A review is given of the current state of searches for, and investigations of, exotic mesonic states in hadronic reactions, $J/\psi$ decays, and $\gamma$, $\gamma$ collisions. These experiments have led in recent years to the discovery of a number of mesonic states whose properties do not fit into the simple quark model of ``ordinary'' ($\mathrm{q\bar q}$) mesons. The new particles appear to be very serious candidates for exotic hadrons. The current state of the E/iota problem and the nature of the E(1420) meson are discussed.

PT Journal Article
TI Exotic mesons
AU Landsberg L G
FAU Landsberg LG
DP 10 Mar, 1990
TA Phys. Usp.
VI 33
IP 3
PG 169-203
RX 10.1070/PU1990v033n03ABEH002551
URL https://ufn.ru/en/articles/1990/3/a/
SO Phys. Usp. 1990 Mar 10;33(3):169-203