Magnetic moment of the pentaquark Θ+(1540) as diquark-diquark-antiquark state with QCD sum rules

Abstract

In this article, we study the magnetic moment of the pentaquark state Θ + (1540) as diquark-diquark-antiquark ([ud][ud]s) state with the QCD sum rules in the external weak electromagnetic field (EFSR) and the light-cone QCD sum rules (LCSR) respectively. The numerical results indicate the magnetic moment is about µ Θ + = −(0.11 ± 0.02)µ N for the EFSR and µ Θ + ≈ −(0.1−0.5)µ N for the LCSR. As the values obtained from the EFSR are more stable than the corresponding ones from the LCSR, µ Θ + = −(0.11 ± 0.02)µ N is more reliable.

Analysis of the Nonet Scalar Mesons as Tetraquark States with New QCD Sum Rules

“…tetraquark states, pentaquark states, hexaquark states, etc., have the spectral densities ρ ∼ s n with the largest n ≥ 4, the integral ∞ 0 s n e − s T 2 ds converges slowly [13,14]. If one don't want to release the criterion of pole dominance, we have to either postpone the threshold parameter s 0 to very large value or choose very small value for the Borel parameter T 2 max .…”

“…For the conventional mesons and baryons, the "single-pole + continuum states" model works well in representing the phenomenological spectral densities, the continuum states are usually approximated by the contributions from the asymptotic quarks and gluons, the Borel windows are rather large and reliable QCD sum rules can be obtained. However, for the light flavor multiquark states, we cannot obtain a Borel window to satisfy the two criteria (pole dominance and convergence of the operator product expansion) of the QCD sum rules [13,14]. In Ref.…”

Electromagnetic multipole moments of the $$P_c^+(4380)$$ P c + ( 4380 ) pent

“…There are many studies in the literature committed to the study the electromagnetic multipole moments of the standard hadrons, but unfortunately relatively little are known about the electromagnetic multipole moments of the exotic hadrons. There are a few studies in the literature where the magnetic dipole moment of the pentaquarks are studied [17,[51][52][53][54][55][56][57].…”

The electromagnetic multipole moments of the charged open-flavor ${Z}_{\bar{c}q}$ states

“…There are many studies in the literature devoted to the investigation of the electromagnetic multipole moments of the standard hadrons, but unfortunately relatively little are known the electromagnetic multipole moments of the exotic hadrons. There are a few studies in the literature where the magnetic dipole and quadrupole moments of the exotic states are studied: see [27][28][29] for tetraquarks and [30][31][32][33][34][35] for pentaquarks. More detailed analyses are needed in order to get useful knowledge on the charge distribution, electromagnetic multipole moments and geometric shapes of the non-conventional hadrons.…”