Polarized target asymmetry in π+ photoproduction between 0.3 and 1.0 GeV at 130°

The polarized target asymmetry for γ + p → π⁺ + n was measured at c.m. angles around 130° for the energy range between 0.3 and 1.0 GeV. A magnetic spectrometer system was used to detect π⁺ mesons from the polarized butanol target. The data show two prominent positive peaks at 0.4 and 0.8 GeV and a deep minimum at 0.6 GeV. These features are well reproduced by the phenomenological analysis made by us.     

Strange particle cross sections and multiplicity distributions in 19 GeV/c proton-proton interactions

Inclusive cross sections are presented for strange-particle production in proton-proton interactions at 19 GeV/c for the pairs $\text{(}\text{K}{}^0\text{K}{}^0{}_{\mathrm{C=+1}}\text{,}\text{K}{}^0\text{Λ,}\text{K}{}^{\mathrm{+}}\text{Λ,}\text{K}{}^0\text{Σ}{}^{\mathrm{+}}\text{,}\text{K}{}^0\text{Σ}{}^{\mathrm{?}}$ and for Λ, K_s⁰, Σ⁺, Σ^? and Ξ^?. The $\text{K}\text{K}$, the KY and the total strange particle cross sections have been found to be 1.40 ± 0.10 mb, 2.69 ± 0.09 mb and 4.23 ± 0.20 mb, respectively. The charged multiplicity distributions for events with K_s⁰, Λ, $\text{(}\text{K}{}^0\text{K}{}^0\text{)}{}_{\mathrm{C=+1}}$ or K⁰ Λ are shown to follow a modified KNO curve, whereas K⁺ Λ does not. For the inclusive reactions $\text{pp}\text{→(}\text{K}{}^0\text{K}{}^0\text{)}{}_{\mathrm{C=+1}}\text{+}\text{X}{}^{\mathrm{++}}\text{,}\text{pp}\text{→}\text{K}{}^0\text{Λ +}\text{X}{}^{\mathrm{++}}\text{and pp}\text{→ Λ +}\text{X}{}^{\mathrm{++}}$, we find that the average charged multiplicity of the remainder system X⁺⁺ is the same as when X⁺⁺ is produced in other reactions with the same system energy and quantum numbers.     

Search for exotic meson and hyperon final states in K-d interactions at 5.5 Gev/c

A search has been made for exotic states produced in K^?d interactions at 5.5 GeV/c. The reactions investigated were: K^?d→X^??pp, $\text{K}{}^{\mathrm{?}}\text{d}\text{→}\text{Y}{}^{\mathrm{1??}}\text{π}{}^{\mathrm{+}}\text{p}$ and K^?d→ M^??Σ⁺p. Upper limits are set for the production cross sections.     

Search for charmed hadrons in neutral strange particle events in pp interactions at 19 GeV/c

A search for charmed hadrons has been made in proton-proton interactions at 19 GeV/c using events with one or two observed neutral strange particles. No evidence for charmed particles has been found. Upper limits for their production cross sections are presented.     

Analysis of the reaction pp → p(ππ)0 p,and the question of double pomeron exchange in high-energy production processes

A low-mass S-wave (ππ)⁰ enhancement is observed in the reaction pp → p (ππ)⁰ p at 12 and 24 GeV/c incident momentum. The mechanism for producing these low-mass pion pairs is investigated, and it is shown that double pomeron exchange can contribute at most 5% to their production cross section at 24 GeV/c.     

The relation between the sea quark distribution and the pomeron

The sum rule of the πN total cross section is derived with use of the anticommutator of currents restricted at the nullplane and PCAC. Through this sum rule, the quantitative relation between the sea quark distribution and the pomeron is given.     

On the relation between inclusive and exclusive p⊥ distributions

Inclusive and exclusive scattering is studied within an impact parameter framework. It is shown that the inclusive p_⊥ distribution at a fixed value of c.m. longitudinal momentum, p_6;, is governed only by the impact parameter structure of the observed particle. Next we introduce to each of the produced particles a radius, which is assumed to be independent of all the other particles, including those in the initial state. This enables us, at a fixed value of p₆, to relate the elastic πN, KN and NN data, at lab momenta of less than 20 GeV, to the pion, kaon, proton and antiproton inclusive p_⊥ distributions at ISR energies.     

Double pomeron exchange in the reaction ifpp → ppπ+π− at ISR energies

Using the split field magnet (SFM) of the CERN ISR, we have investigated the main features of the reaction pp → ppπ⁺π^? in the kinematical region where double pomeron exchange (DPE) is supposed to play an important rôle. Using kinematically fitted events at the five standard ISR energies from √s = 23.4 GeV to √s = 63.4 GeV, we have studied different data subsamples as a means of distinguishing DPE from the tail of single diffraction (SD). Our results are compatible with a significant DPE contribution; in particular there is no correlation between the two protons and the s- and t-dependences follow the expected behaviour.     

A possible connection between the attenuations of the Coriolis interaction and the recoil term

The data require an appreciable attenuation of the recoil term in the particle-rotor model hamiltonian. This fact may be related to the necessity of attenuating the Coriolis interaction.     

The double parton distributions in the hard pomeron model

We study the double parton interaction process in collisions between highly virtual pairs in the BFKL regime. Explicit expressions for the double parton distributions are obtained both in the case of direct coupling of the BFKL pomerons to the pair and in the case of triple pomeron interaction. Received: 9 May 2000 / Revised version: 14 August 2000 / Published online: 23 January 2001     

Rapidity and transverse momentum distributions of heavy quarks produced by double pomeron exchange

Zeitschrift für Physik C Particles and Fields - Rapidity and transverse momentum distributions of heavy quarks produced by double exchange of Donnachie-Landshoff pomeron are presented and...     

Study of double pomeron exchange in pp collisions at √s=31GeV

The reaction pp→ppπ⁺π^? at √s=31GeV was studied at the Split Field Magnet Facility of the CERN-ISR. Selecting events with two leading protons of x>0.9 and a rapidity gap Δy>2 between the protons and both pions a sample of 720 events is obtained representing a cross section of 25±10μb. The mass distribution of the dipion system, x and p_T distributions for the protons are presented and analyzed for the presence of double pomeron exchange.     

The strangeness-conserving effective weak interaction in the quark basis

Strong interaction corrections to the Glashow-Salam-Weinberg model of electroweak interaction are studied, for the up and down quarks only, to all orders of leading logarithms using renormalization-group techniques. The resulting quark effective weak hamiltonian is explicitly written out in a form convenient for obtaining matrix elements. The accuracy of this result is estimated by a comparison with finite, one-loop calculations of parity-violating parts of the interaction.     

Nuclear spin of a new isomer in 119Cs and magnetic moment of 120Cs evidence for strongly deformed nuclear shapes of the light cesium isotopes

The nuclear spin, $\text{I =}\text{3}\text{2}$, of a new isomer in ¹¹⁹Cs and the magnetic moment, μ_I = 3.92(5) n.m., of ¹²⁰Cs have been determined in on-line ABMR experiments at the ISOLDE facility, CERN. The experimental data give evidence for strongly deformed nuclear shapes of the light cesium isotopes.     

Electroproduction of π+ mesons in the resonance region

Results on the reaction ep→e′nπ⁺ are presented in the mass range 1.355 ?W ?1.775 GeV at q₂=1GeV² and in the range 1.415 ? W ? 1.595 GeV at q²=0.6 GeV². From the angular distribution of the π⁺ meson the polarization terms σ_u + ?σ_L, σ_p and σ_I have been determined in the range of production angles 0 <θ_π⁺ ?63°     

Determination of the radiative widths of the η′ and A2 from two-photon exchange production

From the two-photon exchange processes e⁺e^? → e⁺e^?η' (958) → e⁺e^??⁰γ and e⁺e^? → e⁺e^?A₂ (1310) → e⁺e^?π⁺π^?π⁰ observed using the CELLO detector at PETRA the radiative widths of the η' and A₂ have been determined with the results: Γ_γγ(η') = 5.4 ± 1.0[stat.] ± 0.7[syst.] keV; Γ_γγ(A₂) = 0.59 ± 0.14[stat.] _?0.08^+0.31[syst.] keV.     

Momentum transfer and product kinetic energies in the interaction of silver with 86 MeVA12C

Mean kinetic properties of target fragments have been derived from thick target-thick catcher recoil data in a study of the interaction of silver with $\text{86}\text{MeV}\text{A}$¹²C ions. The $\text{F}\text{B}$-ratios reach maximum values of ≈ 200, showing that the angular distributions in the laboratory system are strongly forward peaked. Heay products (A?70) are found to be produced in a normal spallation reaction. However, it is suggested that products found in the mass region A≈60 are to a large fraction binary fission products.