论文标题

$λπ^+$和$λπ^ - $ \ bar {k} n(i = 1)$质量阈值$λ_c^+\rightArrowλπ^+π^+π^ - $ decay的首次观察。

First Observation of $Λπ^+$ and $Λπ^-$ Signals near the $\bar{K}N (I=1)$ Mass Threshold in $Λ_c^+\rightarrowΛπ^+π^+π^-$ Decay

论文作者

Belle Collaboration, Ma, Y., Yelton, J., Tanida, K., Adachi, I., Ahn, J. K., Aihara, H., Said, S. Al, Asner, D. M., Atmacan, H., Aushev, T., Ayad, R., Babu, V., Bahinipati, S., Banerjee, Sw., Behera, P., Belous, K., Bennett, J., Bessner, M., Bhuyan, B., Bilka, T., Biswas, D., Bobrov, A., Bodrov, D., Borah, J., Bozek, A., Bračko, M., Branchini, P., Browder, T. E., Budano, A., Campajola, M., Červenkov, D., Chang, M. -C., Chen, A., Cheon, B. G., Chilikin, K., Cho, H. E., Cho, K., Cho, S. -J., Choi, S. -K., Choi, Y., Choudhury, S., Cinabro, D., Das, S., De Nardo, G., De Pietro, G., Dhamija, R., Di Capua, F., Dingfelder, J., Doležal, Z., Dong, T. V., Epifanov, D., Ferber, T., Ferlewicz, D., Fulsom, B. G., Garg, R., Gaur, V., Garmash, A., Giri, A., Goldenzweig, P., Golob, B., Graziani, E., Gudkova, K., Hadjivasiliou, C., Halder, S., Hayasaka, K., Hayashii, H., Hedges, M. T., Hou, W. -S., Hsu, C. -L., Inami, K., Ipsita, N., Ishikawa, A., Itoh, R., Iwasaki, M., Jacobs, W. W., Jang, E. -J., Jia, S., Jin, Y., Kaliyar, A. B., Kang, K. H., Kawasaki, T., Kiesling, C., Kim, C. H., Kim, D. Y., Kim, Y. -K., Kinoshita, K., Kodyš, P., Korobov, A., Korpar, S., Kovalenko, E., Križan, P., Krokovny, P., Kumar, R., Kumara, K., Kwon, Y. -J., Lam, T., Lange, J. S., Lee, S. C., Lewis, P., Li, L. K., Li, Y., Gioi, L. Li, Libby, J., Lieret, K., Lin, Y. -R., Liventsev, D., Luo, T., Masuda, M., Matsuda, T., Matvienko, D., Maurya, S. K., Meier, F., Merola, M., Metzner, F., Miyabayashi, K., Mohanty, G. B., Mussa, R., Nakamura, I., Nakano, T., Nakao, M., Natkaniec, Z., Natochii, A., Nayak, L., Nayak, M., Nisar, N. K., Nishida, S., Ogawa, S., Ono, H., Oskin, P., Pakhlov, P., Pakhlova, G., Pardi, S., Park, H., Park, J., Patra, S., Paul, S., Pestotnik, R., Piilonen, L. E., Podobnik, T., Prencipe, E., Prim, M. T., Rostomyan, A., Rout, N., Russo, G., Sandilya, S., Santelj, L., Savinov, V., Schnell, G., Schueler, J., Schwanda, C., Seino, Y., Senyo, K., Sevior, M. E., Shan, W., Shapkin, M., Sharma, C., Shen, C. P., Shiu, J. -G., Simon, F., Sokolov, A., Solovieva, E., Starič, M., Sumihama, M., Sumiyoshi, T., Sutcliffe, W., Takizawa, M., Tamponi, U., Tenchini, F., Uchida, M., Uehara, S., Uglov, T., Unno, Y., Uno, K., Uno, S., Urquijo, P., Usov, Y., Vahsen, S. E., van Tonder, R., Varner, G., Vinokurova, A., Vossen, A., Wang, D., Wang, M. -Z., Watanabe, M., Watanuki, S., Werbycka, O., Won, E., Xu, X., Yabsley, B. D., Yan, W., Yang, S. B., Yin, J. H., Yuan, C. Z., Yuan, L., Zhang, Z. P., Zhilich, V., Zhukova, V.

论文摘要

使用980 Fb $^{ - 1} $的数据样本,在Kekb不对称能量$ E^+E^ - $ collider中收集的Belle检测器,我们介绍了对$λπ^+$和$ unvariant质量分布的调查结果,以寻找在decay $λ_c^+ured的质量分布。我们在每个质量分配中发现一个明显的信号。当将其解释为共振时,我们可以找到$λπ^+$($λπ^ - $)组合的组合,质量为$ 1434.3 \ pm 0.6(\ mathrm {stat})\ pm 0.9(\ mathrm {syst}} 2.5(\ Mathrm {syst})$ MEV/$ C^2 $],固有宽度$ 11.5 \ pm 2.8(\ Mathrm {stat})\ pm 5.3(\ Mathrm {syst}} 23.6(\ Mathrm {syst})$ MEV/$ C^2 $],其意义为7.5 $σ$(6.2 $σ$)。由于这两个信号非常接近$ \ bar {k} n $阈值,因此我们还研究了$ \ bar {k} n $ cusp的可能性,发现\我们无法区分由于数据示例的大小有限,因此我们无法区分这两个解释。

Using the data sample of 980 fb$^{-1}$ collected with the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider, we present the results of an investigation of the $Λπ^+$ and $Λπ^-$ invariant mass distributions looking for substructure in the decay $Λ_c^+\rightarrowΛπ^+π^+π^-$. We find a significant signal in each mass dis\ tribution. When interpreted as resonances, we find for the $Λπ^+$ ($Λπ^-$) combination a mass of $1434.3 \pm 0.6 (\mathrm{stat}) \pm 0.9(\mathrm{syst})$ MeV/$c^2$ [$1438.5 \pm 0.9 (\mathrm{stat}) \pm 2.5(\mathrm{syst})$ MeV/$c^2$], an intrinsic width of $11.5 \pm 2.8 (\mathrm{stat}) \pm 5.3(\mathrm{syst})$ MeV/$c^2$ [$33.0 \pm 7.5 (\mathrm{stat}) \pm 23.6(\mathrm{syst})$ MeV/$c^2$] with a significance of 7.5$σ$ (6.2$σ$). As these two signals are very close to the $\bar{K}N$ threshold, we also investigate the possibility of a $\bar{K}N$ cusp, and find that \ we cannot discriminate between these two interpretations due to the limited size of the data sample.

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