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1. chinaXiv:201609.01053 [pdf]

Effect of $Z_b$ states on $\Upsilon(3S)\to\Upsilon(1S)\pi\pi$ decays

Yun-Hua Chen; Johanna T. Daub; Feng-Kun Guo; Bastian Kubis; Ulf-G. Mei遪er; and Bing-Song Zou
Subjects: Physics >> Nuclear Physics

Within the framework of dispersion theory, we analyze the dipion transitions between the lightest?Υ?states,?Υ(nS)→Υ(mS)ππ?with?m

submitted time 2016-09-18 Hits1222Downloads680 Comment 0

2. chinaXiv:201609.01010 [pdf]

The nature of near-threshold XYZ states

Martin Cleven; Feng-Kun Guo; Christoph Hanhart; Qian Wang; Qiang Zhao
Subjects: Physics >> Nuclear Physics

We demonstrate that the recently observed X,Y,Z states cannot be purely from kinematic effect. Especially the narrow near-threshold structures in elastic channels call for nearby poles of the S-matrix which are qualified as states. We propose a way to distinguish cusp effects from genuine states and demonstrate that (not all of) the recently observed X,Y,Z states cannot be purely from kinematic effects. Especially, we show that the narrow near-threshold structures in elastic channels call for nearby poles of the S-matrix, since the normal kinematic cusp effect cannot produce that narrow structures in the elastic channels in contrast to genuine S-matrix poles. In addition, it is also discussed how spectra can be used to distinguish different scenarios proposed for the structure of those poles, such as hadro-quarkonia, tetraquarks and hadronic molecules. The basic tool employed is heavy quark spin symmetry.

submitted time 2016-09-14 Hits1472Downloads857 Comment 0

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