Coherent source radius in pp̄ collisions

We use a recently derived result to extract from two-pion interferometry data from pp̄ collisions the radius of the coherent component in the source. We find a coherent source radius of about 2fm. PACS numbers: 25.75. -q, 25.70. Pq, 25.70 Gh. Two-particle Bose-Einstein interferometry (also known as Hanbury Brown-Twiss intensity interferometry) as a method for obtaining information on the space-time geometry and dynamics of high energy collisions has recently received intensive theoretical and experimental attention. Detailed investigations have shown that high-quality two-particle correlation data can reveal not only the geometric extension of the particle-emitting source but also its dynamical state at particle freeze-out [1–6]. For a partially coherent source, it was suggested that two-pion interferometry can give the coherent degree information of the source [7–9]. In paper [10], we have generalized the two-pion interferometry formula for a partially coherent source and found that twopion interferometry was also senstive to the size of the coherent source component. The