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.
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.
No description provided.
No description provided.
Highly inelastic processes in hadron-nucleus reactions at several GeV have been studied by measuring multi-particle emission in the target-rapidity region. Events with no leading particle(s) but with high multiplicities were observed up to 4 GeV. Proton spectra from such events were well reproduced with a single-moving-source model, which implied possible formation of a local source. The number of nucleons involved in the source was estimated to be (3–5)A 1 3 from the source velocity and the multiplicity of emitted protons. In those processes the incident energy flux seemed to be deposited totally or mostly (>62;75%) in the target nucleus to form the local source. The cross sections for the process were about 30% of the geometrical cross sections, with little dependence on incident energies up to 4 GeV and no dependence on projectiles (pions or protons). The E 0 parameter in the invariant-cross-section formula E d 3 σ /d p 3 = A exp (− E / E 0 ) for protons from the source increases with incident energy from 1 to 4 GeV/ c , but seems to saturate above 10 GeV at a value E 0 = 60–70 MeV. Three components in the emitted nucleon spectra were observed which would correspond to three stages of the reaction process: primary, pre-equilibrium and equilibrium.
BEAM ERROR D(P)/P = 0.300 PCT. X ERROR D(EKIN)/EKIN = 8.00 PCT.
BEAM ERROR D(P)/P = 0.300 PCT. X ERROR D(EKIN)/EKIN = 8.00 PCT.
BEAM ERROR D(P)/P = 0.300 PCT. X ERROR D(EKIN)/EKIN = 8.00 PCT.
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.
No description provided.
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.
D ∗± production via e + e − →D ∗± X has been measured at an average CM energy of 34.4 GeV. The D ∗± energy spectrum is hard, with a maximum near χ = 0.6. The size of the D ∗ cross section, R D ∗ = σ( e + e − → D ∗ X ) σ μμ = 2.50 ± 0.64 ± 0.88 (assuming R D ∗0 = R D ∗+ ) indicates that a large fraction of charm quark production yields D ∗ mesons. The D ∗± angular distribution exhibits a forward—backward asymmetry, A = −0.28 ± 0.13. This is consistent with that expected in the standard theory for weak neutral currents and leads to | g A c | = 0.89 ± 0.44 for the axial vector coupling of the charm quark.
ASSUMES EQUAL RATES FOR CHARGED AND NEUTRAL D*'S. ONLY CHARGED ARE DETECTED.
DATA PEAKS AT X=0.6 TO 0.8.
ASYMMETRY MEASUREMENT. THETA IS THE ANGLE BETWEEN THE E- AND THE D*.
Using the data on deep inelastic muon scattering on iron and deuterium the ratio of the nucleon structure functions F 2 N ( Fe )/ F 2 N ( D ) is presented. The observed x -dependence of this ratio is in disagreement with existing theoretical predictions.
RANGE OF Q*2 VARIES WITH X. E.G. AT X=0.05 , 9<Q2<27. AT X=0.65 , 36<Q2<170 GEV**2.
With a segmented total absorption calorimeter of large acceptance, we have measured the total transverse energy spectrum for pp̄ collisions at s 1 2 = 540 GeV up to ΣE T = 130 GeV in the pseudo-rapidity range | η |< 1.5. Using two different algorithms, we have looked for localized depositions of transverse energy (jets). For ΣE T > 40 GeV , the fraction of events with two jets increases with Σ E T ; this event structure is dominant for ΣE T > 100 GeV. We measure the inclusive jet cross section up to E T (jet) = 60 GeV and the two-jets mass distribution to 120 GeV/ c 2 . The measured cross sections are compatible with the predictions of hard scattering models based on QCD.
DATA TAKEN IN 1981 WITH GLOBAL TRANSVERSE ENERGY TRIGGER.
DATA TAKEN IN 1982 WITH LOCAL TRANSVERSE ENERGY TRIGGER.
Transverse momentum distributions of pions, kaons and protons have been measured around 90° in the UA2 detector at the SPS p p collider, at a CM energy of 540 GeV. All the cross sections have increased by more than a factor of 2 over those measured at ISR energies and exhibit a flatter behaviour with respect to transverse momentum.
No description provided.
The deuteron structure function F 2 d has been measured in 280 GeV μ + d interactions. Existing measurements of F 2 p , made with the same apparatus, are used to calculate F 2 p − F 2 n and F 2 n F 2 p . The ratio F 2 n F 2 p has a similar x dependence to that of earlier measurements at lower Q 2 .
No description provided.
No description provided.
No description provided.
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