InclusiveK *+(892) andK *0(892) production inK + p interactions at 32 GeV/c

Total and semi-inclusive cross sections, longitudinal and transverse momentum distributions and spin density matrix elements of theK ^*+(892) andK ^*0(892) produced in the inclusive reactionsK ⁺ p→K ^*+(892)+X andK ⁺ p→K ^*0(892)+X at 32 GeV/c are studied in detail. The inclusive spectra of theK ^*(892) and their decay products are compared with pion and neutral kaon production. TheK ^*+(892) andK ^*+(892) are dominantly produced by kaon fragmentation processes. The dependence of average transverse momentum <p _T> vs.x for resonances has been investigated for the first time.     

Neutral kaon production inK + p and π+ p interactions at 250 GeV/c

The inclusive production of neutral kaons is studied inK ⁺ p and π⁺ p interactions at 250 GeV/c. Total and semi-inclusive cross sections and average kaon multiplicities are presented and compared with the data at lower energies. The longitudinal and transverse momentum distributions and their energy dependence are analyzed. The results are interpreted in the framework of recent parton models.     

Study of Strangeness Photoproduction on the Neutron in the Threshold Region

Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K ⁰ with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + d → K ⁰ + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K ₁, as ~ ?1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K ⁺ Λ.     

Inclusive production in K+d reactions at 4.6 GeV/c

The investigations presented here are based on the data from a K⁺d experiment at 4.6 GeV/c performed with the 2 m bubble chamber at CERN. The topological K⁺d cross sections are determined. The integrated (semi-) inclusive single-particle cross sections for the production of π^?, K⁰ and Λ as well as (semi-)inclusive x- and p_T² distributions are measured and discussed.     

Neutral kaon production in K+p interactions at 32 GeV/c

The production of neutral kaons in the reaction K⁺p → Kⁿ + X is studied at the incident momentum of 32 GeV/c. Inclusive cross sections and single-particle distributions are presented and compared with the data at lower energies. The total inclusive cross section amounts to 7.9 ± 0.3 mb at 32 GeV/c and is significantly higher than at lower energies due to the rapid rise of multikaon production. The fraction of Kⁿ's coming from the decay of the K¹ resonances stays roughly constant with energy between 8.2 and 32 GeV/c. In the central and beam fragmentation regions the single-particle distributions reveal no energy dependence between the 16 and 32 GeV/c data in contrast with the behaviour at lower energies, while in the proton fragmentation region the data are compatible with the trend observed at lower energies and with theoretical expectations.     

Λ polarization in12C(π −,Λ) reactions atp π=4 GeV/c

We study theΛ formation cross sections andΛ polarizations based on the Regge pole amplitudes in theπ ^?+¹²C→Λ+X(inclusive) reactions and the exclusive kaon channel reactions atp _π =4 GeV/c. We found that the experimental data of inclusive cross sections can be reproduced qualitatively well by our calculation. As for the polarization, we have the experimental data that were reported by two different groups, although they have opposite sign and different magnitudes. Our calculated results do not agree with either set of data. We show that the sign of polarization is sensitive to the outgoingΛ kinetic energy in the inclusive reactions and to the outgoing kaon angle in the exclusive kaon channel reactions.     

Neutral charm production in 400 GeV proton-emulsion interactions

A search has been carried out for neutral charm production in 5,108 proton-emulsion interactions at 400 GeV/c. Nine charm candidates have been observed in our fiducial volume which extends from 100 μm-1,000 μm in the forward cone. One of these is a 4-prong and the others are 2-prong events with opening angle>10 mrad and momenta of both decay tracks>150 MeV/c. Search for associated charm decays was made in an extended fiducial volume around the primary stars of these nine candidates. This yielded two neutral 2-prong events, one associated with the 4-prong and the other with a 2-prong candidate. All unassociated candidates are consistent with being backgrounds due toK _s , Λ decays, neutral interactions and γ conversions whereas the background to associated events is negligible. Based on the two associated decays the inclusive cross section forD ^{0, ?0} production is determined as 27±20 μb/nucleon. Detailed measurements on the 4-prong candidate lead to the identification of one decay track as an electron and another as a kaon. This is interpreted as a semi-leptonic, Cabbibo favouredD ⁰/D ^?0 decay.     

Lambda polarization in the reaction K−p → Λ + anything at 14.3 GeV/c

New results on inclusive lambda polarization in K^?p interactions at 14.3 GeV/c are presented. At the kaon fragmentation vertex, the polarization is compared to that from inclusive experiments at lower momenta and to that from two-body reactions with a Λ. As predicted by the triple-Regge model with N_α (or N_γ) exchange, the polarization is found to be independent of s and M_X²/s. In particular it has the same value as that found in the two-body reactions.     

Inclusive production cross sections of resonances in 32 GeV/c K+p interactions

The inclusive production of resonances is systematically studied in K⁺p interactions at 32 GeV/c. Total production cross sections are given for three baryon resonances, five vector and three 2⁺ tensor mesons. We also compare the central and fragmentation components of the total production cross sections with quark model predictions.     

K° production in e+e− annihilation

The production of enutral kaons in e⁺e^? annihilation has been measured for c.m. energies between 3.4 GeV and 7.6 GeV. Near 4 GeV the inclusive K_S cross section shows an increase and structure similar to total hadron production. Roughly 40–45% of all hadronic final states contain kaons, except at 4.028 GeV and 4.415 GeV, where a significantly larger kaon fraction is observed.     

Associated production of ϕ mesons and neutral kaons in the EXCHARM experiment

The features of the associated production of ? mesons and neutral kaons are studied on the basis of data obtained at the EXCHARM spectrometer (Serpukhov accelerator) in neutron—carbon interactions at neutron-beam energies in the range 20–70 GeV. The cross section for the inclusive associated production of ? and K ⁰/-K ⁰ is obtained. The fraction of processes allowed by the Okubo-Zweig-Iizuka rule is estimated in the reactions of ?-meson inclusive production.     

Correlation femtoscopy of Kaons in the SELEX experiment

Preliminary results from the correlation femtoscopy of identical kaons in the SELEX experiment (Fermilab E781) are presented. Kaons are selected in inclusive reactions of Σ^?C(Cu) interactions at an initial energy of 610 GeV. Kaon pairs are studied in all possible charged states: K _s ⁰ K _s ⁰ , K _s ⁰ K⁺, K _s ⁰ K^?, K⁺K⁺, K⁺K^? and K^?K^?. The source sizes of the hadronization region of neutral and charged kaon pairs are measured.     

Inclusive neutral kaon and lambda production in 69 GeV pp interactions

From a study of 180 neutral vees in the hydrogen bubble chamber Mirabell, we have obtained respectively, for the cross sections of the inclusive reactions pp → K⁰X and pp → λX, 8.4 ± 1.1 and 3.6 ± 0.5 mb. Data presented for the neutral kaons and λ in terms of the invariant cross sections F(x, p_⊥, s) show, when compared with lower and higher energy results, that scaling is approximately valid at our energy for K^o and λ production.     

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.     

Selective excitation in kaon-nucleus inelastic scattering

The K⁺ meson (kaon) inelastic excitation of low-lying (E_x = 0–15 MeV) T = 0 collective states in ¹⁶O is theoretically studied as a function of energy and momentum transfer. The distorted wave impulse approximation is used to calculate angular distributions and total inelastic cross sections for exciting the first J^π = 2⁺, 3^?, 4⁺ and 5^? states at lab energies from threshold to 400 MeV. The distortions are represented in a Kisslinger-type optical potential constructed from elementary K⁺-nucleon amplitudes. Total nuclear elastic and reaction K⁺-nucleus cross sections are computed to demonstrate sensitivity to choice in K⁺-nucleon amplitudes. Fermi motion effects are also assessed using a simple averaging procedure. The weak absorption character of the kaon is reflected in the inelastic calculations which predict selective excitation of low spin states at low momentum transfer and high spin states at high momentum transfer.     

Charged pion production in 70 GeV/cK + p interactions

Inclusive charged pion production is studied in an exposure of BEBC, filled with hydrogen, to an incidentK ⁺ beam of 70 GeV/c. Total cross sections for pion production and inclusive longitudinal and transverse momentum distributions of π^?'s and of positive particles are presented and compared with data at lower energies. Earlier evidence for scaling in the fragmentation regions is confirmed. The central region π^? cross section increases proportionally top _LAB ^?1/4 ; positive particles show almost no energy dependence atx=0. Particle ratios π⁺/π^? are studied as a function ofx andy ^* and a comparison with 70 GeV/cK ^? p data is made. Analysis of structure functions for (ππ) pairs and of particle production associated with π^± triggers at large |x| in the context of quark/parton models, provides qualitative evidence for the diquark-quark structure of the proton.     

Kaon production in S+nucleus and Pb+Pb collisions at CERN SPS

Charged and neutral kaon production in S-nucleus and Pb-Pb collisions has been measured at CERN in the NA35 and NA49 experiments, close to mid-rapidity. The production ofK ^± in S+S, Ag, Au at 200 GeV/nucleon was measured via their one-prong (kink) topology inside a Time Projection Chamber (TPC). The resulting charged kaon yields are in agreement with other measurements done in the same experiment. TheK ⁺/K ^? ratio was found to be 1.30±0.15 in central S+Au interactions. The production ofK _S ⁰ in Pb+Pb collisions was measured using the NA49’s large (Main) TPCs outside the magnetic field. The resulting yields are compatible with other measurements performed in the same experiment, within the quoted systematic errors. The preliminary rapidity distribution in Pb+Pb scales with the number of participants if compared to S+S collisions. From this we conclude that no further strangeness enhancement (relative to nucleon-nucleon collisions) is observed in going from S+S to Pb+Pb.     

Inclusive single and double diffractive dissociations inK + p interactions at 32 GeV/c

We study single and double inclusive diffractive production in a 32 GeV/c K ⁺ p experiment in MIRABELLE at the Serpukhov accelerator. From reactionsK ⁺ p→K ⁺+X ⁺ andK ⁺ p→X ⁺+p we determine the total proton and kaon single diffractive dissociation cross sections \(\sigma (p\xrightarrow{{K^ + }}p_D ) = 0.90 \pm 0.12 mb\) and \(\sigma (K^ + \xrightarrow{p}K_D^ + ) = 0\) . 90±0.17 mb, respectively. In either case the only notable contributions come from dissociations into 1 and 3 charged particles. Kaon dissociation exhibits a pronounced slope-mass correlation. The search for double diffractive production in reactionsK ⁺ p→(K ⁺π^?π⁺)+X ⁺ andK ⁺ p→(pπ ⁺ π ^?)+X ⁺ leads in either case to an estimated total double diffractive cross section σ(K ⁺p→K _D ⁺ p_D) of ?220 μb. The double dissociation differential cross section exhibits a large slope of ?10GeV^?2 in the nearthreshold mass region, rapidly decreasing to ?4 GeV^?2 with increasing excitation mass. At our c.m. energy \((\sqrt s \simeq 8 GeV)\) the ratio σ_{inel dif}/σ_el is 0.85±0.10, the total diffractive cross section σ_dif≡σ_el+σ_{inel dif}=4.41±0.24 mb and the fraction σ_dif(K ⁺ p)/σ_tot(K ⁺ p) is 25±2%. TheK ⁺ andK ^? diffractive excitation mass spectra, differential cross sections and total diffractive cross sections are very similar for both single and double dissociations.     

Charged multiplicity distributions and neutral particle production in 14.75 GeV/c pp interactions

From an exposure of the Brookhaven National Laboratory 80-inch hydrogen bubble chamber to a 14.75 GeV/s separated anti-proton beam we have determined an average charged particle multiplicity of 4.12±0.06. We have also studied the inclusive production of γ, K_S^o, and Λ^o particles. The correlations between π^± and π^o, K_S^o, or Λ^o are described and the strong correlation observed between π^± and π^o is contrasted to the apparent lack of correlation found in other hadron-hadron interactions at similar beam momenta. Invariant cross sections for γ, K_S^o, and Λ^o production are presented as a function of x.     

Inclusive resonance production in 7.3 GeV/c\bar pp interactions

We present results on inclusive baryon and meson resonance production in \(\bar pp\) interactions at 7.3 GeV/c. Total inclusive and semi-inclusive cross sections are given for Δ(1232),∑ ^*(1385), ?⁰,f andK ^*±(892) production. For the meson resonances separation into annihilation and non-annihilation components has been made, the annihilation component being dominant at this energy. We find that the energy dependence of inclusive cross sections for ?⁰ production inpp interactions and \(\bar pp\) non-annihilations shows a type of scaling behaviour previously reported for ?, ψ, ψ′ and ? production inpp interactions.Δ ⁺⁺, ?⁰ andK ^*± production are studied in terms of Feynmanx,y ^* andp _T ² . For the vector mesons we compare they ^* andx dependences with the predictions of simple quark models.