Energy dependence of inclusive distributions in pion-induced reactions

We present data on the inclusive distributions π⁺p → π^± + anything and π⁻p → π⁻ + anything at momenta from 3.7 to 18.5 GeV/c. Distributions are presented in the laboratory, center-of-mass and projectile systems, and the approach to scaling is discussed.     

ee Annihilation into two hadrons in the energy interval 1400–2400 MeV

The proof is given for the existence of the reaction e⁺e⁻ → h^±h^? in the energy range 1400–2400 MeV, and its energy dependence is compared with that of e⁺e⁻ → e^±e^?, in the same experimental conditions of observation. The exponent of the s-dependence of the ratio α = (e⁺e⁻ → h^±h^?)/ (e⁺e⁻ → e^±e^?) is measured to be n = 2.08 ± 0.45, in the s-range (1.96 − 5.76) GeV², on the basis of 51 e⁺e⁻ → h^±h^? events and 8918 e⁺e⁻ → e^±e^? events observed.     

Some consequences of exchange degeneracy and the triple-Regge-hypothesis

We extract the proton-Reggeised rho total cross-section from inclusive data for K⁺ + p → K⁰ + (anything) in the triple-Regge domain and find that it is of the same order as physical meson-proton cross-sections for a range of Reggeon mass. We also relate other processes such as pp→pX and K⁺p→K⁺X to K⁺p→K⁰X, and get good agreement with data. We suggest methods for calculating baryon exchange processes as well.     

Electron-positron annihilation into hadrons at high energies

In the limit of extremely high energies with the transverse momentum of each hadron fixed, the reaction e⁺ + e⁻ → hadrons proceeds by the annihilation of this pair into two virtual photons which turn into two fireballs of hadrons with negligible final-state interaction.     

A modified parton model for reactions with time-like photons

A time-like photon is considered as a kind of mesonic state with valence + sea multipartons configurations; consequences for e⁺e^? annihilation and leptons production in hadronic collisions are examined.     

Properties of the inclusive pion spectrum from pp collisions: 28.5 GeV/c to about 10 GeV/c

The spectra of pions are studied in the inclusive reactions p + p → π^± + anything in bubble chamber data at 28.5 GeV/c. Comparisons are made with ISR π⁺ spectra to examine energy dependence.     

SUSY effects in Higgs production at high energy e+e- colliders

Considering the constraints from collider experiments and dark matter detection, we investigate the SUSY effects in the Higgs production channels e⁺e^-→Zh at an e⁺e^- collider with a center-of-mass energy above 240 GeV and γγ→h→bb at a photon collider with a center-of-mass energy above 125 GeV. In the parameter space allowed by current experiments, we find that the SUSY corrections to e⁺e^-→Zh can reach a few percent and the production rate of γγ→h→bb can be enhanced by a factor of 1.2 over the SM prediction. We also calculate the exotic Higgs production e⁺e^-→Zh₁ in the next-to-minimal supersymmetric model (NMSSM) (h is the SM-like Higgs, h₁ is the CP-even Higgs bosons which can be much lighter than h). We find that at a 250 GeV e⁺e^- collider the production rates of e⁺e^-→Zh₁ can reach 60 fb.     

Effect of weak neutral currents in the process e− + p → e− + γ + X

Polarization effects in the inclusive process e^– + p e^– + + X due to the neutral current are studied in the framework of the Weinberg-Salam model. Expressions for the asymmetry parameters and the degree of circular polarization of the photons are obtained in the quark-parton picture. It is shown that measurement of such quantities gives additional information about the quark structure of the hadronic weak neutral current.Paper presented at the scientific session of the nuclear physics branch, USSR Academy of Sciences and the Moscow State University on Electromagnetic and Weak Interactions (Moscow, January 16–20, 1979).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 96–99, January, 1981.     

Recent results on resolved photon processes

During the last 18 months, experiments at bothe ⁺ e ⁻ andep colliders have begun to test earlier predictions for processes that probe the hadronic structure of the photon. All the main qualitative predictions have already been verified; more detailed analyses are now starting to improve our quantitative understanding of photon structure functions. Some comments on minijets and total cross sections are also included.     

Scaling in semi-inclusive experiments

In bubble chamber experiments (in contrast to counter experiments) the semi-inclusive experiment a+b→c+(n−1) charged + anything neutral is more natural than the corresponding inclusive experiment a+b→c+anything. We argue that the cross sections for semi-inclusive experiments have very neat scaling properties.     

Measurement of the electron-positron annihilation cross-section into ππ,KK-pairs at the total energy 1.18−1.34 GeV

Using the electron-position storage ring VEPP-2 an experiment has been performed in which the cross-sections of the reactions e⁺e⁻→π⁺π⁻ and e⁺e⁻→K⁺K⁻ were measured in the energy regi on 1.18–1.34 GeV. The experimental values of the formfactors lie higher than curves extrapolated from the ?- and ?-meson region.     

SND: New results and opportunities

We present the new results on the e⁺e⁻→K⁺K⁻, e⁺e⁻→K_SK_L, e⁺e⁻→ηγ processes obtained by the SND. We also give a short report on VEPP-2000, the new e⁺e⁻ collider constructed in Novosibirsk. The physical program for this machine is discussed. Special attention is paid to the future nucleon timelike form factor measurements.     

The behaviour in terms of angular variables of the inclusive reactions Kp → KX and Kp → KπX at 5.0 and 8.2 GeV/c

The inclusive reactions K⁺p → K⁰ + X⁺⁺ at 5.0 and 8.2 GeV/c and K⁺p → K⁰ + π⁺ + X⁺ at 8.2 GeV/c are analysed in terms of angular variables θ and ø. The data are compared and found consistent with various theoretical bounds on the s-dependence of the inclusive reaction cross sections. Experimental evidence is presented that dσ/dcos θ = a exp (−b sinθ) with b ∼ √s and a increasing with energy. Correlations between the angular variables and between the variable ø and the K⁰ and π⁺ momenta in the c.m.s. are observed and discussed.     

Photon production in Au+Au collisions at \sqrt {s_{NN} } = 130 GeV

We report raw photon, neutral pion and eta measurements at RHIC. Photons in the energy range from 100MeV ? 4GeV were detected by reconstructing e ⁺ e ^? pair production, γ+Z→e ⁺+e ^?+Z, with the STAR Time Projection Chamber (TPC). Along with the photon detection technique we discuss the purity of the photon candidates and measurements of hadronic decays via their electromagnetic decay channels. The π⁰→γ and η→γγ decay channels are addressed.     

Gluon and quark jets in deep-inelastic scattering of electrons by nucleons

The paper considers the formation of gluon and quark jets in the inelastic scattering of electrons by nucleons with large momentum transfers. It is assumed that these jets are created by the processes e^–+qe^–+q+g and e^–+ g e^–+q+q, where q is a quark and g is a gluon. The angular distributions of gluon and quark jets are calculated in the lowest order in the quark-gluon coupling constant. It is shown that after integration the processes e^–+qe^–+q+g and e^–+g e^–+q+¯q lead to violation of the scaling invariance of deep-inelastic scattering of electrons by nucleons.Translated from Izvestiya Vysshkikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 68–73, September, 1981.     

Coherent π Electroproduction on the Deuteron

A general analysis of polarization phenomena for coherent pion electroproduction on deuterons is presented. The spin and isospin structures of the γ*+d→d+P⁰ amplitudes (where γ* is a virtual photon) are established and relationships between meson electroproduction on deuterons and on nucleons are given in the framework of the impulse approximation. The reaction e+d→e+d+π⁰ is investigated in detail, for a relatively large value of momentum transfer, 0.5 GeV²≤−k²≤2 GeV², both at threshold and in the region of Δ-isobar excitation. Special attention is devoted to the sensitivity of different contributions to the exclusive cross section for d(e, eπ⁰)d, as the γ*πω form factor or the NN-potential. The predicted k²-dependence of the cross section agrees well with the available experimental data.     

Energy spectrum and angular distribution of muons from the decay of heavy leptons produced in colliding electron-positron beams

On the basis of an arbitrary (V, A) structure of the neutral weak ¯ee and LL currents (L=^–, M⁰) a study is made of the processes of production in colliding electron-positron beams of pairs of heavy leptons with subsequent decays in accordance with the schemes e⁺e^––(µ^–v_µv) + ⁺( anything) and e⁺e^–M⁰(µ^–e⁺v_e) + M⁰( anything). The energy spectrum and asymmetry of the distribution of the produced muons are investigated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 66–70, February, 1981.     

Some consequences of neutral current systematics

Two kinds of general consequences of the ΔS=0 weak hadron neutral current independent of a gauge model are presented. Firstly are results which depend on the quark parton model. These involve bounds among neutrino inclusive cross-section and a bound onQ(Z, N) in terms of these inclusive cross-sections. Secondly are results which are independent of the quark-parton model and depend only on the SU(3) structure of the most general ΔS=0 neutral current. These tests of isopin and speciallyU-spin properties of the current are given forv+N→v+hadron+anything,v+N→v+baryon+meson ande ⁺ e ⁻→baryon+anti-baryon. In addition some conjectures are made with regard to the semi-inclusive neutrino-reactions using the quark parton model.     

Inclusive production of D-mesons in e+e− annihilation at 7 GeV

Inclusive momentum and energy spectra of neutral and charged D-mesons produced in e⁺e^? annihilation at energies near 7 GeV are presented. The slope of the energy spectrum is similar to the charged pion spectrum at the same energy. The inclusive cross section σ(e⁺e^?→ D or $\text{D}$ + anything) at 7 GeV is 4.8±1.3 nb.