The polarization parameter for K + n charge exchange scattering has been measured at five momenta between 0.851 GeV/ c and 1.351 GeV/ c for centre of mass angles −0.8 < cos θ ∗ < 0.8 . Results from a phase shift analysis incorporating these results are presented. No Z ∗ resonances are observed.
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Production of pions, kaons, protons and antiprotons has been studied in e + e − annihilations at 12 and 30 GeV centre of mass energy using time of flight techniques. The fractional yield of charged kaons and baryons appears to rise with outgoing particle momentum. At our highest energy at least 40% of e + e − annihilations into hadrons are estimated to contain baryons.
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With use of the LENA detector at the DORIS e+e− storage ring, the hadronic cross section and the μ-pair decay branching ratio of the ϒ(9.46) resonance have been measured. Γee=1.23±0.10 (±0.14) keV, Bμμ=[3.5±1.4 (±0.4)]%, and Γtot=35−10+25 ({+9}{−7}) keV have been obtained. The first set of errors gives the statistical uncertainty. The numbers in parentheses represent systematic errors arising from the uncertainty in the total hadronic cross section.
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In this Letter, a measurement of inclusive muon production (pμ>2 GeV/c) in e+e− annihilation into hadrons at center-of-mass energies from s=12 to 31.6 GeV is reported. The results agree with the expected semileptonic decays from charmed and bottom mesons.
MUONS PER HADRONIC EVENT.
INVARIANT CROSS SECTION, ASSUMING HADRONIC CROSS SECTION HAS R VALUE OF 3.9 +- 0.5.
New data on the inclusive production of the non-strange resonances ϱ0(770), ω(783), ϕ(1020) andf(1270) inK− p interactions at 32 GeV/c are presented. The inclusive production cross sections are equal to (4.32±0.72) mb, (3.7±1.4) mb, (0.65±0.10) mb and (0.91±0.35) mb respectively. Estimates of the topological cross sections are also obtained. The invariant and non-invariantx-distributions for the vector mesons ϱ0 and ϕ indicate the prevalence of forward resonance production in the c.m. system. For the tensorf-meson the rapidity andx-distributions are presented. Thet′-distributions for ϱ0, ϕ, andf have exponential slopes of 0.6±0.1 GeV−2, 1.2±0.2 GeV−2, and 0.8±0.5 GeV−2 respectively. The exponential slope ofpT2-distribution of thef-meson is equal to (2.3±0.5) GeV−2.
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We have measured 618 K + p → π + K S 0 p events at 12.7 GeV/ c incident lab momentum, mass range 790 ⩽ m π + K s 0 ⩽ 990 MeV and t range 0.01 ⩽ − t ⩽ 0.60 (GeV/ c ) 2 . The π + K S 0 mass spectrum is dominated by the K ∗+ (892) resonance and a Breit-Wigner fit yields a mass m = 893.5 ± 1.1 MeV and a width Γ = 33.2 ± 4.1 MeV which is much narrower than measured hitherto. The t distribution of K ∗+ (892) events shows a dip in the forward direction and an exponential fall off thereafter, consistent with dominance of helicity flip amplitudes. The spin density matrix is almost saturated by ρ 11 and ρ 1−1 which are very close to their maximum allowed value of 1 2 throughout the measured t range except in the very forward direction where ρ 00 and Re ρ 10 deviate from zero. Natural parity exchanges, therefore, dominate with unnatural parity exchanges being restricted to a small region in the forward direction. A Regge pole analysis of the differential cross sections of the present measurement in conjunction with previously measured total cross sections supports the f-coupled-pomeron hypothesis.
SUBTRACTED BACKGROUND IS PHASE SPACE.
SUBTRACTED BACKGROUND IS AN INCOHERENT S-WAVE WITH EXPONENTIAL T-DEPENDENCE WITH SLOPE OF 6 GEV**-2.
Axis error includes +- 15/15 contribution.
The reactionsπ−p→K0∑0(1385) andπ−p→K+∑−(1385) are studied at an incident momentum of 3.95 GeV/c using data from a high statistics bubble chamber experiment corresponding to approximately 90 events/μb. The total and differential cross sections and the density matrix elements of the Σ(1385) are presented. The results are compared with those obtained for the related processesπpp→K+∑+(1385) and\(K^ -p \to \pi ^ \mp\sum ^ \pm(1385)\) in this energy range. Evidence is presented for the existence of production mechanisms with exotic exchanges in thet channel.
FROM THE CHANNEL PI- P --> LAMBDA K0 PI0 WHICH HAS A CROSS SECTION OF 72 +- 4 MUB.
FROM THE CHANNEL PI- P --> LAMBDA K+ PI- WHICH HAS A CROSS SECTION OF 79 +- 3 MUB.
FORWARD CROSS SECTION.
The reactions π−p→K0Λ,K0Σ0 are studied at an incident momentum of 3.95 GeV/c using data from a high statistics bubble chamber experiment corresponding to ∼90 events/μb. The differential cross sections and hyperon polarizations are presented and compared with existing data from earlier electronic experiments. The data in the forward hemisphere are used to perform an amplitude analysis of the 0−1/2+→0−1/2+ hypercharge exchange processes.
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The total cross section fore+e− annihilation into hadrons for center of mass energies from 9.4 to 9.5 GeV has been measured with the nonmagnetic DESY-Heidelberg detector at DORIS. A value ofR=σhad/σµµ=3.8±0.7 for the continuum region around the Υ (9.46) resonance has been determined. The ratioΓeeΓhad/Γtot of electronic, hadronic and total widths has been reevaluated to be (1.00±0.23) keV for the Υ resonance and (0.37±0.16) keV for the Υ′. In addition, a search for directly produced pohotons from Υ decays of the type Υ→γ+gluon+gluon has been performed. The Υ decay into muon pairs has also been searched for.
TOTAL CROSS SECTION FOR THE CONTINUUM REGIONS AROUND THE UPSI(9460)0 AND UPSI(10020)0 RESONANCES.
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