Results are presented of a measurement of the proton-proton elastic-scattering spin parameter CLL=(L,L;0,0) at 11.75 GeV/c and θc.m.=48°−90°. The value of CLL is nearly constant and is approximately -0.16 in this angular region. This behavior is consistent with only one of the many models proposed describing the interaction via the hard scattering of two quarks.
NUMERICAL VALUES OF DATA SUPPLIED BY H. SPINKA.
ESTIMATED VALUE OF CSS (90 DEG) DETERMINED FROM PRESENT DATA ON CLL AND DATA OF CRABB ET AL., (PRL 41, 1257) AND CROSBIE ET AL., (PR D23, 600) FOR CNN VIA THE RELATION CNN-CSS-CLL=1 (90 DEG). ERROR CONTAINS BOTH SYSTEMAT8ICS AND STATISTICS.
Recent data are presented on spin-spin correlation parameters CLL=(L,L;0,0) and CSL=(S,L;0,0) at forward angles from 1.18 to 2.47 GeV/c incident momenta in proton-proton elastic scattering. Values for ΔσL (inelastic) are derived and are shown to disagree with predictions of theoretical models attempting to describe p−p scattering without dibaryon resonances. Finally, the CLL and CSL data discriminate among various phase-shift solutions, and will lead to a clarification of the p−p phase shifts.
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Measurements of C LL of pp elastic scattering near θ c.m. = 90° at thirteen energies between 300 and 800 MeV are reported. These, together with previous values of C NN , are used to extract values of two quantities, ƒ s and ƒ t , which contain only spin-singlet and only coupled spin-triplet partial waves, respectively. The ƒ s curve, which is not dependent on C LL , exhibits the behavior expected for the previously conjectured 1 D 2 resonance. The ƒ t curve also exhibits a resonance-like behavior, which could be due either to the 3 P 0 or the 3 P 2 partial wave.
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The difference between total cross sections in pure transverse-initial-spin states for the p−p interaction has been measured at Tp=487, 639, and 791 MeV, using a frozen-spin target. A comparison with previous data and available phase-shift analyses is made.
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The spin-spin correlation parameter CLL=(L, L; 0, 0) has been measured for p−p elastic scattering around θc.m.=90° up to plab=5 GeV/c. An interesting energy dependence is observed in CLL and the results are interpreted by comparison with other available data.
NUMERICAL VALUES OF DATA IN FIGURE SUPPLIED BY A. YOKOSAWA.
We have measured the difference between proton-proton total cross sections for parallel and antiparallel longitudinal spin states [ΔσL=σtot(⇄)−σtot(⇄)] at 13 incident energies between 300 and 800 MeV, which cover the region of possible D21 and F33 diproton resonances. The present experiment has strongly confirmed the structure previously observed at the Argonne Zero Gradient Synchrotron. No additional narrow structure has been found.
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The total-cross-section difference in pure longitudinal spin states for p−d interactions has been measured at momenta from 1.1 to 6 GeV/c. Spin-dependent Glauber-type corrections and other corrections have been made to obtain ΔσL(pn) and ΔσL(I=0). These measurements are of fundamental interest and will also help in determining the existence and nature of dibaryon resonances.
CORRECTED FOR BOTH ELASTIC AND BREAKUP COULOMB-NUCLEAR INTERFERENCE. AUTHORS ALSO ESTIMATE DEUTERIUM CORRECTIONS TO DEDUCE CORRESPONDING P N AND I=0 VALUES.
The first measurements are reported of the asymmetry in resonance-region scattering of longitudinally polarized electrons by longitudinally polarized protons. Data have been obtained at Q2=0.5 and 1.5 (GeV/c)2 in the missing-mass range W=1.1−1.9 GeV. Results are compatible with a multipole analysis of single-pion electroproduction. The spin-dependent behavior is consistent with a duality mechanism as in the unpolarized case.
ELECTRON ASYMMETRY AT Q**2 ABOUT 0.5 GEV**2.
ELECTRON ASYMMETRY AT Q**2 ABOUT 1.5 GEV**2.
PHOTON ASYMMETRY AT Q**2 ABOUT 0.5 GEV**2.
We have measured the asymmetry parameter A and the spin correlation parameter A nn in pp elastic scattering, using the Argonne ZGS polarized proton beam and a polarized proton target. Angular distributions of A and A nn for | t | ≳ 0.2 (GeV/ c ) 2 were obtained at eight momenta between 1.10 and 2 if 2.75 GeV/ c . We find significant structure in both the energy and t -dependence of A nn at these energies. At p lab ≈ 1.34 GeV/ c A nn reaches a very large value of about 0.8–0.9 near θ cm = 90°.
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Toward the goal of experimentally determining pp elastic scattering amplitudes at 6 GeV/c, we have measured a linear combination of triple-spin correlation parameters and also a linear combination of spintransfer parameters over the |t| range between 0.2 and 1.0 (GeV/c)2. A horizontally polarized beam (S direction) was obtained by precessing the spin of the polarized beam from the Argonne Zero Gradient Synchrotron using a superconducting solenoid. The target protons were polarized vertically (N direction) and the polarization of the recoil protons was measured with a carbon polarimeter. The results are consistent with the amplitude corresponding to π exchange being almost real and positive.
KSS = (S00S) AND HSNS = (SN0S) MEASURED HERE CONTAIN SMALL ADMIXTURES OF THE OTHER SPIN-TRANSFER AND TRIPLE-SPIN CORRELATION PARAMETERS RESPECTIVELY DUE TO THE POLARIZED TARGET MAGNETIC FIELD - SEE TEXT. MEAN VALUE OF HSNS OVER THIS T-RANGE IS 0.098 +- 0.085. PARITY CONSERVATION REQUIRES THE VANISHING OF THE PARAMETERS KSN, HSNN, (000S) AND DNS, WHILE (000N) MUST AGREE WITH THE SINGLE SCATTERING POLARIZATION PARAMETER (0N00).
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