Origin of the low-mass electron pair excess in light nucleus-nucleus collisions
Origin of the low-mass electron pair excess in light nucleus-nucleus collisions
复制标题
轻核-核碰撞中低质量电子对过量的起源
DOI：
10.1016/j.physletb.2010.05.010
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发表时间：
2009
影响因子：
4.4
通讯作者：
P. Zhou
中科院分区：
文献类型：
--
作者：
T. H. C. G. Agakishiev;A. Balanda;D. Belver;A. Belyaev;A. Blanco;M. Bohmer;J. Boyard;P. Braun;P. Cabanelas;E. Castro;S. Chernenko;T. Christ;M. Destefanis;J. D'iaz;F. Dohrmann;A. Dybczak;L. Fabbietti;O. Fateev;P. Finocchiaro;P. Fonte;J. Friese;I. Frohlich;T. Galatyuk;J. A. Garz'on;R. Gernhauser;A. Gil;C. Gilardi;M. Golubeva;D. Gonz'alez;F. Guber;T. Hennino;R. Holzmann;I. Iori;A. Ivashkin;M. Jurkovič;B. Kampfer;T. Karavicheva;D. Kirschner;I. Koenig;W. Koenig;B. Kolb;R. Kotte;F. Krizek;R. Krucken;W. Kuhn;A. Kugler;A. Kurepin;S. Lang;J. Lange;K. Lapidus;T. Liu;L. Lopes;M. Lorenz;L. Maier;A. Mangiarotti;J. Markert;V. Metag;B. Michalska;J. Michel;E. Morinière;J. Mousa;C. Muntz;L. Naumann;J. Otwinowski;Y. Pachmayer;M. Palka;Y. Parpottas;V. Pechenov;O. Pechenova;J. Pietraszko;W. Przygoda;B. Ramstein;A. Reshetin;A. Rustamov;A. Sadovsky;P. Salabura;A. Schmah;E. Schwab;Y. Sobolev;S. Spataro;B. Spruck;H. Strobele;J. Stroth;C. Sturm;M. Sudoł;A. Tarantola;K. Teilab;P. Tlustý;M. Traxler;R. Trebacz;H. Tsertos;V. Wagner;M. Weber;M. Wiśniowski;T. Wójcik;J. Wustenfeld;S. Yurevich;Y. Zanevsky;P. Zhou
本文报道用HADES谱仪测量了1.25GeV/u的基元p+p和d+p反应中的电子对产生。第一次，电子对重建的n+p反应通过检测质子旁观者从氘分裂。我们发现，在n+p反应中，质量不变的电子对的产率[公式：见正文]比p+ p反应大一个数量级。与模型计算的比较表明，生产机制还没有得到充分的描述。在C+C反应中测量的电子对光谱与基本n+p和p+p碰撞的叠加是相容的，在这样的光碰撞系统中几乎没有为额外的电子对源留下空间。
We report measurements of electron pair production in elementary p+p and d+p reactions at 1.25 GeV/u with the HADES spectrometer. For the first time, the electron pairs were reconstructed for n+p reactions by detecting the proton spectator from the deuteron breakup. We find that the yield of electron pairs with invariant mass [Formula: see text] is about an order of magnitude larger in n+p reactions as compared to p+p. A comparison to model calculations demonstrates that the production mechanism is not sufficiently described yet. The electron pair spectra measured in C+C reactions are compatible with a superposition of elementary n+p and p+p collisions, leaving little room for additional electron pair sources in such light collision systems.