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Experimental Evidence for the Nonabelian Nature of {QCD}

The AMY collaboration Park, I.H. ; Schnetzer, S. ; Green, J. ; et al.

Phys.Rev.Lett. 62 (1989) 1713, 1989.

Inspire Record 276619 DOI 10.17182/hepdata.20045

We present evidence for the non-Abelian nature of QCD from a study of multijet events produced in e+e− annihilations from √s =50 to 57 GeV in the AMY detector at the KEK storage ring TRISTAN. A comparison of the three-jet event fraction at TRISTAN to the fraction of the DESY storage ring PETRA shows that the QCD coupling strength αs decreases with increasing Q2. In addition, measurements of the angular distributions of four-jet events show evidence for the triple-gluon vertex.

2 data tables

Table 1

No description provided.

Table 2

No description provided.

Measurement of the Ratio of Sea to Valence Quarks in the Nucleon

Heinrich, J.G. ; Adolphsen, C.E. ; Alexander, J.P. ; et al.

Phys.Rev.Lett. 63 (1989) 356-359, 1989.

Inspire Record 285060 DOI 10.17182/hepdata.20030

The ratio of sea to valence quarks for nucleons in tungsten has been measured for the fractional momentum range 0.04<xN<0.36. The determination is based on the relative production rate of muon pairs by π+ and π− beams on a tungsten target. The results provide the most accurate determination to date of this ratio in the region xN<0.1 and Q2>20 GeV2, and are in good agreement with earlier measurements.

1 data table

Table 1

No description provided.

Dimuon Production in 800 GeV Proton Nucleus Collisions

Brown, C.N. ; Cooper, W.E. ; Finley, D. ; et al.

Phys.Rev.Lett. 63 (1989) 2637-2640, 1989.

Inspire Record 288346 DOI 10.17182/hepdata.20031

A measurement of continuum dimuon production in proton-copper collisions at 800-GeV incident energy is presented. The dimuons observed in this experiment cover the mass range from 6.5 to 18 GeV near y=0 in the proton-nucleon center-of-momentum frame. Scaling forms of the cross section for the continuum are compared with the results of other experiments in the context of the parton model and quantum chromodynamics. The present limitations of such scaling comparisons are discussed.

1 data table

Table 1

No description provided.

Search for Narrow Baryonia With Negative and Positive Strangeness

The BIS-2 collaboration Aleev, A.N. ; Arefev, V.A. ; Balandin, V.P. ; et al.

Z.Phys.C 47 (1990) 533-537, 1990.

Inspire Record 285796 DOI 10.17182/hepdata.15148

A search for baryonia with negative and positive strangeness decaying respectively into$\Lambda+ \bar p + pions$ and$\bar \Lambda+ p + pions$ has been carried out in a neutron beam with a mean momentum of ≅40 GeV/c in an experiment performed at the Serpukhov accelerator. There is a strong indication of the existence of these baryonia. The following four charge states are observed for negative and positive strangeness: neutral, negative, positive and doubly charged. Their mean mass is 3055±25 MeV/c2 and the width Γ≦36±15 MeV/c2. The data show that the isotopic spin of the baryonia is ≧3/2. The baryonia production cross sections in the acceptable kinematic regionXF≧0.2 andPT≦1 GeV/c times the branching ratios of the observed decays are of the order of 1 μb per nucleon.

1 data table

Table 1

No description provided.

Photodisintegration of Polarized Deuterons: Measurement of Angular Distributions at $e (\gamma$) = 450-{MeV}, 550-{MeV} and 650-{MeV}

Althoff, K.H. ; Anton, G. ; Bock, B. ; et al.

Z.Phys.C 43 (1989) 375, 1989.

Inspire Record 277082 DOI 10.17182/hepdata.15455

At the Bonn 2.5 GeV electron synchrotron an angular distribution of the target asymmetry of the reaction γ+d↑→p+n has been measured at photon-lab-energies of 450 and 650 MeV and at proton-CM-angles between 25° and 155°. At 550 MeV the data of our previous run [1] have been improved. Using deuterated ammonia as material for the polarized deuteron target a maximum vector polarization of 44% could be achieved. At 450 and 650 MeV the data are consistent with a smooth sin 2Θ-like distribution. The evidence for a structure around 90° at 550 Mev remains. This might be due to the influence of a higher momentum state (like a dibaryon). The feasibility of measuring the tensor asymmetry of the deuteron photodisintegration with a polarized target has been shown for the first time. Data were taken in a short run for one kinematical setting.

1 data table

Table 1

Errors contain both statistics and systematics.

Study of the $\pi^+ \pi^+ \pi^- \pi^-$ System Centrally Produced by Incident $\pi^+$ and $p$ Beams at 85-{GeV}/$c$

The WA76 collaboration Armstrong, T.A. ; Bloodworth, I.J. ; Carney, J.N. ; et al.

Z.Phys.C 43 (1989) 55, 1989.

Inspire Record 276888 DOI 10.17182/hepdata.15434

The reactions π+p→π+(π+π+π-π-)p andpp→p(π+π+π-π-)p, where the (π+ π+ π- π-) system is centrally produced have been studied at 85 GeV/c. The π+π+π-π- mass spectrum shows evidence for thef1 (1285) meson with a mass of 1278±2 MeV and width 41±12 MeV which decays mainly through ρ0(770)π+π-. Thef1(1285) is also observed in the ηπ+π- channel. There is no significant evidence for ηππ or 4π decay modes of thef1(1420). The ρ0ρ0 production is found to be small. A Dalitz plot analysis of the 3π system shows evidence fora2 (1320) production and for a large contribution of theJPC=1++ ρπ wave.

3 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.