Production of four-prong final states in photon-photon collisions

Results are presented on the exclusive production of four-prong final states in photon-photon collisions from the TPC/Two-Gamma detector at the SLAC $e^{+}$ $e^{\mathrm{-}}$ storage ring PEP. Measurement of dE/dx and momentum in the time-projection chamber (TPC) provides identification of the final states 2${\pi }^{+}$2${\pi }^{\mathrm{-}}$, $K^{+}$ $K^{\mathrm{-}}$ ${\pi }^{+}$ ${\pi }^{\mathrm{-}}$, and 2$K^{+}$2$K^{\mathrm{-}}$. For two quasireal incident photons, both the 2${\pi }^{+}$2${\pi }^{\mathrm{-}}$ and $K^{+}$ $K^{\mathrm{-}}$ ${\pi }^{+}$ ${\pi }^{\mathrm{-}}$ cross sections show a steep rise from threshold to a peak value, followed by a decrease at higher mass. Cross sections for the production of the final states ${\rho }^0$ ${\rho }^0$, ${\rho }^0$ ${\pi }^{+}$ ${\pi }^{\mathrm{-}}$, and φ${\pi }^{+}$ ${\pi }^{\mathrm{-}}$ are presented, together with upper limits for φ${\rho }^0$, φφ, and $K^{\mathrm{*}0}$K¯ ${}_{}{}^{\mathrm{*}0}{}_{}{}^{}$. The ${\rho }^0$ ${\rho }^0$ contribution dominates the four-pion cross section at low masses, but falls to nearly zero above 2 GeV. Such behavior is inconsistent with expectations from vector dominance but can be accommodated by four-quark resonance models or by t-channel factorization. Angular distributions for the part of the data dominated by ${\rho }^0$ ${\rho }^0$ final states are consistent with the production of $J^P$