diquark


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diquark

(ˈdaɪkwɑːk)
n
(Atomic Physics) a low-energy configuration of two quarks attracted to one another by virtue of having antisymmetric colours and spins
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References in periodicals archive ?
The significant point to this is that the quark-antiquark coupling (designated ud') is transmuted into a temporary diquark selfstate (designated ud) following a simple exchange of the state-antistate couplings of the neutral pions (designated dd' and uu').
In effect, two of the quarks of the baryonic color-singlet qqq bound state bind to a color [bar.[3.sub.C]] diquark bound state, which then binds by the same color force to the remaining [3.sub.C] quark.
The twist-3 proton with [J.sup.z.sub.p] = +1/2 in AdS/QCD is a bound state of a quark with [S.sup.z.sub.p] = 1/2 and a spin-zero diquark [qq] with [L.sup.z.sub.q[qq]] = 0, and the twist-4 proton in AdS/QCD is a bound state of a quark with [S.sup.z.sub.p] = -1/2 and spin-zero diquark [qq] with relative orbital angular momentum [L.sup.z.sub.q[qq]] = +1.
Since the issue is not settled, we proceed by adopting the NJL model which best highlights the competition between the chiral and diquark condensates in a straightforward way.
Our objective in this paper is a numerical study of the competition between the chiral and diquark condensates at moderately large [mu] and large magnetic field using the NJL model, similar in some respects to previous works [8, 9, 39-41], which treat the quark mass nonperturbatively.
In Section 4, we obtain the gap equations for the chiral and diquark order parameters by minimizing the thermodynamic potential (we work at zero temperature throughout since typical temperature in stars [T.sub.star] [much less than] [mu]).
Therefore the operator [R.sup.[dagger].sub.[lambda]] applied to the negative-chirality component of a baryon will give a wave function [[phi].sub.T] = [R.sup.[dagger].sub.[lambda]][[psi].sub.B-], which can be interpreted as that of a tetraquark consisting of a diquark cluster and an antidiquark cluster.
Considering that the diquark (antidiquark) inside has strong attraction, their masses are expected to be less than 1 GeV and the ordering is expected to be [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], which is consistent with the experiments.
There are two possibilities to construct a flavor single tetraquark current: both of the diquark and antidiquark have the antisymmetric flavor structure [[bar.3].sub.F](qq) [direct sum] [3.sub.F]([bar.q][bar.q]) [right arrow] [1.sub.F] or have the symmetric flavor structure [6.sub.F](qq) [direct sum] [[bar.6].sub.F]([bar.q][bar.q]) [right arrow] [1.sub.F].
Shuryak, "What do lattice baryonic susceptibilities tell us about quarks, diquarks, and baryons at T > [T.sub.c]," Physical Review D: Particles, Fields, Gravitation and Cosmology, vol.
Some theorists, including Karliner, Lipkin, and Wilczek, propose that pentaquarks may involve two-quark subgroups known as diquarks. These are quark-quark or antiquark-antiquark pairs that have seemed to play only bit roles in quark interactions, Wilczek says.
This transport model is based on the covariant propagation of color strings, constituent quarks, and diquarks (as string ends) accompanied by mesonic and baryonic degree of freedom [9].