A phenomenological model of QCD monopole hadron interactions

Abstract

Monopoles have recently been discussed to be a dominant component in strong coupled quark gluon plasma ( QGP ) and to play a role for chiral symmetry breaking as well as quark confinement. We analyze monopole quark interactions and show that massless quarks colliding with the monopoles inevitably change their chiralities keeping their flavors. The monopole quark interaction explicitly breaks the chiral symmetry ( SU$_A(2)\times $U$_A$(1) ) just like bare quark masses. It is given by $\bar{q}q\Phi^{\dagger}\Phi$ with the monopole field $\Phi$. The pions are not Nambu-Goldstone bosons even in the vanishing bare quark masses. Their masses are mainly determined by the interaction because the monopole condensation generates a larger current quark mass than the bare quark masses. Based on the analysis of the monopole quark interaction, we propose a phenomenological linear sigma model coupled with the monopoles. The monopoles couple only with isoscalar scalar mesons e.g. sigma meson $\sigma$ such as $\sigma\Phi^{\dagger}\Phi$ indicated by the monopole quark interaction. The coupling explicitly breaks the chiral SU(2)$_A\times $U$_A$(1) symmetry. Pion masses are generated by the chiral condensate, which arises only when the monopole condensate takes place. We show that one of the monopoles is a color singlet and observable. The monopole decays into hadrons ( pions, kaon, etc. ) through the coupling. Our analysis indicates that $f_0(1500)$ meson is a candidate of the observable monopole. As phenomenological effects of these monopoles, we point out that the masses of hadrons decrease in dense nuclear matters and that chiral magnetic effects disappear in strong coupled QGP.