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. Werthmueller; 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. Werthmueller, F. Zehr

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

Photoproduction of pi(0)pi(0) and pi(0)pi(+/-) pairs from nuclei has been measured over a wide mass range (H-2, Li-7, C-12, Ca-40, and Pb-nat) 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 4 pi 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 pi(0) 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 sigma-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 sigma-in-medium modification. (C) 2013 Elsevier B.V. All rights reserved.

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

Keywords / Materials (for Non-textual outputs)

CHIRAL-SYMMETRY
SIGMA-MESON
THRESHOLD
MATTER
PROTON
RESTORATION
PI(0)PI(0)
RESONANCE
DENSITY
REGION

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10.1016/j.physletb.2013.04.014

Cite this

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 B, 722(1-3), 69-75. https://doi.org/10.1016/j.physletb.2013.04.014

@article{d2339ff2f8374c07885b34ddea0ddb92,

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

abstract = "Photoproduction of pi(0)pi(0) and pi(0)pi(+/-) pairs from nuclei has been measured over a wide mass range (H-2, Li-7, C-12, Ca-40, and Pb-nat) 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 4 pi 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 pi(0) 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 sigma-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 sigma-in-medium modification. (C) 2013 Elsevier B.V. All rights reserved.",

keywords = "CHIRAL-SYMMETRY, SIGMA-MESON, THRESHOLD, MATTER, PROTON, RESTORATION, PI(0)PI(0), RESONANCE, DENSITY, REGION",

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. Werthmueller 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 B",

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, Werthmueller, D & Zehr, F 2013, 'Double pion photoproduction off nuclei - Are there effects beyond final-state interaction?', Physics Letters B, vol. 722, no. 1-3, pp. 69-75. https://doi.org/10.1016/j.physletb.2013.04.014