The reactions π−p→ n+(X0→total) and π−p→ n+(X0→neutrals) have been studied at 1.6 GeV/c with the Bologna-CERN neutron missing-mass spectrometer. Both reactions have been detected without the use of visual techniques. The results are: σ(X0→total)=(108±14) μb and σ(X0→neutrals)=(20.0±3.5) μb, giving a branching ratio Γ(X0→neutrals)/Γ(X0→total)=(18.5±2.2)%. The branching ratio for other possible, so far undetected, neutral decay modes of the X0 turns out to be (2.4±1.9)%.
No description provided.
The possible existence of new vector mesons above the ρ is investigated. The conclusion is that our data are compatible with the existence of the ρ′-meson only if we assume as a firm theoretical prediction the Gounaris-Sakurai tail of the standard ρ-meson. Furthermore our data are compatible with the existence of the ρ″-meson if we assume the validity of the\(\bar p\)p model for the calculation of the multihadron cross-section.
THESE MEASUREMENTS OF THE PION FORM FACTOR ARE GIVEN IN D. BOLLINI ET AL., NCL 14, 418 (1975).
THESE MEASUREMENTS OF THE FOUR CHARGED PION CROSS SECTION ARE GIVEN IN M. BERNARDINI ET AL., PL 53B, 384 (1974).
THESE MEASUREMENTS OF THE TOTAL HADRONIC CROSS SECTION ARE GIVEN IN M. BERNARDINI ET AL., PL 51B, 200 (1974).
The angular distribution of 2720 tracks of 1085 hadronic final states produced from (e+e-) annihilation has been studied in the 1.2 to 3.0 GeV total centre-of-mass energy range. If we parametrize the angular distribution in terms off(θ) =1 + A cos2 θ, where 6 is the angle between the hadronic track produced and the colliding-beam direction, the results show thatA is less than 0.21, with 90% confidence.
ANGULAR DISTRIBUTION OF CHARGED HADRONS FOUND TO BE 1 + (0.07 +- 0.11)*(COS(THETA)**2).
The analysis of 1466 events of the type e + e − → μ ± μ ± , in the time-lifke range from 1.44 to 9.00 GeV 2 , sh that the absolute value of the cross-section and its energy dependence follow QED expectations within (± 3.2%) and (± 1.2%), respectively.
The cross section of the reaction $e^+ e^- \to \mu^\pm \mu^\mp$ integrated over the experimental apparatus at 14 values of the colliding beam energy $E$ corresponding to total centre-of-mass energy $\sqrt{s}=2E$ from 1.2 to 3.0 GeV.
New Results are presented on nuclear effects in deep inelastic muon scattering on deuterium and iron targets at large Q 2 . The ratio F Fe 2 (x) F D 2 2 (x) measured in the kinematic range 0.06⩽ x ⩽0.70, 14GeV 2 ⩽ Q 2 ⩽70 GeV 2 is in good agreement with earlier measurements in the region of x > 0.25. At lower x , the structure function ratio exhibits an enhancement of ≈5%.
Q**2 RANGE FOR EACH X BIN IS AS FOLLOWS: 14 TO 20, 16 TO 30, 18 TO 35, 18 TO 46, 20 TO 106, 23 TO 106, 23 TO 150, 26 TO 200, 26 TO 200, 26 TO 200 GEV**2.
None
No description provided.
No description provided.
F2(FE)/F2(DEUT) AVERAGED OVER Q2.
None
VALUES OBTAINED USING ASSUMPTION R=0.
VALUES OBTAINED USING ASSUMPTION R=0.
New data is presented on the ratios of structure functions F 2 ( x , Q 2 ) measured in deep inelastic muon scattering with deuterium, nitrogen, and iron targets. The existence of nuclear effects at large Q 2 is confirmed with improved systematic accuracy. The ratio F 2 Fe ( x ) F 2 D 2 ( x ) covers the range 0.20 ⩽ x ⩽ 0.70 and is in agreement with earlier measurements. The ratio F 2 N 2 ( x )/ F 2 D 2 ( x ) is measured over the range 0.08 ⩽ x ⩽ 0.70 and is compatible with unity below x = 0.3.
VALUES OF Q2 CORRESPONDING TO THE X-BINS IN THIS TABLE ARE:- 46-106,46-106,53-150,53-200,70-200,80-200 RESPECTIVELY.
VALUES OF Q2 CORRESPONDING TO THE X-BINS IN THIS TABLE ARE:- 26-40,26-61,30-80,30-106,30-106,30-150,30-200,35-200,46-200.
The interference structure function xG 3 ( x ) has been measured for the first time scattering positive and negative muons of opposite helicity off a carbon target. The x dependence observed for Q 2 between 40 and 180 (GeV/c 2 ) is in good agreement with predictions of the quark-parton model. The measured ratio 2( a u Q u + a d Q d )/( Q u 2 + Q d 2 = 1.87 ± 0.25 (stat.) ± 0.24 (syst.) is consistent with the hypothesis of fractional quark charges and determines the sign of Q u − Q d to be positive.
No description provided.
No description provided.
No description provided.
We present results on a high statistics study of the nucleon structure functions F 2 ( x , Q 2 ) and R = σ L / σ T measured in deep inelastic scattering of muons on a deuterium target. The analysis is based on 8×10 5 events after all cuts, recorded at beam energies of 120, 200 and 280 GeV in the kinematic range 0.06⩽ × ⩽0.80 and 8GeV 2 ⩽ Q 2 ⩽260GeV 2 . Scaling violations observed in the data are in agreement with predictions of perturbative QCD and allow to determine the QCD mass scale parameter Λ.
No description provided.
R=SIG(L)/SIG(T) is taken to be zero.
R=SIG(L)/SIG(T) is taken to be zero.
Forum