Forward and midrapidity like-particle ratios from p+p collisions at root s=200 GeV
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We present a measurement of π−/π+π−/π+, K−/K+K−/K+ and p¯/p from p+pp+p collisions at s=200 GeV over the rapidity range 0<y<3.40<y<3.4. For pT<2.0 GeV/cpT<2.0 GeV/c we see no significant transverse momentum dependence of the ratios. All three ratios are independent of rapidity for y≲1.5y≲1.5 and then steadily decline from y∼1.5y∼1.5 to y∼3y∼3. The π−/π+π−/π+ ratio is below unity for y>2.0y>2.0. The p¯/p ratio is very similar for p+pp+p and 20% central Au + Au collisions at all rapidities. In the fragmentation region the three ratios seem to be independent of beam energy when viewed from the rest frame of one of the protons. Theoretical models based on quark–diquark breaking mechanisms overestimate the p¯/p ratio up to y≲3y≲3. Including additional mechanisms for baryon number transport such as baryon junctions leads to a better description of the data.
CitationPhysics Letters B
Copyright 2004 Elsevier B.V. Open access under CC BY license.