| Autor: |
ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BONDAR, A, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CZERWINSKI, E, DEMMICH, K, ENGELS, R, ERVEN, A, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, E, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HEIJKENSKJOLD, L, HEJNY, V, HUSKEN, N, JARCZYK, L, JOHANSSON, T, KAMYS, B, KELKAR, NG, KEMMERLING, G, KHATRI, G, KHOUKAZ, A, KHREPTAK, O, KIRILLOV, DA, KISTRYN, S, KLEINES, H, KLOS, B, KRZEMIEN, W, KULESSA, P, KUPSC, A, KUZMIN, A, LALWANI, K, LERSCH, D, LORENTZ, B, MAGIERAE, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MORSCH, HP, MOSKAL, P, OHM, H, DEL RIO, EP, PISKUNOV, NM, PRASUHN, D, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, RITMAN, J, ROY, A, RUDY, Z, RUNDEL, O, SAWANT, S, SCHADMAND, S, SCHATTI-OZERIANSKA, I, SEFZICK, T, SERDYUK, V, SHWARTZ, B, SITTERBERG, K, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TRZCINSKI, A, VARMA, R, WOLKE, M, WRONSKA, A, WUSTNER, P, YAMAMOTO, A, ZABIEROWSKI, J, ZIELINSKI, MJ, ZLOMANCZUK, J, ZUPRANSKI, P, ZUREK, M |
| Jazyk: |
angličtina |
| Rok vydání: |
2017 |
| Předmět: |
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| Zdroj: |
IndraStra Global. |
| ISSN: |
2381-3652 |
| Popis: |
The search for He-4-eta bound states was performed with the WASA-at-COSY facility via the measurement of the excitation function for the dd -> (3)Hen pi(0) and dd -> (3)Hep pi(-) processes. The deuteron beam momentum was varied continuously between 2.127 GeV/c and 2.422 GeV/c, corresponding to the excess energy for the dd -> He-4 eta reaction ranging from Q = 70 MeV to Q = 30 MeV. The luminosity was determined based on the dd -> (3)Hen reaction and the quasi-free proton proton scattering via dd -> ppn(spectator)n(spectator) reactions. The excitation functions, determined independently for the measured reactions, do not reveal a structure which could be interpreted as a narrow mesic nucleus. Therefore, the upper limits of the total cross sections for the bound state production and decay in dd -> (4He-eta)(bound) -> (3)Hen pi(0) and dd -> (He-4-eta)(bound) -> (3)Hep pi(-) processes were determined taking into account the isospin relation between the both of the considered channels. The results of the analysis depend on the assumptions of the N* (1535) momentum distribution in the anticipated mesic-He-4. Assuming, as in the previous works, that this is identical with the distribution of nucleons bound with 20 MeV in He-4, we determined that (for the mesic bound state width in the range from 5 MeV to 50 MeV) the upper limits at 90% confidence level are about 3 nb and about 6 nb for n pi(0) and p pi(-) channels, respectively. However, based on the recent theoretical findings of the N*(1535) momentum distribution in the N*-He-3 nucleus bound by 3.6 MeV, we find that the WASA-at-COSY detector acceptance decreases and hence the corresponding upper limits are 5 nb and 10 nb for n pi(0) and p pi(-) channels respectively. (C) 2017 Elsevier B.V. All rights reserved. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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