Analysis of $P_c^+(4380)$ and $P_c^+(4450)$ as pentaquark states in the molecular picture with QCD sum rules

Abstract

To better understand the nature and internal structure of the exotic states discovered by many collaborations, more information on their electromagnetic properties and their strong and weak interactions with other hadrons is needed. The residue or current coupling constant of these states together with their mass are the main inputs in determinations of such properties. We perform QCD sum rules analyses on the hidden-charm pentaquark states with spin-parities J P = 3 2 ± and J P = 5 2 ± to calculate their residue and mass. In the calculations, we adopt a molecular picture for± states and a mixed current in a molecular form for J P = 5 2 ± . Our analyses show that the P + c (4380) and P + c (4450), observed by LHCb Collaboration, can be considered as hidden-charm pentaquark states with J P = 3 2 − and J P = 5 2 + , respectively.

Hadronic molecules

“…It has been suggested that their decay patterns could be used to distinguish among various hadronic molecular options (Lin et al, 2017;Shen et al, 2016;Wang et al, 2016a). There are also other dynamical studies with different channel bases (Azizi et al, 2016;Geng et al, 2017;Xiao, 2017;Yamaguchi and Santopinto, 2017).…”

Structure and decays of hidden heavy pentaquarks

“…In particular, the composite structure of the new exotic states has been studied using coupled-channel dynamics [6,7]. An application of QCD sum rules to hidden charm pentaquark states has been done in [8] using diquark-diquark-antiquark type interpolating currents, in [9][10][11] with meson-baryon molecular type currents, and the currents in form of product of two color-octet clusters of three light quarks and charm-anticharm pair [12]. Double polarization observables in pentaquark photoproduction have been studied by JPAC Collaboration using reaction model in Ref.…”

Neural network study of hidden-charm pentaquark resonances

“…The masses of these states were very close to D * Σ * c threshold. This makes comfortable to assume that those two pentaquarks as baryon-meson molecule [9][10][11][12][13][14][15][16][17][18][19]. The other possibilities are compact pentaquark [20][21][22][23], quark model [24][25][26], chiral quark model [27], quark-cluster model [28] and baryocharmonium model [29].…”