Search

The pion radiative scattering (π-p → π-pγ) has been studied at 43 GeV in the interval 0.2 < |tp| < 0.4 (GeV/c)2 of the momentum transfer squared to the proton and in the range of photon energy 2 < ω < 40 GeV. Calculations based on Low theorem agree well with measured ω, tp and mπγ (final πγ-invariant mass) differential cross-sections. The results obtained extend the validity of Low approach to the radiative scattering at high energies.

We present the results of an experimental investigation of the production in the nuclear Coulomb field of low-invariant-mass pions pairs by the reaction ..pi../sup -/Z..--> pi../sup -/..pi../sup 0/Z at 40 GeV. We have obtained for the first time the experimental value of the ..gamma -->..3..pi.. coupling constant F/sup 3pi/(0) = 13.0 +- 0.9 +- 1.3 GeV/sup -3/, where the first (second) error is statistical (systematic). This result is in agreement with calculations based on the theory of chiral anomalies.

The vertex ..gamma -->..3..pi.. has been investigated in the reaction of pion pair production by pions in the nuclear Coulomb field, ..pi../sup -/+(Z,A)..--> pi../sup -/+..pi../sup 0/+(Z,A), in the region of low-invariant-mass ..pi../sup -/..pi../sup 0/ pairs. The experiment has been carried out in the 40-GeV pion beam of the IHEP accelerator (Serpukhov) with the SIGMA spectrometer. We have measured for the first time the cross section of the reaction in the region of momentum transfer squared q/sup 2/ ..3..pi.. coupling constant F/sup 3//sup ..pi../ = 12.9 +- 0.9 +- 0.5 GeV/sup -3/, where the first (second) error is statistical (systematic). The obtained result agrees with the calculations based on the Wess-Zumino-Witten effective Lagrangian. The hypothesis of chiral anomalies and the color-SU(3) quark symmetry are confirmed.

The paper presents the results on differential cross sections for elastic scattering of 7+-, K+-mesons and protons on protons in the 4-momentum transfer squared range 0·08 ≦¦t¦≦ ≦1·0 (GeV/c)2 and incident particle momentum of 29 and 43 GeV/c for pions and kaons and 29, 43, 50 and 65 GeV/c for protons. The measurements were taken with the spectrometer Sigma, installed in the positive beam of the IHEP accelerator.

About 7 × 10 3 events of Compton effect on pion in the reaction π − A → A π − γ st 40 GeV/ c were detected and for the first time the charged pion polarizability was obtained α π = (6.8 ± 1.4) × 10 −43 cm 3 .

The ππ0 production in nuclear Coulomb field at threshold has been studied for the first time experimentally. The cross section of the reaction $$\pi ^ - + (A,Z) \to \pi ^ - + \pi ^0 + (A,Z)$$ at 40 GeV on C, Al, Fe nuclei has been determined for small 4-momentum transferst

The reaction π−A→Aπ− γ at 40 GeV/c was studied on “Sigma” spectrometer on six different nuclear targets in the region of four-momentum transfer |t

Total cross-section data are presented for negative pions, kaons, and antiprotons on protons and deuterons in the momentum range 20 GeV/c to 65 GeV/c in 5 GeV/c steps.

The paper describes differential Cerenkov counters detecting Cerenkov light at the angles of 23 and 12 mrad. The counter lengths are 5 m (θ = 23 mrad) and 10 m (θ = 12 mrad). The spectrum band of the counters is 2500–6000 A. The counter characteristics have been investigated in 35 to 45 GeV/c beams of the 70 GeV accelerator. The velocity resolutions measured are equal to 2×10−6 for a 10 m counter and 6×10−6 for a 5 m counter. The 10 m counter can separate pions and kaons up to 200 GeV/c and kaons and protons (antiprotons) up to 350 GeV/c.

π − p , K − p and p p total cross-sections are measured at momenta up to 65GeV/c with statistical accuracy 0.3 ÷ 0.6% and systematical (scale) error ≈ 0.4%.

Absorption cross sections for pi /sup plus or minus /, K/sup plus or minus mesons, protons andantiprotons on Li, Be, C, Al, Cu, Sn, Pb and V in the momentum range from 6.65 to 60 GeV/c are measured at the 70 GeV IHEP accelerator. The cross sections are compared with calculations using the Glauber multiple- scattering model. Nucleus radii are found to be described by a power dependence on atomic weight R = r/sub o/A/sup 1/3/, where r/sub o/= 1.05 plus or minus 0.02 fm. (auth)

The pion radiative scattering πZ→πZγ at 40 GeV was investigated. Coulomb scattering-i.e. pion Compton-effect-dominates for small fourmomentum transfers in this reaction. In our previous paper we found the pion polarizability to beβ π =(−6.8±1.4)·10−43, cm3, where we assume following the theory that the sum of electrical and magnetic polarizabilities (α π +β π )≃0. More complete analysis of our data is done in order to test this assumption. The result for (α π +β π ) is in agreement with theoretical predictions.

The A -dependence of J/ψ inclusive production by 43 GeV/ c π − -mesons was measured to be σ = (18 ± 6) A (0.92±0.06) nb/nucleus for x > 0.

The yields of pions, kaons, antiprotons and antideuterons, produced by the 70 GeV protons on Al and Be nuclei at the momenta 10 and 13.3 GeV/ c have been measured. Gas Cerenkov counters and time-of-flight spectrometers were used for particle identification.

The E672/E706 Spectrometer, located in the MW beam at Fermilab, was used to collect data on events containing a pair of muons in the final state with large effective mass. The momentum of incident pions and protons was 530 GeV/c. Nuclear targets included Be, C, Al, Cu and Pb. We report on a preliminary measurement of the A‐dependence of the per nucleus cross section for forward J/ψ production. The apparatus also detected charged particles and γ’s produced in association with the muon pair. The expected physics results on the hadroproduction of χ states and beauty particles are discussed.

Data are presented on the yields of π − , K − , and p produced at small angles by 70 GeV proton-aluminium interactions. The momenta of the secondaries studied were greater than 40 GeV/ c . Upper limits have been obtained on the production of antideuterons and possible new particles up to a mass of 2.2 GeV in this new energy region.