Inclusive Cross Sections Research Articles

Recent observation and measurements of diboson processes from the ATLAS experiment

This review covers results at a centre-of-mass energy of [Formula: see text] TeV from the ATLAS experiment that have been published, or submitted for publication, up to April 2020. It summarizes results on the inclusive production cross-section measurements of boson pairs and of the electroweak production of diboson in association with two jets. The measurements either use the full integrated luminosity of 139 fb[Formula: see text] collected by the ATLAS detector at the LHC from 2015 to 2018, or a partial dataset of 36 fb[Formula: see text]. The inclusive production rates of diboson are studied to high precision. These measurements provide stringent tests of the electroweak sector of the Standard Model and allow search for new physics via anomalous triple and quartic gauge boson couplings.

Sequential Nature of (p,3p) Two-Proton Knockout from Neutron-Rich Nuclei.

Twenty-one two-proton knockout (p,3p) cross sections were measured from neutron-rich nuclei at ∼250 MeV/nucleon in inverse kinematics. The angular distribution of the three emitted protons was determined for the first time, demonstrating that the (p,3p) kinematics are consistent with two sequential proton-proton collisions within the projectile nucleus. Ratios of (p,3p) over (p,2p) inclusive cross sections follow the trend of other many-nucleon removal reactions, further reinforcing the sequential nature of (p,3p) in neutron-rich nuclei.

Double-differential inclusive charged-current νμ cross sections on hydrocarbon in MINERvA at ⟨Eν⟩∼3.5 GeV

MINERvA reports inclusive charged-current cross sections for muon neutrinos on hydrocarbon in the NuMI beamline. We measured the double-differential cross section in terms of the longitudinal and transverse muon momenta, as well as the single-differential cross sections in those variables. The data used in this analysis correspond to an exposure of $3.34 \times 10^{20}$ protons on target with a peak neutrino energy of approximately 3.5 GeV. Measurements are compared to the GENIE, NuWro and GiBUU neutrino cross-section predictions, as well as a version of GENIE modified to produce better agreement with prior exclusive MINERvA measurements. None of the models or variants were able to successfully reproduce the data across the entire phase space, which includes areas dominated by each interaction channel.

A statistical model to calculate inclusive hadronic cross sections

Hadronic cross sections are important ingredients in many of the ongoing research methods in high energy nuclear physics, and it is always important to measure and/or calculate the probabilities of different types of reactions. In heavy-ion transport simulations at a few GeV energies, these hadronic cross sections are essential and so far mostly the exclusive processes are used, however, if one interested in total production rates the inclusive cross sections are also necessary to know. In this paper, we introduce a statistical-based method, which is able to give good estimates to exclusive and inclusive cross sections as well in the energy range of a few GeV. The method and its estimates for not well-known cross sections, will be used in a Boltzmann-Uehling-Uhlenbeck (BUU) type off-shell transport code to explain charmonium and bottomonium mass shifts in heavy-ion collisions.

Extraction of the strong coupling \u03b1s(mZ) from a combined NNLO analysis of inclusive electroweak boson cross sections at hadron colliders

The inclusive cross sections of W+, W−, and Z boson production from 34 different measurements performed in proton-(anti)proton collisions at center-of-mass energies sqrt{s} = 1.8–13 TeV, are compared to perturbative QCD calculations at next-to-next-to-leading-order (NNLO) accuracy with four sets of parton distributions functions (CT14, HERAPDF2.0, MMHT14, and NNPDF3.0 PDFs) and varying values of the strong coupling constant at the Z mass pole, αs(mZ). The data-theory agreement is good within the experimental and theoretical uncertainties, with the CT14 and MMHT14 parton densities providing the most overall consistent description of all cross section data. A value of αs(mZ) = {0.1188}_{-0.0013}^{+0.0019} is extracted from a combined fit of the 28 experimental LHC measurements to the corresponding NNLO theoretical predictions obtained with the MMHT14 PDF set, which provides the most robust and stable QCD coupling extraction of this analysis.

Determination of the strong coupling constant \u03b1S(mZ) from measurements of inclusive W\xb1 and Z boson production cross sections in proton-proton collisions at sqrt{mathrm{s}} = 7 and 8 TeV

Twelve measurements of inclusive cross sections of W± and Z boson production, performed in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, are compared with perturbative quantum chromodynamics calculations at next-to-next- to-leading order (NNLO) accuracy obtained with the CT14, HERAPDF2.0, MMHT14, and NNPDF3.0 parton distribution functions (PDFs). Data and theory agree well for all PDF sets, taking into account the experimental and theoretical uncertainties. A novel procedure is employed to extract the strong coupling constant at the Z pole mass from a detailed comparison of all the experimental fiducial cross sections to the corresponding NNLO theoretical predictions, yielding {alpha}_{mathrm{S}}left({m}_{mathrm{Z}}right)={0.1163}_{-0.0031}^{+0.0024} (CT14), {0.1072}_{-0.0040}^{+0.0043} (HERAPDF2.0), 0.1186 ± 0.0025 (MMHT14), and 0.1147 ± 0.0023 (NNPDF3.0). Using the results obtained with the CT14 and MMHT14 PDFs, which yield the most robust and stable αS(mZ) extractions, a value {alpha}_{mathrm{S}}left({m}_{mathrm{Z}}right)={0.1175}_{-0.0028}^{+0.0025} is determined.

Twisted particle collisions: A new tool for spin physics

Collisions of twisted particles --- that is, non-plane-wave states of photons, electrons, or any other particle, equipped with a non-zero orbital angular momentum (OAM) with respect to its propagation direction --- offer novel ways to probe particle structure and interactions. In the recent paper \cite{Ivanov:2019vxe}, we argued that resonance production in twisted photon collisions or twisted $e^+e^-$ annihilation gives access to parity- and spin-sensitive observables in inclusive cross sections, even when the initial particles are unpolarized. Here, we explore these features in detail, providing a qualitative picture and illustrating it with numerical examples. We show how one can detect parity-violating effects in collisions of unpolarized twisted photons and how one can produce almost $100\%$ polarized vector mesons in unpolarized twisted $e^+e^-$ annihilation. These examples highlight the unprecedented level of control over polarization offered by twisted particles, impossible in the usual plane wave collisions.

Doing Spin Physics with Unpolarized Particles

Twisted, or vortex, particles refer to freely propagating non-plane-wave states with helicoidal wave fronts. In this state, the particle possesses a nonzero orbital angular momentum with respect to its average propagation direction. Twisted photons and electrons have been experimentally demonstrated, and creation of other particles in twisted states can be anticipated. If brought in collisions, twisted states offer a new degree of freedom to particle physics, and it is timely to analyze what new insights may follow. Here, we theoretically investigate resonance production in twisted photon collisions and twisted e^{+}e^{-} annihilation and show that these processes emerge as a completely novel probe of spin and parity-sensitive observables in fully inclusive cross sections with unpolarized initial particles. This is possible because the initial state with a nonzero angular momentum explicitly breaks the left-right symmetry even when averaging over helicities. In particular, we show how one can produce almost 100% polarized vector mesons in unpolarized twisted e^{+}e^{-} annihilation and how to control its polarization state.

Update of inclusive cross sections of single and pairs of identified light charged hadrons

We report new measurements of the production cross sections of pairs of charged pions and kaons as a function of their fractional energies using various fractional-energy definitions. Two different fractional-energy definitions were used and compared to the conventional fractional-energy definition reported previously. The new variables aim at either identifying dihadron cross sections in terms of single-hadron fragmentation functions, or to provide a means of characterizing the transverse momentum created in the fragmentation process. The results were obtained applying the updated initial-state radiation correction used in other recent Belle publications on light-hadron production cross sections. In addition, production cross sections of single charged pions, kaons, and protons were also updated using this initial-state radiation correction. The cross sections are obtained from a $558\,{\rm fb}^{-1}$ data sample collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider.

Electron-impact dissociation of N2D+ cations to D+ fragments

Absolute cross sections for electron-impact dissociation of N2D+ cations to the light D+ fragments are reported for the first time. The animated electron-ion crossed-beam method is applied in the energy range from thresholds up to 2 keV. The heavy N2+ fragments are also detected and their kinetic energy distribution is analyzed at a selected electron energy. The measured cross-sections are corrected for incomplete collection of the light D+ fragments by performing careful analyser magnetic field scan together with a Monte-Carlo procedure. Inclusive absolute cross sections are determined. Dissociative excitation (DE) and dissociative ionization (DI) contributions are separated and the corresponding partial cross sections for D+ fragment production are determined at selected electron energies. The inclusive cross section for D+ fragment production has a maximum of (87 ± 7)×10−18 cm2, at 95.1 eV, with the dominant contribution from the DI process.

Shell structure of the neutron-rich isotopes Co69,71,73

The structures of the neutron-rich Co69,71,73 isotopes were investigated via (p,2p) knockout reactions at the Radioactive Isotope Beam Factory, RIKEN. Isotopes of interest were studied using the DALI2 γ-ray detector array combined with the MINOS target and tracker system. Level schemes were reconstructed using the γ-γ coincidence technique, with tentative spin-parity assignments based on the measured inclusive and exclusive cross sections. Comparison with shell-model calculations using the Lenzi-Nowacki-Poves-Sieja LNPS and PFSDG-U interactions suggests coexistence of spherical and deformed shapes at low excitation energies in the Co69,71,73 isotopes. The distorted-wave impulse approximation (DWIA) framework was used to calculate the single-particle cross sections. These values were compared with the experimental findings.

Sustainable Inland and Coastal Fisheries: Key Lessons Drawn from Community-based Fisheries Management in Bangladesh

Aim: To build an appropriate basis for inland and coastal fisheries co-management through the involvement of key government agencies, fishers, traders and relevant stakeholders.
 Study Design: Literature review of the community-based fisheries management projects in Bangladesh during 1995-2017 and examine fisher’s perceptions of co-management approaches from an inclusive cross-section of fishing households.
 Place and Duration of Study: The study sites are located in six riverine districts in Bangladesh, namely Bhola, Chandpur and Laxmipur within fish sanctuary areas and Barisal, Pirojpur and Jhalokathi outside fish sanctuary areas.
 Methodology: The study included community-based fisheries management project’s knowledge in different inland and coastal habitat types in Bangladesh. The study comprised on lessons learned from field activities, workshops on fisheries co-management with the public, NGOs, experts, civil society, fisher’s organizations, traders and related stakeholders, and reviews of several reports on other community-based fisheries management initiatives in Bangladesh. The study also examined stakeholder perceptions of co-management approaches from a cross-section of 1200 fishing households in 24 fishing villages.
 Results: Results indicated that performance of community-based fisheries management in Bangladesh varied widely to improve natural fish production, fish abundance and biodiversity and, with the nature of the community involved. These include the development capabilities of user groups through formation of village level Conservation Groups and fish landing center-based organizations, and capabilities of the key government agencies and law enforcing agencies for enhancing compliance.
 Conclusions: This paper proposes a co-management arrangement for fishery management along the fish sanctuary areas of the Padma-Meghna River systems in Bangladesh. These findings provided the scientific basis of community managed fisheries management and its applications.

Measurements of inclusive jet spectra in pp and central Pb-Pb collisions at sNN=5.02TeV

This article reports measurements of the $p_{\rm{T}}$-differential inclusive jet cross-section in pp collisions at $\sqrt{s}$ = 5.02 TeV and the $p_{\rm{T}}$-differential inclusive jet yield in Pb-Pb 0-10% central collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV. Jets were reconstructed at mid-rapidity with the ALICE tracking detectors and electromagnetic calorimeter using the anti-$k_{\rm{T}}$ algorithm. For pp collisions, we report jet cross-sections for jet resolution parameters $R=0.1-0.6$ over the range $20<p_{\rm{T,jet}}<140$ GeV/$c$, as well as the jet cross-section ratios of different $R$, and comparisons to two next-to-leading-order (NLO)-based theoretical predictions. For Pb-Pb collisions, we report the $R=0.2$ and $R=0.4$ jet spectra for $40<p_{\rm{T,jet}}<140$ GeV/$c$ and $60<p_{\rm{T,jet}}<140$ GeV/$c$, respectively. The scaled ratio of jet yields observed in Pb-Pb to pp collisions, $R_{\rm{AA}}$, is constructed, and exhibits strong jet quenching and a clear $p_{\rm{T}}$-dependence for $R=0.2$. No significant $R$-dependence of the jet $R_{\rm{AA}}$ is observed within the uncertainties of the measurement. These results are compared to several theoretical predictions.

The leading jet transverse momentum in inclusive jet production and with a loose jet veto

We study the transverse momentum of the leading jet in the limit where the jet radius is small, R ≪ 1. We introduce the leading-jet function to calculate this cross section for an inclusive jet sample, and the subleading-jet function when a loose veto on additional jets is imposed, i.e. {}_{PTJ}{underset{sim }{>}}_{P_T^{mathrm{veto}}} . These jet functions are calculated at next-to-leading order in QCD and the resummation of jet radius logarithms is explored. We present phenomenological results for Higgs + 1 jet production, for both the jet and Higgs transverse momentum distribution. We find that, while the R ≪ 1 limit of the cross section provides a good description of the full NLO result, even for values as large as R = 0.8, simply retaining the leading logarithm at this order does not. Indeed, the NLO contribution to the hard function and, to a lesser extent, non-logarithmic corrections to the jet function are sizable and must be included to obtain the correct cross section. In the inclusive cross section we find that the {alpha}_s^2 ln2R corrections are several precent, while in exclusive cross sections at large pT ,J and small R they can reach 20%. However, it is not clear how important the resummation of these logarithms is, given the presence of other large corrections at NNLO.

Impact of isolation and fiducial cuts on qT and N-jettiness subtractions

Kinematic selection cuts and isolation requirements are a necessity in experimental measurements for identifying prompt leptons and photons that originate from the hard-interaction process of interest. We analyze how such cuts affect the application of the qT and N -jettiness subtraction methods for fixed-order calculations. We consider both fixed-cone and smooth-cone isolation methods. We find that kinematic selection and isolation cuts both induce parametrically enhanced power corrections with considerably slower convergence compared to the standard power corrections that are already present in inclusive cross sections without additional cuts. Using analytic arguments at next-to-leading order we derive their general scaling behavior as a function of the subtraction cutoff. We also study their numerical impact for the case of gluon-fusion Higgs production in the H → γγ decay mode and for pp → γγ direct diphoton production. We find that the relative enhancement of the additional cut-induced power corrections tends to be more severe for qT, where it can reach an order of magnitude or more, depending on the choice of parameters and subtraction cutoffs. We discuss how all such cuts can be incorporated without causing additional power corrections by implementing the subtractions differentially rather than through a global slicing method. We also highlight the close relation of this formulation of the subtractions to the projection-to-Born method.

The q_T subtraction method: electroweak corrections and power suppressed contributions

Building upon the formulation of transverse-momentum resummation for heavy-quark hadroproduction, we present the first application of the q_T subtraction formalism to the computation of electroweak corrections to massive lepton pairs through the Drell–Yan mechanism. We then study the power suppressed contributions to the q_T subtraction formula in the parameter r_{mathrm{cut}}, defined as the minimum transverse momentum of the lepton pair normalised to its invariant mass. We analytically compute the leading power correction from initial and final-state radiation to the inclusive cross section. In the case of initial-state radiation the power correction is quadratic in r_{mathrm{cut}} and our analytic result is consistent with results previously obtained in the literature. Final-state radiation produces linear contributions in r_{mathrm{cut}} that may challenge the efficiency of the q_T subtraction procedure. We explicitly compute the linear power correction in the case of the inclusive cross section and we discuss the extension of our calculation to differential distributions.

The gluon-fusion production of Higgs boson pair: N3LO QCD corrections and top-quark mass effects

The Higgs boson pair production via gluon fusion at high-energy hadron colliders, such as the LHC, is vital in deciphering the Higgs potential and in pinning down the electroweak symmetry breaking mechanism. We carry out the next-to-next-to-next-to- leading order (N3LO) QCD calculations in the infinite top-quark mass limit and present predictions for both the inclusive and differential cross sections, albeit the differential distributions other than the invariant mass distribution of the Higgs boson pair are approximated at N3LO. Such corrections are indispensable in stabilising the perturbative expansion of the cross section in the strong coupling αs. At the inclusive level, the scale uncertainties are reduced by a factor of four compared with the next-to-next-to-leading order (NNLO) results. Given that the inclusion of the top-quark mass effects is essential for the phenomenological applications, we use several schemes to incorporate the N3LO results in the infinite top-quark mass limit and the next-to-leading order (NLO) results with full top-quark mass dependence, and present theoretical predictions for the (differential) cross sections in the proton-proton collisions at the centre-of-mass energies sqrt{s} = 13, 14, 27 and 100 TeV. Our results provide one of the most precise theoretical inputs for the analyses of the Higgs boson pair events.

Measurement of top quark pair production in association with a Z boson in proton-proton collisions at sqrt{mathrm{s}} = 13 TeV

A measurement of the inclusive cross section of top quark pair production in association with a Z boson using proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC is performed. The data sample corresponds to an integrated luminosity of 77.5 fb−1, collected by the CMS experiment during 2016 and 2017. The measurement is performed using final states containing three or four charged leptons (electrons or muons), and the Z boson is detected through its decay to an oppositely charged lepton pair. The production cross section is measured to be σ( mathrm{t}overline{mathrm{t}}mathrm{Z} ) = 0.95 ± 0.05 (stat) ± 0.06 (syst) pb. For the first time, differential cross sections are measured as functions of the transverse momentum of the Z boson and the angular distribution of the negatively charged lepton from the Z boson decay. The most stringent direct limits to date on the anomalous couplings of the top quark to the Z boson are presented, including constraints on the Wilson coefficients in the framework of the standard model effective field theory.

Inclusive neutrino-nucleus reaction cross sections at intermediate energies

Inclusive neutrino-nucleus reaction cross sections at intermediate energies (20 MeV &lt; Ey &lt; 500 MeV) are calculated throughout the periodic table for the most interesting nu­ clei from an experimental point of view. The method used had previously proved to be very accurate in calculating the induced reaction cross section for T=0 light nuclei (12C and 16O) and in the study of other similar processes like the ordinary muon capture. The electron-neutrino (ve) cross section weighted by the Michel distribution is also discussed in conjuction with the existing experimental results at LAMPF and ΚARMEN.

Neutrino - Nucleus Reaction Cross Sections at Low and Intermediate Energies

Neutrino-nucleus reactions at low and intermediate energies up to Ev=500 MeV are investigated for the most interesting nuclei from an experimental point of view. We mainly focus on calculations of neutrino-nucleus cross sections for semi-inclusive processes, for which recent measurements from radiochemical experiments at LAMPF and KARMEN have been obtained. Inclusive cross sections are also calculated and discussed. The method employed uses the Lindhard function for the description of the particle-hole excitations of the final nucleus via a local density approximation.