Total cross section for p+p→p+p+π0 close to threshold

Meyer, H. O.; Horowitz, C. J.; Nann, H.; Pancella, P. V.; Pate, S. F.; Pollock, R.E.; Przewoski, B. von; Rinckel, T.; Ross, M. A.; Sperisen, F.

doi:10.1016/0375-9474(92)90130-c

Cited by 154 publications

(84 citation statements)

References 26 publications

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“…pp 0 close to pion production threshold from the Indiana University Cyclotron Facility (IUCF) 1,2] continue to attract the attention of theorists. Early theoretical studies 3,4] followed closely the conventional approach to s-wave meson production which goes back to the work of Koltun and Reitan from 1966 5].…”

Section: Introductionmentioning

confidence: 99%

“…T s (k; k) and T s (q; k) are the on-shell and half-o -shell T-matrices for the strong interaction alone. The Coulomb penetration factor is given by C 2 ( k ) = 2 k e 2 k 1 ; k = M 2 1 k ; (2) with M being the nucleon mass and the ne-structure constant. We consider only the lowest partial waves in the outgoing channel; the pp pair is taken to be in the 1 S 0 and the pion in an s-wave relative to the nucleon pair.…”

Section: Introductionmentioning

confidence: 99%

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The reaction pp → ppπ0 near threshold

et al. 1995

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We perform a momentum-space calculation of the reaction pp ! pp 0 near threshold. Direct production and pion rescattering are taken into account. For the latter a T-matrix obtained from a microscopic model of the N interaction is employed.The e ects of some approximations commonly used in studies of pp ! pp 0 are discussed. We nd that those approximations overestimate the cross section and also modify its energy dependence. We obtain a signi cant contribution from rescattering, but not nearly enough to describe the data.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The reaction pp → ppπ0 near threshold

et al. 1995

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“…PACS: 13.60. Le, 13.85.Lg, 29.20.Dh Typeset using REVT E X 2 New results on η and η ′ meson production in the reaction pp → ppX, measured very recently at the COSY-11 facility [1,2], together with previous data [3,4,5,6,7,8], determine the energy dependence of the near-threshold total cross section with a precision comparable to the measurements of the reaction pp → ppπ 0 [9,10]. These new data encouraged us to perform a phenomenological analysis similar to those of references [11,12,13].…”

Section: Introductionmentioning

confidence: 93%

“…[1,2,3,4,6,7,8,9,10,36]. The proton-proton scattering amplitude was calculated according to equation (4), and the phase shifts were computed using equation (5) (see the solid line in Figure 2).…”

Section: The Curves Inmentioning

confidence: 99%

S-wave η′-proton FSI; phenomenological analysis of near-threshold production of π0, η, and η′ mesons in proton-proton collisions

et al. 2000

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We describe a novel technique for comparing total cross sections for the reactions pp → ppπ 0 , pp → ppη, and pp → ppη ′ close to threshold. The initial and final state proton-proton interactions are factored out of the total cross section, and the dependence of this reduced cross section on the volume of phase space is discussed. Different models of the proton-proton interaction are compared. We argue that the scattering length of the S-wave η ′ -proton 1 interaction is of the order of 0.1 fm. PACS: 13.60. Le, 13.85.Lg, 29.20.Dh Typeset using REVT E X 2 New results on η and η ′ meson production in the reaction pp → ppX, measured very recently at the COSY-11 facility [1,2], together with previous data [3,4,5,6,7,8], determine the energy dependence of the near-threshold total cross section with a precision comparable to the measurements of the reaction pp → ppπ 0 [9,10]. These new data encouraged us to perform a phenomenological analysis similar to those of references [11,12,13]. Here we concentrate on π 0 , η, and η ′ meson production, and complete the analysis of these references by taking into account the interaction between the incident protons, and by introducing a new representation of the data. The production rates of π 0 , η, and η ′ mesons will be compared as a function of the available phase space. We will study the phase-space dependence of the quantity |M 0 | which is derived from the total cross section with the ISI and pp-FSI factored out. Consideration of the dependence of |M 0 | on phase space allows us to infer the η-proton and η ′ -proton interactions. To avoid large ambiguities due to differences in pp-FSI models, we normalize the |M 0 | for η and η ′ mesons to the one for the π 0 meson and show that the resulting η ′ -proton interaction is comparable to the π 0 -proton one.In general, the total cross section is presented as a function of the dimensionless parameter η M [9,10,12] 1 , which is defined as the maximum meson momentum in units of meson mass (η M = q max M ), or as a function of the center-of-mass excess energy Q [3,6,8], where nonrelativistically these variables are related by:with m p and M denoting the proton and meson mass, respectively. The above equationshows that the proportionality factor between the variables Q and η 2 M changes for different mesons, since the masses of the π 0 , η, and η ′ are distinct. Hence, depending which variable is selected, the relation between the cross section values changes for different mesons. For example, as shown in reference [4] the η meson production-cross-section exceeds the π 0 cross 1 In order to avoid ambiguities with the abbreviation for the eta-meson, we introduce an additional suffix M for this parameter, which usually is called η.3 section by about a factor of five using η M , whereas the π 0 meson cross section is always larger when employing the Q scale.The total cross section for pp → ppX is in general an integral over phase space, weighted by the square of the transition matrix element and normalized to the incoming fl...

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“…In recent studies it was found that within 10-20 MeV of threshold, i.e. below 300 MeV, only Ss for pp → ppπ 0 , [1][2][3] or at most two partial waves (Ss and Sp) for pp → dπ + and pp → pnπ + [4][5][6][7][8][9][10] were important, and direct comparisons with simple theoretical approaches can be made. The expected dominance of Ss contributions (l N N = 0, L π = 0) for the final states was seen, but at the same time it was found that for pp → ppπ 0 traditional models under-predicted the cross sections by factors of 3-5.…”

Section: Introductionmentioning

confidence: 99%

Spin correlation coefficients in from 325 to 400 MeV

Saha¹,

Daehnick²,

Flammang³

et al. 1999

Physics Letters B

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The spin correlation coefficient combinations S ≡ Axx + Ayy, D ≡ Axx − Ayy and the analyzing powers Ay(θ) were measured for p p → pnπ + at beam energies of 325, 350, 375 and 400 MeV. A polarized internal atomic hydrogen target and a stored, polarized proton beam were used. These polarization observables are sensitive to contributions of higher partial waves. A comparison with recent theoretical calculations is provided.

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Total cross section for p+p→p+p+π0 close to threshold

Cited by 154 publications

References 26 publications

The reaction pp → ppπ0 near threshold

The reaction pp → ppπ0 near threshold

S-wave η′-proton FSI; phenomenological analysis of near-threshold production of π0, η, and η′ mesons in proton-proton collisions

Spin correlation coefficients in from 325 to 400 MeV

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