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Genuine quark state versus dynamically generated structure for the Roper resonance

Golli, Bojan; Osmanović, Hedim; Širca, Simon; Švarc, Alfred (2018) Genuine quark state versus dynamically generated structure for the Roper resonance. Physical Review. C, 97 (3). ISSN 2469-9985

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In view of the recent results of lattice QCD simulation in the P11 partial wave that has found no clear signal for the three-quark Roper state we investigate a different mechanism for the formation of the Roper resonance in a coupled channel approach including the πN, πDelta, and σN channels. We fix the pion-baryon vertices in the underlying quark model while the s-wave sigma-baryon interaction is introduced phenomenologically with the coupling strength, the mass, and the width of the σ meson as free parameters. The Laurent- Pietarinen expansion is used to extract the information about the S-matrix pole. The Lippmann-Schwinger equation for the K matrix with a separable kernel is solved to all orders. For sufficiently strong σNN coupling the kernel becomes singular and a quasibound state emerges at around 1.4 GeV, dominated by the σN component and reflecting itself in a pole of the S matrix. The alternative mechanism involving a (1s)22s quark resonant state is added to the model and the interplay of the dynamically generated state and the three-quark resonant state is studied. It turns out that for the mass of the three-quark resonant state above 1.6 GeV the mass of the resonance is determined solely by the dynamically generated state, nonetheless, the inclusion of the three- quark resonant state is imperative to reproduce the experimental width and the modulus of the resonance pole.

Item Type: Article
Uncontrolled Keywords: Roper resonace, QCD, genuine quark state, dynamical generated
Subjects: NATURAL SCIENCES > Physics
Divisions: Division of Electronics
Depositing User: Alfred Švarc
Date Deposited: 04 Sep 2018 13:24
DOI: 10.1103/PhysRevC.97.035204

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