Spin-3/2 Pentaquark in QCD Sum Rules

Understand

The QCD sum rule method is formulated for the strangeness +1 pentaquark baryon with isospin I=0 and spin-parity J^P = 3/2^\pm.

• The spin-3/2 states are considered to be narrower than the spin-1/2 ones, and thus may provide a natural explanation for the experimentally observed narrow width of \Theta^+.
• In order to obtain reliable results in QCD sum rule calculations, we stress the importance of establishing a wide Borel window, where convergence of the operator product expansion and sufficient low-mass strength of the spectral function are guaranteed.
• To this end, we employ the difference of two independent correlators so that the high-energy continuum contribution is suppressed.