Inclusive production of charged pions in p+p collisions at 158 GeV/c beam momentum

Abstract

New results on the production of charged pions in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. Pions are identified by energy loss measurement in a large TPC tracking system which covers a major fraction of the production phase space. Inclusive invariant cross sections are given on a grid of nearly 300 bins per charge over intervals from 0 to 2 GeV/c in transverse momentum and from 0 to 0.85 in Feynman x. The results are compared to existing data in overlapping energy ranges.

Measurements of cross sections and charged pion spectra in proton-carbon interactions at 31 GeV/c

“…For normalization and cross section measurements we adopted the same procedure as the one developed by the NA49 Collaboration [26]. The minimum bias trigger on proton interactions, described in Sec.…”

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“…Charged particles, passing through a system of four large TPC's, left ionization "tracks" in their effective gas volume. Dedicated techniques [2,3] were then applied for momentum vector reconstruction as well as for particle identification via ionization energy loss (the dE/dx method). The particle spectra presented below were corrected for a number of experimental effects, including in particular the feed-down from weak decays (like, e.g., Λ → pπ − or K 0 s → π + π − ) into distributions of final state particles.…”

“…The particle spectra presented below were corrected for a number of experimental effects, including in particular the feed-down from weak decays (like, e.g., Λ → pπ − or K 0 s → π + π − ) into distributions of final state particles. A very detailed description of this problematics can be found in [3].…”

“…Taking into account the relatively low statistics and the preliminary status of the n + p measurement [8], one can nevertheless conclude that the two (a) Ratio of produced π + /π − in p + p collisions at 158 GeV beam energy, compared to the π − /π + ratio in n + p reactions. The curve is an interpolation of NA49 data [3], redrawn from [5]. The data points are redrawn from [8].…”

“…The model took account of isospin effects which were estimated on a similar basis as in Sec. 4, from experimental data on elementary interactions [3]. After the propagation of charged pions through the spectators' electromagnetic field, the result of the simulation is shown in Fig.…”