arXiv · 1709.01060
Importance of d-wave contributions in the charge symmetry breaking reaction $dd \to {}^4\text{He}\pi^0$
Abstract
This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction $dd \to {}^4\text{He}\pi^0$ using the WASA-at-COSY detector setup at an excess energy of $Q = 60$ MeV. The determined differential cross section can be parametrized as $\text{d}\sigma/\text{d}\Omega = a + b\cos^{2}\theta^*$, where $\theta^*$ is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are $a = \left(1.55 \pm 0.46 (\text{stat}) ^{+0.32}_{-0.8} (\text{syst}) \right)$ pb/sr and $b = \left(13.1 \pm 2.1 (\text{stat}) ^{+1.0}_{-2.7} (\text{syst})\right)$ pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the $\Delta$ isobar to the $dd \to {}^4\text{He}\pi^0$ reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions.
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P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F. S. Bergmann, M. Berłowski, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, E. Czerwiński, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, C. -O. Gullström, C. Hanhart, L. Heijkenskjöld, V. Hejny, N. Hüsken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, O. Khreptak, D. A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, H. -P. Morsch, P. Moskal, H. Ohm, W. Parol, E. Perez del Rio, N. M. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schätti-Ozerianska, T. Sefzick, V. Serdyuk, B. Shwartz, K. Sitterberg, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Trzciński, M. Wolke, A. Wrońska, P. Wüstner, A. Yamamoto, J. Zabierowski, M. J. Zieliński, J. Złomańczuk, P. Żuprański, M. Żurek. 2017-09-04. Importance of d-wave contributions in the charge symmetry breaking reaction $dd \to {}^4\text{He}\pi^0$. https://doi.org/10.1016/j.physletb.2018.04.037
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