Predictions For Cross Sections Research Articles

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 .

Quark mass effects in Higgs production

We examine the effect of finite top- and bottom-quark masses on the Higgs production cross section in the gluon-gluon fusion channel. We employ both MS¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\overline{\ extrm{MS}} $$\\end{document} and on-shell renormalisation for the quark masses and provide a thorough comparison. Furthermore, we explore alternative treatments of quark masses, in particular in the four-flavour scheme, and investigate their impact on the cross section. Our work also presents novel predictions for differential cross sections in the Higgs rapidity. The results lead to a significant reduction of scale uncertainties, and our analysis enables us to offer well-grounded recommendations for future research in this area.

The theoretical study of pp¯→Λ¯Ση\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p\\bar{p}\\rightarrow \\bar{\\Lambda }\\Sigma \\eta $$\\end{document} reaction

We study the production of hyperon resonances in the pp¯→Λ¯Ση\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p\\bar{p}\\rightarrow \\bar{\\Lambda }\\Sigma \\eta $$\\end{document} reaction within an effective Lagrangian approach. The model includes the production of Σ(1750)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Sigma (1750)$$\\end{document} and Λ(1670)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda (1670)$$\\end{document} in the intermediate state excited by the K and K∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^*$$\\end{document} meson exchanges between the initial proton and antiproton. Due to the large coupling of Σ(1750)Ση\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Sigma (1750)\\Sigma \\eta $$\\end{document} vertex, Σ(1750)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Sigma (1750)$$\\end{document} is found a significant contribution near the threshold in this reaction. We provide total and differential cross section predictions for the reaction and discuss the possible influence of Σ(1750)Ση\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Sigma (1750)\\Sigma \\eta $$\\end{document} vertex coupling and model parameters, which will be useful in future experimental studies. This reaction can provide a platform for studying the features of Σ(1750)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Sigma (1750)$$\\end{document} resonance, especially the coupling to Ση\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Sigma \\eta $$\\end{document} channel.

In-medium changes of nucleon cross sections tested in neutrino-induced reactions

Historically, studied in the context of heavy-ion collisions, the extent to which free nucleon-nucleon cross sections are modified in-medium remains undetermined by these data sets. Therefore, we investigate the impact of NN in-medium modifications on neutrino-nucleus cross section predictions using the GiBUU transport model. We find that including an in-medium lowering of the NN cross section and density dependence on Δ excitation improves agreement with MicroBooNE neutrino-argon scattering data. This is observed for both proton and neutral pion spectra in charged-current muon neutrino and neutral-current single pion production data sets. The impact of collision broadening of the Δ resonance is also investigated. The absence of Δ broadening is slightly favored, but the larger uncertainties on the pion production data prevent definitive conclusions. Published by the American Physical Society 2024

DeepCSNet: a deep learning method for predicting electron-impact doubly differential ionization cross sections

Abstract Electron-impact ionization cross sections of atoms and molecules are essential for plasma modelling. However, experimentally determining the absolute cross sections is not easy, and ab initio calculations become computationally prohibitive as molecular complexity increases. Existing AI-based prediction methods suffer from limited data availability and poor generalization. To address these issues, we propose DeepCSNet, a deep learning approach designed to predict electron-impact ionization cross sections using limited training data. We present two configurations of DeepCSNet: one tailored for specific molecules and another for various molecules. Both configurations can typically achieve a relative L2 error less than 5%. The present numerical results, focusing on electron-impact doubly differential ionization cross sections, demonstrate DeepCSNet's generalization ability, predicting cross sections across a wide range of energies and incident angles. Additionally, DeepCSNet shows promising results in predicting cross sections for molecules not included in the training set, even large molecules with more than 10 constituent atoms, highlighting its potential for practical applications.

Theoretical study of the π+p→pa0+ϕ reaction

We study the production of hyperon resonances in the π+p→pa0+ϕ reaction within an effective Lagrangian approach. The model includes the production of Δ(1940) and Δ(1920) in the intermediate state excited by the ρ and p exchanges between the initial proton and π meson. Because of the large contribution of ρ exchange in Δ(1940) production, Δ(1940) is found to be a significant contribution near the threshold in this reaction. We provide total and differential cross section predictions for the reaction and discuss the possible influence of model parameters, off-shell effects, and branching ratios for Δ(1940)→pa0 and Δ(1920)→pa0 decays, which will be useful in future experimental studies. This reaction can provide a platform for studying the features of Δ(1940) resonance, especially the coupling to the pa0 channel. Published by the American Physical Society 2024

The strong coupling constant: state of the art and the decade ahead

Abstract Theoretical predictions for particle production cross sections and decays at colliders rely heavily on perturbative Quantum Chromodynamics (QCD) calculations, expressed as an expansion in powers of the strong coupling constant α S . The current O ( 1 % ) uncertainty of the QCD coupling evaluated at the reference Z boson mass, α S ( m Z 2 ) = 0.1179 ± 0.0009 , is one of the limiting factors to more precisely describe multiple processes at current and future colliders. A reduction of this uncertainty is thus a prerequisite to perform precision tests of the Standard Model as well as searches for new physics. This report provides a comprehensive summary of the state-of-the-art, challenges, and prospects in the experimental and theoretical study of the strong coupling. The current α S ( m Z 2 ) world average is derived from a combination of seven categories of observables: (i) lattice QCD, (ii) hadronic τ decays, (iii) deep-inelastic scattering and parton distribution functions fits, (iv) electroweak boson decays, hadronic final-states in (v) e+e−, (vi) e–p, and (vii) p–p collisions, and (viii) quarkonia decays and masses. We review the current status of each of these seven α S ( m Z 2 ) extraction methods, discuss novel α S determinations, and examine the averaging method used to obtain the world-average value. Each of the methods discussed provides a ‘wish list’ of experimental and theoretical developments required in order to achieve the goal of a per-mille precision on α S ( m Z 2 ) within the next decade.

Laboratory Benchmark of n ≥ 4 Dielectronic Recombination Satellites of Fe xvii

We calculated cross sections for the dielectronic recombination (DR) satellite lines of Fe xvii and benchmarked our predictions with experimental cross sections of Fe xvii resonances that were monoenergetically excited in an electron-beam ion trap. We extend the benchmark to all resolved DR and direct electron-impact excitation (DE) channels in the experimental data set, specifically the n ≥ 4 DR resonances of Fe xvii, complementing earlier investigations of n = 3 channels. Our predictions for the DR and DE absolute cross sections for the higher n complexes disagree considerably with experimental results when using the same methods as in previous works. However, we achieve agreement within ∼10% of the experimental results by an approach whereby we doubly convolve the predicted cross sections with both the spread of the electron-beam energy and the photon energy resolution of our experiment. We then calculated rate coefficients from the experimental and theoretical cross sections, finding general agreement within 2σ with the rates found in the OPEN-ADAS atomic database.

Production of hidden-heavy and double-heavy hadronic molecules at the Z factory of CEPC

With a clean environment and high collision energy, the Circular Electron Positron Collider (CEPC) would be an excellent facility for heavy flavor physics. Using the Monte Carlo event generator ythia, we simulate the production of the charmed (bottom) hadron pairs in the electron-positron collisions at the Z factory of CEPC, and the inclusive production rates for typical candidates of the hidden/double-charm and hidden/double-bottom S-wave hadronic molecules are estimated at an order-of-magnitude level with the final state interactions after the hadron pair production. The predicted cross sections for the hidden-charm meson-meson molecules X(3872) and Zc(3900) are at pb level, which are about two to three orders of magnitude larger than the production cross sections for the double-charm meson-meson molecules Tcc and Tcc*, as the double-charmed ones require the production of two pairs of cc¯ from the Z boson decay. The production cross sections for the hidden-charm pentaquark states Pc and Pcs as meson-baryon molecules are a few to tens of fb, which are about one magnitude larger than those of the possible hidden-charm baryon-antibaryon and double-charm meson-baryon molecules. In the bottom sector, the production cross sections for the Zb states as B(*)B¯* molecules are about tens to hundreds of fb, indicating 106–107 events from a two-year operation of CEPC, and the expected events from the double-bottom molecules are about 2–5 orders of magnitude smaller than the Zb states. Our results shows great prospects of probing heavy exotic hadrons at CEPC. Published by the American Physical Society 2024

Neutrino rate predictions for FASER

The Forward Search Experiment (FASER) at CERN’s Large Hadron Collider (LHC) has recently directly detected the first collider neutrinos. Neutrinos play an important role in all FASER analyses, either as signal or background, and it is therefore essential to understand the neutrino event rates. In this study, we update previous simulations and present prescriptions for theoretical predictions of neutrino fluxes and cross sections, together with their associated uncertainties. With these results, we discuss the potential for possible measurements that could be carried out in the coming years with the FASER neutrino data to be collected in LHC Run 3 and Run 4. Published by the American Physical Society 2024

Distinguishing Isomeric Cyclobutane Thymidine Dimers by Ion Mobility and Tandem Mass Spectrometry.

Irradiation of the major conformation of duplex DNA found in cells (B form) produces cyclobutane pyrimidine dimers (CPDs) from adjacent pyrimidines in a head-to-head orientation (syn) with the C5 substituents in a cis stereochemistry. These CPDs have crucial implications in skin cancer. Irradiation of G-quadruplexes and other non-B DNA conformations in vitro produces, however, CPDs between nonadjacent pyrimidines in nearby loops with syn and head-to-tail orientations (anti) with both cis and trans stereochemistry to yield a mixture of six possible isomers of the T=T dimer. This outcome is further complicated by formation of mixtures of nonadjacent CPDs of C=T, T=C, and C=C, and successful analysis depends on development of specific and sensitive methods. Toward meeting this need, we investigated whether ion mobility mass spectrometry (IMMS) and MS/MS can distinguish the cis,syn and trans,anti T=T CPDs. Ion mobility can afford baseline separation and give relative mobilities that are in accord with predicted cross sections. Complementing this ability to distinguish isomers is MS/MS collisional activation where fragmentation also distinguishes the two isomers and confirms conclusions drawn from ion mobility analysis. The observations offer early support that ion mobility and MS/MS can enable the distinction of DNA photoproduct isomers.

Merits of atomic cascade computations

Atomic cascades refer—first and foremost—to the stepwise de-excitation of excited atoms owing to the emission of electrons or photons. Apart from dedicated experiments at storage rings and synchrotrons, such cascades frequently occur in astro and plasma physics, material research, surface science and at various places elsewhere. In addition, moreover, “atomic cascades” have been found a useful concept for modeling atomic behavior under different conditions, for instance, when dealing with the photoabsorption of matter, the generation of synthesized spectra, or for determining a rather wide class of (plasma) rate coefficients. We here compile and discuss several atomic cascades (schemes) that help predict cross sections, rate coefficients, electron and photon spectra, or ion distributions. We also demonstrate how readily these schemes have been implemented within JAC, the Jena Atomic Calculator. Emphasis is placed on the classification of atomic cascades and their (quite) natural breakdown into cascade computations, to deal with the electronic structure and transition amplitudes of atoms and ions, as well as the cascade simulation of those properties and spectra, that are experimentally accessible. As an example, we show and discuss the computation of dielectronic recombination plasma rate coefficients for beryllium-like gold ions. The concept of atomic cascades and its implementation into JAC can be applied for most ions across the periodic table and will facilitate the modeling and interpretation of many forthcoming observations.Graphical abstract

NLO QCD corrections to the Bc -pair hadroproduction

The Bc meson pair, including pairs of pseudoscalar states and vector states, productions in proton-proton collisions are investigated at the next-to-leading order (NLO) accuracy in the nonrelativistic quantum chromodynamics factorization formalism. The corresponding cross sections at the Large Hadron Collider (LHC) with s=14 TeV are evaluated. Numerical results indicate that the NLO corrections are substantial, and even dominate over the leading order contributions. Considering the predicted cross sections are sizable, the Bc-pair production is expected to be observable at the high-luminosity LHC experiment. Published by the American Physical Society 2024

Investigation of the cross sections for electron collision ionization of complex molecules

AbstractAn accurate and computationally efficient determination of the cross sections for electron collision ionization of molecules has various applications, such as plasma physics and atmospheric science. In the case of large molecules, ab initio calculations are often difficult and time‐consuming. Here, we develop a feed forward neural network to predict the electron impact ionization cross sections of complex molecules. The training (predicting) set in the method consists of a series of theoretical ionization cross sections for small (large) molecules obtained from the combined model, which integrates the Binary‐Encounter‐Bethe and Deutsch‐Märk models. Several complex systems or targets involving electron collision ionization are evaluated, including molecules such as CH, CH, CH, CH, C, CHO, and CHO. The root mean square errors of the trained and predicted cross sections by the neural network (compared to the values from the combined model) are found to be approximately .0086 and .0930 (in 10 cm), respectively, (using the CHO molecule as an example), indicating our results are very high accuracy. The excellent agreement between the predicted values and the actual values indicates that the neural network is a practical and powerful tool for determining the electron collision ionization cross sections of complex molecules and can provide valuable insights into the dynamics process. Apart from its fundamental importance, this study has far‐reaching implications for gas discharge, low‐temperature plasmas, and fusion edge plasmas and so forth.

Associated production of heavy quarkonia and D mesons in the improved color evaporation model with KaTie

In this article, we study associated production of prompt J/ψ(ϒ) and D mesons in the improved color evaporation model using the high-energy factorization approach as it is realized in the Monte Carlo event generator KaTie. The modified Kimber-Martin-Ryskin-Watt model for unintegrated parton distribution functions is used. We predict cross sections for associated J/ψ(ϒ) and D meson hadroproduction via the single and double parton scattering mechanisms using the set of model parameters which has been fixed early for description of prompt single and pair heavy quarkonium production at the LHC energies. We found the results of calculations agree with the LHCb Collaboration data at the energies s=7, 8 TeV and we present theoretical predictions for the energy s=13 TeV. Published by the American Physical Society 2024

ρ -meson spectroscopy and diffractive production using the holographic light-front Schrödinger equation and the ’t Hooft equation

We determine the mass spectroscopy and light-front wave functions (LFWFs) of the ρ-meson by solving the holographic Schrödinger equation of light-front chiral QCD along with the ’t Hooft equation of (1+1)-dimensional QCD in the large Nc limit. Subsequently, we utilize the obtained LFWFs in conjunction with the color glass condensate dipole cross section to calculate the cross sections for the diffractive ρ-meson electroproduction. Our spectroscopic results align well with the experimental data. Predictions for the diffractive cross sections demonstrate good consistency with the available experimental data at different energies from H1 and ZEUS collaborations. Additionally, we show that the resulting LFWFs for the ρ-meson can effectively describe various properties, including its decay constant, distribution amplitudes, electromagnetic form factors, charge radius, magnetic and quadrupole moments. Comparative analyses are conducted with experimental measurements and the available theoretical predictions. Published by the American Physical Society 2024

Assessing the impact of nuclear mass models on the prediction of synthesis cross sections for superheavy elements

Assessing the impact of nuclear mass models on the prediction of synthesis cross sections for superheavy elements

Short-range correlations in dynamical intranuclear cascade models for describing nucleon knockout reactions

Spallation and fragmentation reactions at incident energies above the Fermi momentum are considered to be the main mechanism for the production of neutron-rich nuclei at worldwide nuclear physics facilities, such as RIBF, FRIB, and GSI-FAIR. Although it is widely known that dynamical reaction models give a rather good prediction of cross sections for nuclear residues produced in spallation and fragmentation reactions, these reaction models fail in the description of peripheral collisions involving short-range nucleon-nucleon correlations (SRCs). Here, we present state-of-the-art dynamical reaction calculations based on the intranuclear cascade approach to describe spallation and fragmentation reactions. The new version of our dynamical model, including SRCs, successfully describes isotopic cross sections of neutron-rich nuclear residues and inclusive single-neutron and single-proton knockout cross sections for various stable and exotic nuclei. Finally, the results show that the systematic strong dependency of the single-knockout cross section reduction factor on the neutron-proton separation energy asymmetry parameter (ΔS) obtained by Tostevin and Gade disappears when SRCs are taken into account.

One-loop electroweak radiative corrections to polarized e+e−→ZZ process

In the paper we recalculate and discuss high-precision theoretical predictions for cross sections of the process e+e−→ZZ. We assume a complete one-loop implementation and a possibility of estimating the initial state polarizations, as well as the full-phase calculation. Numerical results are provided by our Monte Carlo tools integrator and generator for typical energies and degrees of polarization of ILC and CLIC projects in two α(0) and Gμ electroweak schemes. Published by the American Physical Society 2024

Generalized binary-encounter-Bethe model for electron impact ionization of atoms

A generalized binary-encounter-Bethe (GBEB) model is proposed to calculate the partial ionization cross sections of all shells. The present model improves the original version of Kim et al (2000 Phys. Rev.A 62 052710) by incorporating a physically constructed effective charge felt by the ejected electron in the empirical factor, which prevents the selection of specific factors for different shells. A generalized relativistic binary-encounter-Bethe (BEB) formula is also proposed and applied to different inner shells of C, Al, Fe, Ar, Ag, Xe, Sn, Pb, and Bi atoms for impact energies from the thresholds up to 106 keV. The present model improves the partial ionization cross sections in the low-energy region compared to other relativistic BEB models. The GBEB partial and total ionization cross sections of the Xe atom are compared with the original BEB results. The present calculations, combined with the contribution from the direct multiple ionization, show good agreement with the experimental measurements in the intermediate- and high-energy ranges. We conclude that the present GBEB model, without any fitting parameters and ad hoc corrections, improves the BEB prediction of partial and total ionization cross sections for a good variety of atomic targets.