Mark Paris
Thomas Jefferson National Accelerator Facility
Quantum Monte Carlo studies of three-, six-, and five-quark systems
Recent, high-statistics experimental results from Jefferson Lab cast
doubt on the existence of the flavor exotic pentaquark state with
strangeness +1. After reviewing the status of experimental evidence for
and against the pentaquark and some of the recent theoretical
treatments, we make a careful study of the strangeness +1 state within a
non-relativistic constituent quark model (NRCQM). The many-body
Schrodinger equation is solved using the variational Monte Carlo
technique. Improvements over previous NRCQM include full
antisymmetrization of the state of the four light quarks, sometimes
neglected, relaxed assumptions for the spin state of the four light
quarks, and the inclusion of correlations between pairs of quarks which
depend on their isospin-spin-color state. Masses are calculated for
negative and positive parity pentaquark states and found to be
considerably higher than 1.5 GeV.
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