Inclusive meson resonance production inK + p interactions at 250 GeV/c

A detailed analysis of the inclusive production of the vector mesonsφ,K ^*+,0(892) \(\bar K*^0 (892),\rho ^{ + ,0} ,\omega \) and the tensor mesonsK ₂ ^*0 )(1430) andf ₂(1270) inK ⁺ p interactions at 250 GeV/c is presented The data are compared with results at lower energies and with various quark-parton models. The production ofρ ⁰,K ^*0(892) and \(\bar K*^0 (892)\) increases at the same rate as a function ofs, is concentrated in the central region and is not reproduced by the models. Production of the tensor mesonsf ₂(1270) andK ₂ ^*0 (1340) is suppressed relative toρ ⁰ andK ^*0(892) by a factor of about 3.     

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.     

\bar K^{0*} (892) andK 0*(892) production at lowp t and the quark parton model

Data on the production of the neutralK ^*(892) resonances at lowp _t by 200 GeVK ^? and π^? is compared with the predictions of various models based on the quark parton model of hadrons.     

InclusiveK *+(1430),K *0(1430), andf(1270) production inK + p interactions at 32 GeV/c

Results are presented on total and semiinclusive cross sections, longitudinal and transverse momentum distributions of the tensor mesonsK ^*+(1430),K ^*0(1430), andf(1270) observed inK ⁺ p interactions at 32 GeV/c. The data are compared withK ^*+(892).K ^*0(896) and ?⁰ vector meson production in the same experiment. The shapes of inclusive invariantx-spectra for the strange vector and tensor mesons are found to be rather similar, after removal of diffractive and quasi-two-body channels, in agreement with quark-recombination ideas.     

The scalar contribution toτ →K πν τ

We consider the scalar form factor inτ →K πν _τ decays. It receives contributions both from the scalar resonanceK*₀(1430) and from the scalar projection of off-shell vector resonances. We construct a model for the hadronic current which includes the vector resonancesK*(892) andK*(1410) and the scalar resonanceK*₀(1430). The parameters of the model are fixed by matching to theO(p ⁴) predictions of chiral perturbation theory. Suitable angular correlations of theKπ system allow for a model independent separation of the vector and scalar form factor. Numerical results for the relevant structure functions are presented.     

InclusiveK *'s and∑ *'s production in 360 GeV/cpp interactions using the European hybrid spectrometer

We have studied the inclusive production of strange meson and baryon resonances in 360 GeV/cpp interactions. Cross sections forK ^*+(892) andK ^*?(892) are estimated to be 4.42±0.62 mb and 2.54±0.47 mb respectively and those for∑ ⁺(1385) and∑ ^?(1385) are 0.67±0.11 mb and 0.26±0.07 mb respectively. Longitudinal and transverse momentum distributions forK ^*(892) and Σ(1385) are presented, as well as for their decay productsK ⁰ and Λ. An estimation is given on theK ^*(1430) and∑ ^*(1915) productions.     

Heavy Quark Potential and Quarkonium Spectrum in Nonperturbative pNRQCD

The charmonium and bottomonium mass spectra are investigated systematically in potential nonrelativistic QCD with the heavy quark potential computed by lattice QCD simulations nonperturbatively. The potential consists of a static potential and relativistic corrections classified in powers of the inverse of heavy quark mass m, and the effects of the O(1/m) correction, the O(1/m ²) spin–orbit and spin–tensor corrections on the mass spectra are examined systematically. The pattern of the mass spectra is found to be in fairly good agreement with the experimental data, in which the O(1/m) correction gives an important contribution.     

Production of meson resonances as leading particles in jets in proton-proton collisions at\sqrt s = 62 GeV at the CERN ISR

The production of ρ(770)⁰,K ^*(892)⁰, \(\bar K^* (892)^0 \) andf ₂(1270) mesons as leading particles in hadron jets (<z>～0.7) has been measured in deep inelasticpp interactions at the CERN ISR at \(\sqrt s = 62\) GeV. The comparison of vector and pseudoscalar meson production at the same transverse momentum provides a rather model independent way to determine the fragmentation parameterV/P. We determine(V/P) _u,d =1.66±0.18±0.63 from the ρ/π ratio and(V/P) _s =0.90±0.13±0.27 from theK ^*/K ratio. For thef ₂(1270) production we findf ₂/ρ⁰=0.30±0.08.     

Production of vector and tensor mesons in proton-proton collisions at\sqrt s = 52.5 GeV

Inclusive production of ?⁰,f, andg ⁰ mesons and ofK _s ⁰ ,K ^*0 (892), ? andK ^*0(1430)mesons has been measured at <y>～2.6 and <p _T >～1.1 GeV/c in proton-proton interactions at \(\sqrt s = 52.5\) GeV. The negative particle from the two-body decays of these resonances were identified by a threshold Cerenkov counter and used for triggering. Starting from the measured differential cross section, total inclusive cross sections for the vector and tensor mesons were determined using various parametrizations for they andp _T dependence of the differential cross section. The experimental results are discussed in the framework of production models based on the parton picture. The strangeness suppresion factor λ=(0.30±0.10) due toSU(3) symmetry breaking of the quark sea is derived.     

Instanton effects on the interaction potential between light quarks and the isomultiplet mass splitting of baryons

On the basis of current assumptions of instanton theory we derive strictly the explicit dependence on the masses and spins of the instanton induced potential between a pair of light quarks in baryons, namelyV ₁₂=γ+β(m _* ^1+α )(m _* ^2+α )η(1-σ ₁ησ ₁), wherem _i ^* andσ _i (i=1.2) are respectively the mass and Pauli spin of theith quark. On the additional basis of the MIT bag model, we obtain γ=c/R ³ and β=b/R ³>0, and α>0 is independent of the radiusR of the baryon. The magnitudes of the parametersb and α are also estimated. The MIT bag model is improved by taking into account this potential. Isomultiplet mass splitting formulas are derived in good agreement with experiment.     

Inclusive ϱ0,K *±(892) andf production in\bar p p Interactions at 12 GeV/c

Inclusive production of ?⁰,K ^*±(892), andf is studied in \(\bar p\) p interactions at 12 GeV/c. The inclusive cross sections for ?⁰,K ^*±(892), andf are found to be 6.7±0.3 mb, 1.0±0.2 mb, and 1.4±0.3 mb, respectively. The differential cross sections are presented as a function of c.m. rapidity, Feynmanx and square of the transverse momentump _T ² . Comparison with the correspondingpp data shows some interesting differences which can be attributed to the \(\bar p\) p annihilation. The results are compared with the predictions of the quark fusion model.     

ρ0-ω mixing in U(3)L×U(3)R chiral theory of mesons}

In this paper, U(3)_L×U(3)_R chiral theory of mesons is extended to the leading order in quark mass expansion in order to evaluate the ρ⁰-ω mixing. It is shown that the use of path integral method to integrate out the quark fields naturally leads to the ρ⁰-ω mixing vertices, and this mixing is entirely from the quark loop in this theory. The off-shell behaviour of the mixing amplitude is analyzed. The on-shell mixing amplitude is obtained from the decay ω→π⁺π⁻. Furthermore, the constraints on the light quark mass parameters are extracted from the ρ⁰-ω mixing and the mesons masses, and the mass splitting of K^*(892)-mesons is predicted. Received: 30 January 1998 / Revised version: 3 June 1998     

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.     

Radiative decays and transition form factors of strange mesons in the relativistic constituent quark model

Motivated by the recent lattice QCD results indicating that the topological charge contribution to the flavor singlet axial vector current can be traded off by the constituent quark masses, we investigate the radiative decays of pseudoscalar (π,K, η, η′), vector (ρ,K*, ω, ?) and axial vector (A ₁) mesons using a simple relativistic constituent quark model. For both simplicity and relativity, we take advantage of the distinguished features in the light-cone quantization method: (1) the Fock-state expansion of meson wavefunctions are not contaminated by the vacuum fluctuation, (2) the assignment of meson quantum numbers are given by the Melosh transformation. Except the well-known constituent quark masses of (u,d,s) quarks and the spin-averaged meson masses, the only parameter in the model is the gaussian parameter β which determines the broadness (or sharpness) of radial wavefunction. The computed decay widths and the transition form factors of ρ, ω → π(η)γ*,K* →Kγ* andA ₁ → πγ* at 0≤Q ²≤5 GeV² and π⁰(η) → γ*γ at 0≤Q ²≤3 GeV² are in a remarkably good agreement with the experimental data and the result forA ₁ ⁺ → π₊ γ* transition is quite consistent with the experiments of pion scattering on a nucleus using Primakoff effect. This model is potentially useful in the cocktail analyses of the dilepton productions in proton-proton, proton-nucleus and nucleus-nucleus collisions at SPS energies and a little above.     

Quark model relation for kaon charge radii

We derive the equation r²_E(K⁰)/r²_E(K⁺) = -(m²_s ? m²_n)/(2m²_s + m²_n) relating the kaon electric charge radii and the strange (m_s) and non-strange (m_n) quark masses in the nonrelativistic quark model, and suggest an inequality which we expect to hold in the presence of relativistic corrections. New data for these charge radii are presently being analysed by two experimental groups.     

Angular correlations for semileptonic D meson decays

We study the exclusive semileptonicD meson decaysD→K+π+l+ν. For this we develop the general formalism for the joint angular distribution of the charged lepton and theK meson and calculate the helicity dependent decay widths which determine the full angular distribution for several models withK ^*(892) andK ₀ ^* (1430) intermediate state with nonresonant background terms calculated from chiral Lagrangians.     

Decays τ → (η, η')<Emphasis Type="Italic">K</Emphasis>–ν<Subscript>τ</Subscript> in the extended Nambu–Jona-Lasinio model

The decays τ → (η, η')K–ν_τ are described in the framework of the extended Nambu–Jona-Lasinio model. Both full and differential widths of these decays are calculated. The vector and scalar channels are considered. In the vector channel, the subprocesses with the intermediate K*(892) and K*(1410) mesons play the main role. In the scalar channel, the subprocesses with the intermediate and K₀^*(800) and K₀^*(1430) mesons are taken into account. The scalar channel gives an insignificant contribution to the full width of the decay τ → ηK–ν_τ. The obtained results are in satisfactory agreement with the experimental data. The prediction for the width of the process τ → η′K–ν_τ is made.     

Radiative widths of neutral kaon excitations

We observe 147 events of the axial vector pairK ₁(1270)–K ₁(1400) produced in the Coulomb field of a Pb target and measure the radiative widths Γ(K ₁(1400)→K ⁰ + γ) = 280.8 ±23.2(stat.) ±40.4(syst.) keV and Γ(K ₁(1270) →K ⁰ + γ) = 73.2 ±6.1(stat.) ±28.3(syst.) keV. These first measurements are lower than the quark-model predictions. We also place upper limits on the radiative widths forK*(1410) andK ₂ ^* (1430) and find that the latter is very small in accord withSU(3)invariance in the naive quark model.     

A study of K−π+ scattering in the reaction K−p→K−π+n at 11 GeV/c

Results from a high statistics study of the reaction K⁻p→K⁻π⁺n are presented. These results are based on data obtained with an 11 GeV/c beam using the LASS spectrometer at SLAC. The mass dependence of the spherical harmonic moments provides clear evidence for the production of the complete leading orbitally excited K¹ series up through J^P = 5⁻. These moments are used to perform an energy independent partial wave analysis of the K⁻π⁺ system from threshold to 2.6 GeV/c² using a t-dependent parametrization of the production amplitudes. The amplitudes corroborate the leading K¹(892), K₂¹(1430), K₃¹(1780), K₄¹(2060), and K₅¹(2380) resonances observed directly in the moments, and also provide new evidence for underlying states. The 0⁺ amplitude contains the K₀¹(1350) and a second 0⁺K¹(1950) at higher mass. The 1⁻K¹(1790) seen earlier two and three-body analyses is confirmed, and evidence is provided for suppressed K⁻π⁺ decay mode of a second 1⁻ state, the K¹(1410), which has been seen in earlier three-body analyses.