An analysis of the production ofKS0KS0 andK±Ks0π∓ by two quasi-real photons is presented. The cross section forγγ→K0\(\overline {K^0 } \), which is given for the γγ invariant mass range fromK\(\bar K\) threshold to 2.5 GeV, is dominated by thef′(1525) resonance and an enhancement near theK\(\bar K\) threshold. Upper limits on the product of the two-photon width times the branching ratio intoK\(\bar K\) pairs are given forΘ(1700),h(2030), and ξ(2220). For exclusive two-photon production ofK±Ks0π∓ no significant signal was observed. Upper limits are given on the cross section ofγγ→K+\(\overline {K^0 } \)π− orK−K0π+ between 1.4 and 3.2 GeV and on the product of the γγ width times the branching ratio into theK\(\bar K\)π final states for theηc(2980) and the ι(1440), yieldingΓ(γγ)→i(1440))·BR(i(1440)→K\(\bar K\)π<2.2 keV at 95% C.L.
Data read from graph.. Corrected for the angular distribution, which is assumed to be sin(theta)**4 for W > 1.14 GeV and isotropic in the first bin.
Data read from graph.
Production of the p p π + π − final state by two-photon scattering was observed. The cross section for γγ→p p π + π − was determined assuming phase space production. No evidence was found for the production or formation of resonances. Upper limits are given for Λ and Δ pair production, for production of p p ϱ 0 and for the two-photon excitation of c c bound states.
No description provided.
Exclusive production of proton-antiproton pairs by two photon scattering at CM energies between 2.0 GeV and 3.1 GeV has been measured with the TASSO detector at the e + e − storage ring PETRA. The angular distribution is flat within the accepted CM angular range | cos Θ ∗ |⩽0.7 . The integrated cross section (| cos Θ ∗ |⩽0.6) drops from about 4 nb at 2 GeV to less than 0.5 nb above 3 GeV. For the two-photon production of the η c (2984) and its subsequent decay into proton-antiproton the upper limit Γ(η c →γγ)· B (η c → p p )<0.32 keV (95% CL) is found.
No description provided.
No description provided.
UPPER LIMIT FOR THE PRODUCT OF THE ETA/C --> GAMMA GAMMA WIDTH AND THE BRANCHING RATIO OF ETA/C --> P AP IS DETERMINED TO BE 0.32 KEV WITH 90 PCT CL.
The first measurements of spin-rotation in meson-baryon scattering in the resonance region are presented. These measurements, for the reaction π − p → K 0 Λ , confirm the main predictions of a previous partial-wave analysis. Comments are made on resonant couplings in the reaction π − p → K 0 Λ .
SPIN ROTATION ANGLE MEASUREMENTS.
POLARIZATION MEASUREMENTS FROM THIS EXPERIMENT ALONE.
COMBINED WITH DATA FROM BAKER ET AL., AND SAXON ET AL., (SEE COMMENTS).
Production of proton-antiproton pairs by two-photon scattering has been observed at the electron-position storage ring PETRA. A total of eight proton-antiproton pairs have been identified using the time-of-flight technique. We have measured a total cross section of 4.5 ± 0.8 nb in the photon-photon c.m. energy range 2.0–2.6 GeV.
No description provided.
Additional systematic uncertainty 25% not included.
Differential cross-section and polarization measurements for the reaction π − p → K 0 Σ 0 are presented from 1395 to 2375 MeV/ c incident beam momentum. The polarization data from an earlier experiment, from thershold to 1334 MeV/ c , have been re-analysed by an improved method leading to a substantial reduction in the errors.
No description provided.
TOTAL CROSS SECTIONS DERIVED FROM LEGENDRE POLYNOMIAL FITS TO ANGULAR DISTRIBUTIONS.
LEGENDRE POLYNOMIAL FITS TO D(SIG)/DOMEGA.
New data are presented on the reaction π − p→K 0 Λ 0 at 13 incident momenta between 1395 and 2375 MeV/ c . A partial-wave analysis has been performed using these data and previous data at lower momenta. The resulting resonance parameters are in broad agreement with recent πN analyses and with the predictions of SU(6) W × O(3) for the couplings.
No description provided.
TOTAL CROSS SECTION FROM LEGENDRE POLYNOMIAL FIT TO D(SIG)/DOMEGA. ERRORS INCLUDE 20 PCT SYSTEMATIC NORMALIZATION ERROR.
LAMBDA USED TO ANALYZE POLARIZATION, ASSUMING 0.642 FOR THE DECAY ASYMMETRY PARAMETER.
The forward cross sections for the reactions π−p→K+Σ− and K−p→π+Σ− have been determined for incident particle momenta in the range of 2.75 to 3.50 GeV/c, and an upper limit was established at 5.00 GeV/c. These measurements show that the double-charge-exchange process π−p→K+Σ− is suppressed by a factor of 1500 at 3 GeV/c relative to the single-exchange reaction π+p→K+Σ+.
No description provided.
No description provided.
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