共查询到20条相似文献,搜索用时 484 毫秒
1.
R. Brandelik W. Braunschweig K. Gather F.J. Kirschfink K. Lübelsmeyer H.-U. Martyn G. Peise J. Rimkus H.G. Sander D. Schmitz D. Trines W. Wallraff H. Boerner H.M. Fischer H. Hartmann E. Hilger W. Hillen G. Zobernig 《Physics letters. [Part B]》1982,113(1):98-104
The inclusive production of π± mesons in e+e? annihilation has been measured at c.m. energies of 14, 22 and 34 GeV for pion momenta between 0.3 ans 10 GeV/c. The fraction of pions among the charged hadrons is above 90% at 0.4 GeV/c and decreases to about 50% at high momenta. The scaled cross sections () at 14, 22 and 34 GeV as well as the 5.2 GeV data from DASP have a rather similar x dependence. After integration over the x range from 0.2 to 0.6 the cross sections indicate a monotonic decrease with increasing centre-of-mass energy. 相似文献
2.
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 G.R. Court G. DAgostini W.D. Dau S.J. Wimpenny 《Physics letters. [Part B]》1983,133(6):461-466
A search was made at the CERN SPS for long-lived fractionally charged particles produced in deep inelastic muon interactions on a Be target using the existing muon beam line as a spectrometer. No such particles were found, leading to upper limits for the production cross section of the order of 10?36 cm2 for 200 GeV incident muon momentum and quark masses below 9 GeV for the charge and 15 GeV for charge. 相似文献
3.
B. Alper H. Bℷgild P. Booth F. Bulos L.J. Carroll G. von Dardel G. Damgaard B. Duff F. Heymann J.N. Jackson G. Jarlskog L. Jonsson A. Klovning L. Leistam E. Lillethun G. Lynch G. Manning M. Prentice J.M. Weiss 《Physics letters. [Part B]》1973,46(2):265-268
Measurements have been performed on production of particles with mass 1.5 GeV/c2 and charge for θlab = 62.5° and . At pT = 0.7 GeV/c the relative rate of production of antideuterons to π? is (5 ± 1) × 10?5. The deuteron to antideuteron ratio is 3.7 ± 1.2. No new stable particle has been amongst 0.7 × 108 charged particles entering our detector. 相似文献
4.
P.V. Chliapnikov P.A. Gorbunov S.A. Gumenyuk V.V. Kniazev B.A. Manyukov V.M. Perevoztchikov V.N. Riadovikov V.A. Uvarov M.L. Faccini-Turluer M. Loret L. Mosca H. Blumenfeld J. Laberrigue C. Dujardin F. Grard J. Skura R. Windmolders M. Csejthey-Barth M. Gysen 《Nuclear Physics B》1977,131(1):93-106
A study of the inclusive and semi-inclusive Λ and production in K+p interactions at 32 GeV/c is presented. The inclusive cross sections for Λ and amount to 0.78 ± 0.05 and 0.42 ± 0.04 mb thus showing a remarkable growth between 16 and 32 GeV/c with a factor of 1.7 for Λ and 2.8 for . Target and beam fragmentation processes are found to be dominant for Λ and production respectively with the following lower limits for the corresponding cross sections: and . Although the early scaling conditions are fulfilled for the Λ production in the target fragmentation region, and production in the beam fragmentation region, scaling is not observed between 16 and 32 GeV/c in the x and pT2 Feynman variables. The Λ production is found to be very similar in the K+p inclusive reaction at 32 GeV/c and in the semi-inclusive reaction at the same energy. The pair production cross section increases significantly in K+p interactions from 16 to 32 GeV/c where it reaches the value . The cross sections for Λ or produced in association with an identified proton are also given and discussed. 相似文献
5.
J. Badier C. Bemporad J. Boucrot O. Callot P. Charpentier A. M. Cnops M. Crozon P. Delpierre J. F. Detoeuf G. R. Giannini R. Hammarstr?m P. Lariccia R. Lorenzi J. Mas A. Michelini A. Tilquin J. K. Walker NA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1986,31(1):21-32
A sensitive search has been done for the production of new long-lived and penetrating particles by 300 GeV/c negative pions. No new state —decaying into at least two charged known particles —has been detected with mass above 1 GeV/c2 and lifetime in the range 5·10?11 s to 5·10?7s. We give upper limits on production cross sections, and consequences on the existence of heavy “axion-like” particles, heavy neutrinos and supersymmetric particles. In particular, this experiment excludes the existence of light gluinos with lifetime in the range 5·10?11 to 10?8s: this closes the last “window of opportunity” for gluinos withM<2 GeV/c2 and lifetime measurable in particle physics experiments. 相似文献
6.
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
7.
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
8.
C. Evangelista B. Ghidini A. Palano V. Picciarelli G. Zito P. Mättig K. Müller E. Paul W. Rühmer B.R. French W.A. Mitaroff C. Palazzi-Cerrina R. Strub A.S. Thompson P.L. Woodworth M. Edwards T. Armstrong H.D. Lambacher 《Physics letters. [Part B]》1977,72(1):139-143
In a search for resonances coupled to the pπ? system, we have studied π?p interactions at 16 GeV/c giving a forward antiproton, using the Omega spectrometer at CERN. In the final states involving a , p and π? we observe a 5.6 (6.3) standard deviation enhancement in the pπ? mass spectrum at (2.95 ± 0.01) GeV with a width consistent with the resolution (σ = 15 MeV). The production cross section × branching ratio is estimated to be of the order 1 μb. The data are consistent with a resonance decaying partly via intermediate p final states. 相似文献
9.
J. Badier J. Boucrot G. Burgun O. Callot Ph. Charpentier M. Crozon D. Décamp P. Delpierre B. Gandois R. Hagelberg M. Hansroul W. Kienzle P. Le Dû J. Lefrançois Th. Leray G. Matthiae A. Michelini Ph. Miné S. Weisz 《Physics letters. [Part B]》1979,89(1):145-150
We have measured the absolute cross section for dimuon production in hadron collisions at 200 GeV/c in the continuum region M = 4–8.5 GeV. In all the channels studied (pN, N, π±N and π?H2) the experimental cross section is significantly larger by a factor of 2.3 ± 0.5 than expected from the Drell-Yan model. Furthermore, our proton-nucleon data allow a determination of the nucleon valence structure function which agrees with the deep inelastic lepton scattering data. 相似文献
10.
M.J. Corden J.D. Dowell D. Eastwood J. Garvey R.J. Homer M. Jobes I.R. Kenyon T. McMahon R.J. Vallance P.M. Watkins J.A. Wilson J. Gago M. Jung P. Sonderegger D. Treille P.L. Woodworth V. Eckardt J. Fent K.C.T.O. Sumorok 《Physics letters. [Part B]》1977,68(1):96-100
Measurements have been made of relative production cross sections of the by π±, K±, p and p? at 39.5 GeV/c incident on copper. production rates from π?, K? and p? are similar. The relative particle/anti-particle production cross sections for x>0 are , σ(K+)/σ(K?)=(0.85±0.5) and . The small p/p? cross section ratio disagrees with models of J/ψ production by gluon amalgamation. 相似文献
11.
S. Ciampolillo B. Degrange M. Dewit T. François D. Haidt M. Jaffre C. Longuemare C. Matteuzzi F. Mattioli J.B.M. Pattison M. Pohl C. Vander Velde Wilquet P. Vilain H.W. Wachsmuth 《Physics letters. [Part B]》1979,84(2):281-284
Average total cross sections are given for neutrino charged current interactions at neutrino energies of 2.87 GeV and 9.05 GeV. The ratios in units of 10?38 cm2/GeV nucleon, respectively The errors include both statistical and systematic uncertainties. 相似文献
12.
J.F. Martin C. Bolon R.C. Lanza D. Luckey L.S. Osborne D.G. Roth G.J. Feldman G. Hanson D.E. Lyon M.L. Perl T. Pun J.T. Dakin 《Physics letters. [Part B]》1976,65(5):483-486
We present a high statistics study of particle ratios in electroproduction of forward hadrons. The π+/π? ratios for a proton target rise monotonically to a value of 2.4 ± 0.2 at Q2 of 3 (GeV/c)2 and for a neutron target average 1.16 ± 0.04 from Q2 of 0.35 to 3 (GeV/c)2. We report the first data on electroproduction of , and measure the cross sections of K±, p, and relative to pions as a function of Q2. 相似文献
13.
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
14.
Yu.B. Bushnin A.F. Dunaytzev S.V. Golovkin V.P. Kubarovsky L.G. Landsberg V.M. Leontyev T.I. Petrunina V.A. Senko A.M. Zaytzev 《Nuclear Physics B》1973,58(2):476-493
Negative results of a search for heavy quasistable charged leptons at the IHEP accelerator are reported. For the selection of heavy leptons a system of scintillation and gas ?erenkov counters was used. The upper limit estimations of the differential cross sections for heavy lepton production in pN collisions at Ep = 70 GeV are, for example, d2σ/dpω (p = 30 GeV/c, θ = 2 mrad, 1 ? Mλ ? 4.8 GeV) = 4.10?38 cm2/sr · GeV. The results of the present work, together with the data on muon pair production in nucleon-nucleon interactions, show that there are no heavy charged leptons with masses from 0.55 GeV (τλ > 7 · 10?10 sec) up to 4.5 GeV (τλ > 3 · 10?8 sec). 相似文献
15.
J.M. Weiss G.S. Abrams M.S. Alam C.A. Blocker A. Blondel A.M. Boyarski M. Breidenbach D.L. Burke W.C. Carithers W. Chinowsky M.W. Coles S. Cooper W.E. Dieterle J.B. Dillon J. Dorenbosch J.M. Dorfan M.W. Eaton G.J. Feldman H. Zaccone 《Physics letters. [Part B]》1981,101(6):439-443
We have searched 1.4 × 106e+e? annihilation events for particles with 1–3 GeV/c2 mass and charge from the processes e+e?→qX and e+e? → q. Upper limits of RQ ~ 10?4 for each process are presented which improve the previous limits on free quark production in electromagnetic interactions by 2 orders of magnitude. 相似文献
16.
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
17.
V.V. Abramov A.V. Alekseev B.Yu. Baldin S.I. Bityukov V.Yu. Glebov A.S. Dyshkant V.N. Evdokimov A.N. Krinitsin V.I. Kryshkin N.Yu. Kulman G.I. Lanshchikov V.K. Myalitsyn Yu.M. Melnik A.P. Orlov V.I. Povzun R.M. Sulyaev L.K. Turchanovich Yu.N. Vrazhnov V.V. Zmushko 《Nuclear Physics B》1980,173(2):348-364
The cross sections for π±, K±, p, and production in pp collisions have been measured at transverse momenta from 0.48 up to 2.21 GeV/c at 70 GeV. The data are compared with results obtained at lower and higher proton energies and also with the quantum chromodynamics parton model (QPM) calculations. Common behaviour of the cross sections of the form in the energy range above 200 GeV does not take place at lower energies. Qualitatively QPM fits the data and the best agreement is for π+/π? and K+/π+ ratios. 相似文献
18.
W.C. Carithers T. Modis D.R. Nygren T.P. Pun E.L. Schwartz H. Sticker J.H. Christenson 《Nuclear Physics B》1977,118(5):333-338
We have measured the transmission regeneration amplitude for carbon. The invariant amplitude varies from 5.909 ± 0.066 mb at 4.5 GeV/c to 3.933 ± 0.152 mb at 9.5 GeV/c. The results agree with optical model calculations using measured kaon-nucleon total cross sections. The data also provide a value for the ω trajectory intercept αω(0) = 0.42 ± 0.04. 相似文献
19.
W.D. Apel J. Ausländer H. Müller G. Sigurdsson H.M. Staudenmaier E. Bertolucci I. Mannelli G. Pierazzini P. Rehak A. Scribano F. Sergiampietri M.L. Vincelli 《Physics letters. [Part B]》1973,46(3):459-464
The ratio between the cross sections for the reactions and π?p → η→2γ n has been measured to be (2.4 ± 0.9) × 10?2, (2.1 ± 0.6) × 10?2 and (2.8 ± 1.3) × 10?2 at 3.8,6,8 and 12 GeV/c incident momentum respectively.At the same momenta the cross section for πt- p → neutrals is (1.48 ± 0.09) mb, (0.86 ± 0.05) mb, (0.64 ± 0.04) mb and (0.42±0.03) mb. 相似文献
20.
O. Erriquez S. Natali S. Nuzzo A. Pullia F. Romano D.C. Colley G.T. Jones L. Lowe S. ONeale S.J. Sewell G. Bertrand-Coremans H. Mulkens J. Sacton C. Vander Velde-Wilquet J. Wickens V. Brisson P. Petiau T.W. Jones 《Physics letters. [Part B]》1978,77(2):227-232
For e+ energy > 0.3 GeV and 10 GeV < visible energy < 100 GeV we find that: (i) ; (ii) 1.2 ± 0.5 neutral strange particles are produced per μ?e+ event; (iii) the lifetime of possible positron-parent particles is < 3 × 10?10 s (90% C.L.); (iv) the cross section for direct e+ production via the neutral current is < 0.2 times that via the charged current (90% C.L.); (v) the cross section for producing heavy leptons, L+, decaying into e+ … is < 0.7 × 10?3 times that for μ?production, implying M(L+) > 10 GeV. 相似文献