共查询到20条相似文献,搜索用时 0 毫秒
1.
A.Ya. Berdnikov Ya.A. Berdnikov A.N. Ivanov V.A. Ivanova V.F. Kosmach M.D. Scadron N.I. Troitskaya 《The European Physical Journal A - Hadrons and Nuclei》2001,12(3):341-347
Polarization properties of strange baryons produced in pp reactions, p + p↦p + Λ0 + K+ and p + p↦p + Σ0 + K+, near thresholds of the final states pΛ0K+ and pΣ0K+ are analysed relative to polarizations of colliding protons. The cross-sections for pp reactions are calculated within the
effective Lagrangian approach accounting for strong pp rescattering in the initial state of colliding protons with a dominant
contribution of the one-pion exchange and strong final-state interaction of daughter hadrons (Eur. Phys. J. A 9, 425 (2000)).
Received: 22 October 2001 / Accepted: 14 November 2001 相似文献
2.
E. Oset J.A. Oller U.-G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2001,12(4):435-446
We perform a study of the final-state interactions of the K
+
and the
d systems in the reactions pp↦dK
+
and pp↦dπ+η. Since the two-meson system couples strongly to the a
0(980) resonance, these reactions are expected to be an additional source of information about the controversial scalar sector.
We also show that these reactions present peculiar features which can shed additional light on the much debated meson-baryon
scalar sector with strangeness -1. We deduce the general structure of the amplitudes close to the dK
+
threshold, allowing for primary K
+
as well as π+η production with the two mesons in relative S- or P-wave. The interactions of the mesons are accounted for by using chiral unitary techniques, which generate dynamically the
a
0(980) resonance, and the
d interaction is also taken into account. General formulae are derived that allow to incorporate the final-state interactions
in these systems for any model of the production mechanism. We illustrate this approach by considering two specific production
mechanisms based on three flavor meson-baryon chiral perturbation theory. It is demonstrated that in this scenario the
d interactions are very important and can change the cross-section by as much as one order of magnitude. The amount of π+ηversus
K
+
production is shown to depend critically on the primary mixture of the two mechanisms, with large interference effects due
to final-state interactions. These effects are also shown to occur in the event distributions of invariant masses which are
drastically modified by the final-state interactions of the two-meson or the
d system.
Received: 28 September 2001 / Accepted: 26 November 2001 相似文献
3.
V.Yu. Grishina L.A. Kondratyuk E.L. Bratkovskaya M. Büscher W. Cassing 《The European Physical Journal A - Hadrons and Nuclei》2000,9(2):277-285
We investigate the reactions πN↦a
0
N and pp↦da
0
+ near threshold and at medium energies. An effective Lagragian approach and the Regge pole model are applied to analyze different
contributions to the cross-section of the reaction πN↦a
0
N. These results are used to calculate the differential and total cross-sections of the reaction pp↦da
0
+ within the framework of the two-step model in which two nucleons produce an a0-meson via π-meson exchange and fuse to a deuteron. The necessity of new measurements on a0 production and branching fractions (of its decay to the K
and πη channels) is emphasized for clarifying the a0 structure. Detailed predictions for the reaction pp→da
0
+ are presented for the energy regime of the proton synchrotron COSY-Jülich.
Received: 4 August 2000 / Accepted: 17 September 2000 相似文献
4.
Bockhorst M. Burbach G. Burgwinkel R. Empt J. Guse B. Guse B. Haas K. -M. Hannappel J. Heinloth K. Hey T. Hoffmann-Rothe P. Honscheid K. Jahnen T. Jakob H. P. Jöpen N. Jüngst H. Kirch U. Klein F. -J. Kostrewa D. Lindemann L. Link J. Manns J. Menze D. Merkel H. Merkel R. Neuerburg W. Paul E. Plötzke R. Schenk U. Schmidt S. Scholmann J. Schütz P. Schultz-Coulon H. -C. Schweitzer M. Schwille W. J. Tran M. -Q. Umlauf G. Vogl W. Wedemeyer R. Wehnes F. Wißkirchen J. Wolf A. 《Zeitschrift fur Physik C Particles and Fields》1994,63(1):37-47
The reactions pK
+ and pK
+ 0 have been measured with the multiparticle detector system SAPHIR at ELSA in Bonn. Besides the differential cross sections the polarization and, for the first time, the 0 polarization have been determined in a photon induced reaction. All data are presented as functions of the photon energy (from threshold up to 1.47 GeV) and of the kaon production angle (0°–180°). The polarization of both and 0 is substantial at all energies and varies strongly with the production angle.This work is supported by the Bundesminister für Forschung und Technologie (BMFT), FK 06 BN 621 I 相似文献
5.
I. Schulday R. Lawall J. Barth K. -H. Glander S. Goers J. Hannappel N. Jöpen F. Klein E. Klempt D. Menze E. Paul W. J. Schwille 《The European Physical Journal A - Hadrons and Nuclei》2011,47(4):1-6
The reactions γp → K+ Σ± π? were studied with the SAPHIR detector using a tagged photon beam at the electron stretcher facility ELSA in Bonn. The decays Σ ? → nπ ? and Σ + → nπ +, pπ 0 were fully reconstructed. Reaction cross-sections were measured as a function of the photon energy from threshold up to 2.6 GeV with considerably improved statistics compared to a previous bubble chamber measurement. The cross-sections rise monotonically with increasing photon energy. The two-particle mass distributions of Σ ± π ? and K + π ? show substantial production of resonant states. 相似文献
6.
H. Müller 《The European Physical Journal A - Hadrons and Nuclei》2001,11(1):113-119
We investigate the reaction pp↦da
0
+ at COSY and SIS energies together with accompanying background reactions and inclusive particle yields. The a
0
+ is considered as a usual u
quark model state with two decay channels a
0
+↦K
+
and a
0
+↦π+η. Calculated cross-sections for a
0
+ production as well as for the corresponding non-resonant channels pp↦dK
+
and pp↦dπ+η are compared. Especially, in case of the final channel dπ+η, high statistics measurements are necessary to extract the a
0
+ signal from the high non-resonant background.
Received: 20 December 2000 / Accepted: 7 May 2001 相似文献
7.
8.
Ch. de la Vaissière H. Muirhead S. N. Ganguli Ph. Gavillet M. Mazzucato C. Dionisi R. Blokzijl J. C. Kluyver G. F. Wolters E. W. Kittel M. Zralek B. Foster P. Grossman 《Zeitschrift fur Physik C Particles and Fields》1979,1(1):3-17
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. 相似文献
9.
10.
It is shown that the new data on the excitation energy E exc spectrum of the residual nuclear system in the Σ-hypernuclear region in the reactions (K ?, π±) on 9Be and in the reaction (K ?, π+) on 4He and 12C can be described without assuming the existence of excited Σ-hypernuclear states. The basis is formed by a simultaneous consideration of the quasifree Σ production and Σ-nuclear rescattering (elastic and with Σ → Λ conversion) with allowance for the interference of the respective amplitudes. To answer completely the question on the nature of the irregularities in E exc spectrum, it is proposed to study the picture corresponding to the so-called moving complex singularity of the triangle graph with Σ rescattering: the position and the width of the peak in E exc distribution should be appreciably changed with momentum transferred from the initial kaon to the final pion. 相似文献
11.
M. Aguilar-Benitez M. C. Albajar A. Ferrando J. A. Rubio J. Salicio I. Sjögren S. Rodebäck S. O. Holmgren R. Armenteros C. Dionisi Ph. Gavillet M. J. Losty P. F. Loverre M. Mazzucato L. Dobrzynski D. Pennino 《Zeitschrift fur Physik C Particles and Fields》1980,6(2):109-123
The reactionsπ ?p→K 0 ∑ 0(1385) andπ ? p→K + ∑ ?(1385) are studied at an incident momentum of 3.95 GeV/c using data from a high statistics bubble chamber experiment corresponding to approximately 90 events/μb. The total and differential cross sections and the density matrix elements of the Σ(1385) are presented. The results are compared with those obtained for the related processesπ pp→K + ∑ +(1385) and \(K^ - p \to \pi ^ \mp \sum ^ \pm (1385)\) in this energy range. Evidence is presented for the existence of production mechanisms with exotic exchanges in thet channel. 相似文献
12.
《Physics letters. [Part B]》2006,632(2-3):212-214
13.
T. Kadowaki J. Asai W. Imoto S. Iwata M. Kurosawa K. Nakai A. Sato K. Imai H. Takahashi C.J. Yoon T. Maruta M. Ieiri T. Nagae H. Noumi T. Fukuda P.K. Saha B. Bassalleck 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):295-298
In order to study the hyperon-nucleon spin-orbit interaction, asymmetries of the polarized Σ+ elastic scattering on protons have been measured. The polarized hyperons were produced through the p(π+, K+) Σ+ reaction in a liquid-scintillator active target, and tracks of Σ+p scattering events were recorded with a newly developed track detector named SCITIC (scintillating track image camera). Although
analyses of 10 times more data with more sophisticated data-taking systems and more elaborated analyzing tools are under way,
data from an early stage of this experiment indicate a large Σ+p spin-orbit interaction in contrast to the case of the small ΛN spin-orbit interaction.
Received: 27 May 2002 / Accepted: 23 July 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: nakai@post.kek.jp
Communicated by Th. Walcher 相似文献
14.
We investigate the-nucleus potential in the framework of a relativistic mean field approximation. As input for the elementaryN interaction we supplement the-repulsion by the exchange of an effective, complex-meson to account for theN N conversion. As the main result we find that the strength of ths absorptive central potential is smaller than the corresponding real part, whereas in the spin-orbit interaction, which is expected to be much weaker than for a nucleon, the imaginary component dominates.This work was partially supported by CNPq, FINEP (Brazil) and by the Bilateral Cooperation W. Germany — Brazil (KFA — CNPq). 相似文献
15.
N. Kaiser 《The European Physical Journal A - Hadrons and Nuclei》1999,5(1):105-110
We analyze the recent total cross section data for pp→pΛK
+ near threshold measured at COSY. Using an effective range approximation for the on-shell pΛ S-wave final state interaction we extract from these data the combination ?= (2|K
s|2+|K
t|2)−1/2= 0.38 fm4 of the singlet (K
s) and triplet (K
t) threshold transition amplitudes. We present an exploratory calculation of various (tree-level) vector and pseudoscalar meson
exchange diagrams. Pointlike ω-exchange alone and the combined (ρ0,ω,K*+)-exchange can explain the experimental value of ?. The pseudoscalar meson exchanges based on a SU(3) chiral Lagrangian turn
out to be too large. However, when adding π0-exchange in combination with the resonant πN→S
11(1650) →KΛ transition and introducing monopole form factors with a cut-off Λc= 1.5 GeV one is again able to reproduce the experimental value of ?. More exclusive measurements are necessary to reveal
the details of the pp→pΛK
+ production mechanism.
Received: 28 October 1998 / Revised version: 12 January 1999 相似文献
16.
M. Aguilar-Benitez P. J. Done A. D. Martin 《Zeitschrift fur Physik C Particles and Fields》1981,10(4):299-306
We study the interference phenomena between the ? meson and the underlyingK ? K + S wave in the reactionK ? p→K ? K + Λ at 4.2GeV/c. We perform an amplitude analysis of the double multipole moments and investigate the \(K\bar K \to K\bar K\) S wave amplitude. 相似文献
17.
Yu.S. Surovtsev D. Krupa M. Nagy 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):409-416
In a combined analysis of the experimental data on the coupled processes ππ↦ππ, KˉK in the channel with I
G
J
PC = 0+0+ +, the various scenarios of these reactions (with different numbers of resonances) are considered. In a model-independent approach,
based only on analyticity and unitarity, a resonance is represented by a pole cluster (poles on the Riemann surface) of the
definite type that is defined by the state nature. The best scenario contains the resonances f
0(665) (with properties of the σ-meson), f
0(980) (with a dominant sˉs component), f
0(1500) (with a dominant flavour-singlet, e.g., glueball component) and the f
0(1710) (with a considerable sˉs component). If the f
0(1370) exists, it has a dominant sˉs component. The coupling constants of the observed states with the considered channels and the ππ and KˉK scattering lengths are obtained. The conclusion on the linear realization of chiral symmetry is drawn.
Received: 25 April 2002 / Accepted: 4 June 2002 / Published online: 26 November 2002
RID="a"
ID="a"e-mail: surovcev@thsun1.jinr.ru
RID="b"
ID="b"e-mail: krupa@savba.sk
RID="c"
ID="c"e-mail: fyzinami@nic.savba.sk
Communicated by V.V. Anisovich 相似文献
18.
T. A. Armstrong I. J. Bloodworth J. N. Carney B. R. French B. Ghidini J. B. Kinson V. Lenti A. Palano I. C. Print G. Vassiliadis O. Villalobos Baillie M. F. Votruba G. Zito R. Zitoun WA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1987,34(1):33-38
The reactions π+ p→π+(K + K ? π+ π? p andpp→p(K + K ? π+ π?)p where the (K + K ? π+ π?) system is centrally produced have been studied at 85 GeV/c. 48% of the final state proceeds through single or double vector meson resonant production i.e.,K *0(890) (37%), ? (4%),ρ 0 (7%). Evidence is found for associatedK *0 (890) \(\bar K\) *o (890) production (6.4±1.1%) with a cross section ten times higher than that found for associated ? ? production in the same experiment. 相似文献
19.
G. Zech F. Dydak F.L. Navarria O.E. Overseth P. Steffen H. Wahl E.G.H. Williams C. Geweniger K. Kleinknecht H. Taureg 《Nuclear Physics B》1977,124(4):413-425
The mean lifetimes of the Λ and Ξ0 hyperons have been measured in a short neutral beam at the CERN Proton Synchrotron. Λ and Ξ0 decays have been identified by measuring their decay products in a magnetic spectrometer and in a lead glass hodoscope. The experimental results, based on 53 000 Λ decays and 6300 Ξ0 decays are From the result for τΞ0 together with existing data on τΞ? we obtain a violation of the rule in non-leptonic Ξ decays. 相似文献
20.
《Nuclear Physics A》1999,657(3):303-314
We calculate the differential cross section for the weak, strangeness changing, electron scattering process, e− + p → Λ + ν, for incoming electron energies of 0.5, 1.0, 2.0, 4.0, and 6.0 GeV. We obtain as well contributions of the individual form factors to the differential cross sections. We find that the differential cross sections peak as the maximal scattering angle for the Λ is approached and that the peak height increases as the electron energy is increased. The behavior of the differential cross section near the maximal angle is discussed as is the possibility of observing this reaction in a facility such as TJNAF. 相似文献