共查询到20条相似文献,搜索用时 875 毫秒
1.
P. Bosetti M. Deutschmann H. Grässler G. Otter H.H. Seyfert K. Böckmann J. Hofmann J. Lowsky G. Zobernig V.T. Cocconi T. Coghen V. Karimäki G. Kellner D.R.O. Morrison J. Zaorska 《Nuclear Physics B》1975,94(1):21-38
The production of is measured in π+p reactions at 16 GeV/c. The total strange particle cross section is found to be 4.0 ± 0.3 mb, about 20% of the inelastic cross section. Cross sections for single strange particles and for strange particle pairs are determined, both inclusively and as functions of the charged multiplicity. Relative production rates for different strange particle combinations are compared with the prediction of the isospin statistical model. Inclusive spectra for single particles are studied and it is found the KS0 are produced mostly in the forward hemisphere, most probably by fragmentation of the incident pion into . The Λ are mostly backwards, probably deriving from fragmentation of the proton into ΛK pairs. The tend to be produced forwards, but evidence is found for central production. Distributions in rapidity of the Λ particles from π+p interactions are compared in terms of the factorisation hypothesis. Results are given on the Λ transversal polarisation. 相似文献
2.
P.V. Chliapnikov P.A. Gorbunov S.A. Gumenyuk V.V. Kniazev B.A. Manyukov V.M. Perevoztchikov V.N. Riadovikov V.A. Uvarov M.L. Faccini-Turluer M. Loret L. Mosca H. Blumenfeld J. Laberrigue C. Dujardin F. Grard J. Skura R. Windmolders M. Csejthey-Barth M. Gysen 《Nuclear Physics B》1977,131(1):93-106
A study of the inclusive and semi-inclusive Λ and production in K+p interactions at 32 GeV/c is presented. The inclusive cross sections for Λ and amount to 0.78 ± 0.05 and 0.42 ± 0.04 mb thus showing a remarkable growth between 16 and 32 GeV/c with a factor of 1.7 for Λ and 2.8 for . Target and beam fragmentation processes are found to be dominant for Λ and production respectively with the following lower limits for the corresponding cross sections: and . Although the early scaling conditions are fulfilled for the Λ production in the target fragmentation region, and production in the beam fragmentation region, scaling is not observed between 16 and 32 GeV/c in the x and pT2 Feynman variables. The Λ production is found to be very similar in the K+p inclusive reaction at 32 GeV/c and in the semi-inclusive reaction at the same energy. The pair production cross section increases significantly in K+p interactions from 16 to 32 GeV/c where it reaches the value . The cross sections for Λ or produced in association with an identified proton are also given and discussed. 相似文献
3.
R. Sugahara F. Ochiai Y. Fukui A.M. Cooper M. Fukawa S. Kabe H. Kichimi A. Ono T. Sato A. Suzuki Y. Yoshimura K. Takahashi T. Okusawa K. Tanahashi S. Sasaki M. Teranaka O. Kusumoto T. Konishi 《Nuclear Physics B》1979,156(2):237-251
The inclusive production of Λ, KS0, Σ±(1385) and in π?p interactions at 6 GeV/c has been studied. The observed cross sections are: σ(Λ)=0.94±0.06 mb, σ(KS0)=0.98±0.06 mb, σ(Σ+(1385))=60±7 μb, σ(Σ?(1385))=90±9 μb, , respectively. The inclusive spectra of these particles are presented as functions of squared transverse momentum and Feynman scaling variable x. The polarization of Λ has also been investigated. It is found from a comparison with higher-energy data that the inclusive cross sections for Σ±(1385) and the production ratios Σ±(1385)/Λ in π?p at 6 GeV/c have not reached the high-energy limiting values. 相似文献
4.
R.L. Eisner W.J. Fickinger S.L. Glickman J.A. Malko J.F. Owens D.K. Robinson S. Dado A. Engler G.S. Keyes T. Kikuchi R.W. Kraemer 《Nuclear Physics B》1977,123(3):361-381
Results on K0 and Λ production in p↑p interactions at 6 GeV are presented. The data are from an exposure of the Argonne 12 ft bubble chamber to a 60% transversely polarized proton beam. Results include data on Λ and K0 inclusive production, and on the reactions p↑p → pΛK+(pΣ0K+). The beam asymmetry parameter for is determined to be (?0.52 ± 0.12). 相似文献
5.
6.
The dependence of the low-lying spectra of hypernuclei on hyperon-α interaction in the molecular α + α + Λ(Σ) scheme has been studied. A suggestion is made for obtaining the strengths of both p-wave and spin-orbit Λ-α interactions from the experimental spectrum. A relation between the Σ0-binding energies and has been established and on its basis a prediction is made about a possible binding energy of . 相似文献
7.
The characteristics of the decay sequences are discussed for the two sharp levels of 12C1 at excitation energies of 12.7 MeV (Jf = 1+, T = 0) and 16.11 MeV (Jf = 2+, T = 1), which are observed prominently in this decay process. The transition rates for these processes and the angular correlations in the final four-particle state αααπ? are discussed quantitatively, using the intermediate coupling model for both the 12ΛB and 12C1 systems, as a function of the 12ΛB spin J. Three distinct tests are proposed, which are sensitive to the spin J for ground-state 12ΛB, and which have been used by the European K? Collaboration to deduce that J = 1 for 12ΛB. The implications of this conclusion for the ΛN and ΛNN interactions are briefly discussed. 相似文献
8.
I.V. Ajinenko Y.A. Belokopitov P.V. Chliapnikov L.N. Gerdyukov V.V. Kniazev A.I. Kurnosenko A.K. Likhoded V.M. Perevoztchikov V.N. Riadovikov A.M. Rybin O.G. Tchikilev V.F. Tchunikhin V.A. Uvarov A.P. Vorobjev 《Nuclear Physics B》1980,176(1):51-60
The inclusive production of and Ξ? hyperons is investigated in K+ p interactions at 32 GeV/c. The production cross sections, 36.4±9 μb for the and 6.5±3 μb for the Ξ?, are rising strongly with energy similarly to and Λ production in K+ p interactions. The are produced preferentially in the forward direction in the c.m.s., while the Ξ? are produced dominantly backwards. The average transverse momenta and 〈pT〉Ξ?=0.58±0.09 GeV/c. 相似文献
9.
The three-body final states and produced from πp interactions at 1.69 GeV/c are examined. The quasi-two-body state Λ(1405)K0 is discussed in detail. In particular, the spin of Λ(1405) is determined, via the method of Byers and Fenster, to be consistent with . The Σ±π? mass spectrum is compared to that produced by various zero-range and effective-range parametrizations and the Λ(1405) is found to have a mass of 1405 MeV and width of 45–55 MeV. Production and decay characteristics of the quasi-two-body states are reported. 相似文献
10.
11.
H. Taureg G. Zech F. Dydak F.L. Navarria P. Steffen J. Steinberger H. Wahl E.G.H. Williams C. Geweniger K. Kleinknecht 《Physics letters. [Part B]》1976,65(1):92-96
The branching ratio has been determined to be (2.68±0.15)×10?3 for photon energies greater than 50 MeV in the KS0 rest frame. The decay KS0→π+π?γ is found to be dominated by the internal bremsstrahlung transition. The branching rato of a possible direct transition is found to be less than 0.06 × 10?3 at 90% confidence level for . 相似文献
12.
H. Laven G. Otter G. Rudolph R. Klein H.J. Schreiber D.J. Kocher D.R.O. Morrison P. Schmid K.L. Wernhard R.M. Eason T.C. Bacon K.W.J. Barnham P.J. Dornan B. Pollock J. Macnaughton M. Markytan 《Nuclear Physics B》1977,127(1):43-56
The reactions (1) K?p → K+K?Λ and (2) have been studied on samples of 109 and 64 events, respectively, at 10 GeV/c and 125 and 69 events at 16 GeV/c, reasonably free from contaminations. The investigation of the first reaction uses also 84 events of the final state at 10 GeV/c. Analysis of the Van Hove plots indicates that the K+K?Λ and final states are produced by two main mechanisms: (i) a ΔQ = 0 process, with a strong diffractive component near threshold, involving the dissociations p → K+Λ in reaction (1) and in reaction (2) and (ii) a ΔQ = 1 process involving hypercharge exchange, and producing K+K? and systems in reactions (1) and (2), respectively, recoiling off the Λ. With increasing energy, this hypercharge exchange process decreases slowly when K+K? is produced, but fast where the production of , violating the Zweig rule, occurs. 相似文献
13.
Y. Pons D. Denegri J.M. Laffaille M. Spiro B. Chaurand G. Labrosse R. Lestienne K. Paler C. Comber S. Tovey 《Nuclear Physics B》1977,123(3):349-360
We discuss the structure of the momentum transfer distributions for the diffractive dissociation processes p → nπ+, p → Δ++π? and . In the near-threshold mass region a clear break of slope is found around t′KK ~ 0.25 GeV2 for the two baryonic channels, whereas no comparable structure is seen for the mesonic system. The differential cross section exhibits a nearly exponential behaviour up to t′pp ~ 0.6 GeV2, falling over three orders of magnitude. The slope variations and breaks are strongly correlated both to the mass region considered and to the decay angle of the fragmentation system. 相似文献
14.
New spectrograms of CO below 1200 Å reveal that emission bands terminating on the high energy and 1Π states plus most of the previously reported unidentified emission bands of CO actually originate from molecular nitrogen. Four new emission band systems in CO, tentatively identified as V1Π-X1Σ+, W1Π-X1Σ+, Y1Σ+-X1Σ+, and Z1Σ+-X1Σ+, have been observed. The corresponding Tv0′s are 98917, 102804, 99963, and 105724 cm?1, respectively. 相似文献
15.
A theoretical model used to describe the and B3Πg states of N2 is presented. Using recently acquired high resolution spectra of the (0-0) band, rotational energy levels of the v = 0 vibrational levels of these two states are generated with this model. These levels are in excellent agreement with those obtained using a combination differences technique. The precision of the model generated levels is 0.01 cm?1. The previously unpublished rotational levels of Dieke and Heath for the , B3Πg and C3Πu states are referenced to the (v = 0, J = 0) ground level and tabulated here. Estimates of the precision of their work are made. 相似文献
16.
D. Yaffe M. Abramovich V. Chaloupka A. Ferrando M. Korkea-aho M.J. Losty L. Montanet E. Paul J. Zatz Z. Zieminski 《Nuclear Physics B》1974,75(3):365-387
We have investigated the final states K10(890)Σ, and K10(890) Y110(1385) produced in π?p interactions at 3.93 GeV/c. We present the differential cross sections and spin density matrix elements for the resonances as functions of momentum transfer, as well as the gL and Σ0 polarizations. The Σ0 polarization is found to be positive and maximal. An amplitude analysis is performed for the K1 Λ and reactions, and it is found that one natural parity transversity amplitude is dominant for the latter. 相似文献
17.
D. Bertrand D. Johnson J. Lemonne P. Renton F. Van Den Bogaert J. Wickens A. Apostolakis R. Casali C. Caso A. Grant Y. Goldschmidt-Clermont G. Grammatikakis L. Pape J.P. Porte A. Stergiou B. Tallini G. Vassiliadis A. Lloret 《Nuclear Physics B》1977,128(3):365-396
Results are presented on the inclusive reactions at an incident antiproton momentum of 12 GeV/c in BEBC. The cross sections are studied as functions of the Feynman scaling variable x, the rapidity, the transverse momentum of the V0 and the missing mass squared. The dependence of the Λ and polarization on x are also studied. Comparisons with proton-proton data at 12 GeV/c are also made. Finally, events with two detected V0 are analyzed in order to study correlations arising from the production of two strange neutral particles. 相似文献
18.
A simultaneous analysis of low-energy (W ? 2 GeV) data for the reactions π?p→ KOΛ and K?p → πOΛ has been made using the hypothesis of two-component duality combined with fixed-t dispersion relations. Results are presented for the and couplings. The low-energy amplitudes are used to evaluate FESR integrals and lead to large EXD breaking for the helicity flip amplitudes. 相似文献
19.
Ulrich Ellwanger 《Nuclear Physics B》1978,139(4):422-432
We calculate mass splittings of strange and non-strange baryons in the [56, 0+] and the [70, 1?]. As the most important spin-dependent force we only analyse the hyperfine interaction. The exact treatment of the quark mass breaking shows contributions which have not been considered in similar investigations up to now. Taking and popular values for the slope of the linear potential a, the strong coupling constant αs and the p-quark mass, we get excellent results for the four mass splittings 〈Σ-Λ〉, , 〈Δ-N〉 and in the [56, 0+]. The structure of mass spectrum in the [70, 1?] is well described, too; the strong SU(3) mixing of Σ and Λ states is seen to be due to the quark mass breaking. Predictions for missing Σ states in the [70, 1?] as as for splittings between charmed baryons can be made. 相似文献
20.
Otto Nachtmann 《Nuclear Physics B》1974,74(3):422-428
Recent experimental results on electroproduction off protons show that the ratio σ(ep → eK+Σ0)/σ(ep → eK+Λ) decreases strongly with increasing Q2. A simple argument is given in the framework of the quark parton model which could provide a qualitative understanding of this fact. The decrease of the Σ0/Λ ratio is related to the decrease of the ratio as Q2 increases, where are the usual structure functions for deep inelastic electron-nucleon scattering. 相似文献