Novel approach to pion and eta production in proton-proton collisions near threshold

Abstract

We evaluate the threshold matrix-element for the reaction $pp\to pp{\pi }^0$ in a fully relativistic Feynman diagrammatic approach. We employ a simple effective range approximation to take care of the S-wave $pp$ final-state interaction. The experimental value for the threshold amplitude $\mathcal{A}=(2.7-i0.3)$ fm${}^4$ can be reproduced by contributions from tree level chiral (long-range) pion exchange and short-range effects related to vector meson exchanges, with $\omega$ exchange giving the largest individual contribution. Pion loop effects appear to be small. We stress that the commonly used heavy baryon formalism is not applicable in the NN-system above the pion production threshold due to the large external momentum, $|\vec{p}|\simeq \sqrt{M{m}_{\pi }}$, with $M$ and $m_{\pi }$ the nucleon and the pion mass, respectively. We furthermore investigate the reaction $pp\to pn{\pi }^{+}$ near threshold within the same approach. We extract from the data the triplet threshold amplitude as $\mathcal{B}=(2.8-i1.5)$ fm${}^4$. Its real part can be well understood from (relativistic) tree level meson-exchange diagrams. In addition, we investigate the process $pp\to pp\eta$ near threshold. We use a simple factorization ansatz for the $pp\eta$ final-state interaction and extract from the data the modulus of the threshold amplitude, $|\mathcal{C}|=1.32$fm${}^4$. With $g_{\eta N}=5.3$, this value can be reproduced by (relativistic) tree level meson-exchange diagrams and $\eta$-rescattering, whose strength is fixed by the $\eta N$ scattering length. We also comment on the recent near threshold data for ${\eta }^{\prime }$-production.

28 pp, LaTeX, 9 figs, uses epsf, updated version. To be published in Eur. Phys. J. A (1999). **Title changed again**

Cited by in corpus (61)

• Modern Theory of Nuclear Forces
• Effective Field Theory for Few-Nucleon Systems
• Charge Symmetry Breaking and QCD
• Close-to-threshold Meson Production in Hadronic Interactions
• Chiral Three-Nucleon Forces from p-wave Pion Production
• Towards a field theoretic understanding of NN->NNpi
• Energy Dependence of the Near-Threshold Total Cross-Section for the pp --> pp eta' Reaction
• S-wave eta'-proton FSI; phenomenological analysis of near-threshold production of pi0, eta, and eta' mesons in proton-proton collisions
• Systematic calculation of s-wave pion and kaon self-energies in asymmetric nuclear matter
• Experimental study of pp eta dynamics in the pp --> ppeta reaction
• Eta Meson Production in NN Collisions
• $pp\to p{K}^{+}\Lambda$ reaction in an effective Lagrangian model
• Complete next-to-leading order calculation for pion production in nucleon-nucleon collisions at threshold
• Kaon Pair Production in Proton--Proton Collisions
• Production of $\eta \prime$ Mesons in the $pp\to pp\eta \prime$ Reaction at 3.67 GeV/c
• Gluons and the eta' nucleon coupling constant
• Meson-loop contributions to the rho-omega mass splitting & rho charge radius
• Decay width of $d^{\ast }(2380)\to NN\pi \pi$ processes
• Survey of charge symmetry breaking operators for dd -> alpha pi0
• An analysis of the reaction pp --> ppηnear threshold
• Production of eta mesons in nucleon-nucleon collisions
• p-Wave pion production from nucleon-nucleon collisions
• The role of $N^{\ast }(1535)$ in ${\eta }^{\prime }$ production
• Mechanism of the close-to-threshold production of the eta meson
• Phenomenology of pp->pp eta reaction close to threshold
• Threshold $pp\to pp{\pi }^0$ up to one-loop accuracy
• Associated strangeness production in the pp to pK^+K^-p and pp to pK^+ pi^0 Sigma^0 reactions
• eta' meson production in proton-proton collisions
• The near threshold N N -> d pi reaction in chiral perturbation theory
• Consistent analysis of the reaction $\gamma p\to p{\eta }^{\prime }$ and $pp\to pp{\eta }^{\prime }$
• The Reaction $pp\to pp\eta$ and the eta-Nucleon and Nucleon-Nucleon Interactions
• Role of N*(1650) in the near threshold pp --> p Lambda K+ and pp --> p Sigma0 K+ reactions
• Near threshold production of the eta meson via the quasi-free pn --> pn eta reaction
• Effective Field Theory calculations of $NN\to NN\pi$
• Eta meson production in nucleon-nucleon collisions within an effective Lagrangian model
• Remarks on N N -> N N pi beyond leading order
• On the Migdal-Watson approach to FSI effects in meson production in NN collisions
• Hyperon production in near threshold nucleon-nucleon collisions
• Pion production in nucleon-nucleon collisions in chiral effective field theory: next-to-next-to-leading order contributions
• $pp\to pp\omega$ reaction near threshold
• $pp\to pp{\pi }^0$ near threshold in pionless effective theory
• Pion production in nucleon-nucleon collisions in chiral effective field theory with Delta(1232)-degrees of freedom
• On the sign of the pi-rho-omega coupling constant
• Initial-State Coulomb Interaction in the dd -> alpha pi^0 Reaction
• Eta and eta' mesons production at COSY-11
• Nucleon-nucleon interaction: Central potential and pion production
• Threshold pion production in proton-proton collisions at NNLO in chiral EFT
• Near-threshold $\eta$ production in $pp$ collisions
• Chiral perturbation theory calculation for pn -> dpipi at threshold
• Anisotropy in the pion angular distribution of the reaction pp -> pp pi0 at 400 MeV
• Hadronic interaction of the eta meson with two nucleons
• The detailed mechanism of the eta production in pp scattering up to the Tlab = 4.5 GeV
• Pairwise final state interactions in the p d --> p d eta reaction near threshold
• Strangeness production in proton-proton and proton-nucleus collisions
• Impulse approximation in the n p --> d pi^0 reaction reexamined
• Pion absorption from the lowest atomic orbital in 2H, 3H and 3He
• Charged and neutral pion production in the S-matrix approach
• Scalar meson production in nucleon-nucleon collisions near threshold
• Non-Strange Meson Production with Hadronic Probes
• Dynamics of the near threshold eta meson production in proton-proton interaction
• Multiplicity distributions associated to subthreshold events in heavy-ion collisions