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Title: The reaction π{sup −}p → π{sup −}π{sup −}π{sup +}p: Development of the analysis methods and selected results

We present the description of the analysis methods and results of applying them to the exclusive diffractive reaction π{sup −}p → π{sup −}π{sup −}π{sup +}p of 50 · 10{sup 6} events measured with COMPASS detector. The large statistics of π{sup −}π{sup −}π{sup +} events enables the two-dimensional partial-wave analysis independently in 100 bins of m(3π) with 0.5 < m(3π) < 2.5 GeV/c{sup 2} and in 11 intervals of squared momentum transfer with 0.1 < t′ < 1 GeV{sup 2}/c{sup 2}. The partial-wave analysis sub-density matrix is the subject to further mass-dependent fits describing the data in terms of resonances in 3π system and coherent background contributions. The novel approach of extracting J{sup PC} = 0{sup ++}(π{sup +}π{sup −}){sub S} isobar amplitudes as model-free functions, different for several J{sup PC} 3π states, is used. It demonstrates the presence of processes π(1800) → f{sub 0}(980)π and π(1800) → f{sub 0}(1500)π as well as π{sub 2}(1880) → f{sub 0}(980)π and new narrow signal a{sub 1}(1420) → f{sub 0}(980)π, without any established shapes used for (π{sup +}π{sup −}){sub S} isobars. The presented analysis is subject to further development and refinements which currently take place.
Authors:
 [1]
  1. Institute for High Energy Physics, Protvino (Russian Federation)
Publication Date:
OSTI Identifier:
22499042
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1701; Journal Issue: 1; Conference: 11. conference on quark confinement and hadron spectrum, Saint Petersburg (Russian Federation), 8-12 Sep 2014; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; AMPLITUDES; COMPASS DETECTOR; DENSITY MATRIX; F0-980 MESONS; MASS; MOMENTUM TRANSFER; PARTIAL WAVES; SIGNALS; STATISTICS; TWO-DIMENSIONAL CALCULATIONS