Hadron Production Properties Research Articles

Measurements of π±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi ^\\pm $$\\end{document}, K±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^\\pm $$\\end{document}, p and p¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\bar{p}$$\\end{document} spectra in 40Ar+45Sc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{40}\\hbox {Ar+}^{45}\\hbox {Sc}$$\\end{document} collisions at 13A to 150A GeV/c\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts}

The NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the onset of deconfinement in strongly interacting matter through a beam energy scan of particle production in collisions of nuclei of varied sizes. This paper presents results on inclusive double-differential spectra, transverse momentum and rapidity distributions and mean multiplicities of π±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi ^\\pm $$\\end{document}, K±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^\\pm $$\\end{document}, p and p¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\bar{p}$$\\end{document} produced in 40Ar+45Sc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{40}\\hbox {Ar+}^{45}\\hbox {Sc}$$\\end{document} collisions at beam momenta of 13A, 19A, 30A, 40A, 75A and 150A GeV/c\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{ Ge }\\hspace{-1.00006pt}\ ext{ V }\\!/\\!c$$\\end{document}. The analysis uses the 10% most central collisions, where the observed forward energy defines centrality. The energy dependence of the K±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^\\pm $$\\end{document}/π±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi ^\\pm $$\\end{document} ratios as well as of inverse slope parameters of the K±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^\\pm $$\\end{document} transverse mass distributions are placed in between those found in inelastic p+p\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p+p$$\\end{document} and central Pb + Pb collisions. The results obtained here establish a system-size dependence of hadron production properties that so far cannot be explained either within statistical or dynamical models.

NA61/SHINE Overview

NA61/SHINE is a multipurpose fixed-target experiment at the CERN Super Proton Synchrotron. The main goals of the NA61/SHINE strong interaction program are to discover the critical point of strongly interacting matter as well as to study the properties of produced particles relevant for the study of the onset of deconfinement – the transition between the state of hadronic matter and the quark-gluon plasma. An analysis of hadron production properties is performed in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy and size of the colliding nuclei to achieve these goals. The NA61/SHINE results from a strong interaction measurement program are presented. In particular, the latest results from different reactions Ar+Sc, Xe+La, and Pb+Pb on hadron spectra and fluctuations are discussed. Additionally, the recent measurements of kaon production in Ar+Sc collisions at √SNN = 11.94 GeV are mentioned. The NA61/SHINE results are compared with worldwide experiments and predictions of various models, like EPOS, PHSD, UrQMD, and others.

Highlights from the NA61/SHINE

NA61/SHINE is a multipurpose fixed-target facility at the CERN Super Proton Synchrotron. The main goals of the NA61/SHINE stronginteractions program are to discover the critical point of strongly interacting matter as well as to determine the properties of produced particles relevant for the study of the onset of deconfinement - the transition between the state of hadronic matter and the quark-gluon plasma. An analysis of hadron production properties is performed in nucleus-nucleus, proton-proton, and proton-nucleus interactions as a function of collision energy and size of the colliding nuclei to achieve these goals. The selected NA61/SHINE results from this program are presented. In particular, the latest results from different reactions p+p, Be+Be, Ar+Sc, and Pb+Pb on hadron spectra and fluctuations are discussed. The NA61/SHINE results are compared with worldwide experiments and predictions from various theoretical models, like EPOS, PHSD, UrQMD, and others.

Results on system size dependence of strangeness production in the CERN SPS energy range from NA61/SHINE

NA61/SHINE is a multipurpose fixed-target facility at the CERN Super Proton Synchrotron. The main goals of the NA61/SHINE strong interactions program are to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. To reach these goals, hadron production measurements are performed in the form of a two-dimensional scan by varying collision energy and system size. The Collaboration has recently finished data acquisition for its original program on strong interactions, accumulating broad data samples on hadron production in various systems in the SPS energy range. In this contribution, the NA61/SHINE results on identified charged kaon and pion production in p+p, Be+Be and Ar+Sc collisions at the SPS energy range (√SNN = 5.1 - 17.3 GeV) are presented. The NA61/SHINE measurements of small and intermediate-mass ion collisions establish an interesting system size dependence, showing a rapid change of hadron production properties that starts when moving from Be+Be to Ar+Sc system. In particular, Ar+Sc is the smallest system for which a significant enhancement of K+/π+ ratio with respect to p+p collisions is observed. Obtained energy and system size dependence of the measured charged hadron multiplicities are compared with available world data and various theoretical models.

Highlights from the NA61/SHINE strong-interactions programme

NA61/SHINE is a multipurpose fixed-target facility at the CERN SPS. The main goals of the NA61/SHINE strong-interactions programme are to discover the critical point of strongly interacting matter as well as to study the properties of the onset of deconfinement. In order to reach these goals, a study of hadron production properties is performed in nucleus-nucleus, proton-proton and proton-nucleus interactions as a function of collision energy and size of the colliding nuclei. In this contribution, the NA61/SHINE results from a strong interaction measurement programme are presented. In particular, the latest results from different reactions p+p, Be+Be, Ar+Sc, and Pb+Pb on hadron spectra, as well as intermittency, higher-order moments of multiplicity fluctuations and spectator induced electromagnetic effects are discussed.

Production of light-flavor hadrons in pp collisions at sqrt{s}~=~7text { and }sqrt{s} = 13 , text { TeV}

The production of pi ^{pm }, mathrm{K}^{pm }, mathrm{K}^{0}_{S}, mathrm{K}^{*}(892)^{0}, mathrm{p}, phi (1020), Lambda , Xi ^{-}, Omega ^{-}, and their antiparticles was measured in inelastic proton–proton (pp) collisions at a center-of-mass energy of sqrt{s} = 13 TeV at midrapidity (|y|<0.5) as a function of transverse momentum (p_{mathrm{T}}) using the ALICE detector at the CERN LHC. Furthermore, the single-particle p_{mathrm{T}} distributions of mathrm{K}^{0}_{S}, Lambda , and overline{Lambda } in inelastic pp collisions at sqrt{s} = 7 TeV are reported here for the first time. The p_{mathrm{T}} distributions are studied at midrapidity within the transverse momentum range 0le p_{mathrm{T}}le 20 GeV/c, depending on the particle species. The p_{mathrm{T}} spectra, integrated yields, and particle yield ratios are discussed as a function of collision energy and compared with measurements at lower sqrt{s} and with results from various general-purpose QCD-inspired Monte Carlo models. A hardening of the spectra at high p_{mathrm{T}} with increasing collision energy is observed, which is similar for all particle species under study. The transverse mass and x_{mathrm{T}}equiv 2p_{mathrm{T}}/sqrt{s} scaling properties of hadron production are also studied. As the collision energy increases from sqrt{s} = 7–13 TeV, the yields of non- and single-strange hadrons normalized to the pion yields remain approximately constant as a function of sqrt{s}, while ratios for multi-strange hadrons indicate enhancements. The p_mathrm{{T}}-differential cross sections of pi ^{pm }, mathrm {K}^{pm } and mathrm {p} (overline{mathrm{p}}) are compared with next-to-leading order perturbative QCD calculations, which are found to overestimate the cross sections for pi ^{pm } and mathrm{p} (overline{mathrm{p}}) at high p_mathrm{{T}}.

NA61/SHINE experiment at CERN SPS: Recent results, current status and perspectives

The NA61/SHINE experiment at the CERN SPS studies hadron production properties in hadron-nucleus and nucleus-nucleus collisions. Recent results from p+p, Be+Be and Ar+Sc interactions provide new data on the system size and energy dependence of hadron multiplicities, spectra and fluctuations. In particular, they indicate a threshold for formation of large clusters interpreted as the onset of fireball. A scaled-factorial-moment analysis of the proton density fluctuations in Ar+Sc collisions at 150A GeV/c shows an intermittency signal, which may be a first trace of critical behavior. The main objective of the future NA61/SHINE program is to obtain high-precision data on charm hadron production. This new program is planed to start in 2021, after the Long Shutdown 2 of the CERN accelerators. It requires significant upgrades of the NA61/SHINE detectors in order to increase the data readout rate tenfold.

Recent results of strong interaction program from NA61/SHINE experiment at CERN SPS

The NA61/SHINE experiment at the CERN SPS pursues a rich program of strong interactions. The main physics goals of this program are the study of properties of the onset of deconfinement and search for the signatures of the critical point of strongly interacting matter by performing the two-dimensional scan in a broad region of energy (beam momentum 13A-158A GeV/c) and system size (p+p, Be+Be, Ar+Sc and Xe+La). Recent NA61/SHINE results on particle spectra and event-by-event fluctuations in p+p, Be+Be and Ar+Sc collisions are shown with emphasis on the measurements of particle ratios, namely of pion a strangeness production, multiplicity fluctuations versus energy and the system size of colliding nuclei. It will be shown that the hadron production properties in heavy ion collisions which change rapidly in the low SPS energy domain and are interpreted as the beginning of quark-gluon plasma production – onset of deconfinement could be also the case in inelastic p+p interactions and probably in Be+Be collisions. The paper presents a selection of NA61/SHINE results on particle production properties discussed together with existing data from the NA49 collaboration. The evolution of non-monotonic structures in the pion and strangeness production as a function of the system size and energy is addressed. The rapid change of hadron production properties from p+p and Be+Be up to Ar+Sc and Pb+Pb collisions can be interpreted as the beginning of the large clusters formation of strongly interacting matter - the onset of fireball. The NA61/SHINE strong interaction programme is presented including the recent status on proton intermittency analysis and strongly intensive fluctuation observables of particle multiplicity and transverse momentum.

Overview of Results from NA61/SHINE: Uncovering Critical Structures

NA61/SHINE is a multi-purpose experiment to study hadron–proton, hadron–nucleus and nucleus–nucleus collisions at the CERN Super Proton Synchrotron. The experiment performs unique measurements for physics of strong interactions as well as important reference measurements for neutrino and cosmic-ray physics. The results from the strong interaction programme uncover rapid changes in collision-energy and system-size dependence of basic hadron production properties—the critical structures. They are attributed to the onset of deconfinement, onset of fireball and may indicate the critical point of strongly interacting matter.

Heavy ion physics at LHCb

The LHCb detector, with its excellent momentum resolution and particle identification, is ideally suited for measuring heavy quark hadron and quarkonium production properties. Recent LHCb measurements of charmonium and open charm production in several configurations of proton-nucleus collisions are presented.

Recent Results and the Future of the NA61/SHINE Strong Interactions Program

NA61/SHINE is a fixed target experiment at the CERN Super-Proton- Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and study the properties of the onset of deconfnement. In order to reach these goals the collaboration studies hadron production properties in nucleus-nucleus, proton-proton and proton-nucleus interactions. In this talk, recent results on particle production in p+p interactions, as well as Be+Be and Ar+Sc collisions in the SPS energy range are reviewed. The results are compared with available world data. The future of the NA61/SHINE scientifc program is also presented.

On Strangeness in NA61/SHINE

NA61/SHINE is a fixed target experiment at the CERN Super-Proton- Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and to study the properties of the onset of deconfinement. In order to reach these goals, a study of hadron production properties is performed in nucleus-nucleus, proton-proton and proton-nucleus interactions as a function of collision energy and size of the colliding nuclei. In this paper, I will review recent results on strangeness production in p+p, Be+Be and Ar+Sc collisions in the SPS energy range. Kinematic spectra and mean multiplicities of kaons obtained with various analysis methods will be shown. An overview of strangeness production and its dependence on system size in the vicinity of the phase transition will be presented as well.

Neutral meson production in pp, p–Pb and Pb–Pb collisions with ALICE at the LHC

The ALICE experiment is mainly devoted to the study of QGP expected to be created in heavy-ion collisions at the LHC. In the early stage of such collisions, partons can be scattered and photons can be produced in energetic hard processes. High energy partons will interact with the QGP, and from the measurement of the particles originated from the parton fragmentation in vacuum, one can infer transport properties of the QGP. Therefore, study of high-pT hadrons production is important to constrain the properties of the hot and dense medium. The strong suppression of the high-pT hadrons in heavy-ion collisions has been explained by the energy loss of the partons in medium and it can be investigated experimentally via the nuclear modification factor of hadrons.ALICE measured neutral mesons (π0 and η) at mid-rapidity in a wide pT range in pp, p-Pb and Pb-Pb collisions. Neutral mesons are reconstructed via complementary methods, using the electromagnetic calorimeters, PHOS and EMCal, and by the central tracking system, identifying photons converted to e+e− pairs in the material of the inner barrel detectors (ITS and TPC). Measurement of neutral meson spectra in pp collisions at s=0.9,2.76,7 and 8 TeV provides valuable comparison data for pQCD calculations and allows to study scaling properties of hadron production at the LHC energies. The study of neutral mesons production in p-Pb collisions helps to disentangle initial and final state effects on the suppression itself. The latest results of neutral meson measurement in pp, p-Pb and Pb-Pb collisions will be shown in this paper.

Fluctuations in the Statistical Model of the Early Stage of Nucleus--Nucleus Collisions

Predictions on fluctuations of hadron production properties in central heavy ion collisions are presented. They are based on the Statistical Model of the Early Stage and extend previously published results by considering the strongly intensive measures of fluctuations. In several of the considered cases a significant change in collision energy dependence of calculated quantities as a result of the phase transition is predicted. This provides an opportunity to observe new signals of the onset of deconfinement in heavy ion collisions experiments.

Studies of Inclusive Hadron Production at BABAR

The clean environment of the e+e- collisions provided by the B-factory PEP-II and the high performances of the BABAR detector allow for precise measurements of the properties of inclusive hadron production. We present recent results obtained using the full data sample of nearly 500 fb-1 on measurements of the inclusive light hadrons momentum spectra, and on anti-deuteron production from decays of bottomonium states, and from continuum e+e- annihilation. We also present a measurement of the azimuthal asymmetries induced by the Collins effect in inclusive production of pion pairs in e+e- → ππX annihilation, where the two pions are produced in opposite hemispheres.

Properties of inclusive hadron production in deep inelastic scattering on heavy nuclei at lowx

In this paper we present a comprehensive study of inclusive hadron production in DIS at low $x$. Properties of the hadron spectrum are different in different kinematic regions formed by three relevant momentum scales: photon virtuality $Q^2$, hadron transverse momentum $k_T$ and the saturation momentum $Q_s(x)$. We investigate each kinematic region and derive the corresponding asymptotic formulas for the cross section at the leading logarithmic order. We also analyze the next-leading-order (NLO) corrections to the BFKL kernel that are responsible for the momentum conservation. In particular, we establish the asymptotic behavior of the forward elastic dipole--nucleus scattering amplitude at high energies deeply in the saturation regime and a modification of the pomeron intercept. We study the nuclear effect on the inclusive cross section using the nuclear modification factor and its logarithmic derivative. We argue that the later is proportional to the difference between the anomalous dimension of the gluon distribution in nucleus and in proton and thus is a direct measure of the coherence effects. To augment our arguments and present quantitative results we performed numerical calculations in the kinematic region that may be accessible by the future DIS experiments.

Strongly intensive quantities

Analysis of fluctuations of hadron production properties in collisions of relativistic particles profits from use of measurable intensive quantities which are independent of system size variations. They are referred to as strongly intensive quantities. The first family of such quantities was proposed already in 1992. The second is introduced in this paper. We also present a proof of independence of volume fluctuations for quantities from both families within the framework of statistical mechanics.

Underlying events inp + pcollisions at LHC energies

General properties of hadron production are investigated in proton-proton collisions at LHC energies. We are interested in the characteristics of hadron production outside the identified jet cones. We improve earlier definitions and introduce surrounding rings/belts around the cone of identified jets. In this way even multiple jet events can be studied in details. We define the underlying event as collected hadrons from outside jet cones and outside surrounding belts, and investigate the features of these hadrons. We use a PYLHIA generated data sample of proton-proton collisions at √s = 7 TeV. This data sample is analysed by our new method and the widely applied CDF method. Angular correlations and momentum distributions have been studied and the obtained results are compared and discussed.

Ion program of NA61/SHINE at the CERN SPS

The NA61/SHINE experiment at the CERN SPS aims to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. These goals will be reached by measurements of hadron production properties in nucleus–nucleus, proton–proton and proton–lead interactions as a function of collision energy and size of the colliding nuclei. Furthermore, NA61/SHINE will perform numerous precision measurements needed for neutrino (T2K) and cosmic-ray (Pierre Auger Observatory and KASCADE) experiments. This paper summarizes physics arguments for the NA61/SHINE ion program and presents the status and plans of the experiment.

Scaling properties of high pT inclusive hadron production

We analyze the scaling properties of inclusive hadron production in proton-proton and in heavy ion collisions from fixed target to collider energies. At large transverse momentum p{sub T}, the invariant cross section exhibits a power-like behavior Ed{sup 3}{sigma}/d{sup 3}p {proportional_to} p{sub T}{sup -n} at fixed transverse x, x{sub T} = 2|{bar p}{sub T}|/{radical}s, and fixed center-of-mass scattering angle {theta}{sub cm}. Knowledge of the exponent n allows one to draw conclusions about the production mechanisms of hadrons, which are poorly known, even at high p{sub T}. We find that high-p{sub T} hadrons are produced by different mechanisms at fixed-target and collider energies. For pions, higher-twist subprocesses where the pion is produced directly dominate at fixed target energy, while leading-twist partonic scattering plus fragmentation is the most important mechanism at collider energies. High-p{sub T} baryons on the other hand appear to be produced by higher-twist mechanisms at all available energies. The higher-twist mechanism of direct proton production can be verified experimentally by testing whether high p{sub T} protons are produced as single hadrons without accompanying secondaries. In addition, we find that medium-induced gluon radiation in heavy ion collisions can violate scaling.