共查询到20条相似文献,搜索用时 31 毫秒
1.
J. Bailey D.V. Bugg U. Gastaldi P. Hattersley D.R. Jeremiah E. Klempt K. Neubecker E. Polacco J. Warren 《Physics letters. [Part B]》1974,50(3):403-406
X-rays from the Kα transition (2P → 1S) of the π?d mesic atom have been observed. Their energy, 2592.8 ?2.0+1.6, has been measured by the critical absorber technique, using the MV absorption edge in bismuth. The strong interaction shift in the 1S state is ?4.8 eV, corresponding to a scattering length a(πd) = ?(0.052?0.017+0.022)mπ?1, in agreement with recent calculations. The intensity ratio Kα/Ktotal = 0.548 ± 0.015. 相似文献
2.
The energy dependence of the cross sections for the processes e+e? → π+π?π0, K+K?, ηπ+π?, ωπ0, and K+K?π+π? is studied near the production threshold for a nucleon–antinucleon pair. It is shown that, within the measurement errors, the cross sections in question behave smoothly in this energy region. 相似文献
3.
Ph. Gavillet J. Diaz C. Dionisi A. Gurtu R.J. Hemingway M.J. Losty J.C. Marin M. Mazzucato L. Montanet E. Pagiola R. Blokzijl B. Jongejans G.G.G. Massaro H. Voorthuis J.J. Engelen W. Kittel J.S. Vergeest W.L. McDowell 《Physics letters. [Part B]》1978,76(4):517-522
A (Kππ)+ mass enhancement is observed in the reactions K?p → Ξ ?Ko+π+πo? when events with a small (K? → Ξ?) four momentum transfer squared are selected. The signal is also visible in the reaction K?p → Ξ?π++ neutrals. The enhancement, centered at 1.28 GeV, is seen to decay preferentially into K? with spin-parity JP = 1+. The cross section for K?p→ Ξ?C+(1.28) with C+ → K? at 4.15 GeV/c incident K? momentum is (6.2 ± 0.6) μb. 相似文献
4.
S. Barlag H. Becker T. Böhringer M. Bosman V. Castillo V. Chabaud D. Buchholz C. Damerell C. Daum H. Dietl H. Fawcett S. Gill A. Gillman R. Gilmore T. Gooch L. Görlich P. Gras Z. Hajduk E. Higon B. D. Hyams D. P. Kelsey J. Kemmer R. Klanner U. Kötz S. Kwan B. Lücking G. Lütjens G. Lutz J. Malos W. Männer E. Neugebauer H. Palka M. Pepe J. Richardson G. De Rijk K. Rybicki H. J. Seebrunner U. Stierlin H. G. Tiecke M. Turala G. Waltermann S. Watts P. Weilhammer F. Wickens L. W. Wiggers M. Witek A. Wylie T. Zeludziewicz ACCMOR Collaboration 《Zeitschrift fur Physik C Particles and Fields》1988,39(4):451-460
The NA 32 experiment at the CERN SPS has collected 38 million hadronic interactions with incident 200 GeV/c π?,K ? andp beam. Using a segmented silicon active target and a telescope of high resolution silicon microstrip counters we have selected fully reconstructedD 0→K ?π+,D 0→K ?π+π+π?,D +→K ?π+π+,D s + →K ? K +π+π+ and charge conjugate decays. The integrated cross-sections forD o,D + D *+ andD s + meson production and the dependence of the cross-section on longitudinal and transverse momentum of theD are presented. 相似文献
5.
The double charge exchange reaction3He(K?,π +)Xn was studied at 870 MeV/c. In the X missing mass range below the sigma-nucleon production threshold (2130 MeV/c2), events were detected which can be attributed to the two-nucleon process pp(K?,π +)λn. This reaction and mass range also offers good prospects for finding theI=1/2,l=1 (1 P1) spin-singlet dibaryon Ds suggested as the lowest massS=?1 dibaryon in the MIT Bag Model. Although the existence of the Ds is not ruled out by the present data, there is no need to invoke such an object to account for the observed events below σ production threshold. We show that the cross section level for these events is compatible with a dominant two-nucleon mechanism K?p→π 0λ,π 0p →π +n. We also offer an interpretation of the recent (K?,K+) data on nuclear targets from Iijimaet al., which display a broad peak centered around a K+ momentum of 600 MeV/c. We find that the two-nucleon mechanism K?N →πY,πN→K+Y produces cross sections which are at least an order of magnitude smaller than those observed, and we suggest that the one nucleon process K?p →Φλ, followed by the decayΦ → K+K?, accounts for the data. 相似文献
6.
K.L. Giboni D. Dibitonto M. Barone M.M. Block A. B?hm R. Campanini F. Ceradini J. Eickmeyer D. Hanna J. Irion A. Kernan H. Ludwig F. Muller B. Naroska F. Navach M. Nussbaum J. OConnor C. Rubbia R. Wojslaw 《Physics letters. [Part B]》1979,85(4):437-442
In a sample of diffractive events of high multiplicity a sharp five standard deviation signal is observed at M = 2255 MeV/c2 in the K?pπ+ mass distribution and, although with less statistical strength, at the same mass in the Λ0π+π+π? channel. These signals are identified as being due to the decay of the charmed baryon Λ+c which is produced with a cross section times branching ratio σcB in the range 0.7?1.8 μb for the K?π+p decay and 0.3?0.7 μb for the Λ-π+π+ π? system. 相似文献
7.
G. Burgun P. Bertranet E. Lesquoy A. Muller E. Pauli S. Zylberajch F. James L. Montanet E. Paul P. Saetre D.M. Sendall 《Physics letters. [Part B]》1973,46(3):481-485
From a study of 70 000 K° decays in the CERN 2m hydrogen bubble chamber, we have estimated the rate for KS0 → π+π?γ for different cuts in the γ momentum. The results are in good agreement with inner bremsstrahlung on KS0 → π+π?. For γ momentum in the K° c.m. greater than 50 MeV/c, we obtain the branching ratio: Γ(KS → π+π?γ, k>50 MeV/c)/Γ(KS→π+π?)=(2.8. ± 0.6)×10?3. This leads to an estimate for the direct γ emission process: Γ(KS→π+π?γ direct)/Γ(KS → π+π?)=(0.3 ± 0.6) × 10?3. 相似文献
8.
B. Foster P. Grossmann P.R. Lamb W.L. McDowell J. Wells R. Blokzijl G.F. Wolters R. Armenteros C. Dionisi Ph. Gavillet P.F. Loverre M. Mazzucato J.J. Engelen W. Kittel J.S.M. Vergeest R.T. Van De Walle 《Nuclear Physics B》1981,187(2):231-253
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(?π) 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 A1 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?π0. We also find production via baryon exchange of the A2 in all three reactions and the ω and (1975) in the third reaction. 相似文献
9.
M. Piccolo I. Peruzzi V. Lüth H.K. Nguyen J.E. Wiss G.S. Abrams M.S. Alam A.M. Boyarski M. Breidenbach W.C. Carithers W. Chinowsky S. Cooper J.M. Dorfan G.J. Feldman G. Goldhaber G. Hanson J.A. Jaros A.D. Johnson G.H. Trilling 《Physics letters. [Part B]》1977,70(2):260-264
Decay modes of the charmed mesons, D0 and D+, are studied in e+e? annihilation data at 4.03 and 4.41 GeV c.m. energy. The products of cross section times branching ratio are measured for the K?π+, K?π+π+π?, KSπ+π? and K?π+π+ final states. Upper limits are established for the Cabibbo forbidden decays via π+π?, K+K?, K+K? π+, K+π+π? and π+π?π+. The K?π+π+π? final state is shown to be dominated by K?π+ρ0. 相似文献
10.
J.N. Carney D.C. Colley M.F. James M. Jobes G.T. Jones J.B. Kinson K.M. Storr D.C. Watkins D.D. Johnson P. Peeters F. Verbeure C. Ciapetti W. Dunwoodie Y. Goldschmidt-Clermont A. Grant F. Muller J. Quinquard Z. Sekera D. Vignaud 《Physics letters. [Part B]》1975,55(1):117-120
We present the first spin-parity analysis of the K+K+K?) system produced in the reaction K+p → K+K+K?p, and show that the general features of this system resemble those of the (ππ+π?) and Kπ+π?) systems produced in the reactions π(K)p → π(K)π+π?p. There is a low mass enhancement, (47 ± 11)% of which corresponds to 1+ states decaying to Kø. At higher (K+K+K?) masses 2? → Kf′ becomes increasingly significant and at all masses there is a 0? contribution of roughly 30%. 相似文献
11.
C. De Clercq D. Johnson J. Lemonne P. Peeters G. Vanhomwegen J. Wickens 《Zeitschrift fur Physik C Particles and Fields》1980,4(1):1-10
After summarizing the properties of the socalled Dalitz Array (DA), which is a genuine characteristics of a resonance, we determine those of the well known ε, γ, andA 2 resonances produced in theK ? p→π+π?π0 Λ final state at 4.2 Ge V/c. A tentative measurement of the DA of theA 1 meson produced backwards in the reactionK ? p→π+π+π?Σ? is also presented. The data for this analysis come from the high statistics (130 events/μb) experiment performed by the ACNO Collaboration. 相似文献
12.
C. Fernandez M. Aguilar-Benitez M. Cerrada J. A. Garzón J. A. Rubio José Salicio R. Armenteros C. Dionisi Ph. Gavillet P. F. Loverre M. Mazzucato L. Dobrzynski D. Pennino I. Sjögren S. Rodebäck S. O. Holmgren 《Zeitschrift fur Physik C Particles and Fields》1982,16(2):95-100
Results from a partial wave analysis of theKππ system produced in the hypercharge exchange reaction π? p→(K +π?π0)Λ at 3.95 GeV/c are presented. SignificantQ 1 production is observed but no evidence is found forQ 2 production thus confirming the results obtained in a previous decay Dalitz plot analysis of the same reaction. The relative phase behaviour of the 1+(K?) partial waves obtained with the present analysis provides additional confirmation of the resonance interpretation of theQ 1 enhancement. Information is also obtained about its production properties and the role played by the Λ polarization in the hypercharge exchange reaction. This is compared with the results obtained in the reactionK ? p→(π+π?π0)Λ at 4 GeV/c. 相似文献
13.
Ph. Gavillet C. Dionisi A. Gurtu R.J. Hemingway M.J. Losty J.C. Marin M. Mazzucato L. Montanet E. Pagiola R. Blokzijl B. Jongejans J.C. Kluyver G.G.G. Massaro J.J. Engelen J.S.M. Vergeest M. Zralek B. Foster P. Grossmann J. Wells 《Physics letters. [Part B]》1978,78(1):158-161
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 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. 相似文献
14.
Ph. Gavillet P. Berge A. Ferrando R. Hemingway S.O. Holmgren M. Losty J.C. Marin L. Montanet E. Pagiola N. Yamdagni R. Blokzijl B. Jongejans J.C. Kluyver G.G.G. Massaro J. Engeler W. Kittel J. Vergeest R. Van de Walle W.L. McDowell 《Physics letters. [Part B]》1977,69(1):119-124
A spin-parity 1+?π 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 A1 → ?π 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) μb. 相似文献
15.
We analyse theK→πππ decays in the framework of a chiral Lagrangian supplemented by the 1/N expansion (N being the number of colors). The measuredK L →π+π0π+ Dalitz plot is very well reproduced. Contrary to a recent claim, the Li-Wolfenstein relation between the CP impurities associated with theK→πππ(ε′+0?) and theK→ππ(ε′) decay amplitudes is rather stable against isospin-breaking effects and higher-order (in the chiral expansion) weak operator corrections. We also predict a branching ratio of 2.1 10?7 for the CP-conservingK S →π+π0π+ decay. 相似文献
16.
P. Benz O. Braun C. Kiesling U. Idschok G. Knies D. Luke H. Schnackers V. Schulz P. Söding H. Spitzer J. Stiewe F. Storim 《Nuclear Physics B》1976,115(3):385-410
In a study of photoproduction at photon energies up to 5.3 GeV in a deuterium bubble chamber the reactions γn→pπ+π?π? and γn→pπ+π?π?π0 were analyzed. In these reactions production of the resonances Δ++, Δ0, ?0, ω and A2? was observed. Photoproduction of strange particles was investigated and cross sections for the reactions γn→ΛK+π?, Σ?K0π+, pK?K0, ΛK0π+π? and ΛK+π?π0 are presented. Production of Σ?(1385) and K10(890) was observed. 相似文献
17.
S. Barlag H. Becker T. Böhringer M. Bosman V. Castillo V. Chabaud C. Damerell C. Daum H. Dietl A. Gillman R. Gilmore T. Gooch L. Görlich P. Gras Z. Hajduk E. Higon D. P. Kelsey R. Klanner S. Kwan B. Lücking G. Lütjens G. Lütz J. Malos W. Männer E. Neugebauer H. Palka M. Pepé J. Richardson K. Rybicki H. J. Seebrunner U. Stierlin H. G. Tiecke G. Waltermann S. Watts P. Weilhammer F. Wickens L. W. Wiggers M. Witek T. Zeludziewicz 《Zeitschrift fur Physik C Particles and Fields》1991,49(4):555-562
We have studied the hadronic production of charmed mesons in the NA 32 experiment at CERN. A special trigger together with a high resolution vertex detector consisting of charge coupled devices and silicon microstrip detectors allowed the selection of very clean samples of charmed mesons. We have collected 852 fully reconstructed decays: 60D s + →K + K ?π+, 543D°→K ?π+ andK ?π+π?π+ as well as 249D +→K ?π+π+ (or charge conjugate). 147 mesons out of our \({{D^0 } \mathord{\left/ {\vphantom {{D^0 } {\bar D^0 }}} \right. \kern-0em} {\bar D^0 }}\) sample were produced via chargedD * state. For all charmed mesons we determine the total production cross-section and study thex F andp t 2 distributions. 相似文献
18.
T. A. Armstrong M. Benayoun I. J. Bloodworth J. N. Carney C. Evangelista B. R. French B. Ghidini M. Girone A. Jacholkowski J. Kahane J. B. Kinson A. Kirk K. Knudson V. Lenti Ph. Leruste A. Malamant J. L. Narjoux F. Navach A. Palano N. Redaelli L. Rossi M. Sené R. Sené M. Stassinaki G. Vassiliadis O. Villalobos Baillie M. F. Votruba G. Zito 《Zeitschrift fur Physik C Particles and Fields》1993,58(2):257-265
We have performed a search for vector-vector final states centrally produced in proton proton interactions at 300 GeV/c using the CERN Ω spectrometer. Evidence is found for ωρ0 production in the reactionpp→p f (2π+2π?2π0)p s and for ωω production in the reactionpp→p f (2π+2π?2π0)p s . However no evidence is found for ωø production in the reactionpp→p f (K + K ?π+π?π0)p s . 相似文献
19.
The results of the experiment performed by the Belle Collaboration and aimed at observing the f 0(980) resonance in the reaction γγ → π + π ? are analyzed. It is indicated that these results suggest the presence of mechanisms in this reaction that lead to a strong distortion of the f 0(980)-resonance line shape in relation to the line shape expected for a solitary Breit-Wigner resonance. It is shown that the K + K ?-loop mechanism of f 0(980) coupling to the γγ system and the destructive interference between the background and f 0(980)-resonance contributions in the region of the π + π ? invariant mass below the K + K ? threshold are the main factors responsible for the formation of a specific (stepwise) f 0(980)-resonance line shape in the cross section for the reaction γγ → π + π ?. 相似文献
20.
S. Fajfer 《Zeitschrift fur Physik C Particles and Fields》1996,71(1):307-312
The decaysK +→π + e + e ?,K S→π 0 e + e ? andK L→π 0 e + e ? are reinvestigated within the framework of chiral perturbation theory. The counterterms induced by strong, electromagnetic and weak interactions are determined assuming the resonance exchange. The weak deformation model, the factorization model and the largeN c limit are used to create a weak Lagrangian. It is found that the results of the first two approaches depend on theH 1 coupling, defined in the effective chiral Lagrangian of theO(p 4) order. The set of parameters used in the extended Nambu and Jona-Lasinio model can accommodeteK +→π + e + e ? decay rate within the factorization approach. The CP violatingK L→π 0 e + e ? decay rate is discussed. 相似文献