Double pion photoproduction off nuclei - Are there effects beyond final-state interaction?

Y. Maghrbi; R. Gregor; S. Lugert; J. Ahrens; J. R.M. Annand; H. J. Arends; R. Beck; V. Bekrenev; B. Boillat; A. Braghieri; D. Branford; W. J. Briscoe; J. Brudvik; S. Cherepnya; R. Codling; E. J. Downie; P. Dexler; L. V. Fil'kov; A. Fix; D. I. Glazier; E. Heid; D. Hornidge; O. Jahn; I. Jaegle; V. L. Kashevarov; I. Keshelashvili; A. Knezevic; A. Kondratiev; M. Korolija; M. Kotulla; D. Krambrich; B. Krusche; M. Lang; V. Lisin; K. Livingston; I. J.D. MacGregor; D. M. Manley; M. Martinez; J. C. McGeorge; D. Mekterovic; V. Metag; B. M.K. Nefkens; A. Nikolaev; R. Novotny; M. Ostrick; P. Pedroni; F. Pheron; A. Polonski; S. N. Prakhov; J. W. Price; G. Rosner; M. Rost; T. Rostomyan; S. Schadmand; S. Schumann; D. Sober; A. Starostin; I. Supek; A. Thomas; M. Unverzagt; D. P. Watts; D. Werthmüller; F. Zehr

doi:10.1016/j.physletb.2013.04.014

Double pion photoproduction off nuclei - Are there effects beyond final-state interaction?

Y. Maghrbi, R. Gregor, S. Lugert, J. Ahrens, J. R.M. Annand, H. J. Arends, R. Beck, V. Bekrenev, B. Boillat, A. Braghieri, D. Branford, W. J. Briscoe, J. Brudvik, S. Cherepnya, R. Codling, E. J. Downie, P. Dexler, L. V. Fil'kov, A. Fix, D. I. GlazierE. Heid, D. Hornidge, O. Jahn, I. Jaegle, V. L. Kashevarov, I. Keshelashvili, A. Knezevic, A. Kondratiev, M. Korolija, M. Kotulla, D. Krambrich, B. Krusche^*, M. Lang, V. Lisin, K. Livingston, I. J.D. MacGregor, D. M. Manley, M. Martinez, J. C. McGeorge, D. Mekterovic, V. Metag, B. M.K. Nefkens, A. Nikolaev, R. Novotny, M. Ostrick, P. Pedroni, F. Pheron, A. Polonski, S. N. Prakhov, J. W. Price, G. Rosner, M. Rost, T. Rostomyan, S. Schadmand, S. Schumann, D. Sober, A. Starostin, I. Supek, A. Thomas, M. Unverzagt, D. P. Watts, D. Werthmüller, F. Zehr

^*Corresponding author for this work

Physics

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Abstract

Photoproduction of π⁰π⁰ and π⁰π^± pairs from nuclei has been measured over a wide mass range (²H, ⁷Li, ¹²C, ⁴⁰Ca, and ^natPb) for photon energies from threshold to 600 MeV. The experiments were performed at the MAMI accelerator in Mainz, using the Glasgow photon tagging spectrometer and a 4π electromagnetic calorimeter consisting of the Crystal Ball and TAPS detectors. A shift of the pion-pion invariant-mass spectra for heavy nuclei to small invariant masses has been observed for π⁰ pairs but also for the mixed-charge pairs. The precise results allow for the first time a model-independent analysis of the influence of pion final-state interactions. The corresponding effects are found to be large and must be carefully considered in the search for possible in-medium modifications of the σ-meson. Results from a transport model calculation reproduce the shape of the invariant-mass distributions for the mixed-charge pairs better than for the neutral pairs, but also for the latter differences between model results and experiment are not large, leaving not much room for σ-in-medium modification.

Original language	English
Pages (from-to)	69-75
Number of pages	7
Journal	Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume	722
Issue number	1-3
DOIs	https://doi.org/10.1016/j.physletb.2013.04.014
Publication status	Published - 13 May 2013

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10.1016/j.physletb.2013.04.014

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Maghrbi, Y., Gregor, R., Lugert, S., Ahrens, J., Annand, J. R. M., Arends, H. J., Beck, R., Bekrenev, V., Boillat, B., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R., Downie, E. J., Dexler, P., Fil'kov, L. V., Fix, A., ... Zehr, F. (2013). Double pion photoproduction off nuclei - Are there effects beyond final-state interaction? Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 722(1-3), 69-75. https://doi.org/10.1016/j.physletb.2013.04.014

@article{30393e13665d4b1daccb9e9c882a0f87,

title = "Double pion photoproduction off nuclei - Are there effects beyond final-state interaction?",

abstract = "Photoproduction of π0π0 and π0π± pairs from nuclei has been measured over a wide mass range (2H, 7Li, 12C, 40Ca, and natPb) for photon energies from threshold to 600 MeV. The experiments were performed at the MAMI accelerator in Mainz, using the Glasgow photon tagging spectrometer and a 4π electromagnetic calorimeter consisting of the Crystal Ball and TAPS detectors. A shift of the pion-pion invariant-mass spectra for heavy nuclei to small invariant masses has been observed for π0 pairs but also for the mixed-charge pairs. The precise results allow for the first time a model-independent analysis of the influence of pion final-state interactions. The corresponding effects are found to be large and must be carefully considered in the search for possible in-medium modifications of the σ-meson. Results from a transport model calculation reproduce the shape of the invariant-mass distributions for the mixed-charge pairs better than for the neutral pairs, but also for the latter differences between model results and experiment are not large, leaving not much room for σ-in-medium modification.",

author = "Y. Maghrbi and R. Gregor and S. Lugert and J. Ahrens and Annand, {J. R.M.} and Arends, {H. J.} and R. Beck and V. Bekrenev and B. Boillat and A. Braghieri and D. Branford and Briscoe, {W. J.} and J. Brudvik and S. Cherepnya and R. Codling and Downie, {E. J.} and P. Dexler and Fil'kov, {L. V.} and A. Fix and Glazier, {D. I.} and E. Heid and D. Hornidge and O. Jahn and I. Jaegle and Kashevarov, {V. L.} and I. Keshelashvili and A. Knezevic and A. Kondratiev and M. Korolija and M. Kotulla and D. Krambrich and B. Krusche and M. Lang and V. Lisin and K. Livingston and MacGregor, {I. J.D.} and Manley, {D. M.} and M. Martinez and McGeorge, {J. C.} and D. Mekterovic and V. Metag and Nefkens, {B. M.K.} and A. Nikolaev and R. Novotny and M. Ostrick and P. Pedroni and F. Pheron and A. Polonski and Prakhov, {S. N.} and Price, {J. W.} and G. Rosner and M. Rost and T. Rostomyan and S. Schadmand and S. Schumann and D. Sober and A. Starostin and I. Supek and A. Thomas and M. Unverzagt and Watts, {D. P.} and D. Werthm{\"u}ller and F. Zehr",

year = "2013",

month = may,

day = "13",

doi = "10.1016/j.physletb.2013.04.014",

language = "English",

volume = "722",

pages = "69--75",

journal = "Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics",

issn = "0370-2693",

publisher = "Elsevier",

number = "1-3",

}

Maghrbi, Y, Gregor, R, Lugert, S, Ahrens, J, Annand, JRM, Arends, HJ, Beck, R, Bekrenev, V, Boillat, B, Braghieri, A, Branford, D, Briscoe, WJ, Brudvik, J, Cherepnya, S, Codling, R, Downie, EJ, Dexler, P, Fil'kov, LV, Fix, A, Glazier, DI, Heid, E, Hornidge, D, Jahn, O, Jaegle, I, Kashevarov, VL, Keshelashvili, I, Knezevic, A, Kondratiev, A, Korolija, M, Kotulla, M, Krambrich, D, Krusche, B, Lang, M, Lisin, V, Livingston, K, MacGregor, IJD, Manley, DM, Martinez, M, McGeorge, JC, Mekterovic, D, Metag, V, Nefkens, BMK, Nikolaev, A, Novotny, R, Ostrick, M, Pedroni, P, Pheron, F, Polonski, A, Prakhov, SN, Price, JW, Rosner, G, Rost, M, Rostomyan, T, Schadmand, S, Schumann, S, Sober, D, Starostin, A, Supek, I, Thomas, A, Unverzagt, M, Watts, DP , Werthmüller, D & Zehr, F 2013, 'Double pion photoproduction off nuclei - Are there effects beyond final-state interaction?', Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, vol. 722, no. 1-3, pp. 69-75. https://doi.org/10.1016/j.physletb.2013.04.014