Hidden Strangeness in the Proton? Determination of the Real Part of the Isospin Even - Forward Scattering Amplitude of Pion Nucleon Scattering at 54.3-{MeV}

Wiedner, U. ; Goring, K. ; Jaki, J. ; et al.
Phys.Rev.D 40 (1989) 3568-3581, 1989.
Inspire Record 287810 DOI 10.17182/hepdata.23079

The contradiction of the σ term of pion-nucleon scattering as deduced from the Karlsruhe-Helsinki phase shifts with the smaller value calculated by the chiral perturbation theory of QCD is well known. In an effort to clarify the discrepancy we have determined the real part of the isospin-even forward-scattering amplitude of pion-nucleon scattering at a pion energy Tπ=54.3 MeV by measurement of the elastic scattering of positive and negative pions on protons in the Coulomb-nuclear interference region. The deduced value is in agreement with the prediction of the Karlsruhe-Helsinki phase-shift analysis for that energy. The resulting large value of the σ term may be interpreted as being due to the influence of s¯s sea pairs even at large distances (small Q2) as previously suggested by the European Muon Collaboration measurement of deep-inelastic scattering of polarized muons on polarized protons.

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Determination of the Real Part of the Isospin Even Forward Scattering Amplitude of Pion Nucleon Scattering at 55-{MeV} as a Test of Low-energy Quantum Chromodynamics

Wiedner, U. ; Goring, K. ; Jaki, J. ; et al.
Phys.Rev.Lett. 58 (1987) 648-650, 1987.
Inspire Record 246624 DOI 10.17182/hepdata.20153

The real part of the isospin-even forward-scattering amplitude of pion-nucleon scattering has been determined at a pion energy of Tπ=55 MeV by measurement of the elastic scattering of positive and negative pions on protons within the Coulomb-nuclear interference region. The value confirms the prediction of the Karlsruhe-Helsinki phase-shift analysis for that energy. These phases have been used to determine the σ term of pion-nucleon scattering by means of dispersion relations, resulting in a value for σ which is in contradiction with chiral perturbation theory of QCD.

1 data table match query

PI- P cross sections normalised to the Coulomb cross section taken from the Karlesruhe-Helsinki phase shift analysis (R. Koch, E. Pietarinen (NP A336(80)331).


The Real Part of the Forward Elastic Nuclear Amplitude for p p, anti-p p, pi+ p, pi- p, K+ p, and K- p Scattering Between 70-GeV/c and 200-GeV/c

Fajardo, L.A. ; Majka, R. ; Marx, J.N. ; et al.
Phys.Rev.D 24 (1981) 46, 1981.
Inspire Record 152596 DOI 10.17182/hepdata.24028

We have measured the elastic cross section for pp, p¯p, π+p, π−p, K+p, and K−p scattering at incident momenta of 70, 100, 125, 150, 175, and 200 GeV/c. The range of the four-momentum transfer squared t varied with the beam momentum from 0.0016≤−t≤0.36 (GeV/c)2 at 200 GeV/c to 0.0018≤−t≤0.0625 (GeV/c)2 at 70 GeV/c. The conventional parametrization of the t dependence of the nuclear amplitude by a simple exponential in t was found to be inadequate. An excellent fit to the data was obtained by a parametrization motivated by the additive quark model. Using this parametrization we determined the ratio of the real to the imaginary part of the nuclear amplitude by the Coulomb-interference method.

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Polarization Measurements in pi+ p, K+ p and p p Elastic Scattering at 45-GeV/c and Comparison with Regge Phenomenology

The SACLAY-SERPUKHOV-DUBNA-MOSCOW collaboration Gaidot, A. ; Bruneton, C. ; Bystricky, J. ; et al.
Phys.Lett.B 61 (1976) 103-106, 1976.
Inspire Record 113043 DOI 10.17182/hepdata.27714

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.

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A Comparison of the Shapes of pi+ p and p p Diffraction Peaks from 50-GeV/c to 175-GeV/c

The Fermilab Single Arm Spectrometer Group collaboration Ayres, D.S. ; Diebold, Robert E. ; Maclay, G.J. ; et al.
Phys.Rev.Lett. 37 (1976) 548, 1976.
Inspire Record 108238 DOI 10.17182/hepdata.21073

The ratio of π+p to pp elastic scattering is found to be smoothly varying over the range −t=0.03 to 0.4 GeV2. It is well fitted by a single exponential, indicating the forward behavior must be quite similar for the two reactions.

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ACTUALLY THE DATA ARE THE EXPONENTIAL SLOPE OF THE RATIO OF D(SIG)/DT FOR THE TWO REACTIONS.


Polarization in Elastic Scattering of pi+, K+ Mesons and Protons on Protons at 45-GeV/c

The Serpukhov-Saclay-Dubna-Moscow collaboration Bruneton, C. ; Bystricky, J. ; Gaidot, A. ; et al.
Sov.J.Nucl.Phys. 25 (1977) 198, 1977.
Inspire Record 108993 DOI 10.17182/hepdata.19052
1 data table match query

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Polarization Measurements in π p+ p and K p+ p elastic scattering at 6 and 12 GeV/ c with the CERN polarized deuteron target

Fujisaki, M. ; Babou, M. ; Bystricky, J. ; et al.
Nucl.Phys.B 151 (1979) 206-212, 1979.
Inspire Record 145595 DOI 10.17182/hepdata.34795

The polarization in π + p → π + p and K + p → K + p has been measured at 6 and 12 GeV/ c in the four-momentum transfer interval 0.1 ⩽ | t | ⩽ 2.0 (GeV/ c ) 2 by scattering on protons of a polarized deuteron target. Comparison with existing results obtained with polarized proton targets shows good general agreement and no evidence for asymmetry effects due to the presence of the spectator neutron. For K + p elastic scattering polarization the experiment yields improved statistics, especially at 6 GeV/ c

4 data tables match query

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Measurements of the Spin Rotation Parameter R in p p and pi+ p Elastic Scattering at 45-GeV/c

The SERPUKHOV-SACLAY-DUBNA-MOSCOW collaboration Pierrard, J. ; Bruneton, C. ; Bystricky, J. ; et al.
Phys.Lett.B 61 (1976) 107-109, 1976.
Inspire Record 113035 DOI 10.17182/hepdata.27706

The spin rotation sf R in pp and π + p elastic scattering at 45 GeV/c has been measured at the Seppukhov accelarator, for z . sfnc ; t |; ranging from 0.2 to 0.5 (GeV/) 2 . The results are presented, together with previous R measurements at lower energies. The equality of the values for R in proton-proton and pion-proton scattering, within the experimental errors, is a test of factorization of the residues in the pomeron exchange.

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On Measuring the Spin Rotation Parameter in Elastic p p and pi+ p Scattering at 45-GeV/c

Bruneton, C. ; Bystricky, J. ; Gaidot, A. ; et al.
Yad.Fiz. 24 (1976) 762-765, 1976.
Inspire Record 108609 DOI 10.17182/hepdata.19050

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Measurement of the Recoil Proton Polarization in Elastic pi+p Scattering at Tpi=410and492 MeV

Bareyre, P. ; Bricman, C. ; Longo, M.J. ; et al.
Phys.Rev.Lett. 14 (1965) 198-201, 1965.
Inspire Record 944925 DOI 10.17182/hepdata.21847

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