A.V. Barnes

Angular dependence of high-transverse-momentum inclusive π0 production in π±p and pp interactions☆

Abstract We have measured the inclusive π0 production at high transverse momentum from both pion and proton beams at 100 and 200 GeV/c. Salient characteristics are a wide plateau in the cm angular distribution and evidence for scaling in both πp and pp interactions. The π±p→π0X cross sections fall less steeply with x| = (p|/pmax)cm, and peak at x| = 0.14, in contrast to the pp→π0X cross sections, which peak at x| = 0.

Inclusive π0 and η production from 100 GeV/c π±p collisions in the triple regge region☆

Results are given for inclusive π0 and η production in 100 GeV/c π±p collisions. The data cover the large x ≳ 0.7 region and are compared in detail with the predictions of triple Regge theory. These reactions are theoretically clean with ϱ(π0 production) or A2(η production) exchange. We extract the Regge trajectories, α(t), in the t range of 0 to −4 (GeV/c)2. We find good agreement with the determination from π−p → (π0, η) n at low −t while for large −t ≳ 1.5 (GeV/c)2, the value of α becomes approximately −0.5, independent of t. We see evidence for the wrong signature nonsense zero of the ϱ at t ⋍ −0.4 (GeV/c)2 in the π0 production data. In agreement with simple Regge theory, there is no structure in the η production data at this t value.

The production of neutral pions from 200 GeV π−p collisions in the high x region

We present data from the Caltech-LBL experiment at Fermilab using a photon detector to study π0 production from a 200 GeV π− beam. We present cross sections for inclusive π0 production with 0 < − t < 8 GeV2 and for π0 production with an all-neutral final state for 0 < − t < 6 GeV2, both with π0 energies above 100 GeV. The x-dependences of the cross sections agree with the predictions of the triple Regge model and are used to derive a ϱ trajectory. Our new data are compared to earlier results using a 100 GeV beam over a more limited energy and momentum transfer regime.

Inclusive π0 and η production from kaon, proton and antiproton beams in the triple-Regge region☆

Data are presented on the reactions K±p → π0X, K±p → ηX, pp → π0X and pp → π0X in the kinematic region with s ⋍ 200 GeV2, x ≳ 0.7 and −t ≲ 1 GeV2. The data agree well with the predictions of triple-Regge theory and the K∗ and nucleon Regge trajectories extracted from the data agree with the linear trajectories extrapolated from the particle poles.

An SU(3)-based comparison between inclusive kaon and pion charge exchange scattering in the triple Regge region☆

We show that the SU(3) relation σ(K−p → K0X) = 0.5(σ(π−p → π0X) + 2.2σ (π−p → ηX)) is approximately valid at high energy throughout the kinematic range, Feynman χ⩾0.7 and −t⩽1 (GeV/c)2, for the final stae particle. Our data are consistent with the usual SU(3) mixing of the η and η′. The breaking of SU(3) observed in our data corresponds in the Regge formalism to the ratio of the KK to ππ(η) couplings of the ϱ and A2 trajectories being 14% larger than the SU(3) value.

Inclusive π0 and η production in the all neutral mode from 100 GeV/c π−p collisions☆

Results are givenfor π0 and η production in 100 GeV/c π−p collisions, summed over all final states with no charged particles present (the all neutral final states). The data are fitted for x≳0.6 to a modification of triple Regge theory suggested by the multiperipheral model. We find good agreement between the values of the ϱ and A2 trajectories determined in the all neutral process, the full inclusive mode, π−p → (π0, η)X, and the exclusive reactions, π−p → (π0, η)n. The ϱ exchange residue function shows evidence for a dip at t ≈ −0.5 (GeV/c)2 (the ϱ wrong signature nonsense zero), whereas the η data are quite smooth in this region. These successful predictions for both the trajectory and residue function are striking evidence for the validity of triple Regge theory.