Physics Letters B (Nov 2017)

Isoscalar single-pion production in the region of Roper and d⁎(2380) resonances

  • P. Adlarson,
  • W. Augustyniak,
  • W. Bardan,
  • M. Bashkanov,
  • F.S. Bergmann,
  • M. Berłowski,
  • H. Bhatt,
  • A. Bondar,
  • M. Büscher,
  • H. Calén,
  • I. Ciepał,
  • H. Clement,
  • E. Czerwiński,
  • K. Demmich,
  • R. Engels,
  • A. Erven,
  • W. Erven,
  • W. Eyrich,
  • P. Fedorets,
  • K. Föhl,
  • K. Fransson,
  • F. Goldenbaum,
  • A. Goswami,
  • K. Grigoryev,
  • C.-O. Gullström,
  • L. Heijkenskjöld,
  • V. Hejny,
  • N. Hüsken,
  • L. Jarczyk,
  • T. Johansson,
  • B. Kamys,
  • G. Kemmerling,
  • G. Khatri,
  • A. Khoukaz,
  • O. Khreptak,
  • D.A. Kirillov,
  • S. Kistryn,
  • H. Kleines,
  • B. Kłos,
  • W. Krzemień,
  • P. Kulessa,
  • A. Kupść,
  • A. Kuzmin,
  • K. Lalwani,
  • D. Lersch,
  • B. Lorentz,
  • A. Magiera,
  • R. Maier,
  • P. Marciniewski,
  • B. Mariański,
  • H.-P. Morsch,
  • P. Moskal,
  • H. Ohm,
  • W. Parol,
  • E. Perez del Rio,
  • N.M. Piskunov,
  • D. Prasuhn,
  • D. Pszczel,
  • K. Pysz,
  • A. Pyszniak,
  • J. Ritman,
  • A. Roy,
  • Z. Rudy,
  • O. Rundel,
  • S. Sawant,
  • S. Schadmand,
  • I. Schätti-Ozerianska,
  • T. Sefzick,
  • V. Serdyuk,
  • B. Shwartz,
  • K. Sitterberg,
  • T. Skorodko,
  • M. Skurzok,
  • J. Smyrski,
  • V. Sopov,
  • R. Stassen,
  • J. Stepaniak,
  • E. Stephan,
  • G. Sterzenbach,
  • H. Stockhorst,
  • H. Ströher,
  • A. Szczurek,
  • A. Trzciński,
  • R. Varma,
  • M. Wolke,
  • A. Wrońska,
  • P. Wüstner,
  • A. Yamamoto,
  • J. Zabierowski,
  • M.J. Zieliński,
  • J. Złomańczuk,
  • P. Żuprański,
  • M. Żurek

DOI
https://doi.org/10.1016/j.physletb.2017.10.015
Journal volume & issue
Vol. 774, no. C
pp. 599 – 607

Abstract

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Exclusive measurements of the quasi-free pn→ppπ− and pp→ppπ0 reactions have been performed by means of pd collisions at Tp=1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region Tp=0.95–1.3 GeV (s=2.3–2.46 GeV), which includes the regions of Δ(1232), N⁎(1440) and d⁎(2380) resonance excitations. From these measurements the isoscalar single-pion production has been extracted, for which data existed so far only below Tp=1 GeV. We observe a substantial increase of this cross section around 1 GeV, which can be related to the Roper resonance N⁎(1440), the strength of which shows up isolated from the Δ resonance in the isoscalar (Nπ)I=0 invariant-mass spectrum. No evidence for a decay of the dibaryon resonance d⁎(2380) into the isoscalar (NNπ)I=0 channel is found. An upper limit of 180 μb (90% C.L.) corresponding to a branching ratio of 9% has been deduced.

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