Using data from the Fermilab 15 ft hydrogen bubble chamber, we have studied inclusive ϱ 0 production in antineutrino-proton charged-current interactions. We measure (0.21 ± 0.03) ϱ 0 /event, corresponding to ϱ 0 / π − =0.12 ± 0.02. As a function of Q 2 and for hadronic masses above a threshold region, the ϱ 0 / π − ratio shows little variation. At least 50% of the ϱ 0 's are consistent with coming from the current fragmentation region. The results agree reasonably well with the predictions of the quark fragmentation model of Feynman and field.
AVERAGE BEAM ENERGY 31 GEV.
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Data from p+p→p+X at 102, 205, and 405 GeV and from π−+p→p+X at 205 GeV exhibit an approximate scaling property in the charged-prong multiplicity distributions as a function of the missing mass for the range 5<~MX<~13 GeV.
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Charged-particle multiplicity distributions in 400-GeV/c pd interactions have been studied in an experiment in the Fermilab 30-inch bubble chamber. From the fractions of odd-prong and backward-proton events, a rescatter fraction of 0.22±0.01 is found (for N≥3). The pn multiplicity distribution is obtained from the odd-prong distribution plus a no-cascade assumption. After making one-prong and two-prong estimates, mean charged-particle multiplicities of 9.49±0.12 for pd (including slow particles) and 8.57±0.12 for pn are obtained. In the incident momentum range 100 to 400 GeV/c, pd and pp distributions are very similar to each other and are different from pn distributions.
Axis error includes +- 0.0/0.0 contribution (?////SHORT PROTON VISIBILITY, UNOBSERVED DALITZ PAIRS, UNOBSERVED VEES, UNOBSERVED CLOSE SECONDARIES, UNCOUNTABLE EVENTSTHE ONE- AND TWO-PRONG EVENTS WERE NOT MEASURED AND WERE ESTIMATED USING ADDITIONAL ASSUMPTIONS AND DATA OF OTHER EXPERIMENTS//TO OBTAIN THE FREE-NEUTRON DISTRIBUTIONS THE ASSUMPTION THAT RESCATTERING IS MULTIPLICITY INDEPENDENT HAS BEEN MADE, AND CORRECTION FOR DEUTERON-FINAL-STATE EVENTS AND FOR WAVE-FUNCTION SYMMETRY REQUIREMENTS HAS BEEN MADE).
Axis error includes +- 0.0/0.0 contribution (?////SHORT PROTON VISIBILITY, UNOBSERVED DALITZ PAIRS, UNOBSERVED VEES, UNOBSERVED CLOSE SECONDARIES, UNCOUNTABLE EVENTSTHE ONE- AND TWO-PRONG EVENTS WERE NOT MEASURED AND WERE ESTIMATED USING ADDITIONAL ASSUMPTIONS AND DATA OF OTHER EXPERIMENTS//TO OBTAIN THE FREE-NEUTRON DISTRIBUTIONS THE ASSUMPTION THAT RESCATTERING IS MULTIPLICITY INDEPENDENT HAS BEEN MADE, AND CORRECTION FOR DEUTERON-FINAL-STATE EVENTS AND FOR WAVE-FUNCTION SYMMETRY REQUIREMENTS HAS BEEN MADE).
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We have measured inclusive distributions for charged particles in hadronic decays of the Z boson. The variables chosen for study were charged-particle multiplicity, scaled momentum, and momenta transverse to the sphericity axes. The distributions have been corrected for detector effects and are compared with data from e+e− annihilation at lower energies and with the predictions of several QCD-based models. The data are in reasonable agreement with expectations.
Mean corrected charged particle multiplicity.
Corrected charged particle X distributions. Errors are statistical and systematic combined.
Corrected charged particle PTIN distributions. Errors are statistical and systematic combined.
Measurements of fiducial cross sections for the electroweak production of two jets in association with a Z-boson are presented. The measurements are performed using 20.3 inverse femtobarns of proton-proton collision data collected at a centre-of-mass energy of sqrt(s)=8 TeV by the ATLAS experiment at the Large Hadron Collider. The electroweak component is extracted by a fit to the dijet invariant mass distribution in a fiducial region chosen to enhance the electroweak contribution over the dominant background in which the jets are produced via the strong interaction. The electroweak cross sections measured in two fiducial regions are in good agreement with the Standard Model expectations and the background-only hypothesis is rejected with significance above the 5 sigma level. The electroweak process includes the vector boson fusion production of a Z-boson and the data are used to place limits on anomalous triple gauge boson couplings. In addition, measurements of cross sections and differential distributions for inclusive Z-boson-plus-dijet production are performed in five fiducial regions, each with different sensitivity to the electroweak contribution. The results are corrected for detector effects and compared to predictions from the SHERPA and POWHEG event generators.
Unfolded normalised differential Z+2j cross section as a function of dijet invariant mass in the baseline region.
Unfolded normalised differential Z+2j cross section as a function of dijet invariant mass in the search region.
Unfolded normalised differential Z+2j cross section as a function of the rapidity separation between the leading jets in the baseline region.
This paper presents measurements of distributions of charged particles which are produced in proton--proton collisions at a centre-of-mass energy of $\sqrt{s} = 8$ TeV and recorded by the ATLAS detector at the LHC. A special dataset recorded in 2012 with a small number of interactions per beam crossing (below 0.004) and corresponding to an integrated luminosity of $160 \mathrm{\mu b^{-1}}$ was used. A minimum-bias trigger was utilised to select a data sample of more than 9 million collision events. The multiplicity, pseudorapidity, and transverse momentum distributions of charged particles are shown in different regions of kinematics and charged-particle multiplicity, including measurements of final states at high multiplicity. The results are corrected for detector effects and are compared to the predictions of various Monte Carlo event generator models which simulate the full hadronic final state.
Central primary-charged-particle density 1/Nev dNch/deta at eta = 0 for five different phase spaces. The results are given for the fiducial definition tau > 300 ps, as well as for the previously used fiducial definition tau > 30 ps using an extrapolation factor of 1.012 +- 0.004 (for pT > 100 MeV) or 1.025 +- 0.008 (for pT > 500 MeV), which accounts for the fraction of charged strange baryons predicted by Epos LHC simulation.
Charged-particle multiplicities in proton-proton collisions at a centre-of mass energy of 8000 GeV as a function of transverse momentum for events with the number of charged particles >=2 having transverse momentum >100 MeV and absolute(pseudorapidity) <2.5.
Charged-particle multiplicities in proton-proton collisions at a centre-of mass energy of 8000 GeV as a function of transverse momentum for events with the number of charged particles >=1 having transverse momentum >500 MeV and absolute(pseudorapidity) <2.5.
Measurements of the production of jets of particles in association with a Z boson in pp collisions at $\sqrt{s}$ = 7 TeV are presented, using data corresponding to an integrated luminosity of 4.6/fb collected by the ATLAS experiment at the Large Hadron Collider. Inclusive and differential jet cross sections in Z events, with Z decaying into electron or muon pairs, are measured for jets with transverse momentum pT > 30 GeV and rapidity |y| < 4.4. The results are compared to next-to-leading-order perturbative QCD calculations, and to predictions from different Monte Carlo generators based on leading-order and next-to-leading-order matrix elements supplemented by parton showers.
The distribution of Inclusive jet multiplicity. The first (sys) error is the uncorrelated systematic error and the second the correlated systematic error.
The distribution of Ratio of cross sections for successive inclusive jet multiplicities n/(n-1). The first (sys) error is the uncorrelated systematic error and the second the correlated systematic error.
The distribution of exclusive jet multiplicity. The first (sys) error is the uncorrelated systematic error and the second the correlated systematic error.
Charged-particle distributions are measured in proton-proton collisions at a centre-of-mass energy of 13 TeV, using a data sample of nearly 9 million events, corresponding to an integrated luminosity of 170 $\mu$b$^{-1}$, recorded by the ATLAS detector during a special Large Hadron Collider fill. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity and the dependence of the mean transverse momentum on the charged-particle multiplicity are presented. The measurements are performed with charged particles with transverse momentum greater than 500 MeV and absolute pseudorapidity less than 2.5, in events with at least one charged particle satisfying these kinematic requirements. Additional measurements in a reduced phase space with absolute pseudorapidity less than 0.8 are also presented, in order to compare with other experiments. The results are corrected for detector effects, presented as particle-level distributions and are compared to the predictions of various Monte Carlo event generators.
The average charged-particle multiplicity per unit of rapidity for ETARAP=0 as a function of the centre-of-mass energy.
The extrapolated average charged-particle multiplicity per unit of rapidity for ETARAP=0 as a function of the centre-of-mass energy.
Measurements of distributions of charged particles produced in proton-proton collisions with a centre-of-mass energy of 13 TeV are presented. The data were recorded by the ATLAS detector at the LHC and correspond to an integrated luminosity of 151 $\mu$b$^{-1}$. The particles are required to have a transverse momentum greater than 100 MeV and an absolute pseudorapidity less than 2.5. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity and the dependence of the mean transverse momentum on multiplicity are measured in events containing at least two charged particles satisfying the above kinematic criteria. The results are corrected for detector effects and compared to the predictions from several Monte Carlo event generators.
The average charged-particle muliplicity per unit of rapidity for ETARAP=0 as a function of the centre-of-mass energy.
The average charged-particle muliplicity per unit of rapidity for ETARAP=0 as a function of the centre-of-mass energy.
The extrapolated ($\tau > 30$ ps) average charged-particle muliplicity per unit of rapidity for ETARAP=0 as a function of the centre-of-mass energy.
We present the multiplicity distributions of the hadrons produced in antineutrinoproton interactions. The data sample, which consists of 2025 charged-current events with antineutrino energy greater than 5 GeV, comes from exposures of the 15-foot hydrogen bubble chamber to the broad-band antineutrino beam at Fermilab. The distribution in hadronic mass W has an average value of 3.7 GeV but extends up to 10 GeV. The mean multiplicity of charged hadrons depends on the hadronic mass W and varies as 〈nch〉=(−0.44±0.13)+(1.48±0.06)lnW2 for W2>4 GeV2. The mean multiplicities for events with three or more charged tracks averaged over the total data sample are 〈n−〉=1.68±0.03 and 〈n0〉=1.11±0.07 for π− and π0 production, respectively. The mean π0 multiplicity is found to increase slowly with n−. The integrated correlation coefficient f2−− and the dispersion D− are given as a function of n−. When compared to the distributions characteristic of other leptonic and hadronic reactions, we find a similarity between the ν¯ data and results from hadronic reactions that have no diffractive component. Multiplicity data for the heavier particles K0, ρ0, and Λ are also summarized. The pion multiplicities in the current fragmentation region exceed those for the target fragmentation at all W values. They also satisfy the isospin relation 2〈n0〉=〈n+〉+〈n−〉 required for the fragmentation of an I=12 quark when a W>4 GeV selection is imposed.
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