The inclusive production cross sections of η′ (958) andfo (975) mesons are measured ine+e− annihilation in the nonresonant continuum around\(\sqrt s= 10\) GeV and in decays of the υ resonances using the ARGUS detector. For η′ (958) mesons, a production ratio of η′ (958)/ηdir=0.35±0.24, with ηdir=η−BR(η′→ηX)·η′, is determined in direct υ(1S) decays, which can be partially explained by the pseudoscalar singlet/octet mixing. Forfo(975) production, we obtain a production ratio offo(975)/p(770)°=0.17±0.030 in direct υ(1S) decays. In its production features, thefo(975) behaves like an ordinary meson, though aK\(\bar K\) molecule nature cannot be excluded. The substantial production yield of thefo(975) meson demonstrates the important effect of feeddown from mesons beyond the basic multiples on pseudoscalar and vector meson production.
Direct etaprime rates per event for the continuum region (9.36 to 10.45 GeV), the UPSI(1S) (9.46 GeV), UPSI(2S)(10.02 GeV) and UPSI(4S)(10.58 GeV) regions. Data is extrapolated to the full z region.
Radiation corrected normalized cross section for F0(975) production in the continuum events.
Normalized cross section for F0(975) production in direct UPSI(1S) decays.
Two-photon production of the hadronic final states K + K − π + π − and K + K − π + π 0 π − has been studied using the ARGUS detector at the e + e − storage ring DORIS II at DESY. The cross sections of the reactions γγ → øϱ 0 and γγ → øω have been measured for the first time. In addition, angular distrubutions have been determined for the reaction γγ → øϱ 0 → K + K − π + π − .
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The production of $K^*+(892)$, $K^{*0}+(892)$, $\rho^{0}(770)$ and $\omega(783)$ vector mesons in $q\bar{q}$ events as well as in the gluonic $\Upsilon(1S)$ decays and $\Upsilon(4S) \to B\bar{B}$ decays has been studied using the ARGUS detector. Combining these results with data on pseudoscalar meson, $\phi$ meson and baryon production collected with the same detector allow comprehensive studies of quark and gluon fragmentation. Model independent information on $s$ quark and vector meson suppression $(s/u = 0.37 \pm 0.04, V/(V+P)_{\pi} = 0.21 \pm 0.04$ and $V/( V+ P)_K = 0.34 \pm 0.03))$ are derived. The data are compared with predictions from the models Jetset 7.3 and UCLA 7.31.
Vector meson multiplicities in the continuum region (sqrt(s) = 10.45 GeV). Data is also given for production of the pseudoscalar phi meson.
Vector meson multiplicities from Direct UPSI(1S) decays. Data is also givenfor production of the pseudoscalar phi meson.
Vector meson multiplicities from Direct UPSI(4S) decays. Data is also givenfor production of the pseudoscalar phi meson.
We have measured the magnetic moments of the Σ+ and Σ¯ − hyperons produced by 800-GeV protons incident on a Cu target. We determine the Σ+ magnetic moment to be (2.4613±0.0034±0.0040)μN where the uncertainties are statistical and systematic, respectively. In this first measurement we determine the magnetic moment of the Σ¯ − to be -(2.428±0.036±0.007)μN. The magnetic moments of the Σ+ and Σ¯ − are consistent with each other in magnitude but opposite in sign as required by CPT invariance.
No description provided.
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We have mesured the polarization of 375-GeV/c Σ+ and Σ¯ − hyperons produced by 800-GeV/c protons incident on a Cu target. We find that the Σ+ polarization rises with increasing pt to a maximum of 16% at pt=1.0 GeV/c and then decreases to 10% at pt=1.8 GeV/c. We compare this Σ+ polarization with data at lower energies. The Σ¯ − polarization has been measured for the first time. It has the same sign as the Σ+ but smaller magnitude in a similar kinematical region.
Data from Horizontal targeting.
Data from Vertical targeting.
Data from Horizontal targeting.
We have measured the branching ratio for the hyperon radiative decay Ξ−→Σ−γ from a sample of 211±33 events obtained in the polarized 375 GeV/c charged hyperon beam at Fermilab. We find B(Ξ−→Σ−γ/Ξ−→Λ0π−)=(1.22±0.23±0.06)×10−4 where the quoted errors are statistical and systematic, respectively. We have also obtained an indication that the sign of the asymmetry parameter of this decay is positive.
Polarized 375 GeV charged hyperon beam at Fermilab. Sample of 211 +- 33 events.
Differential cross sections have been measured for nucleon-isobar production and elastic scattering in p−p interactions from 6.2 to 29.7 GeVc in the laboratory angle range 8<θsc<265 mrad. N*' s at 1236, 1410, 1500, 1690, and 2190 MeV were observed. Computer fits to the mass spectra under varying assumptions of resonance and background shapes show that conclusions on t and s dependence are only slightly affected despite typical variations in absolute normalization of ± 35%. Logarithmic t slopes in the small- |t| range are ∼15 (GeVc)−2 for the N*(1410), ∼5 (GeVc)−2 for the N*'s at 1500, 1690, and 2190 MeV, and ∼9 (GeVc)−2 for elastic scattering. Also for the small- |t| data, cross sections for N*'s at 1410, 1500, 1690, and 2190 MeV and for elastic scattering vary only slightly with Pinc consistent with the dominance of Pomeranchuk exchange and with diffraction dissociation. A fit of N*(1690) total cross sections to the form σ∝P−n gives n=0.34±0.06, while for elastic scattering n=0.20±0.05. For the N*(1690) the effective Regge trajectory has the slope αeff′(0)=0.38±0.17. When compared with N* production in π−, K−, and p¯ beams these data also agree with approximate factorization of the Pomeranchuk trajectory. N*(1236) cross sections are consistent with other measurements at similar momenta. For −t>1 (GeVc)−2, elastic scattering cross sections decrease approximately as Pinc−2, and they and N*(1500)− and N*(1690)− production cross sections have t slopes consistent with 1.6 (GeVc)−2.
No description provided.
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We utilize the angle and momentum resolution of our apparatus to study the polarization of 375 GeV/c Σ+ hyperons produced by 800 GeV/c protons incident on a Cu target. By examining in detail two of our high statistics data samples, we find evidence for structure in the pt dependence of Σ+ polarization and are able to extract the xF dependence of the Σ+ polarization and compare it with xF behavior in the Λ0 and Ξ− systems.
0.9 mrad horizontal sample.
2.9 mrad horizontal sample.
3.3 mrad horizontal sample.
Using the detector ARGUS at thee+e− storage ring DORIS II, we have investigated inclusive momentum spectra of charged pions, kaons, and protons from decays of the υ(4S) meson. The kaon spectra have been measured in two independent ways, by coherently exploiting the detector's particle identification capabilities, and by detecting decays in-flight. The extracted mean multiplicities for charged hadrons are 7.17±0.05±0.14 pions, 1.56±0.03±0.05 kaons and 0.110±0.010±0.007 protons per υ(4S) decay, where pions and protons fromKso and Δ decays have been subtracted.
Inclusive pion spectrum from UPSI(4S) decays.
Inclusive pion spectrum from UPSI(4S) decays with KS and LAMBDA decay particles included.
Inclusive kaon spectrum from UPSI(4S) decays.
The production ofDS+ mesons inB meson decays, and inq\(\bar q\) continuum events, has been studied with the ARGUS detector at thee+e− storage ring DORIS II. In addition to the measurement of inclusiveDS+ production in γ(4S)→B\(\bar B\) decays, all eight two-body decay modesB→DS(*)D(*) have been measured with branching ratios between 1% and 3%. By comparing our inclusive and exclusive results to predictions of heavy quark effective theory, a value of (267±28) MeV × [2.7%/BR(Ds+→φπ+)]1/2 is obtained for the weak decay constant fDS(*), averaged overDS+ andDS*+ mesons.
Inclusive D/S cross sections in continuum near to UPSI(4S).
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