QQQ¯Q¯ states: Masses, production, and decays

Abstract

The question of whether there exist bound states of two heavy quarks Q = (c, b) and antiquarksQ = (c,b), distinct from a pair of quark-antiquark mesons, has been debated for more than forty years. We estimate masses of Q 1 Q 2Q3Q4 resonant states X Q 1 Q 2Q3Q4 and suggest means of producing and observing them. We concentrate on the cccc channel which is most easily produced and the bbbb channel which has a better chance of being relatively narrow. We obtain M(X cccc ) = 6,192±25 MeV and M(X bbbb ) = 18,826±25 MeV, for the J P C = 0 ++ states involving charmed and bottom tetraquarks, respectively. Experimental search for these states in the predicted mass range is highly desirable.

Analysis of the $$QQ\bar{Q}\bar{Q}$$ Q Q Q ¯ Q ¯ tetraquark states with QCD sum rules

“…The masses of the 0 ++ and 2 ++ Q QQQ tetraquark states from the phenomenological quark models lie above or below those thresholds [3][4][5][6][7][8][9][10][11][12]. In Ref.…”

“…On the other hand, if there exist tetraquark configurations that consist of four heavy quarks, the dynamics is very simple. There has been a variety of work on the mass spectrum of the Q QQQ tetraquark states, such as the nonrelativistic potential models [3][4][5][6][7], the Bethe-Salpeter equation [8], the constituent diquark model with spin-spin interaction [9,10], the constituent quark model with colormagnetic interaction [11], the moment QCD sum rules [12], etc. In this article, we study the tetraquark states consist of four heavy quarks with the Borel QCD sum rules.…”

Discovery of the Doubly Charmed Ξcc Baryon Implies a Stable bbu¯dKarliner1, Rosner2 2017Phys. Rev. Lett.Self Cite322222434View full textAdd to dashboardCite

“…[2] makes use of a scheme in which quarks in baryons are endowed with effective masses about 55 MeV heavier than those in mesons. An alternative approach with universal quark masses compensates for this difference by adding a term S = 165 MeV associated with a "string junction," of which baryons possess one while mesons possess none [12]. Unless the QQ system can be thought of as a pointlike object equivalent to a heavy antiquark, a QQūd tetraquark will have two string junctions, with a corresponding [1] to confirm an assumption about the interaction energy of two heavy quarks Q in a tetraquark T = QQūd.…”

Spectroscopy and decays of the fully-heavy tetraquarks

“…If it does, what are their masses and decay properties? Recently, this debate has given rise to several studies within different approaches, including the constituent quark and diquark models [45][46][47][48], chiral quark model [49], chromo-electric potential model [50], and QCD sum rules [51,52]. All of these predict the existence of fullyheavy (bottom) tetraquarks, except for Ref.…”