Isospin effects in the exclusive dp 3He reaction

M. Mielke; I. Burmeister; D. Chiladze; S. Dymov; C. Fritzsch; R. Gebel; P. Goslawski; M. Hartmann; A. Kacharava; A. Khoukaz; P. Kulessa; B. Lorentz; T. Mersmann; S. Mikirtychiants; H. Ohm; M. Papenbrock; T. Rausmann; V. Serdyuk; H. Ströher; A. Täschner; Yu. Valdau; C. Wilkin

doi:10.1140/epja/i2014-14102-2

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Hadrons and Nuclei

Eur. Phys. J. A (2014) 50: 102
https://doi.org/10.1140/epja/i2014-14102-2

Regular Article - Experimental Physics

Isospin effects in the exclusive dp $\rightarrow$ ³He $\pi^{+}$ $\pi^{-}$ reaction

M. Mielke¹^*, I. Burmeister¹, D. Chiladze²^,3, S. Dymov²^,4, C. Fritzsch¹, R. Gebel², P. Goslawski¹, M. Hartmann², A. Kacharava², A. Khoukaz¹, P. Kulessa⁵, B. Lorentz², T. Mersmann¹, S. Mikirtychiants²^,6, H. Ohm², M. Papenbrock¹, T. Rausmann¹, V. Serdyuk², H. Ströher², A. Täschner¹, Yu. Valdau⁶^,7 and C. Wilkin⁸

¹ Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, D-48149, Münster, Germany
² Institut für Kernphysik and Jülich Centre for Hadron Physics, Forschungszentrum Jülich, D-52425, Jülich, Germany
³ High Energy Physics Institute, Tbilisi State University, GE-0186, Tbilisi, Georgia
⁴ Laboratory of Nuclear Problems, JINR, RU-141980, Dubna, Russia
⁵ H. Niewodniczanski Institute of Nuclear Physics PAN, PL-31342, Cracow, Poland
⁶ High Energy Physics Department, Petersburg Nuclear Physics Institute, RU-188350, Gatchina, Russia
⁷ Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, D-53115, Bonn, Germany
⁸ Physics and Astronomy Department, UCL, Gower Street, WC1E 6BT, London, UK

^* e-mail: maltemielke@uni-muenster.de

Received: 7 April 2014
Revised: 8 May 2014
Accepted: 27 May 2014
Published online: 24 June 2014

Abstract

The differential cross section for the exclusive $dp\rightarrow {}^{3}{\rm He} \pi^+\pi^-$ reaction has been measured with high resolution and large statistics over a large fraction of the backward ³He hemisphere at the excess energy 265 MeV using the COSY-ANKE magnetic spectrometer. Though the well-known ABC enhancement is observed in the $\pi^+\pi^-$ spectrum, the differences detected between the $\pi^+{}^{3}{\rm He}$ and $\pi^-{}^{3}{\rm He}$ invariant-mass distributions show that there must be some isospin-one $\pi$ $\pi$ production even at relatively low excess energies. The invariant-mass differences are modeled in terms of the sequential decay $N^*(1440)\rightarrow\Delta(1232)\pi\rightarrow N\pi\pi$ .