Partial-wave analysis of nucleon-nucleon scattering below the pion-production threshold

The recent measurements of the reactions [Formula: see text] and [Formula: see text] by the ANKE collaboration at COSY are analyzed with the focus on the p-wave pion production amplitudes. These amplitudes are known to provide an important connection between [Formula: see text] and other low-energy few-nucleon reactions. The results of the recent partial wave analysis of the ANKE data are discussed and compared with the theoretical predictions.

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Recent progress in the partial wave analysis of the diffractively produced π−π+π− final state at Compass

EPJ Web of Conferences ◽

10.1051/epjconf/201919902003 ◽

2019 ◽

Vol 199 ◽

pp. 02003 ◽

Cited By ~ 1

Author(s):

Fabian Krinner

Keyword(s):

Partial Wave ◽

Pion Production ◽

Recent Progress ◽

Large Data ◽

Partial Wave Analysis ◽

Wave Analysis ◽

Final State ◽

Data Set ◽

Large Data Set

The Compass spectrometer at CERN has collected a large data set for diffractive three-pion production of 46 × 106 exclusive events. Based on previous conventional Partial-Wave Analyses (PWA), we performed a “freed-isobar PWA” on the same data, removing model assumptions on the dynamic isobar amplitudes for dominating waves. In this analysis, we encountered continuous mathematical ambiguities, which we were able to identify and resolve. This analysis gives an unprecedented insight in the interplay of 2π and 3π dynamics in the process. As an example we show results for a spin-exotic wave $J_{{X^ - }}^{PC} = {1^{ - + }}$ wave.

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PIONIC FUSION AT SUBTHRESHOLD ENERGIES

International Journal of Modern Physics A ◽

10.1142/s0217751x09044024 ◽

2009 ◽

Vol 24 (02n03) ◽

pp. 539-543

Author(s):

L. JOULAEIZADEH ◽

J. BACELAR ◽

M. ESLAMI-KALANTARI ◽

I. GAŠPARIĆ ◽

N. KALANTAR-NAYESTANAKI ◽

...

Keyword(s):

Cross Sections ◽

Pion Production ◽

Detection System ◽

Nucleon Nucleon ◽

Accelerator Facility ◽

Production Threshold ◽

Neutral Pions ◽

Pion Production Threshold ◽

Plastic Ball ◽

Large Acceptance

In order to study the role of pions and clustering phenomena in nuclei, two experiments have been performed using the AGOR accelerator facility. In collisions of two nuclei a pion and a fused nucleus were produced. The examined reactions were 4He(3He, π0)7Be and 6Li(4He, π0)10B at beam energies about 10 MeV above the coherent pion production threshold (256 MeV and 236.4 MeV, respectively). Since the available energy is well below the pion production threshold in an elementary nucleon-nucleon process, a highly coherent mechanism is needed. We identified the reaction by measuring the fused system in the magnetic spectrometer and the produced neutral pions in the Plastic Ball detection system with large acceptance. Our experimental setup provided the exclusive cross sections by identifying all products in overdetermined kinematics. Here we present the preliminary results of the analysis for the second reaction. Angular distribution of neutral pions will be discussed.

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