Inclusive Cross Sections Research Articles

Measurement of inclusive and differential cross sections for single top quark production in association with a W boson in proton-proton collisions at sqrt{s} = 13 TeV

Measurements of the inclusive and normalised differential cross sections are presented for the production of single top quarks in association with a W boson in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data used were recorded with the CMS detector at the LHC during 2016–2018, and correspond to an integrated luminosity of 138 fb−1. Events containing one electron and one muon in the final state are analysed. For the inclusive measurement, a multivariate discriminant, exploiting the kinematic properties of the events is used to separate the signal from the dominant textrm{t}overline{textrm{t}} background. A cross section of 79.2pm 0.9{left(textrm{stat}right)}_{-8.0}^{+7.7}left(textrm{syst}right)pm 1.2left(textrm{lumi}right) pb is obtained, consistent with the predictions of the standard model. For the differential measurements, a fiducial region is defined according to the detector acceptance, and the requirement of exactly one jet coming from the fragmentation of a bottom quark. The resulting distributions are unfolded to particle level and agree with the predictions at next-to-leading order in perturbative quantum chromodynamics.

Observation of gauge boson joint-polarisation states in W±Z production from pp collisions at [formula omitted] TeV with the ATLAS detector

Measurements of joint-polarisation states of W and Z gauge bosons in W±Z production are presented. The data set used corresponds to an integrated luminosity of 139 fb−1 of proton–proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. The W±Z candidate events are reconstructed using leptonic decay modes of the gauge bosons into electrons and muons. The simultaneous pair-production of longitudinally polarised vector bosons is measured for the first time with a significance of 7.1 standard deviations. The measured joint helicity fractions integrated over the fiducial region are f00=0.067±0.010, f0T=0.110±0.029, fT0=0.179±0.023 and fTT=0.644±0.032, in agreement with the next-to-leading-order Standard Model predictions. Individual helicity fractions of the W and Z bosons are also measured and found to be consistent with joint helicity fractions within the expected amounts of correlation. Both the joint and individual helicity fractions are also measured separately in W+Z and W−Z events. Inclusive and differential cross sections for several kinematic observables sensitive to polarisation are presented.

Observation of large missing-momentum (e,e′p) cross-section scaling and the onset of correlated-pair dominance in nuclei

We report the measurement of xB scaling in (e,e′p) cross-section ratios off nuclei relative to deuterium at large missing momentum of 350≤pmiss≤600 MeV/c. The observed scaling extends over a kinematic range of 0.7≤xB≤1.8, which is significantly wider than 1.4≤xB≤1.8 previously observed for inclusive (e,e′) cross-section ratios. The xB-integrated cross-section ratios become constant (i.e., scale) beginning at pmiss≈kF, the nuclear Fermi momentum. Comparing with theoretical calculations we find good agreement with generalized contact formalism calculations for high missing momentum (>375 MeV/c), suggesting the observed scaling results from interacting with nucleons in short-range correlated (SRC) pairs. For low missing momenta, mean-field calculations show good agreement with the data for pmiss<kF, and suggest a potential non-negligible contribution to the measured cross-section ratios from scattering off single, uncorrelated, nucleons up to pmiss≈350 MeV/c. Therefore, SRCs become dominant in nuclei at pmiss≈350 MeV/c, well above the nuclear Fermi Surface of kF≈250 MeV/c.Received 4 September 2022Revised 29 November 2022Accepted 26 May 2023DOI:https://doi.org/10.1103/PhysRevC.107.L061301©2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasElectron-ion collisionsLepton induced nuclear reactionsNuclear many-body theoryNuclear Physics

Neural network predictions of inclusive electron-nucleus cross sections

We investigate whether a neural network approach can reproduce and predict the electron-nucleus cross sections in the kinematical domain of present and future accelerator-based neutrino oscillation experiments. For this purpose, we consider the large amount of data available to the community via the University of Virginia's Quasielastic Electron Nucleus Scattering Archive and use a residual, fully connected feedforward neural network. We illustrate the training performances of the neural network by comparing its results with experimental data for the electron double-differential cross section on carbon. The agreement between predictions and data is remarkable from quasielastic to deep-inelastic scattering. To test the predicting power of the neural network we consider the numerous kinematical conditions for which experimental cross sections on calcium are available. Furthermore, we show the predictions of the electron-scattering cross sections on oxygen, argon, and titanium: Nuclei of particular interest in the context of present and future accelerator-based neutrino oscillation programs. The agreement between these predictions and the data is comparable to the one of other theoretical models commonly used to calculate electron and neutrino cross sections, such as SuSAv2 and GiBUU. Results obtained with genie, a Monte Carlo event generator, are also discussed for comparison. The good performances obtained with our neural network suggest that neural networks could be exploited for theoretical and experimental investigations of electron- and neutrino-nucleus scattering.

STEP: A tool to perform tests of smoothness on differential distributions based on expansion of polynomials

We motivate and describe a method based on fits with polynomials to test the smoothness of differential distributions. As a demonstration, we apply the method to several measurements of inclusive jet double-differential cross section in the jet transverse momentum and rapidity at the Tevatron and LHC. This method opens new possibilities to test the quality of differential distributions used for the extraction of physics quantities such as the strong coupling.

Measurements of the Higgs boson inclusive and differential fiducial cross-sections in the diphoton decay channel with collisions at [formula omitted] with the ATLAS detector

Measurements of the Higgs boson inclusive and differential fiducial cross-sections in the diphoton decay channel with collisions at [formula omitted] with the ATLAS detector

Neutrino structure functions from GeV to EeV energies

The interpretation of present and future neutrino experiments requires accurate theoretical predictions for neutrino-nucleus scattering rates. Neutrino structure functions can be reliably evaluated in the deep-inelastic scattering regime within the perturbative QCD (pQCD) framework. At low momentum transfers (Q2 ≲ few GeV2), inelastic structure functions are however affected by large uncertainties which distort event rate predictions for neutrino energies Eν up to the TeV scale. Here we present a determination of neutrino inelastic structure functions valid for the complete range of energies relevant for phenomenology, from the GeV region entering oscillation analyses to the multi-EeV region accessible at neutrino telescopes. Our NNSFν approach combines a machine-learning parametrisation of experimental data with pQCD calculations based on state-of-the-art analyses of proton and nuclear parton distributions (PDFs). We compare our determination to other calculations, in particular to the popular Bodek-Yang model. We provide updated predictions for inclusive cross sections for a range of energies and target nuclei, including those relevant for LHC far-forward neutrino experiments such as FASERν, SND@LHC, and the Forward Physics Facility. The NNSFν determination is made available as fast interpolation LHAPDF grids, and it can be accessed both through an independent driver code and directly interfaced to neutrino event generators such as GENIE.

Multiple Mechanisms in Proton-Induced Nucleon Removal at ∼100 MeV/Nucleon.

We report on the first proton-induced single proton- and neutron-removal reactions from the neutron-deficient ^{14}O nucleus with large Fermi-surface asymmetry S_{n}-S_{p}=18.6 MeV at ∼100 MeV/nucleon, a widely used energy regime for rare-isotope studies. The measured inclusive cross sections and parallel momentum distributions of the ^{13}N and ^{13}O residues are compared to the state-of-the-art reaction models, with nuclear structure inputs from many-body shell-model calculations. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively. These multiple reaction mechanisms should be considered in analyses of inclusive one-nucleon removal cross sections measured at intermediate energies for quantitative investigation of single-particle strengths and correlations in atomic nuclei.

Dress code for infrared safe scattering in QED

Abstract We study the S-matrix and inclusive cross-section for general dressed states in quantum electrodynamics. We obtain an infrared factorization formula of the S-matrix elements for general dressed states. This enables us to study which dressed states lead to infrared-safe S-matrix elements. The condition for dressed states can be interpreted as the memory effect, which is nothing but the conservation law of the asymptotic symmetry. We derive the generalized soft photon theorem for general dressed states. We also compute an inclusive cross-section using general dressed states. It is necessary to use appropriate initial and final dressed states to evaluate interference effects, which cannot be computed correctly by using Fock states due to the infrared divergence.

Measurement of the double-differential muon-neutrino charged-current inclusive cross section in the NOvA near detector

We report cross-section measurements of the final-state muon kinematics for νμ charged-current interactions in the NOvA near detector using an accumulated 8.09×1020 protons on target in the NuMI beam. We present the results as a double-differential cross section in the observed outgoing muon energy and angle, as well as single-differential cross sections in the derived neutrino energy, Eν, and square of the four-momentum transfer, Q2. We compare the results to inclusive cross-section predictions from various neutrino event generators via χ2 calculations using a covariance matrix that accounts for bin-to-bin correlations of systematic uncertainties. These comparisons show a clear discrepancy between the data and each of the tested predictions at forward muon angle and low Q2, indicating a missing suppression of the cross section in current neutrino-nucleus scattering models.3 MoreReceived 24 September 2021Accepted 14 February 2023DOI:https://doi.org/10.1103/PhysRevD.107.052011Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNeutrino interactionsNucleus-neutrino interactionsParticles & Fields

CNOK: A C++ Glauber model code for single-nucleon knockout reactions

A C++ program package was developed to calculate parallel momentum distributions (including the stripping mechanism and the diffractive dissociation mechanism) of the heavy residue (core) in single-nucleon knockout reactions induced by intermediate-energy (around and more than tens of MeV per nucleon) beams of stable and radioactive atomic nuclei. The program implements the Glauber reaction model that is based on the eikonal approximation and the sudden approximation when dealing with the scattering process, and uses a t-ρ-ρ method to build the projectile-target scattering optical potential, where the nucleonic densities of the core and the target are needed as input. The radial wavefunction of the valence nucleon is solved by a built-in bound-wave solver driven by a globally convergent search engine for optimized potential parameters of the valence nucleon to reproduce user-specified separation energies and root-mean-square (rms) radii of the valence nucleon. The YAML file format is adopted to facilitate user input. The program is expected to especially serve the interpretation of data analysis results of single-nucleon knockout from radioactive ion beams (RIBs), where the experimental practitioners may be more conversant with C++. Program summaryProgram Title: CNOKCPC Library link to program files:https://doi.org/10.17632/dmffpbjhsh.1Developer's repository link:https://gitee.com/asiarabbit/cnokLicensing provisions: GPLv3Programming language: C++Nature of problem: This program calculates the single-particle reaction cross sections of single-nucleon removal from stable and radioactive nuclei impinging on a light composite (i.e. non-hydrogen, e.g. carbon and beryllium) target at intermediate energies (around and more than tens of MeV per nucleon), and the parallel momentum (stripping+diffractive dissociation) distributions of the core, for a pure valence configuration (bound core state+valence nucleon single-particle orbit).Solution method: The bound radial wavefunction of the valence nucleon in a Woods-Saxon (WS) potential is solved following the method of shooting to a fitting point, where the wavefunction is integrated with Runge-Kutta method from 0 and some large distance r∞ to a matching point rm near the nuclear surface. The process is iterated to optimize the eigenvalue Enlj by joining the two waves at rm “smoothly”. Most integrals are evaluated with Simpson's rules, while some with Romberg integration. Searching in the (V0,r0) space of the central WS potential to reproduce the user-specified separation energy and rms radius of the valence nucleon is done via a globally convergent Newton-Raphson root-finding routine for nonlinear systems of equations.Additional comments including restrictions and unusual features: User input is read in with YAML parser (yaml-cpp). Global parameters are readily accessed and uniformly modified in a singleton class. General algorithms (integration, interpolation, minimization, and root-finding routines) are implemented with C++ template class or functors, which adapt to different data types and/or function types. Various batch modes are wrapped in the program package to save user time. For instance, in one run, with the batch mode, one can calculate inclusive single-nucleon removal cross section involving many valence configurations, the relevant inclusive core momentum distribution, and similarly for a series of projectile+target combinations in study of systematics, as is frequently encountered in the study of quenching of single-particle-orbit occupancies (spectroscopic factors) in single-nucleon knockout reactions. Unit tests with Catch are widely deployed to facilitate debugging. C++11 support is required for compilers.

A systematic analysis of deuteron breakup

Inclusive breakup cross sections for deuterons incident on a wide range of nuclei at different incident energies are studied. In our analysis, we use the post-form distorted-wave-Born approximation (DWBA) to calculate the elastic and nonelastic breakup cross sections. We also calculate exciton and statistical compound-nucleus model cross sections to account for pre-equilibrium and equilibrium emissions. The calculations are performed using the code EMPIRE and are compared to the available experimental data. The comparisons of the integrated cross sections reveal a generally good agreement between the calculations and the data. However, systematic discrepancies are observed between the calculated double differential neutron and proton cross sections and the data, especially for heavier targets. Possible reasons for the disagreements between the theoretical predictions and the experimental data are discussed.

Electron and neutrino scattering off the deuteron in a relativistic framework

We build a relativistic model to perform calculations of exclusive, semi-exclusive and inclusive unpolarized cross sections and various polarization observables in electron and neutrino scattering experiments with deuteron targets. The strong interaction dynamics is defined by an explicit dynamical unitary representation of the Poincar\'e group, where representations of space translations and rotations in the interacting and non-interacting representations are the same. The Argonne V18 potential is used to construct a relativistic nucleon-nucleon interaction reproducing the experimental deuteron binding energy and nucleon-nucleon scattering observables. Our formalism does not include the pion production channel and neglects two-body contributions in the electromagnetic as well as in the weak nuclear current operator. We show that it is applicable to processes at kinematics, where the internal two-nucleon energy remains below the pion production threshold but the magnitude of the three-momentum transfer extends at least to several GeV.

N3LO+N3LL QCD improved Higgs pair cross sections

We report a new calculation of the soft-gluon threshold resummation for the Higgs boson pair production in the dominant production mode — gluon-gluon fusion — up to the next-to-next-to-next-to-leading logarithmic (N3LL) accuracy. After matching N3LL to the next-to-next-to-next-to-leading order (N3LO) QCD calculation in the infinite top quark mass approximation, we show that the central values of the inclusive cross sections are quite stable with respect to N3LO, while the conventional renormalisation and factorisation scale uncertainties are reduced by a factor of two, reaching to the subpercent level. Our study further consolidates the good asymptotic perturbative convergence. After combining with the full top-quark mass dependent next-to-leading order QCD results, our most advanced predictions are presented for both the inclusive total cross sections and the differential invariant mass distributions of the Higgs pair.

Measurement of the ν_{e}-Nucleus Charged-Current Double-Differential Cross Section at ⟨E_{ν}⟩=2.4 GeV Using NOvA.

The inclusive electron neutrino charged-current cross section is measured in the NOvA near detector using 8.02×10^{20} protons-on-target in the NuMI beam. The sample of GeV electron neutrino interactions is the largest analyzed to date and is limited by ≃17% systematic rather than the ≃7.4% statistical uncertainties. The double-differential cross section in final-state electron energy and angle is presented for the first time, together with the single-differential dependence on Q^{2} (squared four-momentum transfer) and energy, in the range 1 GeV≤E_{ν}<6 GeV. Detailed comparisons are made to the predictions of the GENIE, GiBUU, NEUT, and NuWro neutrino event generators. The data do not strongly favor a model over the others consistently across all three cross sections measured, though some models have especially good or poor agreement in the single differential cross section vs Q^{2}.

Cross-section measurement of two-photon in-flight annihilation of positrons at s=20 MeV with the PADME detector

A measurement of the inclusive cross section of in-flight electron-positron annihilation to photons, e+e−→γγ, is presented using the PADME detector at the Laboratori Nazionali di Frascati. A beam of 430 MeV positrons, corresponding to a center-of-mass energy of 20 MeV, strikes a thin diamond target. The two photons produced in the interaction are detected by an electromagnetic calorimeter made of BGO crystals. The measurement is the first based on direct detection of the photon pair and one of the most precise for positron energies below 1 GeV. It represents an intermediate step in the ultimate PADME goal of searching for dark sector particles and mediators weakly coupled to photons and electrons, with masses ranging from 1 to 20 MeV. The final value, σe+e−→γγ=(1.977±0.018(stat)±0.119(syst)) mb, agrees with next-to-leading-order QED predictions within the 6% experimental uncertainty.6 MoreReceived 8 November 2022Accepted 20 December 2022DOI:https://doi.org/10.1103/PhysRevD.107.012008Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle interactionsGeneral PhysicsParticles & Fields

Relative population of states in Mg21 from few-nucleon removal reactions

Nuclear reactions with intermediate-energy beams in which three, four, and five nucleons are removed are expected to proceed through a combination of nondissipative and statistical processes. In an experiment at the National Superconducting Cyclotron Laboratory, in-beam $\ensuremath{\gamma}$-ray spectroscopy was utilized to study few-nucleon removal reactions from incoming beams of $^{24}\mathrm{Mg}, ^{25}\mathrm{Al}$, and $^{26}\mathrm{Si}$ projectiles to the same reaction product, $^{21}\mathrm{Mg}$. New $\ensuremath{\gamma}$-ray transitions and $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidences in $^{21}\mathrm{Mg}$ were established using the CsI(Na) array CAESAR and the inclusive cross section for three-neutron removal from $^{24}\mathrm{Mg}$ was measured. Significant differences in the relative population of states in $^{21}\mathrm{Mg}$ from $^{25}\mathrm{Al}$ compared to $^{26}\mathrm{Si}$ were observed and found to be correlated with the spins of the $^{21}\mathrm{Mg}$ states. As a result, this intermediate regime between direct and statistical nucleon removal may have potential as a tool to deliver unique patterns of level populations in fast-beam experiments and alter isomer to ground state ratios in the production of exotic beams.

Forward inclusive jet productions in pA collisions

Motivated by recent experimental LHC measurements on the forward inclusive jet productions and based on our previous calculations on forward hadron productions, we calculate a single inclusive jet cross section in $pA$ collisions at forward rapidity within the color glass condensate framework up to the next-to-leading order. Moreover, with the application of a jet algorithm and proper subtraction of the rapidity and collinear divergences, we further demonstrate that the resulting next-to-leading-order hard coefficients are finite. In addition, in order to deal with the large logarithms that can potentially spoil the convergence of the perturbative expansion and improve the reliability of the numerical predictions, we introduce the collinear jet function and the threshold jet function and resum these large logarithms hidden in the hard coefficients.

Inclusive quarkonium production in pp collisions at sqrt{s} = 5.02 TeV

This article reports on the inclusive production cross section of several quarkonium states, textrm{J}/psi , psi mathrm{(2S)}, Upsilon mathrm (1S), Upsilon mathrm{(2S)}, and Upsilon mathrm{(3S)}, measured with the ALICE detector at the LHC, in pp collisions at sqrt{s} = 5.02 TeV. The analysis is performed in the dimuon decay channel at forward rapidity (2.5< y < 4). The integrated cross sections and transverse-momentum (p_{textrm{T}}) and rapidity (y) differential cross sections for textrm{J}/psi , psi mathrm{(2S)}, Upsilon mathrm (1S), and the psi mathrm{(2S)}-to-textrm{J}/psi cross section ratios are presented. The integrated cross sections, assuming unpolarized quarkonia, are: sigma _{textrm{J}/psi } (p_{textrm{T}} <20 GeV/c) = 5.88 ± 0.03 ± 0.34 ~mu b, sigma _{psi mathrm{(2S)}} (p_{textrm{T}} <12 GeV/c) = 0.87 ± 0.06 ± 0.10~mu b, sigma _{Upsilon mathrm (1S)} (p_{textrm{T}} <15 GeV/c) = 45.5 ± 3.9 ± 3.5 nb, sigma _{Upsilon mathrm{(2S)}} (p_{textrm{T}} <15 GeV/c) = 22.4 ± 3.2 ± 2.7 nb, and sigma _{Upsilon mathrm{(3S)}} (p_{textrm{T}} <15 GeV/c) = 4.9 ± 2.2 ± 1.0 nb, where the first (second) uncertainty is the statistical (systematic) one. For the first time, the cross sections of the three Upsilon states, as well as the psi mathrm{(2S)} one as a function of p_{textrm{T}} and y, are measured at sqrt{s} = 5.02 TeV at forward rapidity. These measurements also significantly extend the textrm{J}/psi p_{textrm{T}} reach and supersede previously published results. A comparison with ALICE measurements in pp collisions at sqrt{s} = 2.76, 7, 8, and 13 TeV is presented and the energy dependence of quarkonium production cross sections is discussed. Finally, the results are compared with the predictions from several production models.

Observation of triple J/ψ meson production in proton-proton collisions

Protons consist of three valence quarks, two up-quarks and one down-quark, held together by gluons and a sea of quark-antiquark pairs. Collectively, quarks and gluons are referred to as partons. In a proton-proton collision, typically only one parton of each proton undergoes a hard scattering – referred to as single-parton scattering – leaving the remainder of each proton only slightly disturbed. Here, we report the study of double- and triple-parton scatterings through the simultaneous production of three J/ψ mesons, which consist of a charm quark-antiquark pair, in proton-proton collisions recorded with the CMS experiment at the Large Hadron Collider. We observed this process – reconstructed through the decays of J/ψ mesons into pairs of oppositely charged muons – with a statistical significance above five standard deviations. We measured the inclusive fiducial cross-section to be 272−104+141(stat)±17(syst)fb\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$27{2}_{-104}^{+141}\\,{{{\\rm{(stat)}}}}\\,\\pm 17\\,{{{\\rm{(syst)}}}}\\,{{{\\rm{fb}}}}\\,$$\\end{document}, and compared it to theoretical expectations for triple-J/ψ meson production in single-, double- and triple-parton scattering scenarios. Assuming factorization of multiple hard-scattering probabilities in terms of single-parton scattering cross-sections, double- and triple-parton scattering are the dominant contributions for the measured process.