Decay properties of Roper resonance in the holographic QCD

TL;DR

This paper uses holographic QCD to analyze the decay properties of the Roper resonance, successfully reproducing coupling ratios and highlighting the collective excitation mechanism distinct from quark models.

Contribution

It demonstrates the decay properties of the Roper resonance within the Sakai-Sugimoto model, emphasizing the collective nature of baryon excitations and matching experimental coupling ratios.

Findings

Reproduces ${ m rac{ ext{π}NN^*}{ ext{π}NN}$ coupling ratio

Highlights collective excitation mechanism

Aligns with experimental data on decay ratios

Abstract

We investigate the one pion decay of the Roper resonance $N^*(1440)$$\to$$N$${\pi}$ in the Sakai-Sugimoto model of the holographic QCD. The nucleon and Roper resonance emerge as ground and first excited states of the collective radial motion of the instanton in the four dimensional space with one extra dimension. It is found that the ratio of the ${\pi}$$NN^*$ and ${\pi}$$NN$ couplings, and hence the ratio of $g_A^{NN^*}$ and $g_A^{NN}$, is well reproduced in comparison with the experimental data. The mechanism of this result is due to the collective nature of excitations, which is very different from that of the single particle nature of the constituent quark model. Our results are obtained in the large-$N_c$ and large ${\lambda}$ ('t~Hooft coupling) limit which are useful to test how baryon resonances share what are expected in these limits.