The two-pion correlation function can be defined as a ratio of either the measured momentum distributions or the normalized momentum space probabilities. We show that the first alternative avoids certain ambiguities since then the normalization of the two-pion correlator contains important information on the multiplicity distribution of the event ensemble which is lost in the second alternative. We illustrate this explicitly for specific classes of event ensembles.PACS numbers: 25.75.Gz, 25.70.Pq.

No abstract

The probability distribution of a neutral pion fraction from independent domains of disoriented chiral condensate is characterized. The signal for the condensate is still clear for a large number of independent domains if one of them is predominant.Comment: 4 pages, one figure. minor correction,title change

We use a recently derived result to extract from two-pion interferometry data from pp collisions, the radius of the coherent component in the source. We find a coherent source radius of about 2 fm. ͓S0556-2813͑98͒50204-X͔ PACS number͑s͒: 25.75. Gz, 13.75.Cs, 24.10.Ϫi, 25.70.Pq Two-particle Bose-Einstein interferometry ͑also known as Hanbury Brown-Twiss intensity interferometry͒ 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 ͓1-6͔.For a partially coherent source, it was suggested that twopion interferometry can give the coherent degree information of the source ͓7-9͔. In Ref. ͓10͔, we have generalized the two-pion interferometry formula for a partially coherent source and found that two-pion interferometry was also sensitive to the size of the coherent source component. The physical reason is clear: The particle spectrum distribution is the Fourier transformation of the source distribution; the coherent source radius information must hide in the spectrum distribution and also must appear in the two-pion interferometry formula. We will show below that a general two-pion interferometry formula satisfies the need to reveal both the degree of coherence and space-time information of the coherent source which was neglected in previous publications ͓9,11-14͔.