Data on the 4π 0 decay mode of mesons have been obtained in a search for glueballs performed at the CERN SPS with the GAMS-4000 multiphoton spectrometer. A new tensor glueball candidate X(1810) appears as a clear peak in the 4π 0 mass spectrum. The 4π 0 decay of G(1590) is also observed. The measured value of BR(G→4 π 0 )/BR(G→ ηη )=0.8±0.3 further supports the glueball assignment of this scalar particle. The rate decay of f(1270) into 4π 0 has been measured: BR(f→4 π 0 ) = (3±1)×10 −3 .
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We report results of an inclusive measurement of the charmed baryon, Λ c , in the forward direction of proton-proton interactions with s =63 GeV . The signal, seen in the final state Λ s π + π + π − , has 6.0 σ significance with about 620 events on a large background and corresponds to a cross section times branching ratio of 2.84±0.50±0.72 μ b for Feynman- x F > 0.5 in both hemispheres. Asymmetries are observed in the decay angular distributions which are characteristic of weak decays and have a combined 3.0 σ significance.
BR. RATIO WAS TAKEN TO BE 0.028+-0.007+-0.011.
The K − η effective mass spectrum in the reaction K − p→K − π + π − π 0 p at 11 GeV/ c has a prominent peak at ≈1.75 GeV/ c 2 , which is shown to be due to the K 3 ∗ (1780) by a spherical harmonic moments analysis and amplitude decomposition; there is no significant signal for K 2 ∗ (1430). The measured branching fractions for the leading L =1 and L =2 K ∗, s, [BF(K 2 ∗ (1430)→Kη) <0.45% at the 95% CL and BF ( K 3 ∗ (1780)→ Kη )=9.4±3.4%] confirm the SU(3) prediction that the Kη channel couples preferentially to odd spin K *, s.
Numerical data of acceptance corrected spherical harmonic moments requested from authors.
Including systematic error.
The total cross section for the process of the e + e - annihilation into hadrons has been measured at the centre-of-mass energies of 50 GeV and 52 GeV and a search has been made for new heavy quarks. The ratios R = σ ( e + e - → hadrons )/ σ point ( e + e - → μ + μ - ) obtained are 4.4±0.5 at 50 GeV and 4.7±0.3 at 52 GeV, respectively. An additional systematic uncertainty is 10%. From the event shape analysis we found no evidence for a new quark with charge 2 3 e .
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We report on high statistics Bhabha scattering data taken with the TASSO experiment at PETRA at center of mass energies from 12 GeV to 46.8 GeV. We present an analysis in terms of electroweak parameters of the standard model, give limits on QED cut-off parameters and look for possible signs of compositeness.
Axis error includes +- 1/1 contribution (The overall uncertainty in the bin-to-bin polar acceptance due to shower corrections, trigger and reconstruction efficiencies was estimated to be less than 1% and was added in quadrature to the statistical errorsData have been corrected for qed radiative effects up to order alpha**3 (F.A.Berends, R.Kleiss, Nucl.Phys.B206(1983)61)//Weak radiative corrections have not yet been provided in a form of a Monte Carlo generator program, but are estimated to be negligible at PETRA energies (M.Bohm, A.Denner, W.Hollik, DESY-86-165)).
Axis error includes +- 1/1 contribution (The overall uncertainty in the bin-to-bin polar acceptance due to shower corrections, trigger and reconstruction efficiencies was estimated to be less than 1% and was added in quadrature to the statistical errorsData have been corrected for qed radiative effects up to order alpha**3 (F.A.Berends, R.Kleiss, Nucl.Phys.B206(1983)61)//Weak radiative corrections have not yet been provided in a form of a Monte Carlo generator program, but are estimated to be negligible at PETRA energies (M.Bohm, A.Denner, W.Hollik, DESY-86-165)).
Axis error includes +- 1/1 contribution (The overall uncertainty in the bin-to-bin polar acceptance due to shower corrections, trigger and reconstruction efficiencies was estimated to be less than 1% and was added in quadrature to the statistical errorsData have been corrected for qed radiative effects up to order alpha**3 (F.A.Berends, R.Kleiss, Nucl.Phys.B206(1983)61)//Weak radiative corrections have not yet been provided in a form of a Monte Carlo generator program, but are estimated to be negligible at PETRA energies (M.Bohm, A.Denner, W.Hollik, DESY-86-165)).
In the analysis of the reactione+e−→e+e−KS0Ks0 clear evidence for exclusive γγ→f2′ resonance production is observed. The productΓγγ ·B(f2′→K\(\bar K\)) is measured to be 0.10−0.03−0.02+0.04+0.03 keV independent of ana priori assumption on the helicity structure. Our data are consistent with a pure helicity 2 contribution and we derive an upper limit for the ratioΓγγ(0)/Γγγ. The absence of events in the mass region around 1.3 GeV clearly proves destructivef2−a2 interference and allows to measure the relative phases betweenf2,a2 andf2′. Upper limits on the production of the glueball candidate statesf2(1720) andX(2230) as well as theKS0KS0-continuum are given.
Data read from graph.
The cross-section ratio of neutral-current and charged-current semileptonic interactions of muon-neutrinos on isoscalar nuclei has been measured with the result:Rv=0.3093±0.0031 for hadronic energy larger than 4 GeV. From this ratio we determined the electroweak mixing angle sin2θW, wheremc is the charm-quark mass in GeV/c2. Comparison with direct measurements ofmw andmz determines the radiative shift of the intermediate boson mass Δr=0.077±0.025(exp.)±0.038(syst.), in agreement with the prediction. Assuming the validity of the electroweak standard theory we determined ϱ=0.990−0.013(mc−1.5)±0.009(exp.)±0.003(theor.).
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STATISTICAL ERROR IN THE VALUE CITED IS REDUCING, WHEN CUT IS MORE STRINGENT?.
Usind data from avp and\(\bar v\)p experiment with BEBC at CERN, the rates for inclusive production ofD*+,Λc+ andD0 invp scattering and ofD*− in\(\bar v\)p scattering are measured. Some examples of the exclusive production ofD*+,Λc+ and∑c++ are given. The cross section for the reactionvp→μ−c++ is estimated.
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We present updated results from the UA1 experiment on cross sections times leptonic branching ratios for intermediate vector bosons produced in proton-antiproton collisions at a centre-of-mass energy of 0.630 TeV. We find that σ·B( W → l βn)=0.63±0.04±0.10 nb and σ·B( Z 0 → l + l − =0.071±0.011 nb where l denotes an average of electron and muon channels. An average over all data (electron and muon channels at 0.546 and 0.630 TeV) gives a ratio of R≡σ·( W → l ν)/σ·B( Z 0 → l + l − ) = 9.1 +1.7 −1.2 . Using current theoretical predictions for this quantity, limits are extracted on the number of light neutrino types. Combining UA1 and UA2 data and imposing the bound N ν ⩾3 we find that N ν ⩽5.9 at 90% CL. Constraints on the mass of the top quark are also discussed.
THE CORRESPONDING VALUE FROM UA2 IS BR*SIG = 0.61+-0.10+-0.07.
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THE CORRESPONDING VALUE FROM UA2 IS BR*SIG = 0.57+-0.04+-0.07.
The final state K + K − π + π − has been studied in γγ interactions using the ARGUS detector at the e + e − storage ring DORIS II at DESY. Production of the vector meson pair K ∗0 (892) K ∗0 (892) is observed for the first time. The cross section for K + K − π + π − , K ∗0 K − π + +c.c. and K ∗0 K ∗0 are all found to be of the order of a few nb. In the W γγ range accessible, a mean upper limit of 0.5 nb at 95% CL is derived for φϱ 0 production.
TOPOLOGICAL CROSS SECTION.
(K*0 K*BAR0) cross section.
(K*0 K- PI+ + CC) CROSS SECTION WITH (K*0 K*BAR0) REMOVED.
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