Systematics of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mrow><mml:mover><mml:mrow><mml:mi>Q</mml:mi></mml:mrow><mml:mrow><mml:mi>¯</mml:mi></mml:mrow></mml:mover></mml:mrow></mml:mrow><mml:mrow><mml:msup><mml:mrow><mml:mi>q</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>systems with a pure chromomagnetic interaction

Leandri, J.; Silvestre‐Brac, B.

doi:10.1103/physrevd.40.2340

Cited by 45 publications

(36 citation statements)

References 24 publications

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“…It was applied to diquonia made of ordinary quarks by Mo and Hogaasen [19]. Within this framework systematic studies of Qq4 systems [37] and dibaryon systems [38] were carried out recently. In these studies more elaborate treatments were done for some of the most interesting candidates, and the conclusion was that, although the chromodynamic binding is always overestimated, a Hamiltonian such as (2.1) is able to predict in a correct way the general trends of the state hierarchy.…”

Section: The Model Hamiltonianmentioning

confidence: 99%

Systematics ofQ2(Q¯2)systems with a chromomagnetic interaction

Silvestre‐Brac¹

1992

Phys. Rev. D

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Within the framework of a simple model including chromomagnetic interactions only, the energies of diquonia QZ (c2) with orbital angular momentum L=O are calculated and compared to the threshold energies. The results are given as functions of mass ratios and all possible diquonia built with u, d , s, c, b quarks and spins S=0,1,2 are studied. A number of new systems which could be bound under strong interactions are proposed.PACS number(s): 12.40.Qq, 11.30.H~ Today quantum chromodynamics (QCD) is recognized as the correct theory for strong interactions; it relies on the color interaction between quarks and gluons. The number of possible color configurations increases dramatically with the number of interacting quarks in a given system. However, the experimental situation forces QCD to be implemented with the physical principle that observable hadrons must be color singlets. The immediate consequence [with a SU(3), gauge group] is the triality rule: any observable hadron must be composed in such a way that the number of quarks minus the number of antiquarks is a multiple of 3. This principle allows one to reduce greatly the number of color configurations. Indeed, the simplest systems, mesons (qq3 or baryons (q3), need only one color wave function. These hadrons are bound by gluon exchange. For more complicated objects the binding due to strong interactions can come either from meson exchange or from gluon exchange. The first category contains the wide and rich variety of atomic nuclei and received a lot of attention, although it is based on less microscopic grounds, for more than fifty years. The second category contains particles of type q "' qn bound by gluons, with the restriction m -n=3B,B being the baryon number. The total set of such systems bears the generic name of "multiquarks" and has been also qualified as "exotic" in the past. The mere existence of these multiquarks is already very important because it is the clue of the reliability of QCD. They are not forbidden by QCD and thus they must exist either as bound states or as typical resonances in some definite channels. If they are not seen experimentally, QCD has to be questioned or, at least, some mechanism must be invoked to explain their absence.Among the possible multiquarks, the diquonia q2q2 with B =O are the simplest samples. Since their introduction by Jaffe [I], a lot of work has been devoted to their study. Even for such simple objects an exact treatment *Electronic address: bsilvest at frcpnl 1 .bitnet 46 -based on QCD is not feasible, and one has to rely upon some approximation. Most of the derived models are called "QCD" inspired." Some of them are very crude, using only special constant matrix elements 12-51. More refined methods have also been used more recently: relativistic strings [6], QCD sum rules [7], bag models [8,9], potential models [lo-161, the simplified Bethe-Salpeter formalism [17].In addition to the problem of the spectrum, the decay of the diquonia is also an interesting question. One can imagine essentially two different d...

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Section: The Model Hamiltonianmentioning

confidence: 99%

Systematics ofQ2(Q¯2)systems with a chromomagnetic interaction

Silvestre‐Brac¹

1992

Phys. Rev. D

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“…Thus, the GBE model suggests that the nonstrange positive parity pentaquarks are the best candidates for stable compact systems. This in contrast to OGE based models where strangeness is required [5] in order to reach stability for heavy-flavoured pentaquarks. The present results have similarities with those obtained in [7] from the Skyrme model : 1) the lowest pentaquark states have positive parity for any flavour content ; 2) stability does not necessarily require strangeness.…”

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confidence: 99%

“…Within better approximations, they turned out to be unstable [3,4]. A systematic theoretical study [5] in a model with OGE interaction suggested several candidates for stability, and among them * …”

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confidence: 99%

Positive parity pentaquarks in a Goldstone boson exchange model

Stancu

1998

Phys. Rev. D

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We study the stability of the pentaquarks uuddQ, uudsQ and udssQ (Q = c, b, or t) of positive parity in a constituent quark model based on Goldstone boson exchange interaction between quarks. The pentaquark parity is the antiquark parity times that of a quark excited to a p-shell. We show that the Goldstone boson exchange interaction favors these pentaquarks much more than the negative parity ones of the same flavour content but all quarks in the ground state. We find that the nonstrange pentaquarks are stable against strong decays.The existence of particles made of more than three quarks is an important issue of QCD inspired model. The interest has been raised so far by particles described by the colour state[222] C , the tetraquarks q 2 q 2 , the pentaquarks q 4 q and the hexaquarks q 6 . The present study is devoted to pentaquarks, first proposed independently by Gignoux, Silvestre-Brac and Richard [1] and Lipkin [2] about ten years ago. Within a constituent quark model based on one-gluon exchange (OGE) interaction, these authors found that the states P 0 cs = |uudsc and P − cs = |uddsc and their conjugates are stable against strong decays. Within better approximations, they turned out to be unstable [3,4]. A systematic theoretical study [5] in a model with OGE interaction suggested several candidates for stability, and among them *

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“…In the constituent quark model, it has been noticed years ago that the chromomagnetic interaction acts favourably in some (QQqqq) configurations [37]. It remains to perform a full five-body calculation to see whether some metastability emerges from the interplay of kinetic energy, confinement and chromomagnetism.…”

Section: Pentaquarksmentioning

confidence: 99%