Susumu Furuichi

On the possible existence of a diproton resonance. A proposal of p-p scattering experiment at about 500 MeV

SummaryThe energy dependence of the1D2 phase shift of protonproton scattering in the region between 500 MeV and 1000 MeV is discussed. The possible existence of a diproton resonance in this energy region is examined with available experimental data by means of the phase-shift analysis and the analysis of the Kantor amplitude. It is shown that solutions both with and without resonance are equally possible. For the purpose of removing this uncertainty, the usefulness of further experiments of proton-proton scattering at about 500 MeV is discussed.RiassuntoSi discute la dipendenza dall’energia dello spostamento di fase1D2 dello scattering protone-protone nella regione fra 500 e 1000 MeV. Si prende in esame la possibile esistenza di una risonanza fra due protoni in questo campo di energia partendo dai dati disponibili e servendosi dell’analisi dello spostamento di fase e dell’analisi dell’ampiezza di Kantor. Si mette in luce che sono ugualmente possibili soluzioni sia con che senza risonanza. Allo scopo di eliminare questa incertezza, si discute sulla utilità di ulteriori esperimenti di scattering protone-protone a circa 500 MeV.РеэюмеОбсуждается знергетическая эависимость фаэового сдвига1D2 протон-протонного рассеяния в области знергий между 500 МзВ и 1000 МзВ. Исследуется воэможное сушествование дипротонного реэонанса в зтой области знергий на основе имеюшихся зкспериментальных данных, исходя иэ аналиэа фаэовых сдвигов и иэ аналиэа амплитуды Кантора. Покаэывается, что рещения с и беэ реэонанса являются одинаково воэможными. С целью устранения зтой неодноэначности обсуждается полеэность дополнительных зкспериментов по протон-протонному рассеянию при знергии около 500 МзВ.

Electromagnetic form factors of nucleons with QCD constraints: Systematic study of space- and time-like regions

Elastic electromagnetic form factors of nucleons are investigated for both the time-like and the space-like momenta by using the unsubtracted dispersion relation with QCD constraints. It is shown that the calculated form factors reproduce the experimental data reasonably well; they agree with recent experimental data for the neutron magnetic form factors for the space-like data obtained by the CLAS Collaboration and are compatible with the ratio of the electric and magnetic form factors for the time-like momentum obtained by the BABAR Collaboration.

Pion Form Factor and Possible Heavy Vector Meson

Recently, various properties have been known about the iso-vector part of electromagnetic form factors; as to the momentum dependence it is generally accepted that the nucleon form factor behaves as a dipole, while that of a pion is nearly a simple pole with p-meson dominance.1> The momentum dependence of the nucleon form factors can most naturally be explained by an accurate evaluation of the uncorrelated two-pion contribution as well as the correlated part corresponding to the p meson.2>-4> The pion electromagnetic form factor Fn (t), which was taken as an input in the above-mentioned computations,2> •4> is expressed in terms of the I =J = 1 denominator function D 1 <1> as follows: Fn(t)=D 1<1l(O)/D 1<1>(t). (1) For the D-function in the small t region, iti<1(GeV/c)2, the p-wave solution of the N / D equation for pion-pion scattering is used.5> As is shown in Fig. 1, Eq. (1) leads us to the result that is very close to the single p-meson dominance; the form factor, thus obtained, agrees qualitatively with the recent experimental pion form factor.6> In order to discuss the nucleon form factor Yn the whole space-like range of existing data, it is necessary to take on the contribution from .,!t =1.3-1.7 and/or 2.4 GeV energy regions.4> In such a higher mass region we have no confirmation of a vector meson with 1°=1 + although there are several indirect experimental reports.7l

The Kantor amplitudes of nucleon-nucleon scattering below 500 MeV

Abstract Using the presently available data of nucleon-nucleon scattering phase shifts, we calculate the Kantor amplitudes below 500 MeV. Comparison is made for some models of the nucleonnucleon interaction with the newly obtained Kantor amplitudes.

Dispersion theoretic approach in nucleon-nucleon scattering

A theoretical dispersion treatment for nucleon-nucleon scatttering is presented. The method presented is based on the potential model, rather than on the scattering matrix. it is shown to be possible to isolate phenomena which are insensitve to the detailed inner structure of the potential. Effects which are dependend on the potential form, such as n-pion exchangen (n= 1,2,...) are also shown to be calculable. (T.F.H.)

Contribution from the Three-Pion State to the Axial Vector Coupling Constant in β-Decay

ABS>The effect of the pion cloud to the ratio g/sub A//g/sub V/ in the ore resistant t decay is investigated with the assumption of the conserved current for the vector interaction. The three-pion state is considered as the simplest state which might improve the result of the static theory, which gives g/ sub A//g/sub V/ 1 ewn-en when the decrease of the bare state probability is taken into account, unless the effect of the suppression of the nucleon pair is tco strong. (auth)

Analysis of the Kantor amplitudes and recent low-energy proton-proton scattering experiments

Abstract The behaviour of the 3 P 0 phase shift for proton-proton scattering in the energy range 25–50 MeV is discussed. It is shown that theoretical analysis of the Kantor amplitudes predicts a larger 3 P 0 phase shift than the experimental value currently accepted. The existing experimental data are examined by means of a phase-shift analysis to see how the individual spin-correlation data affect the 3 P 0 phase shift.

Pion-Pion Correlation Effect in Two-Pion-Exchange Contribution for Nucleon-Nucleon Scattering

The pion-pion correlation effect is investigated, starting from the pion-pion scattering phase shifts which show the presence of a p meson in the l=L=1 state and a strong attraction without resonance in the l=L=O state. By comparing with the OBEC amplitude, the roles of the pion-pion correlation and the normalization f+C+)O(O) =Co in nucleon-nucleon scattering are clarified. Comparison with the empirical phase shifts in the iso-triplet state shows that C0,...,_,0 and a rather small value of g,} are· probable and not inconsistent with the analysis of pion-nucleon scattering.

Note on the scalar boson

SummarySome discussions are made about the « observability » of the isoscalar scalar boson required by the one-boson exchange model of