Charge-symmetry-breaking effects from phase-shift analysis of elastic π± He scattering

A phase-shift analysis of elastic π^±4 He scattering at energies 20–160 MeV was performed to determine pure hadronic phase shifts. No statistically significant difference between the hadronic phase shifts deduced from π⁺⁴ He and π⁻⁴ He scattering was observed.     

Parity violation in πN scattering

The possibility of detecting the ΔS = 0 weak interaction by observing the longitudinal polarisation of the recoil nucleon in πN scattering is considered. It is found that the longitudinal polarisation is in the range 10⁻⁶ to 10⁻⁷, which seems to be beyond the capabilities of the experimental techniques of the immediate future.     

Structure in π+p elastic backward scattering

The energy dependence of the differential cross section for π⁺p elastic scattering at a c.m. angle near 174° has been measured. The momentum range of incident π⁺ was 2.06–4.70 GeV/c. On this energy dependence one can see a structure, i.e. maxima corresponding to the baryon resonances Δ (2420) and Δ (2840). The structurte is used for determination of the parities of these resonances.     

Study of π+π− scattering in π−p → π+π−Xo via a chew low extrapolation

An unconstrained Chew Low extrapolation has been performed using 50 000 events from the reaction π⁻→π⁺π⁻X^o at 15 GeV/c, with −t<0.3 (GeV/c)². An energy independent phase shift analysis was performed. Results on the ππ cross section, p-wave and s-wave phase shifts in the mass range (525–975) MeV are presented. We find a unique solution for the s-wave phase shift below 750 MeV.     

Measurements of π+p,K+p and pp elastic scattering)

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.Presented by F. A. Yotch at the Symposium on Hadron-Hadron Scattering at High Energies, Liblice, Czechoslovakia, June 16–21, 1975.The authors would like to express their gratitude to A. A.Logunov, Yu. D.Prokoshkin, L. D.Soloviev and V. A.Yarba for their support of this experiment. We are indebted to CERN Administration for giving us a permission to use a part of equipment of the CIBS spectrometer and to W.Kienzle for useful discussions.     

Cross sections and asymmetries for elastic π3He scattering in the energy region around the Δ resonance

For a polarized target, π³He interaction is studied in the fixed-center approximation with all rescatterings included. Only the P ₃₃ wave is taken for the πN interaction. The nuclear wave function is taken either as a sum of Gaussian functions or as a Faddeev wave function in the s-wave approximation. The differential cross sections and asymmetries for elastic π⁺³He scattering at the laboratory energies of T _π, 180, and 256 MeV are calculated. The results are compared with experimental data.     

Comparative study of Z′ searches in e+e− and e−e− scattering

We consider indirect searches for additional neutral vector bosons in e⁺e⁻ and e⁻e⁻ collisions, and compare these two linear collider modes with similar analysis procedures and assumptions. Discovery limits and resolving power are discussed in a model-independent way.     

Polarization transfer observables in π-d elastic scattering

Polarization transfer measurements in π⁺ elastic scattering have been performed at two incident pion energies, one below and one at the Δ(3, 3)-resonance. Using a vector polarized deuteron target four polarization transfer observables are determined. The results are compared to predictions from Faddeev calculations.     

Low-energy K− meson elastic scattering from hydrogen

A total of 45 K⁻p low-energy elastic scattering between 0–250 MeV/c has been found by following 276.4 m of K⁻ meson tracks backward from their capture points in nuclear emulsion. The total scattering cross section is plotted as a function of kaon momentum and is compared to previous data. Theoretical values calculated for the elastic scattering cross sections in the low-energy range 30–100 MeV/c are seen to be sensitive to the values of the scattering length parameters used in the S-wave zero-effective range theory which is used here to fit the data in this range. The best fit to the data is given by the scattering length values as given by Cho, i.e. a₀ = −1.21 + 0.56i, a₁ = −0.19 + 44i for the isospin T = 0 and T = 1 channels, respectively. Further evidence for S-wave interaction is discussed through the angular distribution in the center-of-mass system for the elastic events.     

π+ and π− elastic and inelastic scattering on 6Li at 100, 180 and 240 MeV

Angular distributions for scattering from ⁶Li with π⁺ and π⁻ beams were measured at 100, 180 and 240 MeV incident energy. Elastic (J^p = 1⁺, T = 0) and inelastic (J^p = 3⁺, T = 0, E_x = 2.19 MeV) data were obtained over large angular ranges. The elastic results are compared to calculations within the αnp cluster model.     

Experimental study of π− π+ system at low invariant-masses

We report on results of an experiment to study the reaction ^– p ^{– +} in the incident pion momentum region between 295 and 450 MeV/c. A departure from phase space was observed in invariant-mass spectra and angular distributions which cannot be explained with and resonance production. It indicates aI=0,J ^P = 0^{+ – +} final-state interaction.Deceased     

T invariance and polarization effects in the reactions p+3He → π++4He and π++4He → p+3He

On the basis of T invariance, it is established that the dependence of the effective cross section for a binary reaction of the a+b → c+d type on the polarization vectors of primary particles a and b determines completely the polarization vectors and spin correlations for the same particles in the inverse reaction c+d → a+b induced by collisions between unpolarized primary particles c and d. By using the formalism of helicity amplitudes, polarization effects are studied in the process p+³He → π⁺+⁴He and in the inverse process π⁺+⁴He → p+³He. It is shown that, in the reaction π⁺+⁴He → p+³He, the spins of the final-state particles (proton and ³He nucleus) are strongly correlated. An expression for the correlation tensor is obtained for arbitrary values of the (p, ³He) emission angle.     

Spin flip in high energy elastic πN scattering

An upper limit on the magnitude of the spin flip amplitude in gpN elastic scattering is obtained, and the small angle momentum transfer dependence of the reduced spin flip amplitude is found to be comparable with that of the non flip amplitude.     

Polarization in elastic π−p scattering at 16 momenta between 865 and 2732 MeV/c

Polarization distributions and differential cross section data for elastic scattering of negative pions on protons between 865 and 2732 MeV/c are presented. They are compared with published phase-shift analyses.