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Electroproduction of pi0 on the proton near threshold

Welch, T.P. ; Karen, P.H. ; Mitchell, J.H. ; et al.
Phys.Rev.Lett. 69 (1992) 2761-2764, 1992.
Inspire Record 344040 DOI 10.17182/hepdata.19808

The electroproduction of π0 on the proton was measured from 0 to 2.5 MeV above threshold for virtual-photon 4-momenta of -0.05 and -0.1 (GeV/c)2. The sum of the lowest-order contributing multipoles, a0=‖E0+‖2-εL‖L0+‖2, was determined with a precision an order of magnitude better than previously possible. Our results for a0 are consistent with present calculations. Our extracted value for ‖L0+‖2 at the ‘‘photon point’’ is in agreement with recent predictions.

1 data table
Table 1

Joined statistics for two incident electron energy of 300 and 500 MeV.


Determination of anti-proton neutron amplitude from elastic anti-p deuteron scattering at 600-MeV/c

Mahalanabis, J. ;
Z.Phys.A 342 (1992) 101-105, 1992.
Inspire Record 343348 DOI 10.17182/hepdata.16576

The elementary ¯p-neutron amplitude has been obtained from Glauber's model analysis of ¯p-d elastic scattering data at 600 MeV/c, taking into account theD-state component of the deuteron. The results are compared with the ¯p-nucleus analysis and the ¯NN potential model predictions.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


Collective excitation of Delta isobar in the charge exchange reactions (Li-7, Be-7) and (H-3, He-3) at a momentum of 3-GeV/c/nucleon

Avramenko, S.A. ; Abdurakhimov, A.U. ; Aksinenko, V.D. ; et al.
JETP Lett. 55 (1992) 707-712, 1992.
Inspire Record 346156 DOI 10.17182/hepdata.16833

None

2 data tables
Table 1

No description provided.

Table 2

No description provided.


Limit on the anti-d / anti-u asymmetry of the nucleon sea from Drell-Yan production

McGaughey, P.L. ; Moss, J.M. ; Alde, D.M. ; et al.
Phys.Rev.Lett. 69 (1992) 1726-1728, 1992.
Inspire Record 344919 DOI 10.17182/hepdata.19848

We present an analysis of 800-GeV proton-induced Drell-Yan production data from isoscalar targets 2H and C, and from W, which has a large neutron excess. The ratio of cross sections per nucleon, R-σW/σIS, is sensitive to the difference between the d¯(x) and u¯(x) structure functions of the proton. We find that R is close to unity in the range 0.04≤x≤0.27, allowing upper limits to be set on the d¯-u¯ asymmetry. Additionally, the shape of the differential cross section m3 d2σ/dxF dm for 2H at xF≊0 shows no evidence of an asymmetric sea in the proton. We examine the implications of these data for various models of the violation of the Gottfried sum rule in deep-inelastic lepton scattering.

1 data table
Table 1

Upper limit at the 2sigma statistical error level. Mass of MU+ MU- in GeV.


Electron positron pair production in Coulomb collisions of ultrarelativistic sulphur ions with fixed targets

Vane, C.R. ; Datz, S. ; Dittner, P.F. ; et al.
Phys.Rev.Lett. 69 (1992) 1911-1914, 1992.
Inspire Record 343889 DOI 10.17182/hepdata.19818

Angular and momentum distributions have been measured for positrons from electron-positron pairs created in peripheral collisions of 6.4-TeV sulfur ions with fixed targets of Al, Pd, and Au. The data are compared with results of several theoretical treatments. Measured differential cross sections peak at low momentum (≤1 MeV/c), extend significantly to much higher momenta (>17 MeV/c), and concentrate sharply in the forward direction, along the ion-beam axis. Positron yields scale as the square of the target nuclear charge as predicted by theory.

1 data table
Table 1

No description provided.


Precise Measurement of the $\Xi^-$ Magnetic Moment

Duryea, J. ; Guglielmo, G. ; Heller, Kenneth J. ; et al.
Phys.Rev.Lett. 68 (1992) 768-771, 1992.
Inspire Record 335825 DOI 10.17182/hepdata.19850

With 4.36×106 events, spin precession in a magnetic field has been used to measure the magnetic moment of the Ξ− hyperon as -0.6505±0.0025 nuclear magnetons.

1 data table
Table 1

No description provided.


Quasielastic scattering of polarized electrons from polarized He-3 and measurement of the neutron's form-factors

Thompson, A.K. ; Bernstein, A.M. ; Chupp, T.E. ; et al.
Phys.Rev.Lett. 68 (1992) 2901-2904, 1992.
Inspire Record 338099 DOI 10.17182/hepdata.19863

We report measurements of asymmetries in quasielastic scattering of polarized electrons from polarized He3 at Q2=-0.2 GeV/c)2. We measure AT′=(-2.6±0.9±0.46)% and ATL′=(+1.75±1.2±0.31)%. The asymmetry AT′ depends predominantly on the previously measured neutron magnetic form factor and provides a test of theories of spin-dependent quasielastic scattering. Our result for AT′ is consistent with a previously reported measurement and suggests that the current theoretical picture is incomplete and final-state-interaction and meson-exchange corrections are necessary if the electric form factor of the neutron is to be reliably extracted from the asymmetry of ATL′.

1 data table
Table 1

No description provided.


Polarization of Lambda hyperons produced by the quasifree (pi+, K+) reaction on C-12

Ajimura, S. ; Ejiri, H. ; Higashi, A. ; et al.
Phys.Rev.Lett. 68 (1992) 2137-2140, 1992.
Inspire Record 338084 DOI 10.17182/hepdata.19866

The polarization of quasifree Λ hyperons produced by the (π+K+) reaction on C12 and on the deuteron was measured for the first time. The asymmetry of pions from weak decay of the Λ hyperon was used to determine the polarization. The polarization for the deuterium target was found to be consistent with that for the elementary n(π+,K+)Λ reaction. The polarization of the Λ produced by the quasifree process from C12 is consistent with that for the elementary reaction, which demonstrates that the spin characteristics of the elementary reaction are not modified by the nuclear medium.

1 data table
Table 1

No description provided.


Proton polarization from pi+ absorption in He-3

MayTal-Beck, S. ; Aclander, Jaime L.S. ; Altman, A. ; et al.
Phys.Rev.Lett. 68 (1992) 3012-3015, 1992.
Inspire Record 339565 DOI 10.17182/hepdata.19868

We present the first polarization measurements for pion absorption on a nucleus heavier than the deuteron. The polarization of protons resulting from π+ absorption in the He3 was measured at bombarding energies of 120 and 250 MeV. Protons from absorption in a quasideuteron were selected by applying kinematical constraints. A significant discrepancy was observed between the experimental results and theoretical predictions. At 120 MeV the measured polarizations for He3 are consistent with those of the deuteron. At 250 MeV the angular distribution of the polarization is significantly different than for the deuteron, showing sensitivity to the nuclear density, and thus may be sensitive to short range correlations between nucleons.

4 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Measurements at 0-degrees of negatively charged particles and anti-nuclei produced in collision of 14.6-A/GeV/c Si on Al, Cu, and Au targets

Aoki, M. ; Beatty, J. ; Beavis, D. ; et al.
Phys.Rev.Lett. 69 (1992) 2345-2348, 1992.
Inspire Record 344921 DOI 10.17182/hepdata.19827

We report measurements of d¯, p¯, K−, and π− produced at 0° in collisions of 14.6A GeV/c Si28 on Al, Cu, and Au targets. A beam-line focusing spectrometer was used to identify particles at rigidities from -2 to -8 GV. The ratio of d¯/p¯ invariant cross sections at midrapidity (y=1.7) is (1±0.7)×10−5, larger than expected from a calculation of dd¯ direct production but smaller than predicted by a simple coalescence model. We also report limits on the production of exotic particles.

10 data tables
Table 1

No description provided.

Table 2

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Table 3

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