对欧米伽介子在介质中的修正的观测。
Observation of in-medium modifications of the omega meson.
作者信息
Trnka D, Anton G, Bacelar J C S, Bartholomy O, Bayadilov D, Beloglazov Y A, Bogendörfer R, Castelijns R, Crede V, Dutz H, Ehmanns A, Elsner D, Ewald R, Fabry I, Fuchs M, Essig K, Funke Ch, Gothe R, Gregor R, Gridnev A B, Gutz E, Höffgen S, Hoffmeister P, Horn I, Hössl J, Jaegle I, Junkersfeld J, Kalinowsky H, Klein Frank, Klein Fritz, Klempt E, Konrad M, Kopf B, Kotulla M, Krusche B, Langheinrich J, Löhner H, Lopatin I V, Lotz J, Lugert S, Menze D, Messchendorp J G, Mertens T, Metag V, Morales C, Nanova M, Novotny R, Ostrick M, Pant L M, van Pee H, Pfeiffer M, Roy A, Radkov A, Schadmand S, Schmidt Ch, Schmieden H, Schoch B, Shende S, Suft G, Sumachev V V, Szczepanek T, Süle A, Thoma U, Varma R, Walther D, Weinheimer Ch, Wendel Ch
机构信息
II. Physikalisches Institut, Universität Giessen, Germany.
出版信息
Phys Rev Lett. 2005 May 20;94(19):192303. doi: 10.1103/PhysRevLett.94.192303. Epub 2005 May 19.
The photoproduction of omega mesons on nuclei has been investigated using the Crystal Barrel/TAPS experiment at the ELSA tagged photon facility in Bonn. The aim is to study possible in-medium modifications of the omega meson via the reaction gamma + A --> omega + X --> pi(0)gamma + X('). Results obtained for Nb are compared to a reference measurement on a LH2 target. While for recoiling, long-lived mesons (pi(0), eta, and eta;(')), which decay outside of the nucleus, a difference in the line shape for the two data samples is not observed, we find a significant enhancement towards lower masses for omega mesons produced on the Nb target. For momenta less than 500 MeV/c an in-medium omega meson mass of M(medium) = [722(+4)(-4)(stat)+35-5(syst)] MeV/c(2) has been deduced at an estimated average nuclear density of 0.6rho(0).
利用位于波恩的ELSA标记光子设施的Crystal Barrel/TAPS实验，对原子核上ω介子的光生过程进行了研究。目的是通过反应γ + A → ω + X → π⁰γ + X′，研究ω介子在介质中可能发生的变化。将铌靶的实验结果与液氢靶的参考测量结果进行了比较。对于在原子核外衰变的反冲长寿命介子（π⁰、η和η′），未观察到两个数据样本的线形有差异，但我们发现铌靶上产生的ω介子在较低质量处有显著增强。对于动量小于500 MeV/c的情况，在估计平均核密度为0.6ρ₀时，推导出介质中ω介子的质量为M(介质)= [722(+4)(-4)(统计)+35 - 5(系统)] MeV/c² 。
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