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Background: The radiographic appearance of osteochondritis dissecans (OCD) of the humeral capitellum varies according to the stage of the lesion. It is important to evaluate the stage of OCD lesion carefully to guide treatment. We compared the interobserver reliability of currently used classification systems for OCD of the humeral capitellum to identify the most reliable classification system. Methods: Thirty-two musculoskeletal radiologists and orthopaedic surgeons specialized in elbow surgery from several countries evaluated anteroposterior and lateral radiographs and corresponding computed tomography (CT) scans of 22 patients to classify the stage of OCD of the humeral capitellum according to the classification systems developed by (1) Minami, (2) Berndt and Harty, (3) Ferkel and Sgaglione, and (4) Anderson on a Web-based study platform including a Digital Imaging and Communications in Medicine viewer. Magnetic resonance imaging was not evaluated as part of this study. We measured agreement among observers using the Siegel and Castellan multirater kappa. Results: All OCD classification systems, except for Berndt and Harty, which had poor agreement among observers (kappa = 0.20), had fair interobserver agreement: k was 0.27 for the Minami, 0.23 for Anderson, and 0.22 for Ferkel and Sgaglione classifications. The Minami Classification was significantly more reliable than the other classifications (P

The vector meson production, hypercharge exchange reactions K/sup -/p to ( phi , omega , rho ) Lambda and ( phi , rho ) Sigma /sup 0/ are studied at 4.2 GeV/c incident momentum. The data come from a high statistics bubble chamber experiment with a sensitivity of approximately 120 events/ mu b. Total and differential cross sections are presented. The vector meson density matrix elements and hyperon polarization are investigated as functions of momentum transfer. Amplitude analyses are performed for all five reactions. The results are compared with duality and quark model predictions, as well as used to test current ideas in two-body phenomenology. (35 refs).

Een 31-jarige man raakt tijdens het snowboarden uit balans en maakt daarbij een geforceerde adducerende beweging van zijn heup. Hij ervaart direct een scherpe pijn in het rechterbovenbeen. Er is geen evidente functiebeperking. De patient bemerkt een tennisbalgrote zwelling onder de liesregio. Vanwege cosmetische en vooral mechanische bezwaren tijdens wielrennen presenteert de patient zich een jaar na het trauma op de polikliniek. Een dergelijke delay in diagnose werd reeds eerder beschreven.1

RIPE, the European IP coordinating body, is described. The background is explained, as well as the organisational structure. A description of the current work is given; first results are reported. Finally, some general aspects of European networking are discussed.

Cross-sections of the inclusive reactions K−p→ΛX and K−p→∑+X in the region of target fragmentation are analysed. A model is adopted which is based on exchange of K and K* Regge trajectories and on a dual description of the reggeon-particle scattering involved in both reactions. It is shown that the model provides a detailed description of the data of a high-statistics experiment at 4.2 GeV/c incident momentum. Missing-mass distributions with a pronounced resonance structure, for various ranges ofx=p L * /p max * ort pY, as well as distributions inx andp T 2 , are reproduced by the model. The relative amounts of the K and K* exchange contributions to the integrated inclusive cross-sections are evaluated. Implications for coupling strengths and reggeon-particle cross-sections are discussed. The value of theSU 3 parameterF/(D+F) for pseudoscalar coupling is found to be 0.25±0.03. The model is also capable of predicting the missing-mass spectrum K−p→ΛX at 8.25 GeV/c.

Using a high statistics sample of K−p interactions at 4.2 GeV/c, the production and decay properties of the Ξ∗(1820) are discussed. The mass and width are found to be M = (1823 ± 2) MeV and Γ = (21 ± 7) MeV. Evidence is found for Ξ∗(2030) in the Σ K channel and for a new Ξ∗ at a mass of 2120 MeV in the ΛK− channel.

The inclusive production of Σ+ in K−p interactions at 4.2 GeV/c has been studied. Both the target fragmentation of the proton into Σ+ and the beam fragmentation of the kaon into Σ+ have been analysed with a triple-Regge model. In the\(p\bar \Sigma ^ + \) channel an effective exchange trajectory has been obtained which lies between the K and K(890) trajectories. For the\(K^ - \bar \Sigma ^ + \) channel a trajectory is found which may be interpreted as a Δ trajectory lowered by one-half.

A study of inclusive Ξ− production from a high statistics K−p experiment at 4.2 GeV/c has been made. The total Ξ− production cross section is 157 ± 8 μb. Approximately 15% of the Ξ− arise from decay of the Ξ∗0(1530) resonance. The polarization of the Ξ− is found to be negative and is nearly equal in value to that of the Λ0 from the inclusive reaction K− + p → Λ0 + anything. An analysis of the inclusive production of Ξ− has been made in the framework of the triple-Reege formalism.

Using an 880 events per microbarn sample of K − p interactions at 4.2 GeV/ c the production and decay properties of the δ (970) have been investigated in the following reactions: K − p → Σ + (1385) ηπ − and K − p ar Σ + (1385)K 0 K − .

We have investigated the properties of off-shell\(\bar K\)K and\(\bar p\)p annihilations into pions by using the interactionsK−p → Λ + pions at 4.2 GeV/c. The properties considered are multiplicities, hadronic temperatures and angular distributions. These properties appear more akin to those of\(\bar p\)p annihilations in flight than to that of\(\bar p\)p annihilation at rest despite the fact that the annihilation energy is small.

The spin parity of the η′ (958) is studied in the reaction K − p → η ' Λ at 4.2 GeV/ c , using bubble chamber data with a statistical sensitivity of 128 events/μb. The data unambiguously prefer the 0 − assignment.

Properties of Σ ± (1385) inclusively produced in 4.2 GeV/ c K − p interactions are studied. Inclusive cross sections are presented together with differential cross sections as functions of x and p t 2 for both Σ + (1385) and Σ − (1385). The complete density matrix for Σ + (1385) production at small momentum transfer is studied as a function of t and of recoil mass MM 2 . Substantial agreement with the predictions of the additive quark model is found. The Σ + (1385) production in the target fragmentation region is studied in the framework of the triple-Regge model.

The backward production of the B(1235) meson is studied in the reaction K−p→Σ−π+ω. This reaction is observed in the final state Σ−π+π+π−π0. A π+ω mass enhancement is visible in the region of the B meson for events with small |u|K− →Σ−) squared four-momentum transfer. The properties of the enhancement agree with those of the B meson. The cross section for K−p→Σ−B+ at 4.15 GeV c incident K− momentum is (3.2 ± 0.5) μb. The backward production of the B meson is compared with similar baryon exchange productions of the A1 and C(Q1) axial vector mesons observed in the same experiment.

The total and differential cross sections of the reactions K−p → π0Λ (1520), ηΛ(1520) and η′ Λ(1520) have been measured. Prominent forward peaks are onserved in all three reactions. The first reaction shows also a backward peak. The spin density matrix elements of the Λ(1520) in this reaction are determined. For forward production the results show a remarkable alignment of the Λ(1520) corresponding to an M2 transition in the model of Stodolsky-Sakurai for 32− baryon production.

The reaction of K−p → Σ+(1660)π− was studied in a 65 event/μb sample of Σππ(π), Λππ(π) and pK0π− final states. The main production features observed are that the Σ(1660) decaying into Σππ is mostly Λ(1405)π and is produced only at small t; the Σ(1660) decaying into Σπ shows both forward and backward production. This confirms earlier results suggesting the existence of two Σ(1660) resonances. An Adair analysis and a (model-dependent) moments analysis find a J = 32 preference for the Σ+ (1660)→ Λ(1405)π+ → Σ+π−π+; a Dalitz-Miller analysis of the decay Σ+(1660) → Λ(1405)π+ → Σ−π+π+ determines JP to be 32−. For the Σ+(1660) → Σ0π+ a moments analysis suggests J = 32. Branching ratios are determined, which (with the exceptation of the Λ(1405)π mode) are in reasonable agreement with results from formation experiments for the JP = 32− Σ(1660) resonance. We compare our branching ratios with SU(3) and SU(6) predictions; the latter comparison suggests that, unless there is strong configuration mixing, Σ(1660) → Λ(1405)π, if 32−, cannot be a member of the (70, 1−) multiplet.

In the reaction K − +p→ Λ +X at 4.25 GeV/ c both the target fragmentation of the proton into lambda and the beam fragmentation of kaon into lambda have been studied. The sample consists of 21 000 Λ events with t >−1.0 (GeV/ c ) 2 and 9000 Λ events with u > −1.0 (GeV/ c ) 2 . Abundant π 0 and meson resonance production for residual masses M x c 2 is observed. In the t -channel of am effective exchange trajectory is deduced. which lies between the K and K(890) trajectories. In the u -channel the effective exchange trajectory is in good agreement with a nucleon trajectory. The extrapolated average pion multiplicities of the residual mass system in the t -channel are in very good agreement with the values measured in antiproton-proton annihilations at rest.

Evidence is presented for an I = 1 enhancement observed in the reactions K−p→Λ(Σ)K01K±π∓ at 4.2 GeV c inciden momentum. The mass and width of the proposed new Y∗ are, respectively, (1553 ± 7) MeV) and (80 ± 30) MeV. A decay branching ratio Σπ (Σπ + Λπ) = (35 ± 12)% is also obtained.

In a high statistics CERN 2 m bubble chamber experiment the differential cross sections and polarizations of the Λ for the reactions K−p → Λπ0, Λη, Λη′ at 4.2 GeV/c have been measured. The reaction K−p → Λη exhibits a pronounced dip around −t ∼0.5 (GeV/c)2 and all three reactions show a significant backward peaking (−u < 1.0 (GeV/c)2). The Λ polarization in the reaction K−p → Λπ0 is measured to be significantly different from zero throughout most of the available t-range. Forward cross sections enable a determination of RT, the ratio of singlet/octet coupling η1KK∗∗η8KK∗∗. Backward cross sections are utilized to estimate the effective η-nucleon coupling constant gηNN2 over the −u range 0–1.5 (GeV/c)2.

A (K pi pi )/sup +/ mass enhancement is observed in the reactions K /sup -/p to Xi /sup -/K/sup 0+//sub pi //sup +/ pi /sup 0-/ when events with a small (K/sup -/ to Xi /sup -/) four momentum transfer squared are selected. The signal is also visible in the reaction K/sup -/p to Xi /sup -/ pi /sup +/+neutrals. The enhancement, centered at 1.28 GeV, is seen to decay preferentially into K rho with spin-parity JP=1/sup +/. The cross section for K/sup -/p to Xi /sup -/C/sup + /(1.28) with C/sup +/ to K rho at 4.15 GeV/c incident K/sup -/ momentum is (6.2+or-0.6) mu b. (11 refs).

A 2.5 standard deviation signal is observed for the decay K ∗− (1420) → K ∗− (892)π + π − . From this signal a partial width of 13.0 ± 5.0 MeV for the decay mode K ∗ (1420)→ K ∗ (892)ππ is deduced under the assumption that the ππ system is in an I = 1 state. For the rare decay mode K ∗ (892)→ K ππ no signal is observed. The following upper limits can be given for the decay widths: Γ K ∗− (892) → K − π + π − keV , Γ K ∗− (892) → K 0 π − π 0 keV , Γ K ∗0 (892) → K 0 π + π − keV .

A πω enhancement at 1245 MeV is observed in the reaction K−p → Σ+π−ω. Its properties agree with those of a B meson produced by natural-parity exchange thus establishing a coupling of the B to a K K ∗ system.

In this letter results are presented on the reactions K − p → K 0 n and K − p → K − p from a high statistics CERN 2-metre hydrogen bubble chamber exposure at 4.15 GeV/c. The behaviour of the differential cross section as a function of four-momentum transfer shows remarkable similarities between the two reactions studied. From a comparison of our data with K+p elastic scattering at 4.27 GeV/c we draw some conclusions concerning the magnitude of the contributing amplitudes.

The average transverse momentum of pions as a function of their longitudinal momentum is studied in a number of reactions produced by 4.25 GeV/ ac negative kaons or by 7.3 GeV/ c antiprotons on protons. The observed seagull effects are attributed to the dominance of different reaction mechanisms at different values of the longitudinal momentum of the pions.

Peripheral two-body reactions of the type K−p→M0 + Λ, Σ0 or Σ0 (1385) are considered. Predictions based on the additive quark model and SU(6) baryon wave functions are tested against data on cross sections and polarisations for given momentum transfer. Data obtained in a high statistics experiment at 4.2 GeV/c K− momentum, as well as data from a large variety of other experiments are used. Highly significant violations of these predictions are observed in the data. These violations are shown to occur in a systematic fashion, according to which SU(6) must be relaxed, but the amplitude structure implied by additivity would remain valid. As an application an amplitude analysis for natural parity exchange reactions with M0 = π, ϕ and ϱ respectively is performed, which determines a relative phase, which cannot be obtained in a model-independent analysis. Also reactions with M0 = δ or B are considered, and some implications for coupling constants are discussed.

We report on the results of a partial-wave analysis of the 3π system produced by baryon exchange in the reaction K − p→ Σ − π + π + π − at 4.2 GeV/ c . We confirm the existence of an enhancement in the 1 + S( ϱπ ) wave as previously established from a Dalitz plot analysis of the same data. The phase variation of this wave is found to be consistent with that expected for a resonance and thus the enhancement is identified with A 1 production. No clear signal for this state is found in either the reaction K − p→ Σ + π + π + π − π − or K − p→ Λπ + π − π 0 . We also find production via baryon exchange of the A 2 in all three reactions and the ω and ω ∗ (1975) in the third reaction.

A bubble-chamber study is presented of a 10 events/μb experiment using K− mesons of 4.25 GeV/c incident momentum. Differential and total cross sections are determined for 7 different reactions: K−p → K0n (la), → π0Λ (lb), → ηΛ (lc), → η′Λ (ld), → π−Σ (le), → π+Σ− (lf), K+ Ξ− (lg). The experimental characteristics in dσ/dt of each reaction are described: (la) shows a levelling off at t = 0 (GeV/c)2, a break at t = −0.6 (GeV/c)2 and no backward events, (lb) dσ/dt has a smooth behaviour and a measurable backward component with an indication of a dip at u = −0.2 (GeV/c)2, (1c) dσ/dt shows a dip in the region between t ≈ −0.2 and −0.4 (GeV/c)2, (ld) dσ/dt has a smooth behaviour; neither this reaction nor the preceding one shows a clear evidence for backward events, (le) dσ/dt has a break at t = −0.5 (GeV/c)2; there is a significant cross section in the backward region; (lf) and (lg) show mainly backward production. The polarization of the hyperon is measured in the reactions (lb), (lc), (ld) and (le) in the forward production peak. The statistics do not allow the detection of a definite structure in the polarization but the sign and magnitude are determined. An interpretation of the results is given in terms of a dual Regge model, including the effects of absorption as elaborated recently by several authors.

The characteristics of the neutral kaons produced in the reaction 4.2 GeV/c K− + p → Ko + anything are compared with data at other momenta. A survey is made of medium-energy inclusive cross sections obtained by postulating σT(K−p) = σ−(K−) + σ−(Ko) + σ−(Y). The inclusive cross sections σ−(K−) and σ−(Ko) are found to be constant as functions of the incoming kaon momentum. Moreover, a comparison with inclusive K+ production in the reaction K+ + p shows σ−(K−) ≈ σ+(K+) ≈ 11.7 mb.

Using a spin test proposed recently by Minnaert (1977), the spin of the Theta *(1820) resonance is determined to be 3/2. (7 refs).

A partial-wave analysis of the (3π)0 system produced peripherally in the reaction K-p → π+π-π0 Λ at 4.2 GeV/c is presented. The observation of the weak Λ decay allows a determination of all the transversity production amplitudes except for two phases. The production of known resonances having decay modes other than 3π is used to test the isobar model ansatz. Significant ω(783), φ(1020) and A2(1310) production is observed. The spin parity of the ω*(1675) is established as 3-. No evidence for production of other resonances, such as axial vector-mesons, is found. © 1977.

The authors studied the production and decay of the D(1285) meson in the reaction K/sup -/p to Lambda D at an incident K/sup -/ momentum of 4.2 GeV/c. The cross section for this reaction is 11+or-3 mu b and the branching ratios D to KK pi /D to eta pi pi and D to 4 pi /D to eta pi pi are found to be 0.42+or-0.15 and 0.7+or-0.5, respectively. The proportion of D to eta pi /sup +/ pi /sup -/ going through the intermediate delta /sup +or-/ pi /sup -or+/ states is 0.72+or-0.15. Forward and backward exchange mechanisms are found to contribute in the ratio 3:2. (18 refs).

Forty Ω − events have been observed in a large (133 events/βb) experiment at 4.2 GeV/c incident K− momentum. Thirty nine of the events come from the three-body reaction K − p →Ω − K + K 0 . The Ω − is mainly produced in the forward hemisphere (direction of the incident K−). The lifetime is measured to be τ = (0.75 +0.14−0.11 × 10−10 sec substantially less than the Particle Data Group value of (1.3 −0.3+0.2) × 10−10 sec. The mass is determined to be 1671.7 ± 0.6 MeV, in good agreement with other determinations. The decay asymmetry parameter α (for the decay mode Ω − → Λ K − ) is found to be −0.2 ± 0.4.

A well known technique for polarizing a proton beam consists by scattering it off some material, typically carbon. The use of such a method has been proposed(1) also for polarizing antiprotons at LEAR, and it is now part of the program of Experiment PS 172. Here we give a brief review of how one can obtain an estimate of the polarization parameter in pC scattering, a description of the beam which has actually been designed, and a first list of the measurements we plan to do with such a beam.

A spin-parity 1 + ϱπ enhancement is observed for the 3π mass spectrum in the reaction K − p → Σ − π + π + π − where events with a small (K − → Σ − ) momentum transfer are selected. The mass (1040 MeV) and width (230 MeV) of this enhancement are reminiscent of the A 1 → ϱπ bump which has mainly been observed in the diffractive-like processes. The cross section for this enhancement at 4.15 GeV/ c incident K − momentum is (3.6 ± 0.5) μ b.

An enhancement in the (Σ K ) mass spectrum at threshold is observed in K−p interactions at 4.2 GeV/c. It appeats both in the neutral and negative charge states. Corresponding Λ K mass distributions show weak evidence for an effect close to this threshold (∼1680 MeV). Although the interpretation of the (Σ K ) enhancement by itself is ambiguous, a (Σ K )−(Λ K ) coupled channel analysis gives results compatible with its interpretation as a new Ξ∗.

In the beginning of 1980 four letters of intent for experiments at LEAR had been submitted which all proposed to study either pp total cross section or spin effects in pp (elastic) scattering or both. The people who wrote these letters were asked to work together and to submit one proposal covering all the experiments mentioned in the original letter of intent. The proposal resulting from this effort suggests to do a wide range of experiments using a rather complicated set up.

The reactions K/sup -/p to Xi /sup 0-/(1320)K/sup 0+/, Xi /sup - /(1320)K/sup +/(890), Xi /sup 0-/(1530)K/sup 0-/ and Xi /sup 0-/(1530) K/sup 0+/(890) are studied at 4.2 GeV/c incident momentum. The data come from a high-statistics bubble chamber experiment with a sensitivity of approximately 133 events/ mu b. Total and differential cross sections are presented. The results are compared to the SU(3)- related processes K/sup +/p to pK/sup +/ and K/sup +/p to pK/sup + /(890) in the backward hemisphere. In the forward hemisphere 'forbidden' peaks are observed and current ideas about them are discussed. (15 refs).