Regge trajectories of tetraquarks and pentaquarks with massive quarks in the flux tube model

In recent years, many tetraquarks and pentaquarks have been discovered by various experimental groups and X(3872), Zc(3900), X(4430), Pc+(4312), Pc+(4457) are some of the interesting observed tetraquark and pentaquark states. The Regge trajectories of some such states are studied in view of the flux tube model of hadrons with finite quark masses. The effect of flux tube (or string) length variation on the Regge trajectories of these states is analyzed in detail. It is observed that for a fixed angular momentum, the string length has a constant value. Some other states are also proposed and the results obtained are then compared with the studies by others. Our findings correspond rather well with those of other researchers and with those of the experiment.