The role of $q\bar{q}$ components in the N(1440) resonance

Abstract

The role of 5-quark components in the pion and electromagnetic decays and transition form factors of the N(1440) is explored. The $qqqq\bar{q}$ components, where the 4-quark subsystem has the flavor-spin symmetries $[4{]}_{FS}[22{]}_F[22{]}_S$ and $[4{]}_{FS}[31{]}_F[31{]}_S$, which are expected to have the lowest energy of all $qqqq\bar{q}$ configurations, are considered in detail with a nonrelativistic quark model. The matrix elements between the 5-quark components of the N(1440) and the nucleon, $qqqq\bar{q}\to qqqq\bar{q}$, play a minor role in these decays, while the transition matrix elements $qqqq\bar{q}\to qqq$ and $qqq\to qqqq\bar{q}$ that involve quark antiquark annihilation are very significant. Both for the electromagnetic and strong decay the change from the valence quark model value is dominated by the confinement triggered $q\bar{q}$ annihilation transitions. In the case of pion decay the calculated decay width is enhanced substantially both by the direct $q\bar{q}\to \pi$ and also by the confinement triggered $q\bar{q}\to \pi$ transitions. Agreement with the empirical value for the pion decay width may be reached with a $\sim$ 30% $qqqq\bar{q}$ component in the N(1440).

23 pages revtex

Cited by in corpus (12)

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