymptotic expressions for the lowest Regge poles and the associated residues based on the correspondence Regge poles, ``surface waves'' propagating close to the photon (graviton) sphere. This allows us to extract the physical interpretation encoded in the partial wave expansions in the high-frequency regime (i.e., in the short-wavelength regime), and to describe semiclassically with very good agreement both black hole glory and a large part of the orbiting oscillations, thus unifying these two phenomena from a purely wave point of view.

New determination of the production cross section for γ rays in the Galaxy

The flux of $\gamma$ rays is measured with unprecedented accuracy by the $\textit{Fermi}$ Large Area Telescope from 100 MeV to almost 1 TeV. In the future, the Cherenkov Telescope Array will have the capability to measure photons up to 100 TeV. To accurately interpret this data, precise predictions of the production processes, specifically the cross section for the production of photons from the interaction of cosmic-ray protons and helium with atoms of the ISM, are necessary. In this study, we determine new analytical functions describing the Lorentz-invariant cross section for $\gamma$-ray production in hadronic collisions. We utilize the limited total cross section data for $\pi^0$ production channels and supplement this information by drawing on our previous analyses of charged pion production to infer missing details. In this context, we highlight the need for new data on $\pi^0$ production. Our predictions include the cross sections for all production channels that contribute down to the 0.5% level of the final cross section, namely $\eta$, $K^+$, $K^-$, $K^0_S$, and $K^0_L$ mesons as well as $\Lambda$, $\Sigma$, and $\Xi$ baryons. We determine the total differential cross section $d\sigma(p+p\rightarrow \gamma+X)/dE_{\gamma}$ from 10 MeV to 100 TeV with an uncertainty of 10% below 10 GeV of $\gamma$-ray energies, increasing to 20% at the TeV energies. We provide numerical tables and a script for the community to access our energy-differential cross sections, which are provided for incident proton (nuclei) energies from 0.1 to $10^7$ GeV (GeV/n).

Effect of nucleon effective mass and symmetry energy on the neutrino mean free path in a neutron star

The Korea-IBS-Daegu-SKKU energy density functional (KIDS-EDF) models, constructed from the perturbative expansion of the energy density in nuclear matter, have been successfully and widely applied in describing the properties of finite nuclei and infinite nuclear matter. In the present work, we extend the applications of the KIDS-EDF models to investigate the implications of the nucleon effective mass and nuclear symmetry energy for the properties of neutron stars (NSs) and neutrino interaction with the NS constituent matter in the linear response approximation (LRA). At fixed neutrino energy and momentum transfer, we analyze the total differential cross section of neutrinos, the neutrino mean free path (NMFP), and the NS mass-radius (M-R) relations. Remarkable results are given by the KIDS0-m*87 and SLy4 models, in which ${M}_{n}^{*}/M\ensuremath{\lesssim}1$, and their NMFPs are quite higher in comparison with those obtained from the KIDS0, KIDS-A, and KIDS-B models, which result in ${M}_{n}^{*}/M\ensuremath{\gtrsim}1$. For the KIDS0, KIDS-A, and KIDS-B models, we obtain $\ensuremath{\lambda}\ensuremath{\lesssim}{R}_{\text{NS}}$, indicating that these models could predict the slow NS cooling and neutrino trapping in NSs. In contrast, the KIDS0-m*87 and SLy4 models yield $\ensuremath{\lambda}\ensuremath{\gtrsim}{R}_{\text{NS}}$ and thus we expect faster NS cooling and a small possibility of neutrino trapping within NSs. We also calculate the NMFP as a function of the neutrino energy and the nuclear matter density and find that the NMFP decreases as the density and neutrino energy increase, which is consistent with the result obtained in the Brussels-Montreal Skyrme (BSk17 and BSk18) models at saturation density.

Collisions of proton or highly charged ion–atom in a strong magnetic field and dense quantum plasmas

Magneto inertial fusion driven by heavy ions beam (HIB) is a very attractive potential approach for the nuclear energy system. One of the key issues is to investigate the interaction process of the HIB-target considering the condition of plasma screening and strong magnetic field background. In this paper, the influence of the external magnetic field and the plasma screening was investigated by simplifying the process of beam bombarding into a two-body collision between the energetic ions and target atoms. The classical-trajectory Monte Carlo method was accommodated by modifying the Hamiltonian in the collision system, where the effects of plasma screening and the account for the strong magnetic field background were considered. The total cross sections of single electron ionization and charge transfer of the projectile (H+, He2+, Xe32+, Bi31+, U34+)–atom (H, He) collisions are computed. The results indicated that the magnetic field effect becomes more obvious in the low energy regime of the projectiles. With the increase in energy, the change of total cross sections and angular differential cross sections gradually disappears. In the dense quantum plasmas, plasma screening presents very different effects for protons and heavy ion projectiles. This work may pave the way for extending the study to other collision systems calculations.

Resonant tunneling of deuteron-triton fusion in strong high-frequency electromagnetic fields

We investigate deuteron-triton (DT) fusion in the presence of linearly polarized strong electromagnetic fields in high-frequency limit, in which a complex spherical square-well potential is exploited to describe the nuclear potential. Within the framework of the Kramers-Henneberger (KH) transformation, we have calculated the total and angular differential fusion cross sections by investigating the asymptotical phase shifts of the Coulomb wavefunctions. With introducing a dimensionless quantity of $n_d$ representing the ratio of the particle quiver oscillation amplitude to the radius of nuclear potential, we find that, even though the tunneling probability of passing through the Coulomb repulsive potential keeps almost identical to that in the absence of electromagnetic fields, the peak of total fusion sections shows an apparent shift from the well known value of 110 keV to 78 keV for $n_d=0.01$. The angular differential cross sections also show some resonance peaks that shift from zero inclination angle to $\pi/2$ with increasing the parameter $n_d$. The corresponding astrophysical $S$-factors are found to be enhanced by several times in amplitudes. With the help of Wentzel-Kramers-Brillouin (WKB) approximate wavefunctions, the shape-resonance tunneling mechanism of the above findings are uncovered and some implications are discussed.

New determination of the production cross section for secondary positrons and electrons in the Galaxy

The cosmic-ray fluxes of electrons and positrons ($e^{\pm}$) are measured with high precision by the space-borne particle spectrometer AMS-02. To infer a precise interpretation of the production processes for $e^{\pm}$ in our Galaxy, it is necessary to have an accurate description of the secondary component, produced by the interaction of cosmic-ray proton and helium with the interstellar medium atoms. We determine new analytical functions of the Lorentz invariant cross section for the production of $\pi^\pm$ and $K^\pm$ by fitting data from collider experiments. We also evaluate the invariant cross sections for several other channels, involving for example hyperon decays, contributing at the few \% level on the total cross section. For all these particles, the relevant 2 and 3 body decay channels are implemented, with the polarized $\mu^\pm$ decay computed with next-to-leading order corrections. The cross section for scattering of nuclei heavier than protons is modeled by fitting data on $p+C$ collisions. The total differential cross section $d\sigma/dT_{e^\pm}(p+p\rightarrow e^\pm+X)$ is predicted from 10 MeV up to 10 TeV of $e^\pm$ energy with an uncertainty of about 5-7\% in the energies relevant for AMS-02 positron flux, thus dramatically reducing the precision of the theoretical model with respect to the state of the art. Finally, we provide a prediction for the secondary Galactic $e^\pm$ source spectrum with an uncertainty of the same level. As a service for the scientific community, we provide numerical tables and a script to calculate energy-differential cross sections.

Electron ionisation cross sections of CF3Cl and CF2Cl2 molecules

In this paper, we have investigated partial and total integral ionisation cross-sections of CF3Cl and CF2Cl2 molecules by a modified Jain-Khare semi-empirical approach during the direct and dissociative ionisation by electron impact. Present results show good agreement with the available data. Besides integral ionisation cross-sections, for the first time, we evaluated partial and total single differential cross sections for these molecules. No other results are available for single differential cross sections to compare the present calculated results.

Measurement of the relative Bc±/B± production cross section with the ATLAS detector at s=8 TeV

The total cross section and differential cross sections for the production of $B_{c}^{\pm}$ mesons, times their branching fraction to $J/\psi \pi^{\pm}$, are measured relative to those for the production of $B^{\pm}$ mesons, times their branching fraction to $J/\psi K^{\pm}$. The data used for this study correspond to an integrated luminosity of $20.3\,\mathrm{fb}^{-1}$ of $pp$ collisions recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a center-of-mass energy of $\sqrt{s} = 8$ TeV. The measurement is performed differentially in bins of transverse momentum $p_{\mathrm{T}}$ for $13$ GeV $<p_{\mathrm{T}}(B_{c}^{\pm})<22$ GeV and $p_{\mathrm{T}}(B_{c}^{\pm}) > 22$ GeV and in bins of rapidity $y$ for $|y| <0.75$ and $0.75<|y|<2.3$. The relative cross section times branching fraction for the full range $p_{\mathrm T} > 13$ GeV and $|y| < 2.3$ is $(0.34\,\pm\,0.04_{\text{stat}}\,^{+0.06}_{-0.02}\,_{\text{sys}}\,\pm\,0.01_{\text{lifetime}})\%$. The differential measurements suggest that the production cross section of the $B^{\pm}_c$ decreases faster with $p_{\mathrm T}$ than the production cross section of the $B^{\pm}$, while no significant dependence on rapidity is observed.

A quantum mechanical study of the astrophysically important reaction Li + HD+ (v = 0,1, j = 0): the effect of reagent vibrational and translational excitation on the angular distributions of LiH and LiD

Accurate quantum reactive calculations for the reaction Li + HD (, ) have been performed on the potential energy surface of Martinazzo et al. [J. Chem. Phys. 119 (21), 11241 (2003)] with the time-dependent wave packet coupled-channel approach. The reaction probabilities reveal that the Coriolis coupling effect is significant to the title reaction particularly for the larger mass product LiD. The total differential cross-sections for LiH and LiD indicate that vibrational and translational excitation of HD stimulate products scatter in the forward regions. For the reaction, the products LiH and LiD in low vibrational states show pronounced sideways scattering, while products in higher vibrational states scatter preferentially towards forward/backward regions. For the reaction, the scattering in the forward regions is more intense than in the backward regions for both products in each vibrational state. An analysis of the total and state-resolved opacity functions reveal that the reactivity of the title reaction is promoted by high collisions, and that the angular distributions of the products correlate strongly with low and high J values.

Electron impact ionization cross sections of C2H4 molecule

In this paper, we have investigated partial and total integral ionization cross sections of C2H4 molecule by Jain-Khare semiempirical approach during the electron impact. They show good agreement with available data. Besides integral ionization cross sections, the first time we have evaluated its partial and total single and double differential cross sections. No other results are available for single differential cross sections and double differential cross sections to compare the present results calculated.

State-resolved quantum mechanical study of the intramolecular isotope effect in the C+ + HD reaction

Accurate quantum scattering dynamics calculations for the C+ + HD reactions on the ground 12A′ potential energy surface have been performed in the collision energy range of 0.05–1.0 eV. The present integral cross sections and branching ratios are compared with previous experimental and theoretical results. Both the CH+ and CD+ products are distributed in vibrational cold but rotational hot states. Total differential cross sections for both channels exhibit forward–backward symmetry. The state - resolved differential cross sections and the opacity functions show that the product rotational quantum numbers correlate strongly with the total angular momentum J.

Quantum state-to-state dynamics of O+ + H2(ν = 0, j = 0) → OH+ (ν′, j′) + H reaction on a global potential energy surface

The state-to-state quantum dynamics calculation for the reaction is implemented based on a global potential energy surface. The reaction probabilities, state-resolved integral and differential cross sections are obtained and discussed. Due to the existence of the potential well, the reaction probabilities exhibit obvious oscillating features. And as a typical system of heavy-light-light mass combination, this reaction is more conducive to the occurrence of the product rotational excitation. So when the products are mainly concentrated in and states, the distribution of the product rotational, rather than vibrational, state-resolved integral cross section shows an inversion phenomenon. Furthermore, because of the quantum interference of the rovibrational wave functions, the rotational resolution integral cross section of the product displays a multipeak structure, and this phenomenon becomes less obvious as the collision energy increases. Meanwhile, the total differential cross sections are found to be peaked both forwardly and backwardly, which indicates that there exists a complex-forming mechanism in the reaction. With the increase of collision energy, the feature of differential cross section is from the forward-backward scattering to the forward scattering.

Quantum state-to-state study for (H-(D-),HD) collisions on two potential energy surfaces.

Quantum time-dependent wave-packet calculations have been carried out to explore the state-to-state dynamics of the ion-molecule (H-(D-),HD) collisions on two accurate ab initio potential energy surfaces in the collision energy range 0.2-1.2 eV. Total and final state-resolved integral and differential cross sections are elaborated in detail. The differential cross sections vary substantially with the collision energy, turning from predominantly backward-scattering at low collision energies to forward and sideways scattering bias at relatively high collision energies. The rebound, stripping and time-delayed mechanisms are found to be possible in (H-(D-),HD) collisions. A set of quasi-classical trajectory calculations were performed, and the results indicate that the backward-scattering peak is caused by the low impact parameter trajectories, while the trajectories of high impact parameter are responsible for the forward scattering. A set of representative state-to-state differential cross sections at collision energies 0.6 and 1.2 eV are also presented. Different reaction mechanisms are dominant in (H-(D-),HD) collisions at different collision energies, resulting in different product rovibrational state distributions. The differences between the dynamics results based on the two potential energy surfaces are also discussed.

Low-energy electron scattering from molecular hydrogen: Excitation of the X1Σg+ to b3Σu+ transition

We present time-of-flight differential cross-section measurements and convergent close-coupling calculations of differential cross sections for the electron-impact excitation of the $X\phantom{\rule{0.16em}{0ex}}^{1}{\mathrm{\ensuremath{\Sigma}}}_{g}^{+}\ensuremath{\rightarrow}b\phantom{\rule{0.16em}{0ex}}^{3}{\mathrm{\ensuremath{\Sigma}}}_{u}^{+}$ transition in molecular hydrogen. A part of this work was recently published [M. Zawadzki et al., Phys. Rev. A 97, 050702(R) (2018)]. In this work, agreement between theory and experiment is excellent overall, and marks a transition in electron-molecule scattering where differential scattering of excitation is found to be in such precise agreement. We also present total electron-impact excitation differential cross sections for ${\mathrm{H}}_{2}$ for which agreement between theory and experiment is found to be excellent.

Ab initio potential energy surface and quantum scattering studies of $$\hbox {Li}^{+}$$ Li + with $$\hbox {N}_{2}$$ N 2 : comparison with experiments at $$E_{\mathrm{c.m.}}= 2.47\,\hbox {eV}$$ E c . m . = 2.47 eV and 3.64 eV

A new ground electronic state potential energy surface of $$\hbox {Li}^{+}+\hbox {N}_{2}$$ system is presented in the Jacobi scattering coordinates at MRCI level of accuracy employing the augmented correlation-consistent polarized valence quadrupole zeta (aug-cc-pVQZ) basis set. An analytic fit of the computed ab initio surface has also been obtained. The surface has a global minimum for the collinear geometry at the internuclear distance of $$\hbox {N}_{2}, r = 2.078a_{0}$$ , and the distance between $$\hbox {Li}^{+}$$ and $$\hbox {N}_{{2}}$$ , $$R = 4.96a_{0}$$ . Quantum dynamics studies have been performed within the vibrational close coupling-rotational infinite-order sudden approximation at $$E_{\mathrm{c.m.}} = 3.64$$ eV, and the collision attributes have been analyzed. The computed total differential cross-sections are found in quantitative agreement with those available from the experiments at $$E_{\mathrm{c.m.}}= 3.64\,\hbox {eV}$$ . The other dynamic attributes such as angle dependent opacities and integral cross-sections are also reported. Preliminary rigid-rotor and vibrational–rotational coupled-state calculations at $$E_{\mathrm{c.m.}} = 2.47\,\hbox {eV}$$ also support the experimental observation that the system exhibits a large number of rotational excitations in the vibrational manifold $$v = 0$$ . SYNOPSIS Quantum scattering dynamics studies for vibrational-rotational excitations of N2 upon collisions of Li+ have been carried out on a newly computed ground electronic state potential energy surface and the computed collision attributes are compared with those available from the experiments at collision energies, $$E_{\mathrm{c.m.}} = 2.47$$ eV and 3.64 eV

State-to-state quantum dynamics of F(2P)+HO(2Π)→O(3P)+HF(1Σ+) reaction on 13A′ and 23A′′ surfaces

ABSTRACTThe state-to-state dynamics of reaction F + HO() is studied on the potential energy surfaces (PESs) of the and states. The time-dependent wave packet method, which is carried out on the graphics processing units, is used for this accurate calculation. The emphasis is on the exploration of different dynamical behaviours happening on the PESs of two excited states. The obvious vibrational and rotational inversion is found in the state-resolved integral cross section on PES, but the rotational inversion does not appear on PES. Both the total and state-resolved differential cross sections (DCSs) of the reaction on two PESs exhibit the behaviour of sideward and backward scattering, but the backward scattering of is much stronger because of its higher energy barrier, and the sideward scattering is enhanced with the increasing of collision energy. In addition, a multi-peak structure is discovered in the distribution of the product rotational state-resolved integral and DCSs, which is attributed to the quantum interference of the resonance wave functions.

Lorentz violation, gravitoelectromagnetism and Bhabha scattering at finite temperature

Gravitoelectromagnetism (GEM) is an approach for the gravitation field that is described using the formulation and terminology similar to that of electromagnetism. The Lorentz violation is considered in the formulation of GEM that is covariant in its form. In practice, such a small violation of the Lorentz symmetry may be expected in a unified theory at very high energy. In this paper, a non-minimal coupling term, which exhibits Lorentz violation, is added as a new term in the covariant form. The differential cross-section for Bhabha scattering in the GEM framework at finite temperature is calculated that includes Lorentz violation. The Thermo Field Dynamics (TFD) formalism is used to calculate the total differential cross-section at finite temperature. The contribution due to Lorentz violation is isolated from the total cross-section. It is found to be small in magnitude.

Nonlinear effects in the laser-assisted scattering of a positron by a muon

The scattering of a positron by a muon in the presence of a linearly polarized laser field is investigated in the first Born approximation. The theoretical results reveal: (1) At large scattering angle, an amount of multiphoton processes take place in the course of scattering. The photon emission processes predominate the photon absorption ones. (2) Some nonlinear phenomena about oscillations, dark angular windows, and asymmetry can be observed in angular distributions. We analyze the cause giving rise to dark windows and geometric asymmetry initially noted in the potential scattering. (3) We also analyze the total differential cross-section, the result shows that the larger the incident energy is, the smaller the total differential cross-section is. The reasons of these new results are analyzed.