We report on the exclusive production of π, K and proton pairs from photon-photon interactions at momentum transfers | t |⩾1 GeV 2 . Using the PLUTO detector at the e + e − storage ring PETRA, we have observed 15 events in an integrated luminosity of 41.7 pb −1 . The data lie far below the expectations for point-like hadrons, and are in reasonable agreement with the QCD-based predictions of Brodsky and Lepage.
THIS METHOD OF ANALYSIS OF THE OBSERVED RATIO OF HADRON TO MUON PAIRS, IS TIED TO THE SPECIFIC DETECTOR ACCEPTANCE, BUT HAS THE ADVANTAGE OF BEING VIRTUALLY INDEPENDENT OF THE HADRON MASSES.
SEE COMMENT IN PREVIOUS TABLE.
THIS METHOD OF ANALYSIS OF THE CROSS SECTION AT 90 DEG IN THE CM AS A FUNCTION OF PCM IS MORE EASILY COMPARED WITH THEORETICAL PREDICTIONS BUT MORE DEPENDENT ON THE SPECIFIC HADRON MASSES.
Identification of muons in hadronic events from e+e− annihilation observed in the MAC detector at the storage ring PEP provides flavor tagging of heavy primary quarks. A sample enriched in events from bb¯ production is obtained and the b-quark fragmentation function is inferred from the momentum spectrum of the muons. The b quark is found to fragment predominantly with high values of z, with 〈zb〉=0.8±0.1, and to have an over-all semimuonic branching fraction of (15.5−2.9+5.4)%.
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The high mass μ + μ − pairs produced by 280 GeV μ + on a carbon target are studied in a search for the Y production. The high mass continuum in the region 2–18 GeV is interpreted in terms of QED pair production and of μ pairs originating from the decay of hidden and open charm particles as well as of hadrons ( π , K) from deep inelastic interactions. The upper limit for the upsilon production by muons is found to be, at the 90% confidence level, σ γ ·(γ→μ + μ − )<13·10 −39 cm 2 /nucleon.
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