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Abstract: We test the validity of the QCD sum rules applied to the meson , by considering a diquark–antidiquark type of current with and with . We find that, with the studied currents, it is possible to find an acceptable Borel window. In such a Borel window we have simultaneously a good OPE convergence and a pole contribution which is bigger than the continuum contribution. We get and for the currents with and , respectively. We conclude that the QCD sum rules results favors quantum numbers for the meson. [Copyright &y& Elsevier]

Abstract: Production of pentaquark baryons in central relativistic heavy ion collisions is studied in a kinetic model. Assuming that a quark–gluon plasma is produced in the collisions, we first determine the number of produced from the quark–gluon plasma using a parton coalescence model, and then take into consideration its production and absorption in subsequent hadronic matter via the reactions , and . We find that although the final number is affected by hadronic interactions, it remains sensitive to the initial number of produced from the quark–gluon plasma, particularly in the case of a small width as imposed by the and scattering data. Because of small baryon chemical potential in the hot dense matter produced in these collisions, the number of produced anti-Θ is only slightly smaller than that of . [Copyright &y& Elsevier]

We consider a [ud]2s¯ current in the QCD sum rule framework to study the mass of the recently observed pentaquark state Θ+(1540), obtaining good agreement with the experimental value. We also study the mass of the pentaquark [ud]2d¯. Our results are compatible with the interpretation of the [ud]2d¯ state as being the Roper resonance N(1440), as suggested by Jaffe and Wilczek. [Copyright &y& Elsevier]