共查询到20条相似文献,搜索用时 15 毫秒
1.
H.H. Bingham C.W. Farwell W.B. Fretter G.M. Irwin S. Kahn A. Lu B. Daugeras D. Fournier J. Hennessy M. Novak J.J. Veillet A.M. Cnops F.R. Huson R.I. Louttit D.J. Miller J.S. ONeall M. Di Carato M. Rollier J. Ginestet 《Nuclear Physics B》1973,52(1):31-69
Coherent production of final states from A ~ 20 nuclei by K? beams of 5.5, 10.0 and 12.7 GeV is analyzed. Final states with ? 2πO are included. Coherent production occurs (although forbidden via 0+ exchange) and is dominated by the 1 (890). The shape of the t distribution, the alignment of the produced meson and the ratio of the cross section on nuclei to that on hydrogen are consistent with optical model predictions assuming that 1 (890) are produced on single nucleons by exchange of isoscalar trajectories of natural parity (JP = 1?, 2+, etc.) and that the 1 (890) absorption in nuclear matter equals that of the K?. Coherent production (allowed via 0+, 1?, 2+, etc. exchange) is dominated by the Q phenomenon. A Dalitz plot and angular correlation analysis yields values for fractions, and shows that dominates the coherently produced Q. The helicity of the Q is found to be compatible with 0. The Q? -nucleaon total cross section is estimated to be 0.98?0.37+024 times the ? -nucleon total cross section from a comparison of the coherent Q-production cross section with corresponding hydrogen cross sections at 10 and 12.7 GeV. We observe coherent production of ω. The ration coherently produced in the Q mass region is (4 ± 1)%. Coherent production of is observed in the L region. Coherent production is not observed in the K4π channels. 相似文献
2.
M. Baubillier L. De Billy M. Rivoal R. Zitoun V. Vuillemin R. Brenzikofer 《Nuclear Physics B》1976,104(2):277-289
The reaction does not exhibit any s-channel resonance effect between 1 and 2.5 GeV/c. On the contrary, the data on are compatible with an exchange mechanism in the t- and u-channels above 1.5 GeV/c. Strong similarities are found with . The polarisation of K1± is given. The reaction vanishes above 1.5 GeV/c 相似文献
3.
R.J. Hemingway R. Armenteros C. Dionisi Ph. Gavillet A. Gurtu S.O. Holmgren M.J. Losty J.C. Marin M. Mazzucato L. Montanet M. Banting R. Blokzijl A.J. De Groot B. Jongejans J.C. Kluyver W.M. Van Leeuwen G.G.G. Massaro J. Wells 《Nuclear Physics B》1978,142(3):205-219
Forty 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 . The 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 ) is found to be ?0.2 ± 0.4. 相似文献
4.
H.G. Kirk R. Schulte P. Sixel M. Klein M. Walter M.J. Counihan D.J. Kocher P. Kostka P.K. Malhotra D.R.O. Morrison H. Saarikko K.L. Wernhard K.W.J. Barnham R.M. Eason D.P. Dallman F. Mandl M. Markytan 《Nuclear Physics B》1976,116(1):99-117
The inclusive production of K?1(890) and K?1(1420) is studied in K??p interactions at 10 and 16 GeV/c. At 10 GeV/c an enhancement in the () mass distribution is found at 1.74 GeV, but no clear signal is seen at 16 GeV/c. The fraction of coming from decay of the is large, being (50 ± 6)% and (45 ± 5)% at 10 and 16 GeV/c, respectively. The inclusive cross sections for K1?(890) and production are almost constant with energy from 8 to 32 GeV/c with values of 3.5 and 3.3 mb, respectively. The production cross section is studied as a function of transverse and longitudinal variables and found to derive mainly from fragmentation of the incident K? meson. The spectra of resulting from the decay of are studied. 相似文献
5.
Elastoresistances of TCNQ high conducting salts have been measured at room temperature by an original strain gauge technique. The effects, on the longitudinal and transverse resistivities ?, of an elementary uniaxial strain ? applied along one of the three axes, a, b or c1 respectively, have been estimated.For TTF-TCNQ, they are: ; ; (5% risk).So, in an hydrostatic pressure experiment, the fraction of piezoresistivity attributable to transverse effects is 43± 10% of the total value χb (Kba and Kbc effects accumulated).Low values have been found for the anisotropy (?a/?b) variations due to strains. So one may write: ; ; .The TTF-, HMTTF-, TSF-, HMTSF-TCNQ elastoresistance values are coherent with the previously measured hydrostatic pressure piezoresistivity values.All these experimental results are in good agreement with a model where the longitudinal but also the transverse elastoresistivities are essentially due to variations with strains of the longitudinal scattering time τν defined by σb = ne2τν/m1. 相似文献
6.
C. Cochet C. Lewin R. Barloutaud D. Denegri A. Givernaud M.L. Turluer U. Gensch U. Kriegel H. Vogt H. Kirk D.R.O. Morrison H. Saarikko F.A. Triantis Yu. Arestov E.P. Kistenev E.A. Kozlovsky A.M. Moïseev F. Mandl 《Nuclear Physics B》1979,155(2):333-356
Inclusive production of vector and tensor mesons is studied in a K?p experiment at 32 GeV/c in the MIRABELLE bubble chamber. The , ?0 and ω cross sections are comparable, about 4 mb each. The and cross sections are also comparable, about 1 mb each. The (890), Φ, (1420) and f cross sections beam fragmentation; ? production is almost forward-backward symmetric in the c.m.s. The pT production slopes of and ? are similar, the Φ slope is shallower. Vector and tensor mesons alone are responsible for ?50% (?60%) of final-state pions 相似文献
7.
J. Heintze G. Heinzelmann P. Igo-Kemenes R. Mundhenke H. Rieseberg B. Schürlein H.W. Siebert V. Soergel H. Stelzer K.-P. Streit A.H. Walenta 《Nuclear Physics B》1979,149(3):365-380
The decay K+ → e+υγ has been investigated. For the structure-dependent part with positive γ-helicity (SD+) the branching ratio is obtained from 51 ± 3 events observed in the kinematical region Ee ? 235 MeV, Eγ > 48 MeV and θeγ > 140°. For the corresponding part with negative γ-helicity we obtain an upper limit Γ(SD?)/Γ(SD+) < 11 (90% CL) from the sample of electrons with energies 220 MeV ? Ee < 230 MeV and with no γ in the backward direction. This upper limit implies that the ratio of structure-dependent axial vector amplitudes lies outside the region .For the decay the limit 90% confidence level) was found. 相似文献
8.
C. Evangelista B. Ghidini A. Palano V. Picciarelli G. Zito P. Mättig K. Müller E. Paul W. Rühmer B.R. French D.H. Miller W.A. Mitaroff C. Palazzi-Cerrina R. Strub A.S. Thompson P.L. Woodworth M. Edwards L. Pregernig 《Physics letters. [Part B]》1977,70(3):373-376
Inclusive production is studied in π?p interactions at 16 GeV/c with x? > 0.2. The is found to be pre-dominantly centrally produced with cross section for x? > 0.2 and compares closely to data on production in π+p interactions at the same energy. 相似文献
9.
Results are presented of a 12 event/μb bubble-chamber experiment; the reactions discussed in detail are .The K1 (890)?p channel is dominated by the forward peak. The suggestion of flattering at cos θ = 1 is more pronounced in ; which is mainly natural-parity exchange. Pseudoscalar exchange contributes to ; this is more sharply peaked in t. The value of is somewhat larger than the upper limit from the dominant natural-parity exchange. There is significant structure in .The K1 (1420)?p channel is much more pronounced at 3.3 GeV/c than at 3.13 GeV/c, but is not markedly peripheral. The width of the K1 (1420) in the 3.3 GeV/c data is 42 ± 12 MeV/c2.The cross section for agrees with that expected from , assuming a single t-channel exchange. Our measured density matrix elements are consistent with a strong pseudoscalar exchange. 相似文献
10.
We present a parametrization of the ? and A2 exchange amplitudes which fits all the available data on the reactions in the momentum range from 2.5 to 200 GeV/c and for momentum transfers up to t = ?2.0 (GeV/c)2. 相似文献
11.
12.
Using the Neveu-Schwarz-Ramond model as a starting point, attempts have been made to construct a phenomenological dual amplitude for the reaction . The amplitude contains trajectories of both natural and unnatural spin-parity in the exchange channel as well as Nα, Nγ and Δ trajectories in the production channel. Furthermore, it has the correct Regge behaviour in both meson and fermion channels. Reasonable agreement between the predictions and the data with respect to differential cross sections and density matrix elements has been found. 相似文献
13.
J.N. Carney D.C. Colley M.F. James M. Jobes G.T. Jones J.B. Kinson K.M. Storr D.C. Watkins W. Dunwoodie A. Grant Y. Goldschmidt-Clermont F. Muller M. Nikolic Z. Sekera A. Stergiou 《Nuclear Physics B》1976,107(3):381-421
The reactions , and K+p → K0Δ++ have been systematically studied for eleven incident momenta between 3.0 and 16.0 GeV/c. Cross sections, differential cross sections and density matrix elements are presented. For K1(890) production the contributions from natural and unnatural parity exchanges have also been separated into I = 0 and I = 1 components. Effective trajectories have been extracted in the case of natural parity exchange, and also for Δ++ production. 相似文献
14.
D. Denegri Y. Pons R. Barloutaud A. Borg C. Louedec M. Spiro K. Paler T.P. Shah S.N. Tovey B. Chaurand B. Drevillon G. Labrosse R. Lestienne R.A. Salmeron 《Nuclear Physics B》1975,91(1):54-68
We have studied the reaction K-p → K-π+π-π+π-p at 14.3 GeV/c to search for evidence of the double dissociation process . In the channel π1-π2-Δ++ (1236) there is evidence for simultaneous production of low-mass enhancements in the and Δ++(1236)π2- subsystems which correspond to the and decay modes. In this particular final state the double fragmentation system is produced with a cross section of the order of a few microbarns. Our data are consistent with the factorizable pomeron exchange model of double diffractive dissociation. 相似文献
15.
16.
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
17.
L Nemes 《Journal of Molecular Spectroscopy》1978,72(1):102-123
Medium resolution infrared grating spectra of gaseous ketene, H2CCO were recorded between 1000 and 400 cm?1, both at instrument temperature (40°C) and with cooling (?40°C). Interferometric Fourier spectra were also measured at ?70°C with resolution 0.22 cm?1 between 450 and 330 cm?1. The K structure of the fundamentals ν5, ν6, ν8, and ν9 was assigned. These fundamentals are coupled by a-axis Coriolis interactions. These couplings were analysed on the symmetric top basis for setting up the perturbation matrix and by utilizing the K-dependent Coriolis shifts of levels. A preliminary analysis of the Coriolis intensity anomalies was also undertaken.Band center values from combination differences are and . Synthetic spectra indicate the band origins of ν8 and ν9 to be close to 977.8 and 439.0 cm?1, respectively. Estimates of Coriolis coupling constants obtained from synthetic spectra are , , , and . Approximate ratios of unperturbed vibrational transition moments obtained from spectral simulations are . 相似文献
18.
L. Görlich B. Niczyporuk M. Różańska K. Rybicki J. Turnau H. Becker G. Blanar W. Blum H. Dietl J. Gallivan B. Gottschalk E. Lorenz G. Lütjens G. Lutz W. Männer D. Notz R. Richter J. De Groot 《Nuclear Physics B》1980,174(1):16-44
The reaction π?p→K+K?n has been studied on a hydrogen target (27 000 events) at 18.4 GeV/c and on a polarized target (54 000 events) at 17.2 GeV/c. A combination of results of both experiments allows a partial-wave analysis of the K+K? system between 1.1 and 1.74 GeV mass without any model assumptions. In general our fits yield unique solutions. Using results of our previous analysis of π+π? final states and assuming the dominance of the positive G-parity states in the K+K? system, the branching ratios of partial waves into are determined. The S-wave appears to be mainly a broad ε (1300) with . The weak P-wave can be described by a tail of the . The D-wave is interpreted in terms of a superposition of f(1270) + A2(1310) + f′(1515) resonances. The fit yields for the f(1270) and BR(ππ/all) = 0.027?0.013+0.071 for the f′(1515). The F-wave shows the g(1690) meson with . All the above values refer to the t bin between 0.01 and 0.20 (GeV/c)2. Some results are also given for the high-t region. 相似文献
19.
F.W. Büsser L. Camilleri L. Di Lella G.B. Pope A.M. Smith B.J. Blumenfeld S.N. White A.F. Rothenberg S.L. Segler M.J. Tannenbaum M. Banner J.B. Chèze H. Kasha J.P. Pansart G. Smadja J. Teiger H. Zaccone A. Zylberstejn 《Physics letters. [Part B]》1976,61(3):309-312
Transverse momentum distributions of , and Ko, produced in pp collisions at x = 0, have obtained at the CERN ISR. The Ko yield is in agreement with published K+, K? results, obtained at this centre-of-mass energy (√s≈44 GeV). The results on production obtained in this experiment are compared with results obtained at lower centre-of-mass energies. 相似文献
20.
K. Alpgård G. Ekspong P.O. Hulth U. Svedin N. Yamdagni F.O. Breivik A.G. Frodesen A. Krogstad V.-M. Hagman V. Karimäki P. Villanen 《Nuclear Physics B》1976,103(2):234-246
Inclusive cross sections are presented for strange-particle production in proton-proton interactions at 19 GeV/c for the pairs and for Λ, Ks0, Σ+, Σ? and Ξ?. The , 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 Ks0, Λ, or K0 Λ are shown to follow a modified KNO curve, whereas K+ Λ does not. For the inclusive reactions , 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. 相似文献