共查询到20条相似文献,搜索用时 31 毫秒
1.
U. Sennhauser L. Felawka T. Kozlowski H.K. Walter F.W. Schlepuetz R. Engfer E.A. Hermes P. Heusi H.P. Isaak H.S. Pruys A. Zglinski W.H.A. Hesselink 《Physics letters. [Part B]》1981,103(6):409-412
A particle unstable state of 4H has been identified in the reaction by observing the two emitted tritons. A resonance energy EΓ=(2.7±0.6) MeV and a reduced width γ2=(2.3±0.6) MeV were deduced, in agreement with the parameters of the ground-state level (Jπ=2?) found in the p-wave of n-t-scattering. The yield per stopped pion is (5.6±1.8)×10?4. Previous measurements in pion absorption are in disagreement with our results. 相似文献
2.
Using plausibility arguments, Mandelstam has shown that the solutions of the Bethe-Salpeter equation in the ladder approximation have branch points in the coupling constant g complex plane. This information is vital for the understanding of the analytic properties and the convergence properties of infinite sums of Feynman diagrams. In this paper we develop a formalism which permits an exact analysis of the coupling constant branch point location for approximate Bethe-Salpeter Pseudopotential equations with nonlocal Pseudopotentials. We apply this formalism to the two-nucleon interaction with the pseudoscalar pion exchange. Exact analytic expressions are found for the branch points which are confirmed by a computer test. The branch point position does not depend either on the pion and nucleon masses, or on the total energy. 相似文献
3.
A. Quenzer M. Ribes F. Rumpf J.L. Bertrand J.C. Bizot R.L. Chase A. Cordier B. Delcourt P. Eschstruth F. Fulda G. Grosdidier J. Jeanjean M. Jeanjean R.J. Madaras J.L. Masnou J. Perez-Y-Jorba 《Physics letters. [Part B]》1978,76(4):512-516
The pion form factor is measured in the reaction e+e? → π+π? for center of mass energies in the range 480–1100 MeV. Our results are first analysed in terms of the conventional Vector Meson Dominance formalism, and then taking into account the ωπ inelastic channel. The result of this later formalism is a pion form factor (Fπ) which fits quite well all the existing data on Fπ both in the timelike and spacelike regions, and pion mean square radius of 〈rπ2〉 = 0.460 ± 0.011 fm2 or . 相似文献
4.
R. Barloutaud A. Borg F. Brun D. Denegri C. Louedec F. Pierre M. Spiro B. Drevillon B. Chaurand G. Labrosse R. Lestienne D. Linglin R.A. Salmeron T.P. Shah K. Paler R.J. Miller J.J. Phelan 《Nuclear Physics B》1973,59(2):374-411
We have studied the system in the 14.3 GeV/c reactions K?p → K?π+π?p, . The data have been obtained from a 500 000 picture exposure of the CERN 2m HBC. The first two final states are dominated by Q-production in the Kππ system; there is also an L-signal at M (Kππ) ~ 1.75 GeV. The reaction cross sections are compared to K?p data at other energies. We discuss the Kππ mass dependence of the diffractive production slope. Evidence is presented for a Q?p versus Q+p differential cross section cross-over around |t| = 0.17 GeV2. A t-channel isospin analysis for the channels in the Q-region shows that the I = 1 exchange amplitude is of the dominant I = 0 exchange amplitude. The Kππ decay distributions indicate a predominant JP = 1+ state in the Q-region, and an important JP = 2? contribution in the L-region. We find neither s-channel nor t-channel helicity conservation at the meson vertex in the Q- or L-regions. The Kπ angular correlation moments within the Kππ diffractive system are characteristic of Kπ elastic scattering, suggesting a π-exchange Deck-type production mechanism. There is evidence for a Kf0 and κπ contribution (where κ is the JP(Kπ) = 0+ state) to the diffractive Kππ system. A fit to the Dalitz-plot distributions for the Q-re gion indicates that the ratio of decay amplitudes decreases with increasing Kππ mass. 相似文献
5.
Robert S. Mulliken 《Journal of Molecular Spectroscopy》1976,61(1):92-99
Predissociations in the y1Πg and Rydberg states of N2 (configurations and , respectively) and their likely causes, are discussed. Peaking of rotational intensity at unusually low J values, without sharp breaking off, is interpreted as due to case c? or case ci predissociation. Λ doubling in the y state, attributed to interactions with the state and with another, 1Σ+, state of the same electron configuration as x, is analyzed. From this analysis the location of the (unobserved) state, here labeled x′, is obtained. It is concluded that the predissociation in the Π+ levels of the y state is an indirect one mediated by the interaction with x′ coupled with predissociation of x′ by a state dissociating to atoms: combined, however, with perturbation of the y state by the k1Πg Rydberg state (configuration ), whose Π+ levels are completely predissociated. 相似文献
6.
P.M. Heinen J.J. Engelen E.W. Kittel W.J. Metzger M.M. Schouten J.S.M. Vergeest R.T. Van De Walle B. Jongejans H. Voorthuis M. Cerrada R.J. Hemingway S.O. Holmgren M.J. Losty 《Nuclear Physics B》1977,122(3):443-463
A partial-wave analysis of the low-mass (π+π?p) system produced in the reaction K?p → K?(π+π?p) at 4.2 GeV/c incident momentum is performed in order to study the two (π+π?p) enhancements around 1500 and 1700 MeV. It is found that the low-mass (π+π?p) system can be described using the spin-parity states and only. In the 1500 MeV region contributions are observed from the wave decaying into p? and the wave decaying into Δ++π?; in the 1700 MeV region contributions are found from the wave decaying into Δ++π?, the wave decaying into p?, and the wave decaying into p?. 相似文献
7.
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
8.
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
9.
Y. Eisenberg A. Engler B. Haber U. Karshon G. Mikenberg S. Pitluck E.E. Ronat A. Shapira G. Yekutieli 《Physics letters. [Part B]》1974,52(2):239-242
Rare decay modes of the f meson are studied in the final states Δ++π+π?π+π?, Δ++π+π?MM and Δ++π+π?π+π?MM. The ratio is 0.23 ± 0.09 and Γ(f → 4 π) saturates the f inelasticity. A 2 s.d. upper limit of 0.09 is found for the branching ratio . 相似文献
10.
11.
C.P. Bust J.R. Carter W.W. Neale J.G. Rushbrooke D.R. Ward R.E. Ansorge B.Y. Oh M. Pratap G. Sionakides G.A. Smith J. Whitmore R. Raja L. Voyvodic 《Nuclear Physics B》1978,140(3):409-422
We have investigated the reactions . The final state is dominated by diffractive production of a system which shows a strong tendency to form . The process is also observed in this reaction, indicating an energy dependence of s?1.5±0.1. The channel shows less single diffraction, and has a doubly diffractive component consistent with pomeron factorization. Strong Δ++(Δ++) production is agoain seen, but in contrast to the channel we also observe considerable ?0 production. 相似文献
12.
R.R. Johnson B. Bassalleck K. Erdman B. Gyles T. Marks T. Masterson D.R. Gill C. Sabev 《Physics letters. [Part B]》1978,78(5):560-563
We have measured the differential cross section for π? elastically scattered from . The scattered π? were detected with pion range telescopes. The measured angular distribution is compared with a momentum space optical potential calculation. Derived phase shifts are compared with those obtained from π+ data and from momentum and coordinate space calculations. 相似文献
13.
The spectrum seen in single neutron pickup leading to the doubly odd nucleus 84Rb is remarkably clean, with only five levels populated by l = 4 and six by l = 1 transitions. A simple 2J+1 weighting for the l = 4 data, combined with previous information on 84Rb, allowed the Jπ = 2?–7? states of the () multiplet to be identified. These data are used to determine the two-hole interaction matrix elements. 相似文献
14.
C. Bruneton J. Bystricky G. Cozzika J. Deregel A. Derevschikov Y. Ducros A. Gaidot Yu. Kazarinov M. Kazarinov V. Kanavets B. Khatchaturov F. Lehar A. De Lesquen Yu. Matulenko J.P. Merlo A. Mecshanin S. Miyazhita J. Movchet V. Solovyanov 《Physics letters. [Part B]》1973,44(5):471-473
We report our first measurements of the polarization in the elastic scattering of negative pions from polarized protons at an incident pion momentum of 40 GeV/c. The momentum-transfer region covered was 0.08 < |t| < 1.3 (GeV/c)2. The angular distribution of the polarization exhibits a first minimum of ~ ? 5% and the well-known zero around t ≈ ? 0.6 (GeV/c)2. The energy variation of the first minimum (at around t = ? 0.2) may be expressed in a simple form, . 相似文献
15.
The ground-state spectroscopic quadrupole moments of and have been determined by nuclear orientation as +2.2(4) b and ?2.03(3) b, respectively. The negative QM of 185Ir can be explained only by a ground-state configuration. The positive QM of 184Ir implies K ? 4 in contradiction to expectations of K=0, 1 in analogy to 186Ir. 相似文献
16.
M.J. Corden J.D. Dowell J. Garvey M. Jobes I.R. Kenyon J. Mawson T. McMahon I.F. Corbett R.J. Esterling N.H. Lipman P.J. Litchfield K.C.T.O. Sumorok G. Alexander S. Dagan Y. Gnat E.H. Bellamy M.G. Green N. Harnew D.H. Thomas 《Nuclear Physics B》1978,138(2):235-252
Data on the reaction π?p → π+π?π0 have been taken at 12 and 15 GeV/c with the CERN Omega multiparticle spectrometer. In a 3-pion partial-wave analysis strong production of is observed. Total and differential cross sections are determined and density matrix elements presented as a function of t in the t- and s-channel frames. The energy dependence of A20 production is studied, and a comparison of production is made. 相似文献
17.
C.V.K. Baba D.B. Fossan T. Faestermann F. Feilitzsch M.R. Maier P. Raghavan R.S. Raghavan C. Signorini 《Nuclear Physics A》1976,257(1):135-143
Lifetime and g-factor measurements have been made with pulsed beam-γ time-differential techniques using the 89Y(α, 2n)91Nb and 88Sr(α, n)91Zr reactions. A mean lifetime τ = 14.4 ± 0.5 nsec and a g-factor of 1.26 ± 0.04 were obtained for the 1985 keV level in 91Nb and τ = 41.9 ± 1.2 nsec and g = 0.70 ± 0.01 were obtained for the 2288 keV level in 91Zr. These results are compared to theoretical calculations for and configurations in 91Nb and 91Zr, respectively. 相似文献
18.
The cross-channel isospin amplitude is measured in the single reaction γn → ?0(pπ?) at 7.5 GeV assuming the ?0 dominance model. A low-mass enhancement is found for in the range of m(pπ?) of ~1.2 to ~1.7 GeV. The reaction strongly violates s-channel helicity conservation but is consistent with t-channel helicity conservation. The features are found to be very similar to those obtained in previous analyses of πp → π(Nπ) reactions. 相似文献
19.
A. Berglund T. Buran P.J. Carlson C.J.S. Damerell I. Endo A.R. Gillman V. Gracco R.J. Homer M.J. Hotchkiss A. Lundby M. Macri B.N. Ratcliff A. Santroni T. Tso F. Wickens J.A. Wilson 《Nuclear Physics B》1978,137(3):276-282
The reaction has been studied at 10.1 GeV/c in the ?t interval from 0.15 to 1.5 (GeV/c)2. A line-reversal comparison with backward elastic scattering π+p → pπ+ shows good agreement for ?t > 0.3 (GeV/c)2. 相似文献
20.
J. Boucrot B. Bouquet B. DAlmage A. Ferrer A. Jacholkowski A. Lahellec P. Petroff P. Roudeau J. Six F. Navach P. Sonderegger D. Treille P. Rivet A. Volte P. Benkheiri G. de Rosny A. Rouge R. Salmeron H. Yoshida 《Nuclear Physics B》1977,121(2):251-269
Negative results on backward production, via baryon exchange, of exotic non-strange mesons are presented. The reactions π?p→pforwardX?and π?n→ pforwardX?? have been studied with a 12 GeV/cπ? beam in the Omega spectrometer at CERN. No resonant peak in has been seen. The upper limits obtained on cross sections for exotic meson production are lower than the ?? backward production cross section in the π?p→p?? reaction; this result seems to contradict the predictions of the two-component duality model. Compared to already published experiments in the search for exotics produced via baryon exchange, the sensitivity of this experiment is increased by an order of magnitude. 相似文献