Physics Letters B (Jun 2018)

Importance of d-wave contributions in the charge symmetry breaking reaction dd→4Heπ0

  • P. Adlarson,
  • W. Augustyniak,
  • W. Bardan,
  • M. Bashkanov,
  • F.S. Bergmann,
  • M. Berłowski,
  • 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,
  • C. Hanhart,
  • 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,
  • M. Wolke,
  • A. Wrońska,
  • P. Wüstner,
  • A. Yamamoto,
  • J. Zabierowski,
  • M.J. Zieliński,
  • J. Złomańczuk,
  • P. Żuprański,
  • M. Żurek

Journal volume & issue
Vol. 781
pp. 645 – 650

Abstract

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This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction dd→4Heπ0 using the WASA-at-COSY detector setup at an excess energy of Q=60MeV. The determined differential cross section can be parametrized as dσ/dΩ=a+bcos2⁡θ⁎, where θ⁎ is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are a=(1.55±0.46(stat)+0.32−0.8(syst))pb/sr and b=(13.1±2.1(stat)−2.7+1.0(syst))pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the Δ isobar to the dd→4Heπ0 reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions. Keywords: Charge symmetry breaking, Deuteron–deuteron interactions, Pion production