We present results on the production of high transverse momentum pizero and eta mesons in pp and pBe interactions at 530 and 800 GeV/c. The data span the kinematic ranges: 1 < p_T < 10 GeV/c in transverse momentum and 1.5 units in rapidity. The inclusive pizero cross sections are compared with next-to-leading order QCD calculations and to expectations based on a phenomenological parton-k_T model.
Invariant differetrial cross sections/nucleon for the inclusive reaction p Be --> pi0 X at 530 and 800 GEV, averaged over the c.m. rapidity interval -0.75 to 0.75 and -1.0 to 0.5 respectively.
Invariant differetrial cross sections/nucleon for the inclusive reaction p p --> pi0 X at 530 and 800 GEV, averaged over the c.m. rapidity interval -0.75 to 0.75 and -1.0 to 0.5 respectively.
The averaged invariant differential cross section/nucleon as a function of rapidity in the PT intervals 1.0-1.5, 1.5-2.0 and 2.0-2.5 GeV for the inclusive reaction p BE --> pi0 X at 530 and 800 GeV GeV.
We report on a study of inclusive particle production in pp-interactions at 400 GeV/c. The data are based on 472 K reconstructed events recorded in the NA 27 experiment using the LEBC-EHS facility at CERN. The production cross sections are determined of pseudo scalar (π±,0, η andK±), scalar (f0(975)), vector (ρ±,0(770), ω(783), ϕ(1020),K*0(892), and\(\bar K^{ * 0} \)(892)), and tensorf0 mesons, of protons and antiprotons, and theΔ++,+,0(1232), and Λ(1520) baryon resonances in the forward hemisphere of the center of mass system, as well as longitudinal and transverse momentum distributions. The results are compared with predictions of the FRITIOF model and with other experimental data.
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Errors are combined statistical and systematic.
Errors are combined statistical and systematic.
Errors are combined statistical and systematic.
Inclusive π 0 and η production at large transverse momentum were studied in both p̄p and pp interactions at √ s = 24.3 GeV. The experiment was performed using an internal molecular hydrogen gas jet target in the CERN SPS collider. No significant differences between production in p̄p and pp were observed in the transverse momentum range 2.5 < P T < 5.1 GeV/ c .
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Cross sections for inclusive π0 production at large transverse momentum pT were measured in π−p, π+p, and pp collisions at 300 GeV/c. The cross-section ratio σ(π−p→π0X)/σ(π+p→π0X) was found to be consistent with unity in the pT region of 1 to 5 GeV/c. The cross-section ratio σ(π+p→π0X)/σ(pp→π0X) however is growing with increasing pT and increasing π0 c.m.-system rapidity in agreement with parton-model expectations, where the partons in the pions have on average higher momenta than in the proton.
THERE IS ALSO A 1 PCT UNCERTAINTY IN THE PT SCALE AND A 7 PCT UNCERTAINTY IN THE NORMALISATION.
We have measured the production of direct photons, π 0 's, and η's in p p and pp collisions at √ s =53 GeV in the range 2≈ p T ≈6 GeV/ c for the central rapidity region | y | 0.4. No statistically significant difference between pp̄ and pp interactions is observed.
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The intermediate and forward gamma detectors of EHS are used to reconstructπ°'s produced by 360 GeV/cpp interactions in the Rapid Cycling Bubble Chamber (RCBC). Using thepp forwardbackward symmetry, the inclusiveπ° production cross section is obtainedσπ°=(132±11) mb. The averageπ° multiplicity is determined as a function of the charged particle multiplicity. The (1−x) dependence is given for differentpT regions.
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Axis error includes +- 4/4 contribution.
The inclusive π0 production cross-section and the η/π0 ratio have been measured inpp collisions at\(\sqrt s= 63 GeV\) at the CERN Intersecting Storage Rings in the rapidity range 2.00<y<2.75. The π0 cross-section exhibits a strongy-dependence and falls more steeply as a function ofpT, compared with the cross-section measured aty∼0. We find a value of 0.46±0.07 for the η/π0 ratio with no significantpT dependence over the range 2.0<pT<4.0 GeV/c.
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We have measured direct photon production in pp collisions at the CERN intersecting storage rings for c.m. energies 31 < √ s < 63 GeV and transverse momenta up to 9GeV/ c , using segmented lead/liquid-argon calorimeters. The ratio of direct photon to π 0 production is significantly larger than zero, starting at p T ≈ 4 GeV/ c and increasing to values of about 0.4 at 9GeV/ c . No significant √s dependence is seen.
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Single photon production in pp collisions at 30 < √ s < 62 GeV has been measured with liquid-argon-lead calorimeters at the CERN ISR. This process remains approximately constant with increasing √ s . For fixed √ s , the single photon to π 0 ratio increases strongly with increase in p T . The γ π 0 ratio is about 0.2 for p T above 4.5 GeV/c.
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Charged- and neutral-particle production from 400-GeV/c pp collisions are measured simultaneously using the Fermilab 15-ft bubble chamber. The π0 and K0 cross sections are rising at Fermilab energies, while the Λ0 cross section remains fairly constant. Similarly, the average number of π0's and K0's increases as a function of the number of negative particles in an event, yet no such dependence is noted for the Λ0's. The ratio of average number of π0 to average number of π− per inelastic collisions is found to be constant at Serpukhov and Fermilab energies (40 to 400 GeV/c) and equal to 1.22±0.02. Cross sections for Σ0 and Σ¯0 production are measured and limits are found for η0 and ω0 production. Neutral- and charged-pion correlations are compared with five pion-production models.
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We have measured the ratio of inclusive production of η to π0 at transverse momenta above 1.5 GeV/c. Results are presented for various meson and proton beams with momenta of 100, 200, and 300 GeV/c incident upon a hydrogen target. The ηπ0 production ratio is found to be independent of incident beam momentum and of the transverse and longitudinal momenta of production. The ratio for pion- and proton-induced reactions is 0.44 ± 0.05; for kaons, it is 0.74 ± 0.12.
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We have measured large-transverse-momentum (p⊥) inclusive π0 production at c.m. angles centered near 90° for π±p and pp interactions at 100 and 200 GeV/c. This is the first such measurement using a pion beam. The ratio σ(pp→π0X)σ(πp→π0X) decreases with increasing p⊥ and is independent of energy when expressed as a function of x⊥=p⊥pmax. We compare the data with predictions of various models.
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We present a study of the transverse momentum spectrum of π 0 's produced at c.m. angles θ = 90° and 53° in pp collisions at √ s = 23.6, 30.8, 45.1, 53.2, and 62.9 GeV. The experiment was performed with a lead-glass detector. The data can be described with the usual parametrization p T −n ƒ;(x T , θ) , with n = 7.2 ± 0.2. Comparison between the 90° and 53° data further indicates no appreciable dependence on θ , at least for x T < 0.3. Two-particle inclusive cross sections for π 0 's produced alongside are also presented. They are observed to have a dependence upon the transverse momentum of the dipion similar to that of single-particle cross sections and with the same value of n . Two-photon decays of η mesons are observed between 3 and 4 GeV/ c transverse momentum with a production cross section half of that of π 0 .
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