共查询到20条相似文献,搜索用时 31 毫秒
1.
W.D. Apel K.H. Augenstein E. Bertolucci S.V. Donskov A.V. Inyakin V.A. Kachanov R.N. Krasnokutsky M. Kruger G. Leder A.A. Lednev I. Mannelli Yu.V. Mikhailov H. Müller G.M. Pierazzini Yu.D. Prokoshkin M. Quaglia H. Schneider A. Scribano M.L. Vincelli 《Physics letters. [Part B]》1978,72(4):500-502
The invariant mass spectrum of neutral final states produced in π?p charge-exchange scattering at 40 GeV/c has been studied, searching for heavy particles decaying in 2γ. A peak is observed around 2.85 GeV/c2. The cross section of the reaction π?p→X(2.85)+n, times the branching ratio of the X→2γ decay, is measured to be . 相似文献
2.
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
3.
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
4.
J.J. Aubert G. Bassompierre K.H. Becks C. Best E. B?hm X. de Bouard F.W. Brasse C. Broll S. Brown J. Carr R.W. Clifft J.H. Cobb G. Coignet F. Combley J.M. Crespo G. DAgostini P.F. Dalpiaz S.J. Wimpenny 《Physics letters. [Part B]》1981,106(5):419-422
Two trimuon events of the type μ+N→μ+μ+μ+X and one μ+N→μ+μ?μ?X have been observed in 250 GeV μ+ -iron interactions. The expected rate from the decay of hadrons (charm, π, K) is about one event. Other processes that may contribute are both beauty production and charm production with mixing. The data give upper limits of 12×10?36 cm2 for the cross section of beauty pair production by muons, and 20% for transitions due to mixing, both at 90% confidence level. 相似文献
5.
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
6.
R. Cottrell M. Della Negra D. Drijard H.G. Fischer G. Fontaine H. Frehse C. Ghesquiere P. Hanke P.G. Innocenti W. Isenbeck E.E. Kluge V. Korbel S. Kryzwdzinski A. Minten A. Putzer K.H. Schmidt H. Schneider W.J. Schwille D. Wegener 《Physics letters. [Part B]》1975,55(3):341-344
The inclusive spectrum of positive particles has been measured at the ISR energy √s = 52.5 GeV as function of transverse momentum, pT for large pT values using the Split Field Magnet facility. The angular dependence of the distribution is observed and discussed in the range . An upper limit for the production of ? meson with pT ? 3 GeV/c is derived from the same sample of data. 相似文献
7.
C. Pigot J.P. de Brion A. Caillet J.B. Cheze J. Derre G. Marel E. Pauli G. Vrana G. dAgostini G. Auriemma G. Marini G. Martellotti F. Massa A. Nigro A. Rambaldi A. Sciubba S. Reucroft E.G.H. Williams 《Nuclear Physics B》1985,249(1):172-188
The production of a strange dibaryonic system called H+1 (M = 2.13 GeV/c2, S = ?1), has been studied with a missing mass spectrometer, at the CERN Proton Synchrotron, in the reaction K?d → π?H+1 and in the line-reversed reaction π+d → K+H+1 between 0.9 and 1.4 GeV/c.The reactions , ,have been studied in a missing mass spectrometer at CERN. The experiment (PS159) is well adapted to search for a signal in the missing mass X+ (B = 2, S = ?1) produced in the backward c.m.s. direction, between 2.0 and 2.3 GeV/c2. The two reactions have been analysed at three different beam settings: 1.4, 1.06 and 0.92 GeV/c for reaction (1) and 1.4, 1.2 and 1.06 GeV/c for reaction (2). 相似文献
8.
J.G.H. de Groot T. Hansl M. Holder J. Knobloch J. May P. Palazzi A. Para F. Ranjard A. Savoy-Navarro D. Schlatter J. Steinberger W. von Rüden H. Wahl F. Eisele K. Kleinknecht H. Lierl H.J. Willutzki F. Dydak F.L. Navarria 《Physics letters. [Part B]》1979,86(1):103-107
290 events of the type νFe→μ?μ?X and 53 events from the reaction and muon momenta pμ>6.5GeV/c have been observed in the CDHS detector. After subtracting the background from charged-current processes with one π or K meson of the hadronic shower decaying into , we obtain for neutrinos a rate of prompt like- sign dimuon production of (3.4±1.8)×10?5 relative to the rate of charged-current events with the same cuts, or (4.1 ± 2.2)% relative to the prompt μ?μ+ rate, and for antineutrinos the corresponding relative rates (4.3±2.3)×10?5 and (4.2 ± 2.3)%. A possible explanation for the events is charm pair production at a level of 10?3 relative to all charged-current reactions. 相似文献
9.
K. Böckmann J. Hofmann U. Idschok J. Lowsky B. Schröder V. Blobel H. Fesefeldt R. Schulte G. Kellner D.R.O. Morrison H. Saarikko T. Coghen 《Nuclear Physics B》1980,166(2):284-300
A study is presented of the inclusive production cross sections of K1±(892) vector mesons in pp interactions at 12 and 24 GeV/c and in π+p interactions at 16 GeV/c. The K1± inclusive cross section is ~0.9 mb for both pp at 24 GeV/c and π+p interactions at 16 GeV/c. For pp interactions, and are seen to rise with energy, showing a threshold behaviour. In both pp and π+p interactions, largely exceeds at these energies and this excess is interpreted as K1+ production by beam and target fragmentations. The decays of K1±0 yield ~30% of the K0 observed in the final states. The pT2 dependence of both K1+ and K1? cross sections is described by an exponential with slope of ~3.3 (GeV/c)?2. The longitudinal momentum spectra for K1+ in 16 GeV/cπ+p and 24 GeV/c pp interactions are similar in shape in the target hemisphere. The K1? spectra are similar over the whole kinematic region when viewed in the quark c.m.s. and point to a central production mechanism. Comparing K1+ and ρ0 production, striking similarities are found. 相似文献
10.
Anil K. Bhatnagar B. Bhanu Prasad N. Ravi R. Jagannathan T.R. Anantharaman 《Solid State Communications》1982,44(6):905-909
Amorphous Fe40Ni40B20 (VITROVAC 0040) alloy has been investigated using 57Fe Mössbauer Spectroscopy. The Curie temperature Tc is found to be well defined and is 695 ± 1 K. The quadrupole splitting just above Tc is 0.64 mm sec?1. The crystallization temperature is 698 ± 2 K, close to but definitely above Tc. The average hyperfine field Heff(T) of the glassy state shows a temperature dependence of indicative of the existence of spin wave excitations. The values of and are found to be 0.40 and 0.06, respectively, for T/Tc ? 0.72. At temperatures close to Tc, Heff(T) varies as (1 ? T/Tc)β where β is one of the critical exponents and its value is found to be 0.29 ± 0.02. 相似文献
11.
A determination of the decay α parameter of the omega? → K? λ decay mode on the basis of fifteen omega-events from K?p interactions at 10 GeV/c yields the value . 相似文献
12.
The parameter η̄ of muon decay has been measured in the radiative decay of unpolarized positive muons. The result (68% confidence) or with ρ fixed at yields an improvement of the previous value by more than a factor of two. An analysis of all data on muon decay that are presently available slightly improves the constraints on the weak coupling constants to: gs?0.29gv, gp?0.27gv, gT?0.23gv and 0.92gv?gA?1.2gv 相似文献
13.
R. Stroynowski D. Blockus W. Dunwoodie D.W.G.S. Leith M. Marshall C.L. Woody B. Barnett C.Y. Chien T. Fieguth M. Gilchriese D. Hutchinson W.B. Johnson P. Kunz T. Lasinski L. Madansky W.T. Meyer A. Pevsner S. Williams 《Physics letters. [Part B]》1980,97(2):315-319
The production of prompt electron-positron pairs in 16 GeV/c π-p collisions has been measured using the LASS spectrometer at SLAC. An excess of events is observed above the estimated contribution of direct and Dalitz decays of known resonances in the kinematic range defined by and . The excess signal decreases slowly with increasing M, but exhibits very steep χ and pT2 dependence. 相似文献
14.
Results are reported on the reaction at six lab momenta spanning the region from 0.686 to 1.098 GeV/c. The cross section for this process drops from 5.2 ± 0.4 mb at 0.686 GeV/c to 2.9 ± 0.2 mb at 1.098 GeV/c. Resonance production is determined by means of a model which includes Bose symmetrization and Breit-Wigner amplitudes. The likelihood fit to the resonance channels yields a few per cent ?ππ, approximately 10% in each of the channels fππ, ??, and A2π, and about 40% ?f production, with errors on the order of 5%. Excellent fits to the mass distributions are obtained. Essentially all production and decay angular distributions are found to be uniform, with only a few small deviations from isotropy reported. The angular correlations between like and unlike charged pion pairs are also found to be fit extremely well by the simple model of resonance production with Bose symmetrization. 相似文献
15.
We studied the energy width and the width in reciprocal space Δq of the central mode of SrTiO3 above Tc. At Tc+4° we observed an energy width of about 6×10?7 eV. If the measured Δq is interpreted by a correlation length we obtain . 相似文献
16.
R. Brandelik W. Braunschweig H.-U. Martyn H.G. Sander D. Schmitz W. Sturm W. Wallraff D. Cords R. Felst R. Fries E. Gadermann H. Hultschig P. Joos W. Koch U. Kötz H. Krehbiel D. Kreinick S. Yamada 《Physics letters. [Part B]》1977,70(3):387-392
The semileptonic and leptonic decay modes of charmed hadrons produced in e+e? collisions above 4 GeV in the cm have been investigated by selecting events with a single electron plus at least two charged tracks. The electron momentum spectrum peaks near 0.5 GeV/c with few events above 0.7 GeV/c. The spectrum excludes large rates for the decays and , but is compatible with , or a mixture of both. The semileptonic branching ratio is obtained both by comparing the inclusive electron cross section with the total cross section attributable to charm, and by studying the fraction of events containing a second electron. The semileptonic charm branching ratios obtained are 0.11 ± 0.03 and 0.16 ± 0.06 respectively. A single event with three electrons and hadrons is found, consistent with the estimated background. The 90% confidence upper limit for σ(e+e? → 3e + hadrons) is 0.1 nb. 相似文献
17.
B. Niczyporuk T. Zełudziewicz K.W. Chen R. Hartung G. Folger B. Lurz H. Vogel U. Volland H. Wegener J.K. Bienlein R. Graumann J. Krüger M. Leissner M. Schmitz F.H. Heimlich R. Nernst A. Schwarz M. Scheer 《Physics letters. [Part B]》1981,100(1):95-100
We report the first observation of the decay . The 7 events seen yield a branching ratio B(?′→?π+π?)=(19±8)%. A consistent value of B=(26±13)% is obtained from the charged multiplicities of the ?′ and ? decays. Using these values we deduce Γtot(?′)=(31+10?8) keV and Bee(?′)=(1.8±0.5)%. Furthermore we estimate Γ(?′→gg?)=(10±5) keV in agreement with QCD predictions using vector gluons while one would expect 100 keV with scalar gluons. 相似文献
18.
The mass distributions obtained from a K?p experiment at 5.5 GeV/c are used to study the recent suggestion of an s-wave Kπ resonance at 1360 MeV. Using a model including s- and p- wave and , s-, p- and d-wave amplitudes, we analyze the spherical harmonic moments 〈Yl0〉 of the Kπ decay angular distribution in the K1 (1420) mass region and obtain the result that the reported mass of 1360 MeV does not necessarily represent the resonance position and is influenced by cuts made in the Kπ decay angle. 相似文献
19.
G. Bassompierre G. Binder P. Dalpiaz P.F. Dalpiaz G. Gissinger S. Jacquey C. Peroni M.A. Schneegans L. Tecchio 《Physics letters. [Part B]》1977,68(5):477-479
From the measurement of , obtained in an experiment at CERN with antiprotons at rest, a value of the proton electromagnetic form factors at the threshold of the time-like region is derived: |GE| = |GM| = 0.51 ± 0.08 at q2 = -3.52 (GeV/c)2. 相似文献
20.
E. Amaldi M. Beneventano B. Borgia A. Capone F. De Notaristefani U. Dore F. Ferroni E. Longo L. Luminari P. Pistilli I. Sestili G.F. Dell L.C.L. Yuan G. Kantardjian 《Physics letters. [Part B]》1979,84(3):360-362
We present data obtained at the ISR, on the determination of the ratio GeV and we compare the results with our previous measurement at GeV. The ratio integrated over the interval 0.1 ? χT ? 0.2 is (1.6 ± 0.5) × 10?2 and we obtain an indication of a universal χT dependence. 相似文献