Two-Pion Production in Proton-Proton Collisions -- Experimental Total Cross Sections and their Isospin Decomposition

Abstract

The two-pion production in pp-collisions has been investigated at CELSIUS in exclusive measurements from threshold up to $T_p$ = 1.36 GeV. Total and differential cross sections have been obtained for the channels $pn{\pi }^{+}{\pi }^0$, $pp{\pi }^{+}{\pi }^{-}$, $pp{\pi }^0{\pi }^0$ and also $nn{\pi }^{+}{\pi }^{+}$. For intermediate incident energies $T_p>$ 1 GeV, i.e. in the region which is beyond the Roper excitation but at the onset of $\Delta \Delta$ excitation, the total $pp{\pi }^0{\pi }^0$ cross section falls behind theoretical predictions by as much as an order of magnitude near 1.2 GeV, whereas the $nn{\pi }^{+}{\pi }^{+}$ cross section is a factor of five larger than predicted. An isospin decompostion of the total cross sections exhibits a s-channel-like energy dependence in the region of the Roper excitation as well as a significant contribution of an isospin 3/2 resonance other than the $\Delta (1232)$. As possible candidates the $\Delta (1600)$ and the $\Delta (1700)$ are discussed.

References in corpus (7)

• Double-Pionic Fusion of Nuclear Systems and the ABCEffect -- Aproaching a Puzzle by Exclusive and Kinematically Complete Measurements
• Theoretical study of the N N --> N N pi pi reaction
• The WASA Detector Facility at CELSIUS
• Study of the p p -> p p pi+ pi- Reaction in the Low-Energy Tail of the Roper Resonance
• Exclusive Measurements of $pd{\to }^{3}He\pi \pi$ : the $ABC$ Effect Revisited
• Two-Pion Production in Proton-Proton Collisions with Polarized Beam
• Single- and Double-Pion Production in Nucleon Collisions on the Nucleon and on Nuclei -- the ABC Effect and its Possible Origin in a Dibaryonic Resonance

Cited by in corpus (33)

• Parametrization of gamma-ray production cross-sections for pp interactions in a broad proton energy range from the kinematic threshold to PeV energies
• ABC Effect in Basic Double-Pionic Fusion --- Observation of a new resonance?
• The NUMEN project: NUclear Matrix Elements for Neutrinoless double beta decay
• On the History of Dibaryons and their Final Observation
• Isospin Decomposition of the Basic Double-Pionic Fusion in the Region of the ABC Effect
• Phenomenological analysis of the double pion production in nucleon-nucleon collisions up to 2.2 GeV
• Measurement of the $pn\to pp{\pi }^0{\pi }^{-}$ Reaction in Search for the Recently Observed Resonance Structure in $d{\pi }^0{\pi }^0$ and $d{\pi }^{+}{\pi }^{-}$ systems
• Neutron-Proton Scattering in the Context of the $d^{\ast }$(2380) Resonance
• Measurement of the $np\to np{\pi }^0{\pi }^0$ Reaction in Search for the Recently Observed $d^{\ast }(2380)$ Resonance
• A model for the Delta(1600) resonance and gamma N -> Delta(1600) transition
• Delta Delta Excitation in Proton-Proton Induced pi0pi0 Production
• ABC Effect and Resonance Structure in the Double-Pionic Fusion to ${}^3$He
• Stability of hexaquarks in the string limit of confinement
• On the shape of the gamma-ray spectrum around the "${\pi }^0$-bump"
• Study of the quasi-free $np\to np{\pi }^{+}{\pi }^{-}$ reaction with a deuterium beam at 1.25 GeV/nucleon
• Exclusive Measurements of pp -> dpi+pi0: Double-Pionic Fusion without ABC Effect
• On a Possible Explanation of the DLS-Puzzle
• Dibaryons: Molecular versus Compact Hexaquarks
• π^0 π^0 Production in Proton-Proton Collisions at Tp=1.4 GeV
• Measurement of the $\vec{n}p\to d{\pi }^0{\pi }^0$ Reaction with Polarized Beam in the Region of the $d^{\ast }(2380)$ Resonance
• Nature of $\mathbf{S}$-wave $\mathbf{NN}$ interaction and dibaryon production at nucleonic resonance thresholds
• On the Production of ${\pi }^{+}{\pi }^{+}$ Pairs in pp Collisions at 0.8 GeV
• Search for an Isospin I =3 Dibaryon
• An Isotensor Dibaryon in the $pp\to pp{\pi }^{+}{\pi }^{-}$ Reaction?
• From CELSIUS to COSY: on the observation of a dibaryon resonance
• Coupled channels calculation of a pion-Lambda-nucleon quasibound state
• Chiral perturbation theory calculation for pn -> dpipi at threshold
• Isospin symmetry breaking in double-pion production in the region of $d^{\ast }(2380)$ and the scalar $\sigma$ meson
• On the Production of an Isotensor Dibaryon in the $pp\to pp{\pi }^{+}{\pi }^{-}$ Reaction
• On the nature of the Roper resonance
• Test of charge conjugation invariance in eta->pi0 e+e- and eta->pi+pi-pi0 decays
• Dibaryons at COSY
• The ABC Effect in Double-Pionic Nuclear Fusion and a pn Resonance as its Possible Origin