Four-jet production in e+e−-annihilation

Ali, Ahmed; Körner, Jürgen; Kunszt, Z.; Willrodt, J.; Krämer, G.; Schierholz, G.; Pietarinen, E.

doi:10.1016/0370-2693(79)90757-3

Cited by 87 publications

(49 citation statements)

References 10 publications

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“…This is akin to a complete solution of the confinement problem, for which practical techniques are not yet available. As a consequence, a variety of models (Ali et al, 1979a, Andersson et al, 1983;Odorico, 1980aOdorico, ,1980bOdorico, ,1983Mazzanti and Odorico, 1980;Field and Wolfram, 1983;Gottschalk, 1984;Field, 1983) have been constructed to simulate the evolution of partons into hadrons. Although they differ in detail, all have the common feature that jets become easier to isolate at high energies.…”

Section: A Generalitiesmentioning

confidence: 99%

Supercollider physics

et al. 1984

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Eichten et ah summarize the motivation for exploring the 1-TeV (=10 12 eV) energy scale in elementary particle interactions and explore the capabilities of proton-(anti)proton colliders with beam energies between 1 and 50 TeV. The authors calculate the production rates and characteristics for a number of conventional processes, and discuss their intrinsic physics interest as well as their role as backgrounds to more exotic phenomena. The authors review the theoretical motivation and expected signatures for several new phenomena which may occur on the 1-TeV scale. Their results provide a reference point for the choice of machine parameters and for experiment design.

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Section: A Generalitiesmentioning

confidence: 99%

Supercollider physics

et al. 1984

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“…According to the classes of diagrams contributing to v H , those involving the triple-gluon coupling and the QED-type diagrams, R can be written (N number of colors) (7) We found that, apart from the edges of phase space where R gets very small, r c *r E .…”

Section: Institut Fur Theoretischementioning

confidence: 93%

Evidence for Three-Gluon Coupling ine+e−Annihilation

et al. 1980

Self Cite

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The forward-backward asymmetry of the normal to the event plane for e e" annihilation into three jets in higher-order perturbation-theory (^ o> s 2 ) quantum chromodynamics is calculated. This could serve to establish the non-Abelian gluon self-couplings.PACS numbers: 14.80. Kx, 12.40.Cc, 13.65.+ i Quantum chromodynamics (QCD) predicts a multijet structure in e + e~ annihilation into hadrons, 1 " 8 which has been nicely confirmed by the recent PETRA data. 9 " 11 The mere observation of three-(and higher-) jet final states, however, does not prove QCD. Almost any other field theory with a small fixed-point coupling will lead to a similar structure, and a quantitative test of QCD at this level might be opposed by nonperturbative and the unavoidable higher-twist contributions. 2 ' 12 In order to furnish unambiguous evidence of perturbative QCD, it is essential to construct observables that are sensitive to the distinctive elements of the theory. Since QCD shows its full gauge structure only in order a s 2 , these must either involve four-jet final states or go beyond the tree-graph level. In this note we propose a discriminative test of QCD falling into the latter category, which has the unique feature of giving direct indication of the chromodynamic gluon selfcouplings and which appears to be feasible experi-:mentally.The observables we discuss concern three-jet production in e*e~ annihilation. One requires longitudinally polarized beams, the other the presence of weak and electromagnetic interferences.Let us first assume that the electrons and/or positrons are longitudinally polarized. Electrons and positrons naturally tend to polarize themselves in the direction of the magnetic field, i.e., transversally, and it seems feasible to rotate the transverse polarization into a longitudinal one. 13 The achievement of longitudinal polarization is also important in the exploration of weak-interaction contributions to the e^e" annihilation process. It allows the extraction of physical information similar to that obtainable from helicity measurements of the final state. At DESY PETRA (-19 GeV/beam) and SLAC PEP (-18 GeV/beam) energies and higher we can hope for a large sample of cleanly separated three-jet events. The cross section for e*e~ -^y^^qip^ip^ip^) for longitudinally polarized beams is given by 5 * 14 2ir d 4 G dcos6dxdx 1 dx •=i-(l +Z)(1 + cos 2 e)f Q u + j_ (1 +z)sin 2 e J!£L_ + |-(1+Z)sin 2 0cos2x dx 1 dx 2 d 2 o T dx±dx 2 dx ± dx 2 2V2" 3 (l + z)sin2 ec osx^-+4.isin0 8inx^-, Z = S ( -¥ +) , L = 4 ( -) +l (+) , h 7f J lA/Jv -I LisJv €}(1) where x lt2 = 2E U2 /(q 2 ) 1/2 and ^ and ^ denote the longitudinal polarization of the electron and positron beam, respectively. For pure helicity states £®=±h®, where ft (±) is the helicity of e ± , respectively. The first part of the cross section (1) being proportional to (l+Z) [i.e., the remnant of (1) for L = 0] is familiar. 5 The angle 6 is the polar angle between the electron beam direction and the direction of the fastest of either quark or antiquark jet, while x ...

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“…This observation is interesting in the context of the threefold increase in the A/K ratio seen at the Y(15) resonance 4 which, according to QCD, decays predominantly into three gluons. Hence it appears that there is an enhancement in baryon production associated either with gluon fragmentation, 9,10 or with three-parton kinematics. 12 For the understanding of the mechanism of baryon production, it is of prime importance to determine if baryon number is conserved locally or globally.…”

mentioning

confidence: 98%

ΛProduction ine+e−Annihilation at 29 GeV

Vaissière¹,

Lüth²,

Abrams³

et al. 1985

Phys. Rev. Lett.

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The production of A hyperons in e + e~ annihilation has been measured as a function of their total momenta, transverse jnomenta, and the event thrust. The total production rate is 0.213 ±0.012 ±0.018 A or A per hadronic event. The observation of correlations in rapidity and angles for events with two detected A decays supports fragmentation models with local baryonnumber compensation.PACS numbers: 13.65. + i, 13.30.Eg The knowledge of the particle composition of the hadronic final states produced in e+e~ annihilation is important for the understanding of the fragmentation of quarks and gluons. Baryons, both strange and nonstrange, are produced at a substantial rate, 1-4 but so far little is known about their production mechanism. In particular, it is important to determine if baryon number is compensated locally or globally. In this Letter, we report measurements of the inclusive production of A hyperons 5 at the cm. energy of E cm = 29 GeV. The production relative to the thrust axis is studied in terms of the transverse momentum of the A and the thrust of the events. For events with two detected A decays, correlations are given in terms of the relative rapidity, angles, and orientation in the plane transverse to the thrust axis.The measurements are based on data recorded by the Mark II detector at the e + e~ storage ring PEP at Stanford Linear Accelerator Center over a period of three years. The total sample corresponds to an integrated luminosity of 205 ±8 pb~]. The properties of the detector and the selection criteria for hadronic events have been described elsewhere. 6,7The charged-particle trajectories are reconstructed in two concentric cylindrical drift chambers which operate in a solenoidal field of 2.3 kG. In the plane transverse to the beam, momenta p (GeV/c) are measured with a resolution of bp/p = [(0.010/?) 2 + (0.025) 2 ] 1/2 (the trajectories are not constrained to include the interaction point).Only events with at least five charged particles and the total energy exceeding 0.25£ cm are included in this analysis. These particles are required to have momenta transverse to the beam of more than 100 MeV/c, and polar angles © with |cos@| < 0.75. After these cuts 67 500 events are retained, containing small contaminations due to T + T~ production [(2.0 ±0.5)%], e+e~ scattering events [(1.5 ±0.5)%], two-photon processes [(1.5 ± 0.8)%], and beam-gas interactions [(1.0 ± 0.5)%]

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Four-jet production in e+e−-annihilation

Cited by 87 publications

References 10 publications

Supercollider physics

Supercollider physics

Evidence for Three-Gluon Coupling ine+e−Annihilation

ΛProduction ine+e−Annihilation at 29 GeV

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