Measurement of γγ → pp̄ production at Belle
A high precision study of the process γγ→pp̄ has been performed using a data sample of 89 fb-1 collected with the Belle detector at the KEKB e+e- collider. The cross section of pp̄ production has been measured at two-photon center-of-mass (c.m.) energies between 2.025 and 4.0 GeV and in the c.m. angular range of |cosθ*|<0.6. Production of γγ→ηc→pp̄ is observed and the product of the two-photon width of the ηc and its branching ratio to pp̄ is determined. © 2005 Elsevier B.V. All rights reserved.