Measurement of Exclusive \rho^+\rho^- Production in High-Q^2 Two-Photon Collisions at LEP

TL;DR

This study measures the cross section of exclusive rho+ rho- production in high-Q^2 two-photon collisions at LEP, revealing its dependence on photon virtuality and energy, and comparing it to neutral rho pair production.

Contribution

It provides the first detailed measurement of gamma gamma* -> rho+ rho- cross sections as functions of Q^2 and W_gg at LEP energies, extending understanding of two-photon processes.

Findings

Cross section magnitude similar to gamma gamma* -> rho^0 rho^0

Observed similar W_gg and Q^2 dependences for charged and neutral rho pairs

Cross section decreases with increasing Q^2 and W_gg

Abstract

Exclusive rho^+ rho^- production in two-photon collisions involving a single highly-virtual photon is studied with data collected at LEP at centre-of-mass energies 89 GeV < \sqrt{s} < 209 GeV with a total integrated luminosity of 854.7 pb^-1. The cross section of the process gamma gamma^* -> rho^+ rho^- is determined as a function of the photon virtuality, Q^2, and the two-photon centre-of-mass energy, W_gg, in the kinematic region: 1.2 GeV^2 < Q^2 < 30 GeV^2 and 1.1 GeV < W_gg < 3 GeV. The \rho^+\rho^- production cross section is found to be of the same magnitude as the cross section of the process gamma gamma^* -> rho^0 rho^0, measured in the same kinematic region by L3, and to have similar W_gg and Q^2 dependences.