Single-particle Inclusive Reactions Research Articles

Fragmentation of carbon ions at 250 MeV/nucleon.

The single particle inclusive reactions $^{12}\mathrm{C}$${+}^{12}$C\ensuremath{\rightarrow}x+anything (3\ensuremath{\le}Z\ensuremath{\le}6) have been studied at 250 MeV/nucleon at nine production angles from 0\ifmmode^\circ\else\textdegree\fi{} to 4\ifmmode^\circ\else\textdegree\fi{}. Production cross sections for most isotopes (Z>2) were determined. The longitudinal and transverse momentum distributions were constructed. The results at this energy are compared to the data at other energies and to the model of Friedman. It appears that, after the Coulomb effects are separated, there is very little energy dependence in the fragmentation process.

Determination of the sea-quark distributions in the proton by single-particle inclusive reactions

We have determined the sea-quark distributions of the proton by using recent data on meson production in the proton fragmentation region in high-energy proton-proton collisions. We find that the magnitude of the sea distributions in hadron reactions is larger than the sea measured in lepton experiments. We interpret this enhancement as due to the additional contribution of quark-antiquark pairs created in the initial hadron collision. From our determination of the sea-quark distributions we are able to predict a number of particle ratios in single-particle inclusive production in p-p collisions. In addition, we have calculated the production cross section for low-mass muon pairs by the Drell-Yan mechanism and have obtained good agreement with experiment.

Inclusive charged-hadron production in 100-400-GeVp−pcollisions

Measurements have been made on the single-particle inclusive reactions $p+p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}, {K}^{\ifmmode\pm\else\textpm\fi{}}, or \overline{p}+\mathrm{anything}$ at 100, 200, and 400 GeV incident proton energies at Fermilab. The data cover a wide range in the radial scaling variable ${x}_{R}(0.05<~{x}_{R}\ensuremath{\le}1.0)$ in the low-${p}_{\ensuremath{\perp}}$ region ($0.25\ensuremath{\le}{p}_{\ensuremath{\perp}}\ensuremath{\le}1.5$ GeV/c). The ${x}_{R}$ and ${p}_{\ensuremath{\perp}}$ distributions are presented. The $\frac{{\ensuremath{\pi}}^{+}}{{\ensuremath{\pi}}^{\ensuremath{-}}}$, $\frac{{K}^{+}}{{K}^{\ensuremath{-}}}$, and $\frac{{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}}{K\ifmmode\pm\else\textpm\fi{}}$ ratios are shown and are compared with data at higher ${p}_{\ensuremath{\perp}}$. The experimental techniques and the data analysis procedures are described in detail.

Erratum: Analysis of radial scaling in single-particle inclusive reactions

An analysis of an extensive sample of the world's data has been performed to test the hypothesis of radial scaling. We have studied the inclusive reactions $p+p\ensuremath{\rightarrow}({\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{},0} or {K}^{\ifmmode\pm\else\textpm\fi{}} or p or \overline{p})+\mathrm{anything}$ to determine the behavior of the invariant cross section as a function of ${p}_{\ensuremath{\perp}}$, ${x}_{R}=\frac{{E}^{*}}{{{E}^{*}}_{max}}$, the radial scaling variable, and $s$. The data cover a range in ${p}_{\ensuremath{\perp}}$ from 0.25 to \ensuremath{\sim}6.0 GeV/c and a range in $\ensuremath{\surd}s$ from 3.0 to 63 GeV. For small ${x}_{R}$ and all available ${p}_{\ensuremath{\perp}}$ the single-particle inclusive cross sections for the reactions studied scale to a good approximation for all $\ensuremath{\surd}s$, even down to the kinematic threshold. For large ${x}_{R}$, the single-particle inclusive cross sections for increasing $\ensuremath{\surd}s$ show a rapid approach to the scaling limit from above. In these cases the scaling limit is always approached by $\ensuremath{\surd}s\ensuremath{\approx}10$ GeV. Thus, data for all particles to a good approximation exhibit radial scaling at all available ${p}_{\ensuremath{\perp}}$ and ${x}_{R}$ over the CERN ISR energy range. A comparison of radial scaling with Feynman scaling is given. It is shown that in the Feynman case the cross sections for small ${x}_{\ensuremath{\parallel}}$ (${x}_{\ensuremath{\parallel}}=\frac{{{p}^{*}}_{\ensuremath{\parallel}}}{{{p}^{*}}_{max}}$) approach their scaling limit from below, and that the approach to the scaling limit is slower than is exhibited for the case of small ${x}_{R}$. The systematic differences among the inclusive cross sections of various particles are discussed in the range of $\ensuremath{\surd}s$ where radial scaling has been shown to be valid. In particular, the ${p}_{\ensuremath{\perp}}$ and ${x}_{R}$ distributions of $E\frac{d\ensuremath{\sigma}}{d{p}^{3}}$ are examined.

Analysis of radial scaling in single-particle inclusive reactions

An analysis of an extensive sample of the world's data has been performed to test the hypothesis of radial scaling. We have studied the inclusive reactions $p+p\ensuremath{\rightarrow}({\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{},0} or {K}^{\ifmmode\pm\else\textpm\fi{}} or p or \overline{p})+\mathrm{anything}$ to determine the behavior of the invariant cross section as a function of ${p}_{\ensuremath{\perp}}$, ${x}_{R}=\frac{{E}^{*}}{{{E}^{*}}_{max}}$, the radial scaling variable, and $s$. The data cover a range in ${p}_{\ensuremath{\perp}}$ from 0.25 to \ensuremath{\sim}6.0 GeV/c and a range in $\ensuremath{\surd}s$ from 3.0 to 63 GeV. For small ${x}_{R}$ and all available ${p}_{\ensuremath{\perp}}$ the single-particle inclusive cross sections for the reactions studied scale to a good approximation for all $\ensuremath{\surd}s$, even down to the kinematic threshold. For large ${x}_{R}$, the single-particle inclusive cross sections for increasing $\ensuremath{\surd}s$ show a rapid approach to the scaling limit from above. In these cases the scaling limit is always approached by $\ensuremath{\surd}s\ensuremath{\approx}10$ GeV. Thus, data for all particles to a good approximation exhibit radial scaling at all available ${p}_{\ensuremath{\perp}}$ and ${x}_{R}$ over the CERN ISR energy range. A comparison of radial scaling with Feynman scaling is given. It is shown that in the Feynman case the cross sections for small ${x}_{\ensuremath{\parallel}}$ (${x}_{\ensuremath{\parallel}}=\frac{{{p}^{*}}_{\ensuremath{\parallel}}}{{{p}^{*}}_{max}}$) approach their scaling limit from below, and that the approach to the scaling limit is slower than is exhibited for the case of small ${x}_{R}$. The systematic differences among the inclusive cross sections of various particles are discussed in the range of $\ensuremath{\surd}s$ where radial scaling has been shown to be valid. In particular, the ${p}_{\ensuremath{\perp}}$ and ${x}_{R}$ distributions of $E\frac{d\ensuremath{\sigma}}{d{p}^{3}}$ are examined.

Production of positive particles in 8-GeV/cπ−pand 18.5-GeV/cπ±psingle-particle inclusive reactions

Inclusive cross sections and invariant single-particle distributions are presented for positive pions and protons produced in 8.05-GeV/c ${\ensuremath{\pi}}^{\ensuremath{-}}p$ and 18.5-GeV/c ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}p$ inclusive reactions. Distributions in $p_{T}^{}{}_{}{}^{2}$ and in the longitudinal variables $x$, $y$ (c.m.) and ${p}_{l}$ (lab) are shown. Comparisons are made with inclusive distributions for other particles produced in the same reactions.

Compilation of Data forπ±pInclusive Reactions at 8 and 18.5 GeV/c. I. Single-Particle Distributions

Production of negative pions in the single-particle inclusive reactions ${\ensuremath{\pi}}^{\ensuremath{-}}+p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}+\mathrm{anything}$ at 8 and 18.5 GeV/c and ${\ensuremath{\pi}}^{+}+p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}+\mathrm{anything}$ at 18.5 GeV/c is analyzed in terms of different sets of kinematic variables for various reference frames. Proton fragmentation is studied in terms of (${P}_{l}$, ${{P}_{T}}^{2}$) in the lab system. In the c.m. system, the variables ($x$, ${{P}_{T}}^{2}$) are useful for the study of incident-particle effects and the energy dependence of cross sections. The variables ($y$, ${{P}_{T}}^{2}$) allow a more detailed study of the kinematic region near $x=0$. The variables (${y}_{r}$, ${{P}_{T}}^{2}$) are particularly useful in that the reduced rapidity ${y}_{r}$ has a fixed kinematic boundary independent of $s$ and ${{P}_{T}}^{2}$. Topological cross sections and multiplicity moments are presented.

Discontinuities Across Branch Cuts in the Angular Momentum Plane

Integral equations for coupled-particle and Reggeon partial-wave amplitudes are presented. A construction of these equations proceeds from the unitarity relation using the notion of two-Reggeon irreducibility. From these equations, which are appropriate matrix elements of a Lippmann-Schwinger equation in two-dimensional nonrelativistic quantum mechanics, we demonstrate that the discontinuity across the two-Reggeon cut in particle scattering is equal to an integral over Reggeon-particle absorptive parts actually measurable in single-particle inclusive reactions. This provides one with a handle on the magnitude of Regge cuts. Finally we make a little model of coupled Reggeon and particle states and solve for the allowed partial-wave amplitudes when a pole and a two-Reggeon cut are close by. This has clear relevance for the physics of diffraction scattering near $l=1$ and $t=0$.

Triple-Regge phenomenology from finite-mass sum rules in single-particle inclusive reactions

Triple-Regge phenomenology from finite-mass sum rules in single-particle inclusive reactions