E.V. Smirnov

Polarization measurements in π+p, K+p and pp elastic scattering at 45 GeV/c and comparison with Regge phenomenology

Abstract The polarization parameter P has been measured for elastic π + p, K + p and pp scattering at 45 GeV/c. Four-momentum transfer ranges from −0.08 to −1.1 (GeV/) 2 for pp, and from −0.08 to −0.9 (GeV/) 2 for π + p and K + p. The energy dependence of the polarization P ( t ) in π + p and in K + p above 6 GeV/c incident momentum is compatible with interference between pomeron and Regge poles. On the other hand, the polarization in p p elastic scattering decreases faster than ordinary Regge model predictions. This result can be explained by interference between non flip and flip amplitudes of the pomeron, leading to negative values for the polarization.

Polarization measurements in π−p, K−p and p¯p elastic scattering at 40 GeV/c

Abstract We report final results on the polarization parameter P in elastic scattering of π − , K − and antiprotons at 40 GeV/ c incident momentum. The energy dependence of P (t) in π − p above 10 GeV/ c is well fitted by P (t) α s αR(t)-α P (t) where α R (t) are the effective Regge and Pomeron trajectories respectively. The data in K − p are compatible with exchange degeneracy. The results inp¯p show an important structure for |t|> 0.3 (GeV/c) 2 demonstrating the existence of a large helicity flip amplitude.

Elastic scattering of π±p, K±p, pp AND prmpp AT 39 AND 44.5 GeV/c

Abstract The differential cross sections for elastic π − p, K − p , p p and π + p, pp scattering at 39 and 44.5 GeV/ c , respectively, have been measured in the interval of momentum transfer squared 0.15 ≤ ovbt | ≤ 2 (GeV/ c ) 2 .

Elastic scattering of π− mesons on protons in the coulomb-nuclear interference region at 33–60 GeV/c

Differential cross sections for the elastic scattering of negative pions on protons, as well as total cross sections have been measured for the incident momentum range from 33 up to 60 GeV/c. The values for four-momentum transfer were within the limits of −(10−3−8·10−2) (GeV/c)2. The energy dependence of the ratio ϱ(0) of the real part of the forward elastic scattering amplitude to the imaginary part has been determined from the experimental data. The magnitude ϱ(0) smoothly increases from (−10.9 ± 1.2)% at momenta 33.52 GeV/c up to (−1.8 ± 1.8)% at 59.4 GeV/c. The results obtained are compared with the predictions of theoretical models.

Measurement of the polarization parameter in π−p elastic scattering at 40 GeV/c

Abstract We report our first measurements of the polarization in the elastic scattering of negative pions from polarized protons at an incident pion momentum of 40 GeV/ c . The momentum-transfer region covered was 0.08 t | c ) 2 . The angular distribution of the polarization exhibits a first minimum of ∼ − 5% and the well-known zero around t ≈ − 0.6 (GeV/ c ) 2 . The energy variation of the first minimum (at around t = − 0.2) may be expressed in a simple form, P avr = −(0.48±0.06) s −0.52±0.05 .

Apparatus for Simultaneous Measurements of the Polarization and Spin-Rotation Parameters in High-Energy Elastic Scattering on Polarized Protons

Abstract The main parts of an apparatus for simultaneous measurements of the polarization and spin-rotation parameters in high-energy elastic scattering on polarized protons are described, including the beam design, the polarized target, detectors, fast electronics, and the data acquisition. Measurements have been performed in 1972 to 1974 at the Serpukhov accelerator with π − , K − and p of 40 GeV/ c , and with p, π + and K + of 45 Ge V / c incident momentum. In addition to the results for P and R , the experiment also yields information on the unpolarized differential cross section.

Polarization in charge exchange reaction π−+p→π0+n at 40 GeV/c for the 4-momentum transfer range 0<|t|<2 (GeV/c)2

The results on measuring polarization in charge exchange reaction π−+p→π0+n at 40 GeV/c are presented for the 4-momentum transfer range from 0 up to 2 (GeV/c)2. At |t|≦0.4 (GeV/c)2 the polarization has a positive sign. In the “crossover” region of π± elastic scattering a possible minimum in the polarization behaviour has been seen for the first time. the polarization is zero within the statistical accuracy near this point. In the “deep” region of the charge-exchange differential cross-section the polarization has a negative sign. The presented data are not in agreement with the modern theoretical models.

On studying energy dependences of π− p elastic scattering cross sections in the 33–55 GeV/c range

Abstract The π − p differential elastic scattering cross sections have been measured for eight momenta in the 33–55 GeV/ c range. The energy dependence of the slope and of the total elastic scattering cross sections has been determined experimentally. The results are compared with the known data. The experimental data are compared both with the Regge pole model and with the quasi-potential one.

Measurements of the spin rotation parameterR in high energy elastic scattering and helicity amplitudes at Serpukhov energies

The spin rotation parameterR in pp and π+ p elastic scattering at 45 GeV/c has been measured at the Serpukhov accelerator, for ¦t¦ ranging from 0·2 to 0·5 (GeV/c)2. The results are presented, together with previousR measurements at lower energies, and are compared with the predictions of Regge pole models. The equality of the values forR in proton-proton and pion-proton scattering, within the experimental errors, is a test of factorization of the residues.Ans-channel helicity amplitude analysis for pion-nucleon scattering at 40 GeV/c is made using all available data, Significant results are obtained for the isoscalar exchange amplitudes. The helicity flip in isoscalar exchange is non negligible. The energy dependence of this amplitude, at 6, 16 and 40 GeV/c, is compared with predictions of Reggs pole models.

Observation of the polarization in reaction π−→ηn at 40 GeV/c

The preliminary results of polarization measurements in reaction π−+p→η+n at 40 GeV/c for the 4‐momentum transfers up to 1 (GeV/c)2 are presented. Averaged blue of the polarization in the t‐range 0,5<‖t‖<1 (GeV/c)2 is −(24±8)%. The presented data are in a contraction with existant Regge model predictions.