Dortmund 2021 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 62: Search for New Particles V
T 62.7: Vortrag
Mittwoch, 17. März 2021, 17:30–17:45, Tl
Study of the X(3915) at Belle — •Yaroslav Kulii1, Thomas Kuhr1, and Boris Grube2 — 1Ludwig-Maximilians-Universität München — 2Technische Universität München
Many of the charmonium states, which consist of a charm and anti-charm quark, have been found and studied experimentally. Detailed theoretical predictions of the charmonium excitation spectrum agree well with the experimental data.
However, in recent years experiments discovered a growing number of charmonium-like states that do not fit into the predicted charm-anticharm excitation spectrum. One such state is X(3915). It has been discovered by the BaBaR and Belle collaborations in the reaction e+e−→ e+e−X(3915)→ e+e−Jψω, where the final-state electron and positron were not detected. The analysis of projections of angular distributions preferred the JPC=0++ hypothesis, but other quantum numbers, in particular JPC = 2++, could not be excluded.
Because of this the X(3915) was initially identified as the χc0(2P) charmonium state, although its mass and decay width were not in good agreement with the theory predictions. Following the Belle discovery of the X*(3860), which agrees much better with the χc0(2P) hypothesis, opinions shifted towards interpreting the X(3915) as an exotic state. It could be, for example, a meson molecule or a so-called hybrid meson.
We will present the current state of affairs as well as the research prospects of studying the X(3915) in its Jψω decay using Belle and, in the future, Belle II data.