Spin and parity measurement of the Λ (1405) baryon

K. Moriya, R. A. Schumacher, M. Aghasyan, M. J. Amaryan, M. D. Anderson, S. Anefalos Pereira, J. Ball, N. A. Baltzell, M. Battaglieri, M. Bellis, A. S. Biselli, J. Bono, S. Boiarinov, W. J. Briscoe, W. K. Brooks, V. D. Burkert, D. S. Carman, A. Celentano, S. Chandavar, G. CharlesP. L. Cole, P. Collins, M. Contalbrigo, O. Cortes, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, B. Dey, C. Djalali, Michael Dugger, R. Dupré, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, J. A. Fleming, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, W. Gohn, E. Golovatch, R. W. Gothe, M. Guidal, K. A. Griffioen, K. Hafidi, H. Hakobyan, K. Hicks, M. Holtrop, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, H. S. Jo, K. Joo, D. Keller, M. Khandaker, W. Kim, S. Koirala, V. Kubarovsky, S. V. Kuleshov, P. Lenisa, H. Y. Lu, I. J D Macgregor, N. Markov, M. McCracken, B. McKinnon, M. D. Mestayer, C. A. Meyer, M. Mirazita, V. Mokeev, R. A. Montgomery, H. Moutarde, E. Munevar, P. Nadel-Turonski, S. Niccolai, I. Niculescu, M. Osipenko, L. L. Pappalardo, E. Pasyuk, P. Peng, J. J. Phillips, S. Pisano, O. Pogorelko, S. Pozdniakov, J. W. Price, S. Procureur, A. J R Puckett, B. A. Raue, D. Rimal, M. Ripani, Barry Ritchie, A. Rizzo, G. Rosner, P. Roy, F. Sabatié, C. Salgado, D. Schott, E. Seder, I. Senderovich, E. S. Smith, D. Sokhan, G. D. Smith, S. Stepanyan, S. Strauch, W. Tang, H. Voskanyan, E. Voutier, N. K. Walford, D. P. Watts, L. B. Weinstein, M. Williams, M. H. Wood, N. Zachariou, L. Zana, J. Zhang, V. Ziegler, Z. W. Zhao, I. Zonta

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Abstract

A determination of the spin and parity of the Λ(1405) is presented using photoproduction data from the CLAS detector at Jefferson Lab. The reaction γ+p→K++Λ(1405) is analyzed in the decay channel Λ(1405)→Σ++π-, where the decay distribution to Σ+π- and the variation of the Σ+ polarization with respect to the Λ(1405) polarization direction determines the parity. The Λ(1405) is produced, in the energy range 2.55<W<2.85 GeV and for 0.6<cosθK+c.m.<0.9, with polarization P=0.45±0.02(stat) ±0.07(syst). The analysis shows that the decays are in S wave, with the Σ+ polarized such that the Λ(1405) has spin-parity JP=12-, as expected by most theories.

Original languageEnglish (US)
Article number082004
JournalPhysical Review Letters
Volume112
Issue number8
DOIs
StatePublished - Feb 28 2014

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ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Moriya, K., Schumacher, R. A., Aghasyan, M., Amaryan, M. J., Anderson, M. D., Anefalos Pereira, S., Ball, J., Baltzell, N. A., Battaglieri, M., Bellis, M., Biselli, A. S., Bono, J., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., ... Zonta, I. (2014). Spin and parity measurement of the Λ (1405) baryon. Physical Review Letters, 112(8), [082004]. https://doi.org/10.1103/PhysRevLett.112.082004