The total momentum and transverse momentum spectra of electrons in e+e− annihilation at 29 GeV have been measured. The inclusive cross section is determined to be 14.4±1.6±5.2 pb for momenta greater than 2 GeV/c. The average semielectronic branching ratios of charm and bottom quarks are measured to be (6.3±1.2±2.1)% and (11.6±2.1±1.7)%, respectively. The fragmentation function for bottom quarks is determined to be peaked at high z, with 〈z〉b=0.75±0.05±0.04.
PT is the transverse momentum of the muon relative to the event thrust axis.
PT is the transverse momentum of the muon relative to the event thrust axis.
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No description provided.
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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Differential cross sections for the deuteron photodisintegration process were measured for photon energies between 200 and 440 MeV using the tagged photon beam facility of the Bonn 500 MeV synchrotron. At eight angles between 18° and 145° charged particles were detected simultaneously in time-of-flight spectrometers consisting of scintillation counters. Above the resonance region the measured cross sections agree fairly well with earlier results, whereas there are larger discrepancies at low photon energies.
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InclusiveKs0, Λ and\(\bar \Lambda\)-production has been investigated in\(\bar p\)p-interactions at 22.4 GeV/c. Total and topological cross sections and multiplicity characteristics of neutral strange particles have been determined. DifferentialKs0 and Λ-cross sections and also characteristics of annihilation processes with neutral kaon production have been studied. It is shown that the difference of the shapes of the invariantx-distributions forK-mesons in the fragmentation region for annihilation and non-annihilation processes can be described in the framework of the “dual” valon model, but not by considering the current (undressed) quark recombination mechanisms only. The polarization of Λ and\(\bar \Lambda\)-hyperons has been measured.
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The np elastic differential cross section has been measured for incident neutron momenta 100–400 GeV/ c in the | t | range 6 · 10 −6 − 5 · 10 −1 (GeV/ c ) 2 . The np data of this experiment provide a first direct measurement of the hadronic amplitude for | t | < 10 −2 (GeV/ c ) 2 , which is consistent with the extrapolations from higher | t | values. Our data for | t | < 10 −4 (GeV/ c ) 2 are consistent with a rise which can be attributed to Schwinger scattering, caused by the interaction of the neutron magnetic moment with the proton.
No description provided.
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Measurements of C LL of pp elastic scattering near θ c.m. = 90° at thirteen energies between 300 and 800 MeV are reported. These, together with previous values of C NN , are used to extract values of two quantities, ƒ s and ƒ t , which contain only spin-singlet and only coupled spin-triplet partial waves, respectively. The ƒ s curve, which is not dependent on C LL , exhibits the behavior expected for the previously conjectured 1 D 2 resonance. The ƒ t curve also exhibits a resonance-like behavior, which could be due either to the 3 P 0 or the 3 P 2 partial wave.
No description provided.
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The forward production of charm states in 350 GeV p-Fe interactions has been studied via the production of prompt single muons with momentum p ≳ 20 GeV/ c . The data indicate equal production of single μ + and μ − events. The observed momentum distributions can be fit with the hypothesis that D mesons are produced with an invariant cross section proportional to (1 − x F ) 5.0±0.8 exp[−(2 ± 0.3) P t ] and do not favor a large diffractive cross section predicted by intrinsic charm models. Extrapolation of the distributions to x F = 0 yields a total D D production cross section of 22.6 ± 2.1(±3.6)ωb/nucleon on the assumption of a linear A dependence and 8% average semileptonic branching ratio of charm states.
No description provided.
Multiple-neutron events ( γ , i n…) for Pb have been recorded according to their neutron multiplicity i , for i ⩾ 1 with a quasi-monoenergetic photon beam obtained by the annihilation in flight of monochromatic positrons. These experimental results, taken with photon energies E γ from 145 up to 440 MeV, are subsequently used to determine the partial sum σ (2) ( E γ )= Σ i ⩾2 σ ( γ , i n…) and to evaluate the ensuing total photonuclear absorption cross section σ (tot: Eγ ).
DATA FROM ARENDS ET AL., PL 98B/ 423/81 AND ROST (DISSERTATION) BONN IR-80-10 (1980).
DATA FROM ARENS ET AL. PHOTOPION NUCLEAR PHYSICS, ED. P. STOLER (PLENUM NEW YORK, 1969) P. 385.
DATA FROM LEPRETRE ET AL., NP A367/237/81 AND CARLOS ET AL., NP A378/317/82 FOR E<140 MEV AND THIS EXPERIMENT FOR E>140 MEV.
A precision measurement of the angular distribution of the analyzing power of the reaction p + p → d + π + has been made at 0.8 GeV. It is shown that none of the existing theoretical calculations, including those which introduce resonant dibaryon amplitudes, reproduce even the qualitative features of the data. It is concluded that our data do not require dibaryon admixtures of the kind proposed for the interpretation of recent data on vector analyzing power, i T 11 (θ), of π− d elastic scattering at the same center of mass energy.
LOWER ENERGY DATA NOT IN PUBLICATION.
LOWER ENERGY DATA NOT IN PUBLICATION.
LOWER ENERGY DATA NOT IN PUBLICATION.
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