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Inclusive cross sections for the production of π ± and K ± mesons in proton-proton collisions have been measured at a c.m. energy √ s = 45 GeV, in the range 0.41 < x < 0.95 and 0.35 < p T < 1.45 GeV, where x = 2 p L/√ s and p L , p T are the longitudinal and transverse components of the momentum of the meson. Within the measured range the p T dependence of the invariant cross section is essentially independent of x and weakly dependent on the type of particle. For all particles the invariant cross sections at fixed p T fall by three orders of magnitude between x = 0.4 and 0.95. Except at the highest values of x and p T , the statistical accuracy is better than 10%. The data are compared with a triple-Regge model and with a simple quark-parton model.
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Invariant single-particle cross sections for pion and proton production in π ± p interactions at 8 and 16 GeV/ c are presented in terms of integrated distributions as functions of x , reduced rapidity ζ and p ⊥ 2 , and also in terms of double differential cross sections E d 2 σ /(d x d p ⊥ 2 ) and d ζ d p ⊥ 2 ). A comparison of π ± and π − induced reactions is made and the energy dependence is discussed. It is shown that the single-particle structure function cannot be factorized in its dependece on transverse and longitudinal momentum. For the beam-unlike pion, there is an indication for factorizability in terms of rapidity and transverse momentum in a small central region.
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Measurements of the production of high transverse momentum direct photons by a 515 GeV/c piminus beam and 530 and 800 GeV/c proton beams in interactions with beryllium and hydrogen targets are presented. The data span the kinematic ranges of 3.5 < p_T < 12 GeV/c in transverse momentum and 1.5 units in rapidity. The inclusive direct-photon cross sections are compared with next-to-leading-order perturbative QCD calculations and expectations based on a phenomenological parton-k_T model.
Invariant cross sections per nucleon for P BE collisions at 800 GeV.
Invariant cross sections per nucleon for P BE collisions at 530 GeV.
Invariant cross sections per nucleon for PI- BE collisions at 515 GeV.
An estimate of the temperature of protons andπ− mesons in central He−Li, He−C, C−C, C−Ne, C−Cu, C−Pb, O−Pb, Mg−Mg interactions is presented. The results indicate an increase of the proton temperature with increasing mass numbers of projectile and target nuclei (Ap,AT) fromTp=(118±3) MeV for He−Li toTp=(141±2) MeV for C−Pb. The temperature ofπ− mesons does not depend onAP,AT andTπ≃95 MeV. A satisfactory fit forπ− mesons in C−Cu, C−Pb, O−Pb, Mg−Mg collisions can be achieved by using a form involving two temperatures,T1 andT2. The relative yield of the high temperature component (T2) is ≅24% for C−Cu, C−Pb, and Mg−Mg interactions. The observed results forTP in C−Ne, C−Cu and C−Pb collisions are consistent with the prediction of the thermodynamic hagedorn model.
for C-CU and C-PB YRAP=0.3-1.7.
THE D(N)/D(PT) distribution has been fitted by the form: PT*ET*K1(SLOPE*ET), where K1 is Mac-Donaldis function. for C-CU and C-PB YRAP=0.3-1.7.
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An experiment using the Fermilab Single Arm Spectrometer (SAS) facility and an associated nonmagnetic vertex detector studied the reactions a+p→c+X, where a and c were π±, K±, p, or p¯. Extensive measurements were made at 100 and 175 GeV/c beam momenta with the outgoing hadrons detected in the SAS covering a kinematic range 0.12<x<1.0 and pT<1.25 GeV/c. Additional data covering a more restricted range in x were also gathered at 70 GeV/c incident momentum. In this high-statistics experiment, the identification of both the incoming and outgoing charged hadrons were made with a total of eight Čerenkov counters. New and extensive single-particle inclusive data for charged-particle production in low-pT hadronic fragmentation are presented. The average associated charged-particle multiplicity and pseudorapidity distributions are also given.
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The inclusive cross section for the production ofKs0 mesons, Λ and\(\bar \Lambda\) particles in proton-proton interactions at\(\sqrt s= 63\) GeV is presented. The produced particles have been detected in the full phase space. Behaviour of the longitudinal and transversal depandences of the cross sections are discussed. The total production cross sections fors0 mesons and Λ particles was determined to\(\sigma _{{\rm K}_S^0 }= (25.5 \pm 1.4)\) mb andσΛ=(7.8±1.2) mb respectively. A strong energy dependence of the production cross sections is observed.
THE SIG(KS) ERROR INCLUDES THE UNCERTAINTY OF THE NORMALIZATION AND THE PT EXTRAPOLATION.
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In an experiment with the 30-inch Hybrid Spectrometer at Fermilab we have obtained the inclusive and semi-inclusive production cross sections of the ϱ0 meson using a conventional background subtraction technique. Production cross sections for the ϱ0 are derived as a function of the Feynman scaling variablex, and the transverse variablespt2 andEt=(pt2+M2)1/2. The longitudinal distributions are compared with the (1−x) dependence of the proton and meson valence quark structure functions, using various forms of recombination and fragmentation models. The transverse distributions are compared with thermodynamic models. We give density matrix elements for the ϱ0 production from pions in the extreme forward region.
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New results on the inclusive and semi-inclusive production of π + mesons and protons in the whole phase space are given for about 2.2 · 10 4 inelastic p p interactions at 22.4 GeV/ c . A method of statistical separation for spectra of particles of the same charge which are produced in CP -symmetrical reactions is discussed in detail. Experimental data are compared with quark-parton model predictions.
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NON-ANNIHILATION EVENTS ONLY.
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The production of ρ 0 (770) and f(1270) is studied in π − p interactions at 16 GeV/ c . By comparison with inclusive K ∗0 production in the reaction K − p → K ∗0 + anything, and with inclusive ρ 0 production in the reaction pp → ρ 0 + anything, it is found that the data can be interpreted in terms of two production processes: the central production of resonances and the fragmentation of the beam particle. For the π − p reaction, the inclusive ρ 0 beam fragmentation cross section is 3.1 ± 0.3 mb while that for central production is 1.6 ± 0.5 mb. The ρ 0 central production cross section is consistent with increasing with energy as ln s behaviour. The ratio of ρ 0 to π − inclusive cross sections (excluding the leading π − ) is ∼0.2, independent of energy. The ρ 0 to π − ratio increases as a function of p T to a constant value of ∼ 1 2 above 1 GeV/ c . The ρ (charged and neutral) and f decays account for (25 ± 4)% and (1.4 ± 0.3)%, respectively, of all pions produced.
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The properties of the diffractive peak observed in the mass spectra of systems recoiling against observed high-momentum protons emerging from pp collisions at the CERN ISR have been investigated. The cross sections in this peak have been found to have a steep t dependence which flattens out as | t | increases. The high mass side of the peak varies approximately as 1/ M 2 (where M is the missing mass of the recoiling system) and scales well in terms of the variable M 2 / s . The position of the maximum has been observed to move to lower values of M 2 / s as the kinematic boundary of this variable decreases with increasing s . The measured cross sections, integrated up to M 2 / s =0.05, rise by (15±5)% over the s range 549 to 1464 GeV 2 .
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Results are given on the inclusive production of charged pions, kaons, and nucleons, in proton-proton collisions at c.m. energies from √ s = 23 to 63 GeV at large angles and for the transverse momentum range 0.1 < p T < 4.8 GeV/ c . The dependence of the production spectra on the collision energy √ s , the transverse momentum p T , and the longitudinal rapidity is discussed.
Axis error includes +- 15.0/15.0 contribution (NORMALIZATION ERROR - THE LARGEST SYSTEMATICS).
Axis error includes +- 15.0/15.0 contribution (NORMALIZATION ERROR - THE LARGEST SYSTEMATICS).
Axis error includes +- 15.0/15.0 contribution (NORMALIZATION ERROR - THE LARGEST SYSTEMATICS).
Results are presented from an experiment with a large acceptance spectrometer that measured the production cross section of high mass muon pairs from the collision of 225 GeV/c hadron beams with a nuclear target including, for the first time, measurements using positive and negative pion beams. Various features of the data, such as the helicity anqle of the muon pairs and the ratio of the cross sections for positive and negative pions provide conclusive evidence for the quark-antiquark annihilation model for the production of muon pairs. This model is then used to determine the momentum distribution for valence quarks in pion. our best fit to the distribution,$\bar{\mu} (x) = (.73 \pm .11) x^{-1/2} [1-x] ^{(1.28 \pm .15)}$ , shows that the pion's structure! is clearly different from the proton's structure.
DATA ON (E/2*PI*PMAX(RF=CM))*D2(SIG)/D(XL)/D(PT)/PT WHERE THE CENTER OF MASS DEFINITION OF THE XL ASSUMED THAT THE TARGET WAS A SINGLE NUCLEON OF MASS 0.938 GEV. Axis error includes +- 0.0/0.0 contribution (?////SYSTEMATIC ERRORS NOT GIVENFERMI//COULOMBRES-DEF(RES=J/PSI,BACK=UNCORRECTED,DEF=2.7 < M(MU+ MU-) IN GEV < 3.5)).
DATA ON (E/2*PI*PMAX(RF=CM))*D2(SIG)/D(XL)/D(PT)/PT WHERE THE CENTER OF MASS DEFINITION OF THE XL ASSUMED THAT THE TARGET WAS A SINGLE NUCLEON OF MASS 0.938 GEV. Axis error includes +- 0.0/0.0 contribution (?////SYSTEMATIC ERRORS NOT GIVENFERMI//COULOMBRES-DEF(RES=J/PSI,BACK=UNCORRECTED,DEF=2.7 < M(MU+ MU-) IN GEV < 3.5)).
DATA ON (E/2*PI*PMAX(RF=CM))*D2(SIG)/D(XL)/D(PT)/PT WHERE THE CENTER OF MASS DEFINITION OF THE XL ASSUMED THAT THE TARGET WAS A SINGLE NUCLEON OF MASS 0.938 GEV. Axis error includes +- 0.0/0.0 contribution (?////SYSTEMATIC ERRORS NOT GIVENFERMI//COULOMBRES-DEF(RES=J/PSI,BACK=UNCORRECTED,DEF=2.7 < M(MU+ MU-) IN GEV < 3.5)).
We report measurements of the invariant cross section in the forward hemisphere for inclusive photoproduction of π±, K±, p, and p¯ from hydrogen and deuterium with an incident photon energy of 18 GeV. A small amount of data was also taken at incident energies of 9 and 13 GeV. The measurements were made using the SLAC 20-GeV/c spectrometer, and a bremsstrahlung-subtraction technique was used to obtain the cross sections at the specified incident energy. The data are compared with those from lower-energy experiments and interpreted within the context of the Mueller-Regge model and the constituent-interchange model.
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Transverse momentum distributions of λ o , λ o , and K o , produced in pp collisions at x = 0, have obtained at the CERN ISR. The K o yield is in agreement with published K + , K − results, obtained at this centre-of-mass energy (√ s ≈44 GeV). The results on λ o and λ o production obtained in this experiment are compared with results obtained at lower centre-of-mass energies.
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We have measured the single-particle inclusive cross sections for p+p→π±+X, K±+X, p+X, p¯+X in the low-p⊥ region (≲ 1.5 GeV/c) as a function of the radial scaling variable XR in p−p collisions at 100, 200, and 400 GeV at Fermilab. The measured π+π− and K+K− ratios are shown to be remarkably similar to the same ratios which have recently been measured at large p⊥ at 90° in the center-of-mass system.
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Results are reported for the invariant differential cross-section of charged pions produced at x = 0 in proton-proton collisions at the CERN ISR. The range covered is 40 to 400 MeV/c in transverse momentum and 23 to 63 GeV in collision energy. The inclusive cross-section for π + and π − are increasing by 36 ± 2% and 41 ± 2%, respectively over the ISR energy range with a somewhat stronger increase at the lowest transverse momenta. The transverse momentum distribution is well described by an exponential in the transverse energy.
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We present high-statistics results on the reactions a+p→c+X where a and c can be any of π±, K±, p, or p¯. The data were taken at 100 and 175 GeV/c incident momenta using the Fermilab Single-Arm Spectrometer operated over the kinematic range 0.2<x<1.0 and pt<~1.0 GeV/c. Investigating the x dependence of the data, we find agreement with a quark-parton picture, namely the cross sections have a power-law behavior in 1−x independent of pbeam and pt.
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The inclusive production of π and η mesons at 90° from proton-proton collisions has been measured at the CERN ISR at centre-of-mass energies between 23.5 and 62.4 GeV. The momentum correlation of charged particles emitted together with a large transverse momentum pion has also been studied, using two magnetic spectrometers each centred at 90°.
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We have measured the production of π+ and π− in 200-, 300-, and 400-GeV p−p and 400-GeV p−d collisions for transverse momenta (p⊥) ranging from 0.77 to 7.67 GeV/c. At large values of x⊥=2p⊥s, where s is the c.m. energy, we have fitted the p−p data to the form A(1−x⊥)bp⊥−n; we obtain n=8.2±0.5 for π+ and 8.5±0.5 for π−. At x⊥>0.3 the π+π− ratio in p−p collisions rises appreciably with increasing x⊥ whereas the π+π− ratio obtained from the difference of p−d and p−p cross sections is ∼ 1.0 at all x⊥.
Axis error includes +- 0.0/0.0 contribution (5 AND 10//(C//).
Axis error includes +- 0.0/0.0 contribution (5 AND 10//(C//).
Axis error includes +- 0.0/0.0 contribution (5 AND 10//(C//).
Measurements of the cross section for the reaction p+p→π0+anything have been completed. The data cover a range of incident proton energies 50-400 GeV, π0 transverse momenta 0.3-4 GeV/c, and laboratory angles 30-275 mrad. The experiment was performed using the internal proton beam at the Fermi National Accelerator Laboratory. A lead-glass counter was used to detect photons from the decay of π0's produced by collisions in thin targets of hydrogen or carbon. Tables of the measured cross sections are presented.
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We compare high-transverse-momentum (P⊥) inclusive π0 production from π−, K−, p, and p¯ beams, at 100 and 200 GeV/c, for center-of-mass (c.m.) angles ranging from 2° to 115° and P⊥<4.5 GeV/c. The ratio σ(pp→π0X)σ(πp→π0X) decreases with increasing P⊥, and changes dramatically with c.m. angle. Also, the ratios σ(K−p→π0X)σ(π−p→π0X) and σ(p¯p→π0X)σ(pp→π0X) are approximately constant. These measurements are consistent with a theoretical viewpoint in which constituents of the incident hadrons undergo a hard-scattering subprocess.
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