Abstract.
We report on the investigation of dielectron production in tagged quasi-free neutron-proton collisions by using a deuteron beam of kinetic energy 1.25GeV/u impinging on a liquid hydrogen target. Our measurements with HADES confirm a significant excess of \(e^{+}e^{-}\) pairs above the \(\pi^{0}\) mass in the exclusive channel \(dp \rightarrow npe^{+}e^{-}(p_{spect})\) as compared to the exclusive channel \( ppe^{+}e^{-}\) measured in proton-proton collisions at the same energy. That excess points to different bremsstrahlung production mechanisms. Two models were evaluated for the role of the charged pion exchange between nucleons and double- \(\Delta\) excitation combined with intermediate \(\rho\)-meson production. Differential cross sections as a function of the \(e^{+}e^{-}\) invariant mass and of the angles of the virtual photon, proton and electrons provide valuable constraints and encourage further investigations on both experimental and theoretical sides.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
References
U. Mosel, Annu. Rev. Nucl. Part. Sci. 41, 29 (1991)
M. Schäfer, H.C. Dönges, A. Engel, U. Mosel, Nucl. Phys. A 575, 429 (1994)
F. de Jong, U. Mosel, Phys. Lett. B 379, 45 (1996)
L. Kaptari, B. Kämpfer, Phys. Rev. C 80, 064003 (2009)
L. Kaptari, B. Kämpfer, Nucl. Phys. A 764, 338 (2008)
R. Shyam, U. Mosel, Phys. Rev. C 67, 065202 (2003)
R. Shyam, U. Mosel, Phys. Rev. C 79, 035203 (2009)
R. Rückl, Phys. Lett. B 64, 39 (1976)
C. Gale, J. Kapusta, Phys. Rev. C 35, 2107 (1987)
C. Gale, J. Kapusta, Phys. Rev. C 40, 2397 (1989)
W.K. Wilson et al., Phys. Rev. C 57, 1865 (1998)
G. Agakishiev et al., Phys. Lett. B 690, 118 (2010)
J. Weil, H. van Hees, U. Mosel, Eur. Phys. J. A 48, 111 (2012)
E.L. Bratkovskaya, W. Cassing, R. Rapp, J. Wambach, Nucl. Phys. A 634, 168 (1988)
K. Shekhter, C. Fuchs, A. Faessler, M. Krivoruchenko, B. Martemyanov, Phys. Rev. C 68, 014904 (2003)
G. Ramalho, M.T. Peña, Phys. Rev. D 85, 113014 (2012)
G. Ramalho, M.T. Peña, J. Weil, H. van Hees, U. Mosel, Phys. Rev. D 93, 033004 (2016)
R. Shyam, U. Mosel, Phys. Rev. C 82, 062201 (2010)
J.J. Sakurai, Ann. Phys. 11, 1 (1960)
M. Bashkanov, H. Clement, Eur. Phys. J. A 50, 107 (2014)
HADES Collaboration (G. Agakichiev et al.), Phys. Lett. B 750, 184 (2015)
P. Adlarson et al., Phys. Lett. B 721, 229 (2013)
B. Martemyanov, M. Krivoruchenko, A. Faessler, Phys. Rev. C 84, 047601 (2011)
HADES Collaboration (G. Agakichiev et al.), Eur. Phys. J. A 41, 243 (2009)
EDDA Collaboration (D. Albers et al.), Eur. Phys. J. A 22, 125 (2004)
I. Fröhlich et al., PoS ACAT2007, 076 (2007) arXiv: 0708.2382v2
F. Dohrmann et al., Eur. Phys. J. A 45, 401 (2010)
M. Bashkanov, private communication
HADES Collaboration (J. Adamczewski-Musch et al.), Phys. Rev. C 95, 065205 (2017)
V.V. Sarantsev et al., Eur. Phys. J. A 21, 303 (2004)
J. Bystricky et al., J. Phys. (Paris) 48, 901 (1987)
S. Teis, W. Cassing, M. Effenberger, A. Hombach, U. Mosel, Gy. Wolf, Z. Phys. A 356, 421 (1997)
HADES Collaboration (G. Agakishiev et al.), Eur. Phys. J. A 51, 137 (2015)
P. Benz et al., Nucl. Phys. B 65, 158 (1973)
S. Huber, J. Aichelin, Nucl. Phys. A 573, 587 (1994)
E.L. Bratkovskaya, O.V. Teryaev, V.D. Toneev, Phys. Lett. B 348, 283 (1995)
HADES Collaboration (G. Agakichiev et al.), Eur. Phys. J. A 48, 74 (2012)
M. Zétényi, Gy. Wolf, Heavy Ion Phys. 17, 27 (2003)
Q. Wan, F. Iachello, Int. J. Mod. Phys. A 20, 1846 (2005)
Author information
Authors and Affiliations
Consortia
Corresponding author
Additional information
Communicated by M. Guidal
Rights and permissions
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
About this article
Cite this article
HADES Collaboration., Adamczewski-Musch, J., Arnold, O. et al. Analysis of the exclusive final state npe+e- in the quasi-free np reaction. Eur. Phys. J. A 53, 149 (2017). https://doi.org/10.1140/epja/i2017-12341-3
Received:
Accepted:
Published:
DOI: https://doi.org/10.1140/epja/i2017-12341-3