Deep inelastic electron-photon scattering is studied in the Q**2 range from 1.2 to 30 GeV**2 using the LEP1 data taken with the ALEPH, L3 and OPAL detectors at centre-of-mass energies close to the mass of the Z boson. Distributions of the measured hadronic final state are corrected to the hadron level and compared to the predictions of the HERWIG and PHOJET Monte Carlo models. For large regions in most of the distributions studied the results of the different experiments agree with one another. However, significant differences are found between the data and the models. Therefore the combined LEP data serve as an important input to improve on the Monte Carlo models.
The individual differential cross sections (DSIG/DW) in the low Q**2 regions for the three experiments.. The data are corrected using the HERWIG-kt model.
The combined differential cross sections (DSIG/DW) separately for the low and high Q**2 regions. The data are corrected using the HERWIG-kt model.
The combined differential cross sections (DSIG/DW) separately for the low and high Q**2 regions. The data are corrected using the PHOJET model.
The inclusive production of D$^{*\pm}$ mesons in two-photon collisions is measured with the ALEPH detector at $\epem$ centre-of-mass energies from 183$\unit{GeV}$ to 209$\unit{GeV}$. A total of $360 \pm 27$ D$^{*\pm}$ meson events were observed from an integrated luminosity of 699\unit{pb^{-1}}$. Contributions from direct and single-resolved rocesses are separated using the ratio of the transverse momentum $p_{\rm t}^{\rm D^{*\pm}}$ of the D$^{*\pm}$ to the visible invariant mass $W_{\mathrm{vis}}$ of the event. Differential cross sections of D$^{*\pm}$ production as functions of $p_{\rm t}^{\rm D^{*\pm}}$ and the pseudorapidity $|\eta^{\rm D^{*\pm}}| $ are measured in the range $ 2\unit{GeV}/c < p_{\rm t}^{\rm D^{*\pm}} < 12\unit{GeV}/c $ and $ |\eta^{\rm D^{*\pm}}| < 1.5 $. They are compared to next-to-leading order (NLO)perturbative QCD calculations. The extrapolation of the integrated visible D$^{*\pm}$ cross section to the total charm cross section, based on the Pythia Monte Carlo program, yields $ \sigma (\epem \to \epem \ccbar)_ {=197\unit{GeV}} = 731 \pm 74_{\mathrm{stat}} \pm 47_{\mathrm{syst}} \pm 157_{\mathrm{extr}} \unit{pb} $.
Total extrapolated charm production cross section. The second DSYS error isdue to the uncertainty in the extrapolation.
Visible cross section with the acceptance range.
Visible cross section within the acceptance ranges for the three decay modes observed.
Measurements of the inclusive cross-sections forK0 and Λ production in hadronic decays of the Z are presented together with measurements of two-particle correlations within pairs of Λ andK0. The results are compared with predictions from the hadronization models Jetset, based on string fragmentation, and Herwig, based on cluster decays. TheK0 spectrum is found to be harder than predicted by both models, while the Λ spectrum is softer than predicted. The correlation measurements are all reproduced well by Jetset, while Herwig misses some of the qualitative features and overestimates the size of the\(\Lambda \bar \Lambda \) correlation. Finally, the possibility of Bose-Einstein correlation in theKS0KS0 system is discussed.
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Inclusive charged particle distribution as a function of XP.
Inclusive charged particle distribution as a function of rapidity (YRAP).
Inclusive charged particle distribution as a function of PT in the event plane.
The $p_{\rm T}$-differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D$^0$, D$^+$, and D$^{*+}$ in the rapidity range $|y|<0.5$, and for transverse momentum $1< p_{\rm T} <12$ GeV/$c$, were measured in proton-proton collisions at $\sqrt{s} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. The analysis exploited the hadronic decays D$^0 \rightarrow $K$\pi$, D$^+ \rightarrow $K$\pi\pi$, D$^{*+} \rightarrow $D$^0\pi$, and their charge conjugates, and was performed on a $L_{\rm int} = 1.1$ nb$^{-1}$ event sample collected in 2011 with a minimum-bias trigger. The total charm production cross section at $\sqrt{s} = 2.76$ TeV and at 7 TeV was evaluated by extrapolating to the full phase space the $p_{\rm T}$-differential production cross sections at $\sqrt{s} = 2.76$ TeV and our previous measurements at $\sqrt{s} = 7$ TeV. The results were compared to existing measurements and to perturbative-QCD calculations. The fraction of cdbar D mesons produced in a vector state was also determined.
Production cross section in |y| < 0.5 for prompt D0, D+, and D*+ mesons in pp collisions at sqrt(s) = 2.76 TeV, in transverse momentum intervals. The second (sys) error is the uncertainty on the respective branching ratios.
Visible production cross sections of prompt D mesons for |y|<0.5 in pp collisions at sqrts=2.76 and 7 TeV. The normalization systematic uncertainty of 1.9% (3.5%) at sqrts=2.76 (7) TeV and the decay BR uncertainties are not quoted here.
Production cross sections dsig/dy of D mesons, integrated over all pt for |y|<0.5. The second (sys) error is the from the luminosity uncertainty, the third from the branching-ratio uncertainties and the fourth is from the extrapolation uncertainty.
The production of muons from heavy flavour decays is measured at forward rapidity in proton-proton collisions at $\sqrt{s} = 7$ TeV collected with the ALICE experiment at the LHC. The analysis is carried out on a data sample corresponding to an integrated luminosity $L_{\rm int} = 16.5$ nb$^{-1}$. The transverse momentum and rapidity differential production cross sections of muons from heavy flavour decays are measured in the rapidity range 2.5 < y < 4, over the transverse momentum range 2 < $p_{\rm T}$ < 12 GeV/$c$. The results are compared to predictions based on perturbative QCD calculations.
pT-differential production cross section of muons from heavy flavour decays, in the rapidity range 2.5<y<4.
y-differential production cross section of muons from heavy flavour decays, in the range 2<pT<12 GeV/C.
pT-differential production cross section of muons from heavy flavour decays, in the rapidity range 2.5<y<2.8.
The $p_{\rm T}$-differential inclusive production cross sections of the prompt charmed mesons $D^0$, $D^+$, and $D^{*+}$ in the rapidity range |y|<0.5 were measured in proton-proton collisions at $\sqrt{s} = 7$ TeV at the LHC using the ALICE detector. Reconstructing the decays $D^0\rightarrow K^-\pi^+$, $D^+\rightarrow K^-\pi^+\pi^+$, $D^{*+}\rightarrow D^0\pi^+$, and their charge conjugates, about 8,400 $D^0$, 2,900 $D^+$, and 2,600 $D^{*+}$ mesons with 1<$p_{\rm T}$<24 GeV/$c$ were counted, after selection cuts, in a data sample of 3.14x10$^8$ events collected with a minimum-bias trigger (integrated luminosity $L_{\rm int}$ = 5/nb). The results are described within uncertainties by predictions based on perturbative QCD.
Differential cross section for prompt D0 production.
Differential cross section for prompt D0 production.
Differential cross section for prompt D+ production.
The ALICE Collaboration has measured the inclusive production of muons from heavy flavour decays at forward rapidity, 2.5 < y < 4, in pp and Pb-Pb collisions at $\sqrt {s_{NN}}$ = 2.76 TeV. The $p_{\rm T}$-differential inclusive cross section of muons from heavy flavour decays in pp collisions is compared to perturbative QCD calculations. The nuclear modification factor is studied as a function of pt and collision centrality. A weak suppression is measured in peripheral collisions. In the most central collisions, a suppression of a factor of about 3-4 is observed in 6 < $p_{\rm T}$ < 10 GeV/$c$. The suppression shows no significant $p_{\rm T}$ dependence.
Transverse momentum differential inclusive cross section of muons from heavy-flavour decays in the rapidity range 2.5-4.
RAA of muons from heavy-flavour decays in the rapidity range 2.5-4 as a function of PT in the 0-10% and 40-80% centrality classes. The second (sys) error is the separate normalization error for each class.
RAA of muons from heavy-flavour decays as a function of the mean number of participating nucleons, NPART, in the rapidity range 2.5-4.0 and PT 6-10 GeV. The first (sys) error is the correlated systematic error and the second is the uncorrelated systematic error.
We present cross section measurements for inclusive jet production in almost-real photon-photon interactions at TRISTAN using the AMY detector. The results are compared with leading-order QCD calculations for different parameterizations of the parton density in the photon.
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The prompt and non-prompt production cross-sections for the chi_c1 and chi_c2 charmonium states are measured in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector at the LHC using 4.5 fb^-1 of integrated luminosity. The chi_c states are reconstructed through the radiative decay chi_c -> J/psi gamma (with J/psi -> mu+mu-) where photons are reconstructed from gamma -> e+e- conversions. The production rate of the chi_c2 state relative to the chi_c1 state is measured for prompt and non-prompt chi_c as a function of J/psi transverse momentum. The prompt chi_c cross-sections are combined with existing measurements of prompt J/psi production to derive the fraction of prompt J/psi produced in feed-down from chi_c decays. The fractions of chi_c1 and chi_c2 produced in b-hadron decays are also measured.
Differential cross-section for prompt chi_c1 production, measured in bins of J/psi pT, assuming unpolarised chi_c production. The measurements are not corrected for the branching fractions of the decays chi_c --> J/psi + gamma and J/psi --> mu+ mu-. The uncertainty envelope associated with the unknown chi_c spin alignment is also shown.
Differential cross-section for prompt chi_c2 production, measured in bins of J/psi pT, assuming unpolarised chi_c production. The measurements are not corrected for the branching fractions of the decays chi_c --> J/psi + gamma and J/psi --> mu+ mu-. The uncertainty envelope associated with the unknown chi_c spin alignment is also shown.
Differential cross-section for non-prompt chi_c1 production, measured in bins of J/psi pT, assuming unpolarised chi_c production. The measurements are not corrected for the branching fractions of the decays chi_c --> J/psi + gamma and J/psi --> mu+ mu-. The uncertainty envelope associated with the unknown chi_c spin alignment is also shown.
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