The pseudorapidity density and multiplicity distribution of charged particles produced in proton-proton collisions at the LHC, at a centre-of-mass energy $\sqrt{s} = 7$ TeV, were measured in the central pseudorapidity region |$\eta$| < 1. Comparisons are made with previous measurements at $\sqrt{s}$ = 0.9 TeV and 2.36 TeV. At $\sqrt{s}$ = 7 TeV, for events with at least one charged particle in |$\eta$| < 1, we obtain dNch/deta = 6.01 $\pm$ 0.01 (stat.) $^{+0.20}_{-0.12}$ (syst.). This corresponds to an increase of 57.6% $\pm$ 0.4% (stat.) $^{+3.6}_{-1.8}$% (syst.) relative to collisions at 0.9 TeV, significantly higher than calculations from commonly used models. The multiplicity distribution at 7 TeV is described fairly well by the negative binomial distribution.
Charged-particle pseudorapidity densities at central pseudorapidity (ETRAP from -1.0 to 1.0) for the INEL>0 class of events. Data are also given for the lower energy ALICE data.
Relative increase in pseudorapidity density between the different energies.
Multiplicity distribution normalized to the bin width in the pseudorapidity region -1.0 to 1.0 for INEL>0 collisions at a centre-of-mass energy of 7000 GeV. See the paper arXiv:1004.3034 for the lower energy data. Note that the statistical as well as the systematic uncertainties are strongly correlated between neighbouring points. See text of paper for details.
Charged-particle pseudorapidity densities are presented for the d+Au reaction at sqrt{s_{NN}}=200 GeV with -4.2 <= eta <= 4.2$. The results, from the BRAHMS experiment at RHIC, are shown for minimum-bias events and 0-30%, 30-60%, and 60-80% centrality classes. Models incorporating both soft physics and hard, perturbative QCD-based scattering physics agree well with the experimental results. The data do not support predictions based on strong-coupling, semi-classical QCD. In the deuteron-fragmentation region the central 200 GeV data show behavior similar to full-overlap d+Au results at sqrt{s_{NN}}=19.4 GeV.
$\frac{\mathrm{d}N}{\mathrm{d}\eta}$ versus $\eta$ for $x^{\pm}$ in $\mathrm{d}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=200\,\mathrm{Ge\!V}$ for $0-30$% central, $30-60$% central, $60-80$% central, Min.Bias
We present charged particle densities as a function of pseudorapidity and collision centrality for the 197Au+197Au reaction at Sqrt{s_NN}=200 GeV. For the 5% most central events we obtain dN_ch/deta(eta=0) = 625 +/- 55 and N_ch(-4.7<= eta <= 4.7) = 4630+-370, i.e. 14% and 21% increases, respectively, relative to Sqrt{s_NN}=130 GeV collisions. Charged-particle production per pair of participant nucleons is found to increase from peripheral to central collisions around mid-rapidity. These results constrain current models of particle production at the highest RHIC energy.
$\mathrm{d}N/\mathrm{d}\eta$ versus $\eta$ for $x^{\pm}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=200\,\mathrm{Ge\!V}$ for $0-5$% central, $5-10$% central, $10-20$% central, $20-30$% central, $30-40$% central, $40-50$% central
$\mathrm{d}N/\mathrm{d}\eta$ versus $\eta$ for $x^{\pm}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=200\,\mathrm{Ge\!V}$ for $0-5$% central, $5-10$% central, $10-20$% central, $20-30$% central, $30-40$% central, $40-50$% central
$\mathrm{d}N/\mathrm{d}\eta$ versus $\eta$ for $x^{\pm}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=200\,\mathrm{Ge\!V}$ for $0-5$% central, $5-10$% central, $20-30$% central, $40-50$% central
We present charged particle densities as a function of pseudorapidity and collision centrality for the 197Au+197Au reaction at sqrt{s_{NN}}=130 GeV. An integral charged particle multiplicity of 3860+/-300 is found for the 5% most central events within the pseudorapidity range -4.7 <= eta <= 4.7. At mid-rapidity an enhancement in the particle yields per participant nucleon pair is observed for central events. Near to the beam rapidity, a scaling of the particle yields consistent with the ``limiting fragmentation'' picture is observed. Our results are compared to other recent experimental and theoretical discussions of charged particle densities in ultra-relativistic heavy-ion collisions.
NPART, $\mathrm{d}N/\mathrm{d}\eta$, $N_{\mathrm{ch}}^{\mathrm{tot}}$ versus $\mathrm{Centrality}$ for $x^{\pm}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=130\,\mathrm{Ge\!V}$
$\mathrm{d}N/\mathrm{d}\eta$ versus $\eta$ for $x^{\pm}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=130\,\mathrm{Ge\!V}$
$\mathrm{d}N/\mathrm{d}\eta$ versus $\eta$ for $x^{\pm}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=130\,\mathrm{Ge\!V}$
This study reports the first measurement of the azimuthal decorrelation between jets with pseudorapidity separation up to five units. The data were accumulated using the D\O\ detector during the 1992--1993 collider run of the Fermilab Tevatron at $\sqrt{s}=$ 1.8 TeV. These results are compared to next--to--leading order (NLO) QCD predictions and to two leading--log approximations (LLA) where the leading--log terms are resummed to all orders in $\alpha_{\scriptscriptstyle S}$. The final state jets as predicted by NLO QCD show less azimuthal decorrelation than the data. The parton showering LLA Monte Carlo {\small HERWIG} describes the data well; an analytical LLA prediction based on BFKL resummation shows more decorrelation than the data.
Distribution of the pseudorapidity interval of the two jets at the extremes of pseudorapidity. Data are read from the graph and the errors are statistical only.
Normalized distributions of the azimuthal angle difference of the two jets at the extremes of pseudorapidity in 3 pseudorapididity difference intervals. Data are read from the graph and the errors are statistical only.
The correlation between the PHI and ETARAP difference distributions as used in the analysis.Data are read from the graph and the errors include the statiucal and un-correlated systematic errors added in quadrature.
Central collisions of 800-GeV protons with the heavy components of nuclear emulsion, Ag107 and Br80, have been investigated to determine the characteristics of small-impact-parameter collisions and, by comparison with the analysis of inclusive proton-emulsion inelastic interactions and inelastic proton-nucleon collisions, to study the dependence of the interaction process on the mean number of intranuclear collisions 〈ν〉. The data are also compared with the results obtained in proton-emulsion collisions, both central and inclusive, at 200 GeV. The variations in the secondary-particle multiplicities and the normalized pseudorapidity density correlate with 〈ν〉 and demonstrate that proton-nucleus interactions, both central and inclusive, can be described adequately by the incoherent superposition of proton-nucleon collisions.
NUCLEUS IS AVERAGE NUCLEUS OF EMULSION.
NUCLEUS IS AVERAGE NUCLEUS OF EMULSION.
NUCLEUS IS AVERAGE NUCLEUS OF EMULSION.
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