Spectra in the central region and the multiplicities of secondaries at high energies

The inclusive spectrum in the central region, ρ_n(x→0)/<ρ(x→0)> is considered as a function of the multiplicity of charged secondariesn/〈n〉. The calculations in framework of the quark-gluon strings model and the minijet model agree with theSppS-collider data, but both models predict a slow dependence of this value on the energy.     

Regge phenomenology of inclusive spectra in the central region

In the light of new data from the ISR, initial steps are taken towards the Regge analysis of inclusive spectra in the central region. It is shown that some features in the data necessitate the introduction of a further singularity in addition to the Pomeron and the meson trajectories ? - f - ω - A₂. The resulting model yields many predictions via duality and factorisation which can easily be tested at ISR and Batavia energies.     

Soft multihadron production from partonic structure and fragmentation functions

We describe a two-chain model for soft multiparticle production in hadronic collisions. The model is formulated in a parton framework and is consistent with the dual topological scheme for the Pomeron. The sole inputs are valence quark structure functions in the colliding hadrons and parton fragmentation functions, both of which are known from “hard” processes. Our model, which contains no adjustable parameters, reproduces the shape, the energy dependence, and the normalization of inclusive spectra both in the central region and in the fragmentation region. The model provides a natural explanation for the ratio of πp topp cross sections.     

Internal structure for the pionization spectrum

Peripheral models for the inclusive q_τ² spectrum in the central plateau region are considered in a unified treatment. The highest energy ISR spectrum for p + p → π + X is fit for all q_τ.     

Determination of meson resonance contributions to pion and kaon inclusive spectra

π- andK-meson inclusive spectra with low transverse momenta inK-meson fragmentation region inKp-interactions are determined on the basis of the assumption on a recombination mechanism of hadron production. It is shown that the pion and kaon spectra (both “direct” and from resonance decay) inK-meson fragmentation region can be expressed by structure functions of initialK-meson. Contributions from resonance decays from different meson multiplets (vector, axial and tensor) to pion and kaon inclusive spectra are determined. α=(3A _T /5A _V )=0.28±0.02 is found for the suppression factor ofP-wave meson state production as compared to theS-wave one. It is shown that with decreasing final meson mass the relative contribution of direct production to meson inclusive spectrum increases. In the limits of available experimental errors in meson resonance spectra there is found no dependence of meson yields on the value of summary spin of quark and antiquark producing meson (β=3A _P /A _V =1). It is shown that analysis of meson resonance inclusive spectra allows one to determine not only the parameters of valence quark distribution in the initialK-meson but also the sea parton distributions. For the strange sea quark distribution inK-meson there is founds _S(x) ～(1?x) ^ns wheren _S =4.8±1.0, which agrees with the prediction of the quark counting rules for this quantity.     

Measurement of the inclusive forward γ, Λ0 and KS0 spectra produced in proton-copper interactions at 24 GeV/c

We present data on the inclusive γ, λ⁰ and K_Sspectra produced forward direction by interactions of 23.85 GeV/c protons in a copper target. The Λ⁰ spectra are compared with the predictions of the Hagedorn-Ranft model.     

Transverse energy spectrum in the central region of αα interactions: calculations using various models

On the basis of exact Glauber expressions for various processes in inelastic interactions of α particles, transverse energy (E _T ) spectra are calculated within the framework of the leading hadron cascade model and the additive quark model at \(\sqrt {S_{NN} } \) in the central region. The calculations are in good agreement with the data on transverse energy spectra with charged particles atE _T ≦12 GeV. The similarity between experimental spectra for neutral and charged particles was used to justify the theory in a broaderE _T region.     

An experimental check of the quark-model relations for inclusive reactions

The quark-model relations for inclusive reactions obtained in the previous paper by two of the authors are compared with existing experimental data. The x and p_T² distributions are considered for hadrons produced as a result of fragmentation of an incident meson or nucleon, with the kinematics of the resonance decay being taken into account. The predictions of the quark model are in a reasonable agreement with experiment, both in the shape of spectra and in the absolute magnitude of cross sections. A number of predictions is obtained for cross sections of some inclusive reactions which are not yet measured.     

Process dependence of the target jet remnants in the photoproduction of large transverse momentum jets

We use the quark recombination model of Das and Hwa to predict the inclusive meson spectra (π⁺, π^?,K ⁺,K ^?) in the target fragmentation region for processes in which a large transverse momentum jet is produced by a nearly real photon. We find that the antiparticle ratios of such target jet mesons are sensitive to the type of process which has produced the largep _t jet. By comparing the ratios found in photoproduction to those in deep inelastic scattering we point out that it is in principle possible to identify the presence of the Bethe-Heitler photoproduction subprocess. We conclude that the target jet remnants can contribute to separating the subprocesses responsible for the photoproduction of largep _t jets.     

Inclusive production of Σ±(1385) in pp interactions at 12 and 24 GeV/c

The inclusive production of Σ^±(1385) is studied in pp interactions at 12 and 24 GeV/c. In this energy range, the inclusive cross sections for Σ⁺(1385) and Σ^?(1385) rise from 0.20 ± 0.03 mb to 0.28 ± 0.03 mb and from 0.07 ± 0.02 mb to 0.12 ± 0.02 mb. The decays of Σ^±(1385) account for ～20% of all observed Λ hyperons. The p_T² distributions are compatible with an exponential decrease and the slopes are in agreement with a common value of B ～ 3 (GeV/c)^?2. The longitudinal spectra are significantly different: Σ^?(1385) is mainly produced in the central region, whereas proton fragmentation contributes strongly to Σ⁺(1385) production.     

Hadron-nucleus interactions and the leading particle effect in a dual-parton model

We describe hadron-nucleus interactions at smallP _T in the framework of a dual-parton model which is a generalization of the two-chain dual-partonmodel of hadron-hadron interactions introduced recently in the literature. The model (of a multiple scattering type) is formulated in the framework of the 1/N expansion in dual theories. Regge singularities are used to determine the (joint) momentum distribution functions of the various sets of constituents (valence and sea quarks) which yield hadron jets in successive orders of the 1/N expansion. These jets result from a standard color separation mechanism, inspired by QCD. We study the inclusive spectra of various types of secondaries for various projectiles and targets. Particular emphasis is laid on theA-dependence in the projectile fragmentation region. A comparison with available experimental data is presented.     

Correlation with large transverse momentum photons and the gluon structure function

The inclusive two-particle cross section for the production of largep _T photons and opposite side charged hadrons in proton-proton collisions is examined in detail in the framework of QCD. The model, with the parametrization as in our previous work, agrees with the measured single photon spectra. Quantitative predictions are made for two-particle distributions to be measured at the ISR. The contributions due to the photon bremsstrahlung and the effects coming from the intrinsic constituent motion are estimated. It is shown that indeed the direct subprocess gluon+quark→photon+quark gives the dominant contribution in the experimentally relevant region of phase space, and that direct information about the gluon structure function can be obtained from such measurements.     

Inclusive jet production within the two gluon exchange model

The work presents the predictions for the inclusive jet production in the two gluon exchange model for the LEP energies. It is shown that there is a region of the produced jet transverse momentap _T where the two gluon contribution is the only important one. The two gluon exchange model is not able to reproduce the exponential slope of the jet inclusive production cross section, which seems to be an essential feature of the hadronic component of a photon.     

Inclusive neutron and lambda production in proton-proton interactions at 12 and 24 GeV/c

A method for the determination of neutron spectra in a bubble chamber experiment is developed. Double differential cross sections for inclusive neutron and lambda production are presented. The n/Λ particle ratios are determined as functions of x and p_T; at p_T = 0 GeV/c they are compatible with the ratios measured in pCu interactions at 24 GeV/c. Our neutron spectra are compared with spectra for protons produced near the direction of the incident neutron in pn interactions at FNAL and with neutron spectra measured in pp interactions at the ISR. Exchange mechanisms are studied in the framework of single diffraction dissociation and the triple-Regge model. The scattering of virtual pions and kaons on real protons is investigated.     

Ξ− and Ξ− inclusive production in Ξ− Be interactions at 116 GeV/c

The cross sections for Ξ^? and Ω^? inclusive production in Ξ^? Be collisions at 116 GeV/c have been measured in the kinematic domain [0.1<x _F <0.9, 0<p _T <1.7 GeV/c]. The integrated cross sections per nucleon are found to be about twice as large as in Ξ^? p collisions. The invariant cross sections increase by a factor of 70 for the Ξ^? s and of 100 for the Ω^? s between the central region (x _F ～0.2) and the projectile fragmentation region (x _F ～0.8). In the central region, they have about the same magnitude as the ones for Ξ^? and Ω^? inclusive production inp nucleon collisions. The Ξ^? and Ω^? polarisations have been measured over the same kinematic domain and are found to be compatible with zero.     

Transverse momentum distributions of hadrons produced in αα and αp collisions at the CERN intersecting storage rings

The inclusive production of charged hadrons has been measured in αα and αp collisions at nucleon-nucleon c.m. energies (√s_nn)of 31 and 44 GeV, respectively, for transverse momenta p_T up to 5 GeV/c in the central rapidity (y) region. at high p_T the yields are consistent with being 4 times and 16 times highere than the ones in pp interactions at y=0, for αp and αα interactions, respectively. However, an enhancement over these factors, as expected from an earlier FNAL experiment, cannot be ruled out.     

Transverse correlations and perturbative reggeon calculus

We investigate the transverse momentum structure of multiparticle production phenomena in the perturbative reggeon calculus. We find that concerning the transverse correlation <p_c·p_d>(y_c,y_d) in the central region, the cutting rules of Abramovskii, Gribov, Kancheli are modified and tha inclusive long-range transverse correlation is asymptotically zero to the second order in the triple-pomeron coupling constant.     

Beauty-up quarks coupling and duality sum rule

Critical analyses of the electron energy spectrum in the end-point region are made for both inclusive and exclusive semi-leptonic decays of the B meson. While on the one hand, the b quark decay model describing the inclusive mode may not be justified when only few low-lying states contribute, the shape of the spectrum given by the exclusive B_e3 modes, on the other hand, is sensitive to the form factors and very model dependent. In view of these difficulties, a duality sum rule is proposed, trying to remedy both of them. We obtain |V_bu/V_bc|<0.12.     

The hypothesis of statistical jet evolution confronted withe + e − annihilation data

We describe the processe ⁺ e ^?→ hadrons in a “dynamical” phase space, where energy and momentum are quantised in a volume, which expands with velocity of light in a sequence of discrete time steps. Our hypothesis of statistical evolution which is based on an appropriate application of the equipartition principle, determines uniquely the distribution over the resolvable states in this dynamical phase space and leads to a branching process. Neglecting all degrees of freedom except energy and momentum, and restricting to final state pions we arrive at a minimal model with no other parameters thanh, c andm _π. We compare this model in detail with data on multiplicities, inclusive spectra and energy-energy correlations; new energy flow measurements will be proposed. The low energy region (1<W<5 GeV) may provide a clue on the role of color as a new degree of freedom.     

Forward particle production in π− p andK − p collisions at 58 GeV/c and comparison with quark models

We present single inclusive π^±, π⁰ andK ^± spectra in the forward fragmentation region (x>0.2,p _T <1.5 GeV/c) as well as correlations between two charged particles. The data were recorded in an unseparated negative hadron beam at the CERN SPS using a large acceptance forward spectrometer. Our maasurements are compared in detail with several models which emphasise the role of the beam valence quarks in this production process. The connection to measurements at largep _T is also investigated.