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Polarization at Small Angles in Anti-proton - Carbon Elastic Scattering at {LEAR} Energies

The SING collaboration Martin, A. ; Birsa, R. ; Bos, K. ; et al.
Nucl.Phys.A 487 (1988) 563-590, 1988.
Inspire Record 261245 DOI 10.17182/hepdata.37001

A double-scattering experiment of antiprotons on carbon has been carried out at the Low-Energy Antiproton Ring (LEAR) at CERN, to measure the polarization parameter A p C in antiproton-carbon elastic scattering at small angles. The polarization parameter has been inferred from the azimuthal distribution of the antiprotons after the second scattering. Data have also been collected with a liquid-hydrogen target as the second scatterer, thus allowing the sign of A p C to be determined. The experiment has been performed at two momenta of the extracted antiproton beam, 800 and 1100 MeV/c. A small positive value of the polarization has been observed, compatible with energy independence and a linear increase with the momentum transfer q . Parametrizing A p C as a c q , we get a c = +0.72 0.10 +0.09 ( GeV / c ) −1 . This result is compared with potential model predictions for N̄N amplitudes through a Glauber theory calculation.

6 data tables match query
Table 1

THETA1(RF=LAB)=8 DEG, THETA POINTED IN TABLE IS THE SECOND SCATTERING ANGLE.

Table 2

THETA1(RF=LAB)=5 DEG, THETA POINTED IN TABLE IS THE SECOND SCATTERING ANGLE.

Table 3

THETA1(RF=LAB)=8 DEG, THETA POINTED IN TABLE IS THE SECOND SCATTERING ANGLE.

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Recoil properties of nuclei produced in the photospallation of Cu-65

Arakelian, A.A. ; Balabekian, A.R. ; Danagulian, A.S. ; et al.
Nucl.Phys.A 534 (1991) 535-540, 1991.
Inspire Record 325657 DOI 10.17182/hepdata.36689

Photospallation 65 Cu by bremsstrahlung photons at 4.5 GeV maximum energy has been investigated using the thick-target thick-catcher method. Kinetic properties of some product nuclei were obtained in terms of the two-step mechanism. The observed results coincide with similar data for reactions of Cu induced by 28 GeV protons. This provides additional support for the hypotheses of limiting target fragmentation and factorization.

1 data table match query
Table 1

BREMSSTRAHLUNG PHOTONS AT 4.5 GEV MAXIMUM ENERGY.


Energy Dependence of the Charge Asymmetry a ($T (\pi$), $\theta$) in $\pi d$ Elastic Scattering

Smith, G.R. ; Gill, D.R. ; Ottewell, D. ; et al.
Phys.Rev.C 38 (1988) 240-250, 1988.
Inspire Record 250814 DOI 10.17182/hepdata.26223

Angular distributions of charge asymmetry A(Tπ,θ), have been measured for πd elastic scattering. Data were obtained in the backward hemisphere for pion bombarding energies of 143, 180, 220, and 256 MeV. The results are compared with predictions employing different mass and width parameters for the delta isobars.

4 data tables match query
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Angular and polarization dependence of Compton scattering from He-4 in the Delta resonance region

Kraus, A. ; Selke, O. ; Wissmann, F. ; et al.
Phys.Lett.B 432 (1998) 45-50, 1998.
Inspire Record 487231 DOI 10.17182/hepdata.28171

Using linearly polarized tagged photons from coherent bremsstrahlung, differential cross sections and beam asymmetries for Compton scattering by 4 He have been measured at MAMI in the energy interval between 150 MeV and 500 MeV for scattering angles of θ γ lab =37°, 93° and 137°, thus largely increasing the available data base. Improved calculations in terms of the Δ -hole model completely fail to describe the data at large scattering angles. The same proved to be true for a schematic model, even after taking into account properties of nuclear photo-absorption in very detail.

1 data table match query
Table 1

Axis error includes +- 0.0/0.0 contribution.


Measurement of the polarized forward - backward asymmetry of Z0 ---> b anti-b using a lifetime tag and momentum weighted track charge

The SLD collaboration Abe, K. ; Abt, I. ; Ahn, C.J. ; et al.
SLAC-PUB-6979, 1995.
Inspire Record 398301 DOI 10.17182/hepdata.18618

None

1 data table match query
Table 1

No description provided.


A Measurement of the Weak Axial Couplings of the $b$ and $c$ Quark

The JADE collaboration Elsen, E. ; Allison, J. ; Ambrus, K. ; et al.
Z.Phys.C 46 (1990) 349-360, 1990.
Inspire Record 282535 DOI 10.17182/hepdata.15241

The forward-backward charge asymmetries of theb andc quarks are measured with the JADE detector at PETRA at\(\sqrt s= 35\) GeV and 44 GeV using both electrons and muons to tag the heavy quarks. At\(\sqrt s= 35\) GeV, a simultaneous fit for the two asymmetries yields the resultAb=−9.3±5.2% (state.) ndAc=−9.6±4.0% (stat.). The systematic errors are comparable with the statistical uncertainties. Combining the measurements at both energies and alternately constraining the weak coupling of thec andb quark to their Standard Model values (ac=1,ab=−1) increases the precision of the measurement of coupling constant of the other quark. Using this procedureab=−0.72±0.34 andac=0.79±0.40, where the numbers are corrected for\(B\bar B - mixing\) and the errors include both statistical and systematic contributions. The mixing parameter for continuum\(b\bar b - production\) is determined to be χ-0.24±0.12 if both heavy quark coupling constants are constrained to their values in the Standard Model.

4 data tables match query
Table 1

Results of simultaneous fit to both asymmetries. This table is for the CHARMED quark.

Table 2

Results of simultaneous fit to both asymmetries. This table is for the BOTTOM quark.

Table 3

Results for BOTTOM quark asymmetry with c asymmetry constrained to the standard model value.

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Heavy Quark Charge Asymmetries With the Cello Detector

The CELLO collaboration Behrend, H.J. ; Criegee, L. ; Field, J.H. ; et al.
Z.Phys.C 47 (1990) 333-342, 1990.
Inspire Record 282536 DOI 10.17182/hepdata.15243

The production ofb andc quarks ine+e− annihilation has been studied with the CELLO detector in the range from 35 GeV up to the highest PETRA energies. The heavy quarks have been tagged by their semileptonic decays. The charge asymmetries forb quarks at 35 and 43 GeV have been found to beAb=−(22.2±8.1)% andAb=−(49.1±16.5)%, respectively, using a method incorporating jet variables and their correlations for the separation of the heavy quarks from the back ground of the lighter quarks. Forc quarks we obtainAc=−(12.9±8.8)% andAc=+(7.7±14.0)%, respectively. The axial vector coupling constants of the heavy quarksc andb are found to beac=+(0.29±0.46) andab=−(1.15±0.41) taking\(B^0 \overline {B^0 } \) mixing into account. The results are in agreement with the expectations from the standard model.

2 data tables match query
Table 1

BOTTOM quark charge asymmetry.

Table 2

CHARMED quark charge asymmetry.


A Measurement of the $e^+ e^- \to b \bar{b}$ Forward - Backward Charge Asymmetry at $\sqrt{s}=29$-{GeV}

The MAC collaboration Band, H.R. ; Camporesi, T. ; Chadwick, G.B. ; et al.
Phys.Lett.B 218 (1989) 369-373, 1989.
Inspire Record 276692 DOI 10.17182/hepdata.29845

High p ⊥ inclusive muon events produced in e + e − annihilations at √ s =29 GeV have been analyzed to obtain a measurement of the b b forward-backward charge asymmetry. The result A b =0.034±0.070±0.035 differs from the theoretical expectation (−0.16) unless substantial B 0  B 0 mixing is assumed.

1 data table match query
Table 1

No description provided.


Enhanced leading production of D+- and D*+- in 250-GeV pi+- - nucleon interactions

The E769 collaboration Alves, G.A. ; Amato, S. ; Anjos, J.C. ; et al.
Phys.Rev.Lett. 72 (1994) 812-815, 1994.
Inspire Record 361344 DOI 10.17182/hepdata.42499

A leading charm meson is one with longitudinal momentum fraction, xF>0, whose light quark (or antiquark) is of the same type as one of the quarks in the beam particles. We report on the production asymmetry, A=[σ(leading-σ(nonleading)]/[σ(leading)+σ(nonleading)] as a function of xF. The data consist of 1500 fully reconstructed D± and D*± decays in Fermilab experiment E 769. We find a significant asymmetry for the production of charm quarks is not expected in perturbative quantum chromodynamics.

2 data tables match query
Table 1

Asymmetry as function of XL.

Table 2

Asymmetry as function of PT**2.


Measurement of the spin asymmetry in the photoproduction of pairs of high p(T) hadrons at HERMES.

The HERMES collaboration Airapetian, A. ; Akopov, N. ; Amarian, M. ; et al.
Phys.Rev.Lett. 84 (2000) 2584-2588, 2000.
Inspire Record 503784 DOI 10.17182/hepdata.43919

We present a measurement of the longitudinal spin asymmetry A_|| in photoproduction of pairs of hadrons with high transverse momentum p_T. Data were accumulated by the HERMES experiment using a 27.5 GeV polarized positron beam and a polarized hydrogen target internal to the HERA storage ring. For h+h- pairs with p_T^h_1 > 1.5 GeV/c and p_T^h_2 > 1.0 GeV/c, the measured asymmetry is A_|| = -0.28 +/- 0.12 (stat.) +/- 0.02 (syst.). This negative value is in contrast to the positive asymmetries typically measured in deep inelastic scattering from protons, and is interpreted to arise from a positive gluon polarization.

1 data table match query
Table 1

Asymmetry measurement with a PT cut of 1.5 GeV on the hadron with the higher PT, and 1.0 GeV on the hadron with the lower PT.