共查询到20条相似文献,搜索用时 31 毫秒
1.
J. Burmester L. Criegee H.C. Dehne K. Derikum R. Devenish G. Flügge J.D. Fox G. Franke Ch. Gerke P. Harms G. Horlitz Th. Kahl G. Knies M. Rössler R. Schmitz U. Timm H. Wahl K. Wacker 《Physics letters. [Part B]》1977,68(3):297-300
We have measured inclusive muon production in e+e? annihilation for CMS energies between 3.6 and 5.0 GeV. Above 4 GeV the cross section cannot be explained by conventional sources like higher order QED processes or inclusive production of the (3.1). It is, however, compatible with the pair production of heavy particles of a mass of about 1.9 GeV/c2. Spin assignment and decay parameters are investigated. 相似文献
2.
The possibility of observing Higgs particles through virtual effects is considered in detail for a general gauge theory. The effect of charged Higgs particles on low-energy weak interaction processes, like muon decay, tau decay, nuclear beta decay, pion decay, and some higher-order processes is analyzed. The effect of flavor-changing neutral Higgs particles on rare decay modes of the muon and kaon, μe conversion, Ko-o and Do-o mixing is also studied. We discuss constraints on possible extensions of the Weinberg-Salam model and experiments sensitive to their Higgs particles. In particular, we analyze the neutral Higgs which couple to fermions in the minimal SU(2)L×SU(2)R×U(1) model and find that they probably have mass greater than 100 GeV. 相似文献
3.
P. Bosetti H. Deden P. Fritze H. Grässler F.J. Hasert R. Schulte K. Böckmann Th. Kokott B. Nellen B. Wünsch D.C. Cundy A. Grant P.O. Hulth H. Klein D.R.O. Morrison E. Pagiola L. Pape D. Vignaud 《Physics letters. [Part B]》1982,110(2):167-172
Exposures of the Ne/H2 filled Big European Bubble Chamber (BEBC) to a dichromatic neutrino (antineutrino) beam produced by 400 GeV protons of the CERN SPS yielded ~ 3100 events with a negative, and ~ 1100 with a positive, muon. The neutrino flux is determined from the muon flux in the shielding. Assuming a linear energy dependence of the cross section, the values between 20 and 200 GeV are found to be 0.657 ± 0.012 (stat.) ± 0.027 (syst.) and 0.309 ± 0.009 (stat.) ± 0.013 (syst.) cm2 (GeV nucleon)?1, for neutrinos and antineutrinos, respectively. The scaling variable decreases significantly with increasing energy both for neutrinos and antineutrinos. 相似文献
4.
W. Bozzoli A. Bussière G. Giacomelli E. Lesquoy R. Meunier L. Moscoso A. Muller D.E. Plane F. Rimondi S. Zylberajch 《Nuclear Physics B》1979,159(3):363-382
A search for long-lived particles (τ ? 10?8 sec), with changes , produced in 200 GeV pN collisions was performed at the CERN-SPS in a secondary beam equipped with superconducting r.f. separators. Upper limits were obtained for the production of long-lived hadrons and leptons. For charge - 1 particles the limits are at the level of 10?7 of the pions at a mass m = 0.2 GeV and reach the 10?11 level from . The production of light antinuclei was measured. The cross sections for 3He production are (1.3 ± 0.3) and (1.9 ± 0.3) × 10?34 cm2/sr · GeV/c at 21 and 47.4 GeV/c respectively; for t the cross section is (7.6 ± 0.9) × 10?34 cm2/sr · GeV/c at 23.7 GeV/c. 相似文献
5.
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
6.
J.P. Albanese V. Alpe S. Aoki R. Arnold G. Baroni M. Barth J.H. Bartley D. Bertrand G. Bertrand-Coremans V. Bisi A.C. Breslin G. Carboni E. Chesi K. Chiba G.S. Cook M. Coupland G. Crosetti D.H. Davis Y. Yanagisawa 《Physics letters. [Part B]》1985,158(2):186-192
The associated production of a pair of beauty particles B? and by a 350 GeV π? interaction has been observed in an emulsion target inserted in an array of silicon microstrip detectors. Both beauty particles decay into charm particles, both of which are also observed to decay in the emulsion. Two negative muons were identified and their momenta measured in a large muon spectrometer. One muon has a pT of 1.9 GeV/c and is associated with a beauty particle decay. The other, with a pT of 0.45 GeV/c is associated with a charm particle decay. The flight times of the two beauty particles are respectively (0.8 ± 0.1) × 10?13 s and (5+2?1) × 10?13 s. Alternative interpretations of this event have negligible probability. 相似文献
7.
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
8.
J.G. Lee A. Harckham M. Letheren W. Beusch F. Bourgeois E. Polgár D. Websdale K. Freudenreich R. Frosch F.X. Gentit P. Mühlemann 《Nuclear Physics B》1973,52(1):292-300
The differential cross section for the charge exchange has been measured with high statistics at 7.76 GeV/c and at 5.0 GeV/c. The 7.76 GeV/c data show a very narrow [Δt ? 0.01 (GeV/c)2] forward peak superposed on a slow exponential fall-off. 相似文献
9.
L. Satta J. Duflo F. Plouin P. Picozza L. Goldzahl J. Banaigs R. Frascaria F.L. Fabbri A. Codino J. Berger M. Boivin P. Berthet 《Physics letters. [Part B]》1984,139(4):263-266
Elastic scattering differential cross sections of α particles have been measured at Pα=7.0 GeV/c () on 1H, 2H, 3He and 4He target up to a momentum transfer of ~4 (GeV/c)2. A preliminary interpretation of the data is given in the framework of the Glauber theory. 相似文献
10.
E.G. Boos D.I. Ermilova V.V. Samojlov T. Temiraliev B.V. Batyunya I.V. Boguslavsky N.B. Dashian I.M. Gramenitsky R. Lednický S.V. Levonian L.A. Tikhonova A. Valkárová V. Vrba Z. Zlatanov S. Dumbrajs J. Ervanne E. Hannula V.D. Tsintsadze 《Nuclear Physics B》1980,174(1):45-67
New results on the inclusive and semi-inclusive production of π+ mesons and protons in the whole phase space are given for about 2.2 · 104 inelastic interactions at 22.4 GeV/c. A method of statistical separation for spectra of particles of the same charge which are produced in CP-symmetrical reactions is discussed in detail. Experimental data are compared with quark-parton model predictions. 相似文献
11.
D. Errede C. Akerlof J. Chapman N. Harnew P. Kesten S. Kooijman D.I. Meyer D. Nitz D. Rubin A.A. Seidl R. Thun T. Trinko M. Willutzky M. Derrick E. Fernandez R. Fries L. Hyman P. Kooijman J. VaVra 《Physics letters. [Part B]》1984,149(6):519-523
A search was made in 29 GeV e+e? annihilations for heavy, neutral leptons decaying to e±X?(ν), where X is a muon or charged meson. Six events with isolated e±X? pairs were found for an intergrated luminosity of 106 pb?1. The expected background is 5.5 ± 2.2 events. Limits on depend on mass and range from 8 to 20 × 10?5 nb. 相似文献
12.
A. Bodek R. Breedon R.N. Coleman W. Marsh S. Olsen J.L. Ritchie B.C. Barish R.L. Messner M.H. Shaevitz E.J. Siskind F.S. Merritt H.E. Fisk Y. Fukushima P.A. Rapidis G. Donaldson S.G. Wojcicki 《Physics letters. [Part B]》1982,113(1):82-86
The rates for same-sign and opposite-sign dimuon events with missing energy (indicative of final-state neutrinos) have been measured in 278 GeV π?-Fe and 350 GeV proton-Fe collisions. The main source of opposite-sign events is two semi-leptonic decays of hadronically produced charm states. The same-sign events are consistent with background from pion and kaon decays. We obtain a limit of 0.044 (90% CL) on the fraction of D0 semileptonic decays that result in the wrong-sign muon and conclude that less than 9% (90% CL) of same-sign dimuon events produced in neutrino interactions can be attributed to D0-0 mixing. The data imply δm < 6.5 × 10?4 eV and for the difference in mass and inverse lifetime of the CP eigenstates of the D0. Limits on diffractive bottom production cross sections in proton and pion collisions are also presented. 相似文献
13.
W.E. Cleland A. Delfosse P.A. Dorsaz P. Extermann J.L. Gloor O. Guisan V. Hungerbühler M.N. Kienzle-Focacci G. Mancarella A.D. Martin M. Martin P. Mühlemann C. Nef E.N. Ozmutlu T. Pal P. Rosselet J. Rutschmann R. Sutter H. Zeidler 《Physics letters. [Part B]》1980,89(2):290-294
We have collected 6100 events in the reactions and K?p→(Λ)p at an incident energy of 50 GeV, with the Geneva-Lausanne spectrometer at the SPS. We have investigated the productioon of strangeness S = ± 1 baryon-antibaryon pairs with mass up to 3 GeV, by performing a moment analysis of the decay angular distribution. An amplitude analysis of the moments shows evidence for two broad states with spin-parity 2? and 4?, at 2.3 GeV and 2.5 GeV, respectively, coupling to p and Λ. 相似文献
14.
H. Braun D. Brick A. Fridman J.-P. Gerber P. Juillot G. Maurer A. Michalon M.-E. Michalon-Mentzer C. Voltolini 《Physics letters. [Part B]》1976,60(5):481-484
Based on 4085 events, X denoting a neutral N or system, we present evidence for 5.1 and 3.1 standard deviation enhancements at the X mass of 2.85 and 3.05 GeV/c2, respectively. The lower mass bump has a width of Λ ? 39 GeV/c2 while the 3.05 GeV/c2 is seen as a one bin accumulation (20 GeV/c2 width). The relevance of these peaks is discussed. 相似文献
15.
John Ellis J.S. Hagelin D.V. Nanopoulos K. Olive M. Srednicki 《Nuclear Physics B》1984,238(2):453-476
We consider the cosmological constraints on supersymmetric theories with a new, stable particle. Circumstantial evidence points to a neutral gauge/Higgs fermion as the best candidate for this particle, and we derive bounds on the parameters in the lagrangian which govern its mass and couplings. One favored possibility is that the lightest neutral supersymmetric particle is predominantly a photino with mass above GeV, while another is that the lightest neutral supersymmetric particle is a Higgs fermion with mass above 5 GeV or less than O(100) eV. We also point out that a gravitino mass of 10 to 100 GeV implies that the temperature after completion of an inflationary phase cannot be above 1014 GeV, and probably not above 3 × 1012 GeV. This imposes constraints on mechanisms for generating the baryon number of the universe. 相似文献
16.
S.J. Watts D.V. Bugg A.A. Carter M. Coupland E. Eisenhandler W.R. Gibson P.I.P. Kalmus H. Sandhu A. Astbury G.H. Grayer A.W. Robertson T.P. Shah C. Sutton 《Physics letters. [Part B]》1980,95(2):323-326
The polarization parameter for K+n charge exchange scattering has been measured at five momenta between 0.851 GeV/c and 1.351 GeV/c for centre of mass angles . Results from a phase shift analysis incorporating these results are presented. No Z1 resonances are observed. 相似文献
17.
U. Amaldi W. Bartel G. Cocconi A.N. Diddens Z. Dimcovski R.W. Dobinson P. Duinker A.M. Thorndike A.M. Wetherell G. Bellettini P.L. Braccini R. Castaldi T. Del Prete P. Laurelli G. Sanguinetti M. Valdata A. Baroncelli G. Matthiae R. Thun 《Physics letters. [Part B]》1975,58(2):206-212
Data obtained from p-p collisions at centre-of-mass energies between 31 and 63 GeV are presented on correlations between momentum analysed forward π?, K? and and charged particles observed in an omnidirectional hodoscope. The data show that significant correlations are present over the whole rapidity range for all three types of negative particles. The dependence on various kinematic variables suggests a cluster mechanism for the production of particles. In this picture, pions would be produced in clusters emitted in the fragmentation region while K? and emanate from non-leading clusters. 相似文献
18.
On the possibility of finding light uncolored supersymmetric partners at present and future machines
Supersymmetric models allow the possibility of finding new light fermions (m <mw, and perhaps m < 10–15 GeV, charged or neutral) that are (apart from mixing effects) the supersymmetric partners of W, Z0, and Higgs bosons. We provide a detailed analysis of their expected properties, production mechanisms, and signatures, with emphasis on detection at e+e- colliders. Although the charged, particles resemble sequential leptons, it turns out that their properties differ enough that they might have been missed in the standard searches with normal cuts, and they still might be found with m < 18 GeV. A neutral, particle with m below about 30 GeV could exist with a clear decay signature and be singly produced at detectable rates at present machines (picobarn cross sections). 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》1980,176(2):346-354
The differential cross sections for K?p and p elastic scattering have been measured over the range of four-momentum transfer squared 0.18<?t<3.3 (GeV/c)2. The K?p data decrease smoothly as a function of ?t, whereas, the data shows a break at ?t = 0.6 (GeV/c)2 followed by a fast drop to ?t ? 1.6 (GeV/c)2 where the differential cross section levels off and stays constant out to ?t = 3 (GeV/c)2. 相似文献
20.
The paper contains results (a) for the general optimal polarization formalism with constraints from time reversal invariance, identical particles, and parity conservation, (b) for the specific reaction involving four particles, (c) for the application of the formalism to elastic p?p scattering at 6 GeV/c and at 800 MeV. The choice of the orientation axes under various symmetry constraints is discussed for the general optimal formalism, showing the narrowing of the choices which nevertheless retains an infinite continuum of possibilities. The transformation properties of amplitudes among these various optimal frames are specified. The transformation of observables among these frames is also discussed for the reaction with four particles. Then the relationship between the observables and the bilinear combination of amplitudes is given for the reaction with four particles, for the constraints of identical particles, identical particles and time reversal invariance, and identical particles and time reversal invariance and parity conservation. The results are applied to the analysis of the Argonne data at 6 GeV/c, t = ?0.6 GeV2/c2, for elastic p?p scattering. The amplitudes are easily determined when the proper optimal frame is used, and the display of the amplitudes in other optimal frames suggest some features that may be significant in searching for dynamics. Another application is presented to 800 MeV elastic p?p scattering at several angles, showing that in the proper optimal frame very accurate results can be obtained about a subset of amplitude parameters on the basis of an incomplete set of data. Such an analysis is shown to be helpful in the design of future experiments. 相似文献