Ambrozewicz, P.
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Cross Section and Tensor Analysing Power of the $\vec{d}d\to \eta\alpha$ Reaction Near Threshold

The GEM collaboration Budzanowski, A. ; Chatterjee, A. ; Gebel, R. ; et al.
Nucl.Phys.A 821 (2009) 193-209, 2009.
Inspire Record 803178 DOI 10.17182/hepdata.52401

The angular distributions of the unpolarised differential cross section and tensor analysing power $A_{xx}$ of the $\vec{d}d\to\alpha \eta$ reaction have been measured at an excess energy of 16.6 MeV. The ambiguities in the partial-wave description of these data are made explicit by using the invariant amplitude decomposition. This allows the magnitude of the s-wave amplitude to be extracted and compared with results published at lower energies. In this way, firmer bounds could be obtained on the scattering length of the $\eta \alpha$ system. The results do not, however, unambiguously prove the existence of a quasi-bound $\eta \alpha$ state.

3 data tables
Table 1

Total cross section from fit to the differential angular distribution.

Table 2

Differential angular distribution.

Table 3

Analysing power measurements.


Dependence of p(pol.) p(pol.) --> p p pi0 near threshold on the spin of the colliding nucleons.

Meyer, H.O. ; Balewski, J.T. ; Dzemidzic, M. ; et al.
Phys.Rev.Lett. 81 (1998) 3096-3099, 1998.
Inspire Record 472992 DOI 10.17182/hepdata.39971

A polarized internal atomic hydrogen target and a stored, polarized beam are used to measure the spin-dependent total cross section Delta_sigma_T/sigma_tot, as well as the polar integrals of the spin correlation coefficient combination A_xx-A_yy, and the analyzing power A_y for pp-> pp pi0 at four bombarding energies between 325 and 400 MeV. This experiment is made possible by the use of a cooled beam in a storage ring. The polarization observables are used to study the contribution from individual partial waves.

1 data table
Table 1

SIG(C=DEL_T) defined as the cross section with the spins of the colliding protons antiparallel, minus the cross section with spins parallel, using transversely polarized beam and target.


Study of the reaction anti-p p ---> anti-Lambda Lambda at 1.546-GeV/c and 1.695-GeV/c

Barnes, P.D. ; Diebold, G. ; Franklin, G. ; et al.
Nucl.Phys.A 526 (1991) 575-601, 1991.
Inspire Record 301648 DOI 10.17182/hepdata.36756

The PS185 experiment at the CERN Low Energy Antiproton Ring (LEAR) has studied the reaction p ̄ p → \ ̄ gLΛ at several momenta. In this paper results from two runs with high statistics at 1.546 GeV/ c and 1.695 GeV/ c are described. Based on 4063 and 11362 analysed events, respectively, differential and integrated cross sections, polarizations and spin correlations are presented. The singlet fraction, extracted from the spin correlations, is consistent with zero at both momenta, showing that the \ ̄ gLΛ pairs are produced in a pure triplet state. A comparison of the decay asymmetry parameters of Λ and \ ̄ gL reduces the upper limits for the violation of the CP invariance for this system.

10 data tables
Table 1

No description provided.

Table 2

THE BESTFIT WITH LMAX=3, HI2=1.204.

Table 3

THE BESTFIT WITH LMAX=6, HI2=0.547.

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Partial-wave analyses of the (3π)-system in the reaction π − p → π − π − π + p at 11.2 GeV/ c

The Bologna-Florence-Genoa-Milan-Oxford-Pavia collaboration Thompson, G. ; Antich, P. ; Boldetti, A. ; et al.
Nucl.Phys.B 101 (1975) 285-303, 1975.
Inspire Record 2860 DOI 10.17182/hepdata.36138

The results are presented of two partial-wave analyses of the (3π) − system in 30 000 events of the reaction π − p → π − π − π + p at 11.2 GeV/ c . Both techniques incorporate the assumptions of the isobar model and are (a) the University of Illinois program which fits in terms of the (3π) density matrix elements and (b) an amplitude parametrisaton including possible effects of both spin non-flip and spin flip at the baryon vertex. The results obtained with these independent programs are found to be very close.

2 data tables
Table 1

NORMALIZED TO A TOTAL REACTION CROSS SECTION OF 1.17 +- 0.24 MB. ALL QUOTED CROSS SECTIONS ARE FOR INTEGRATED BREIT-WIGNERS.

Table 2

A2 2+D-WAVE FOR 1.2 < M(3PI) < 1.4 GEV. THE FIRST THREE COMBINATIONS OF DENSITY MATRIX ELEMENTS ARE FOR NATURAL PARITY EXCHANGE, AND THE REMAINDER UNNATURAL.