Deciphering the recently discovered tetraquark candidates around 6.9 GeV

被引:38
作者
Sonnenschein, Jacob [1 ]
Weissman, Dorin [2 ]
机构
[1] Tel Aviv Univ, Raymond & Beverly Sackler Sch Phys & Astron, IL-69978 Tel Aviv, Israel
[2] Okinawa Inst Sci & Technol, 1919-1 Tancha, Onna Son, Okinawa 9040495, Japan
来源
EUROPEAN PHYSICAL JOURNAL C | 2021年 / 81卷 / 01期
基金
以色列科学基金会;
关键词
STATE;
D O I
10.1140/epjc/s10052-020-08818-7
中图分类号
O412 [相对论、场论]; O572.2 [粒子物理学];
学科分类号
摘要
Recently a novel hadronic state of mass 6.9 GeV, that decays mainly to a pair of charmonia, was observed in LHCb. The data also reveals a broader structure centered around 6490 MeV and suggests another unconfirmed resonance centered at around 7240 MeV, very near to the threshold of two doubly charmed Xi cc baryons. We argue in this note that these exotic hadrons are genuine tetraquarks and not molecules of charmonia. It is conjectured that they are V-baryonium , namely, have an inner structure of a baryonic vertex with a cc diquark attached to it, which is connected by a string to an anti-baryonic vertex with a c<overbar></mml:mover>c<overbar></mml:mover> anti-diquark. We examine these states as the analogs of the V-baryonium states Psi (4360) and Y(4630)/Psi (4660) which are charmonium-like tetraquarks. One way to test these claims is by searching for a significant decay of the state at 7.2 GeV into Xi cc<mml:mover>Xi <mml:mo><overbar></mml:mover>cc. Such a decay would be the analog of the decay of the state Y(4630) into to Lambda c<mml:mover>Lambda <mml:mo><overbar></mml:mover>c. We further argue that there should be trajectories of both orbital and radial excited states of the X(6900). We predict their masses. It is possible that a few of these states have already been seen by LHCb.
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页数:13
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