2006/02/28 by Toru Kojo, A. Hayashigaki, Arata Hayashigaki +1
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ex #hep-lat #hep-ph #nucl-ex #nucl-th
paper · pdf · doi:10.1103/physrevc.74.045206
published as Phys.Rev. C74 (2006) 045206 · 8 pages, 7 figures
arxiv created 2006/08/18 · openalex publication_date 2006/10/30 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We propose a new approach in QCD sum rules applied for exotic hadrons with a number of quarks, exemplifying the pentaquark \ensuremathΘ+(I=0,J=1/2) in the Borel sum rule. Our approach enables reliable extraction of the pentaquark properties from the sum rule with good stability in a remarkably wide Borel window. The appearance of its valid window originates from a favorable setup of the correlation functions with the aid of chirality of the interpolating fields on the analogy of the Weinberg sum rule for the vector currents. Our setup leads to large suppression of the continuum contributions which have spoiled the Borel stability in the previous analyses, and consequently enhances importance of the higher-dimensional contributions of the OPE, which are indispensable for investigating the pentaquark properties. Implementing the OPE analysis up to dimension 15, we find that the sum rules for the chiral-even and odd parts independently give the \ensuremathΘ+ mass of 1.68\ifmmode±\else\textpm\fi0.22 GeV with uncertainties of the condensate values. Our sum rule indeed gives rather flat Borel curves almost independent of the continuum thresholds both for the mass and pole residue. Finally, we also discuss possible isolation of the observed states from the KN scattering state on view of chiral symmetry.