Using data taken at PETRA we present results on deep inelastic electron photon scattering at momentum transfers 1 < Q 2 < 15 GeV 2 . The results are expressed in terms of the photon structure function F 2 and are compared with QCD predictions and “hadronic” models of the photon. The pointlike component of the photon is found to be dominant.
Data read from graph.. Data for W < 3.5 in Berger et al. 1981, PL 99B,287 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1164> RED = 1164 </a>).
PHOTON STRUCTURE FUNCTION. NUMERICAL VALUES OF DATA ON FIGURE SUPPLIED BY W. WAGNER.
A measurement of the nucleon structure function F 2 on iron is presented. The data cover a kinematic range of 3.25 ⪕ Q 2 ⪕ 200 GeV 2 and 0.05 ⪕ x ⪕ 0.65 . The data clearly show scaling violation. Fits in leading-order QCD have been made and values for the scale breaking parameter λ are given.
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The proton structure function F 2 has been measured in the range 2.5 ⪕ Q 2 ⪕ 170 GeV 2 and 0.03 ⪕ x ⪕ 0.65 . Scaling violation is clearly seen in the data. Results of fits to leading-order QCD are presented, together with values of the scale-breaking parameter λ.
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By using three different c.m. energies in pp interactions,\(\sqrt s \), 44, 62 GeV, it is shown that the average charged-particle multiplicity <nch> sclaes with\(\sqrt s \) once the correct hadronic energy available for multiparticle production,Ehad, is used as basic parameter. The pp data, analysed in this way, are compared with e+e− data at equivalent energies. The agreement is very satisfactory.
WITH SQRT(S) OF 30 GEV.
WITH SQRT(S) OF 44 GEV.
WITH SQRT(S) OF 62 GEV.
Deep inelastic scattering cross sections have been measured with the CERN SPS muon beam at incident energies of 120 and 200 GeV. Approximately 100 000 events at each energy are used to obtain the structure function F 2 ( x , Q 2 ) in the kinematic region 0.3< x <0.7 and 25 GeV 2 < Q 2 <200 GeV 2 .
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Two-photon interactions have been studied with the SLAC-LBL Mark II magnetic detector at SPEAR. The cross section for η′ production by the reaction e+e−→e+e−η′ has been measured at beam energies from 2.0 to 3.7 GeV. The radiative width Γγγ(η′) has been determined to be 5.8±1.1 keV (±20% systematic uncertainty). Upper limits on the radiative widths of the f(1270), A2(1310), and f′(1515) tensor mesons have been determined. A search has been made for production of the E(1420) by γγ collisions, but no signal is observed.
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NO SIGNAL ABOVE BACKGROUND SEEN. UPPER LIMITS AT 95 PCT CL GIVEN.
We have measured the relative cross sections for muon pair production by 280 GeV/ c negative pions on three different targets: carbon, copper, and tungsten. The value of α obtained from the parametrization σ = constant × A α is 0.94 ± 0.02 ± 0.02, whereas the parametrization σ≈σ 0 ( Z A ) A α′ , where σ 0 ( Z A ) is given by the Drell-Yan model, leads to α ′ = 0.97 ±0.02±0.02. This last result is in agreement with the quark additivity rule which is inherent in the Drell-Yan model, no dependence is observed on the transverse momentum of the muon pair.
PARAMETRISATION OF CROSS-SECTION IS SIG=CONST.*A**POWER.
PARAMETRISATION OF CROSS-SECTION IS SIG=SIG0(Z/A)*A**POWER WHERE SIG0(Z/A) IS GIVEN BY DRELL-YAN MODEL.
A significant rate of forward proton and antiproton production has been observed in 120 and 280 GeV muon-proton scattering. The z and p T 2 distributions are presented. The dependence of the normalized production cross section on the muon variables x and Q 2 is studied.
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In a selected sample of 6770 charged current (CC) events of νp interactions with 〈 E ν 〉 = 43 GeV and 〈W〉 = 4.6 GeV , 359 K 0 , 180 Λ and 13 Λ have been observed, which corresponds to a corrected production rate at least one neutral strange particle in (17.4±0.8)% of the CC events. The ratio of the inclusive Λ to K 0 production cross section is found to be 0.26±0.03. The number of CC events containing at least one K 0 increases with increasing E ν and Q 2 , while the CC events containing at least one Λ remain practically constant. The fractions of the total hadronic energy carried by K 0 and Λ are found to be approximately the same in νp as in ep and μp interactions. In the hadronic c.m.s., the K 0 are produced mostly forwards, the Λ mostly backwards, with asymmetry parameters of +0.32±0.02 and −0.45±0.06, respectively. The total strange particle production cross section is estimated to be (25±4)% of the cross section for production of CC events with W >1.5 GeV and that for charm production (10±2)% of the CC cross section well above charm threshold ( W >3 GeV). The production of the resonances K ∗+ (890) and Σ + (1385) has been observed. The production rate of K ∗+ (890) is comparable to that of D ∗+ (2009), above the corresponding thresholds.
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