共查询到20条相似文献,搜索用时 31 毫秒
1.
R. Bailey E. R. Belau T. Böhringer M. Bosman V. Chabaud C. Damerell C. Daum H. Dijkstra S. Gill A. Gillman R. S. Gilmore Z. Hajduk C. Hardwick W. Hoogland B. D. Hyams J. Kemmer R. Klanner U. Kötz S. W. L. Kwan G. Lütjens G. Lutz J. Malos W. Männer E. Neugebauer H. Paŀka M. Pepe J. Richardson G. de Rijk M. Rozanska K. Rybicki H. Seebrunner U. Stierlin R. J. Tapper H. G. Tiecke M. Turala G. Waltermann P. Weilhammer F. Wickens L. W. Wiggers A. Wylie T. Zeludziewicz ACCMOR-Collaboration 《Zeitschrift fur Physik C Particles and Fields》1986,30(1):51-63
We have measured the differential and total cross sections ofD meson production in 200 GeV π?-beryllium interactions, using a sample of 48 fully reconstructed and nearly background-freeD mesons in the decay channelsK ?π±,K ?π±π± andK ?π?π±π±. A single electron trigger has been used to select events containing a pair of charmed particles. A vertex telescope of 6 silison microstrip detectors allowed the reconstruction of tracks of charged secondaries and the reconstruction of primary and decay vertices with high precision. The ratio of branching fractions for \(\mathop {D^0 }\limits^{( - )} \to K^ \mp \pi ^ \pm \) to \(\mathop {D^0 }\limits^{( - )} \to K^ \mp \pi ^ \mp \pi ^ \pm \pi ^ \pm \) , and an upper limit for \(D^0 - \bar D^0 \) mixing are presented. 相似文献
2.
V. F. Kurshetsov Yu. M. Antipov A. V. Artamonov V. A. Batarin O. V. Eroshin V. Z. Kolganov A. S. Konstantinov A. P. Kozhevnikov A. E. Kushnirenko L. G. Landsberg V. M. Leontiev G. S. Lomkatsi V. V. Molchanov V. A. Mukhin A. F. Nilov D. I. Patalakha S. V. Petrenko V. T. Smolyankin D. V. Vavilov V. A. Victorov 《Physics of Atomic Nuclei》2005,68(3):439-454
A search for narrow Θ+(1540), a candidate for a pentaquark baryon with positive strangeness, has been performed in an exclusive proton-induced reaction $p + C(N) \to \Theta ^ + \bar \kappa ^0 + C(N)$ on carbon nuclei or quasifree nucleons at $E_{beam} = 70GeV(\sqrt s = 11.5GeV)$ studying nK +, pK S 0 , and pK L 0 decay channels of Θ+(1540) in four different final states of the $\Theta ^ + \bar K^0 $ system. In order to assess the quality of the identification of the final states with neutron or K L 0 , we reconstructed Λ(1520) → nK S 0 and ? → K L 0 K S 0 decays in the calibration reactions p + C(N) → Λ (1520)K ++C(N) and p+C(N) → p?+C(N). We found no evidence for a narrow pentaquark peak in any of the studied final states and decay channels. Assuming that the production characteristics of the $\Theta ^ + \bar K^0 $ system are not drastically different from those of the Λ(1520)K + and p? systems, we established upper limits on the cross-section ratios $\sigma (\Theta ^ + \bar K^0 )/\sigma (\Lambda (1520)K^ + ) < 0.02$ and $\sigma (\Theta ^ + \bar K^0 )/\sigma (p\phi ) < 0.15$ at 90% C.L. and a preliminary upper limit for the forward-hemisphere cross section $\sigma (\Theta ^ + \bar K^0 )$ nb/nucleon. 相似文献
3.
T. A. Armstrong M. Benayoun W. Beusch I. J. Bloodworth J. N. Carney R. Childs B. R. French B. Ghidini A. Jacholkowski J. Kahane J. B. Kinson A. Kirk K. Knudson V. Lenti Ph. Leruste A. Malamant J. L. Narjoux F. Navach A. Palano E. Quercigh N. Redaelli L. Rossi M. Sené R. Sené M. Stassinaki M. T. Trainor G. Vassiliadis O. Villalobos Baillie M. F. Votruba G. Zito R. Zitoun WA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1990,46(3):405-410
The reactionpp→p f (K + K -π+π-)p s , where theK + K ? π+π- system is centrally produced, has been studied at 300 GeV/c. TheK *0 \(K^{*0} \bar K^{*0} \) final state has been observed and the cross sections for its central production are found to be the same at 300 and 85 GeV/c. TheK *0 \(K^{*0} \bar K^{*0} \) final state appears to be produced as a non-resonant threshold enhancement. 相似文献
4.
We have performed a two-channel calculation of Cabibbo-angle favoured decays,D s + →VP. We find a satisfactory fit toS s + →φπ +,ρ 0 π + andK + \(\bar K^{ * 0} \) data from ARGUS and E-691. We have also studied Cabbibo-angle favouredD→VP decays in a coupled channel formalism. We coupleD→K *π,K ? and \(\bar K^0 \phi \) channels inI=1/2 state, andK *π andK ? channels inI=3/2 state. We leave the two channels, \(\bar K^0 \omega \) and \(\bar K^{ * 0} \eta \) out of our unitarization scheme. Particular attention is paid to the role of the weak annihilation term in these decays. 相似文献
5.
6.
E. A. De Wolf J. J. Dumont F. Verbeure I. V. Ajinenko P. V. Chliapnikov V. P. Falaleev L. N. Gerdyukov A. E. Kurnosenko V. N. Riadovikov V. F. Tchumikin V. A. Uvarov A. P. Vorobjev F. Grard CERN-Soviet Union Collaboration 《Zeitschrift fur Physik C Particles and Fields》1982,12(2):105-112
Results are presented on inclusive production of resonant and non-resonant particle systems produced inK + p interactions at 32 GeV/c. We compareK *+(892), \(\bar \Sigma ^{ * - } \) (1385), Σ*±(1385), and ?0 inclusivex-spectra with the ones of non-resonantK s 0 π±, \(\bar \Lambda \pi ^ - \) , Λπ± and π+π? pairs at the same effective mass. Resonance-particle pairsK *+π±, Σ*+π?, and \(\bar \Sigma ^{ * - } \pi ^ - \) are also studied together with non-resonant tripletsK s 0 π±, Λπ+π?, \(\bar \Lambda \pi ^ - \pi ^ - \) . The invariantx-spectra of resonant particle pairs decrease less rapidly withx then the corresponding non-resonant pairs. Comparison with quark-recombination predictions indicates that the particles, resonances and multiparticle systems are probably created off a single valence quark or diquark instead of carrying all possible valence-quarks. 相似文献
7.
I. I. Y. Bigi 《Zeitschrift fur Physik C Particles and Fields》1980,6(1):83-84
Based onV spin consideration, it is argued that20 dominance in the effective weak Lagrangian does not strongly reduce theinclusive decay rate ofD + mesons. Decays of the typeD→Kρ,K *π, ρπ are discussed in pointing out that 20 dominance should lead to a large enhancement of \(D^ + \to \bar K^0 \rho ^ + ,\left( {\bar K^0 } \right) * \pi ^ + \) over \(D^ + \to \bar K^0 \pi ^ + \) ;W exchange, on the other hand, leads to a sizeable suppression ofD 0→K ? ρ +,(K ?)*π+ relative toD 0→K ?π+. 相似文献
8.
D. Bisello G. Busetto A. Castro M. Nigro L. Pescara P. Sartori L. Stanco A. Antonelli R. Baldini M. E. Biagini M. Schioppa J. E. Augustin A. Calcaterra G. Cosme F. Couchot F. Fulda G. Grosdidier B. Jean-Marie V. Lepeltier F. Mane G. Szklarz 《Zeitschrift fur Physik C Particles and Fields》1991,52(2):227-230
The \(e^ + e^ - \to K_s^0 K^ \pm \pi ^ \mp \) andK + K ?π0 cross sections have been measured in the energy interval \(1350 \leqq \sqrt s \leqq 2400\) with the DM2 detector at DCI. The \(K_s^0 K^ \pm \pi ^ \mp \) cross section shows the contribution of an isoscalar vector meson at ≈1650 MeV/c2 in agreement with a previous experiment. The low statisticsK + K ?π0 measurement is consistent with the above result. 相似文献
9.
F. Buccella O. Pisanti F. Sannino 《Zeitschrift fur Physik C Particles and Fields》1995,66(1-2):135-140
We relate the asymmetries in the charged pions energy in the decay into π+π?π0 ofK L and of the tagged neutral kaons. The former asymmetry is a given combination of $\Re (\varepsilon ), \Im (\varepsilon )$ , and üε'ü. Moreover, the non-violating CP asymmetry allows a test for theχ PT predictions within the Zel'dovich approach for the final state interaction. 相似文献
10.
E. A. De Wolf J. J. Dumont M. Van Immerseel F. Verbeure F. Grard D. Denegri C. Lewin I. V. Ajinenko P. V. Chliapnikov L. N. Gerdyukov V. V. Kniazev V. N. Riadovikov V. A. Uvarov CERN-Soviet Union Collaboration French-Soviet Union Collaboration 《Zeitschrift fur Physik C Particles and Fields》1981,8(3):189-197
Results are presented on two-particle inclusive production inK + p interactions at 32 GeV/c. We study thex 1,2=x 1+x 2 dependence of invariant structure functions of (ππ)-pairs and compare them to single particle inclusive distributions in the fragmentation regions. Distributions of particles observed at Feynmanx 2 in association with various “trigger” particles or systems atx 1 in the same hemisphere are dicussed in terms of the reduced variable \(\tilde x_2 = x_2 /(1 - |x_1 |)\) . We further present absolute production rates and production ratios of π+'s and π?'s associated with π±,K s 0 , Λ, \(\bar \Lambda \) ,K *+ (890), (K s 0 π+), and (π+ π?)-triggers, and compare them with qualitative predictions of the quark recombination model. Forwardbackward correlations between (K s 0 π±), (K s 0 ,p), (Λ, π?), \((\bar \Lambda \pi ^ \pm )\) , and (p, π?) pairs are also discussed. 相似文献
11.
Dephasing in open quantum chaotic systems has been investigated in the limit of large system sizes to the Fermi wavelength ratio, L/λF 〉 1. The weak localization correction g wl to the conductance for a quantum dot coupled to (i) an external closed dot and (ii) a dephasing voltage probe is calculated in the semiclassical approximation. In addition to the universal algebraic suppression g wl ∝ (1 + τD/τ?)?1 with the dwell time τD through the cavity and the dephasing rate τ ? ?1 , we find an exponential suppression of weak localization by a factor of ∝ exp[? $\tilde \tau $ /τ?], where $\tilde \tau $ is the system-dependent parameter. In the dephasing probe model, $\tilde \tau $ coincides with the Ehrenfest time, $\tilde \tau $ ∝ ln[L/λF], for both perfectly and partially transparent dot-lead couplings. In contrast, when dephasing occurs due to the coupling to an external dot, $\tilde \tau $ ∝ ln[L/ξ] depends on the correlation length ξ of the coupling potential instead of λF. 相似文献
12.
V. V. Anisovich A. A. Kondashov Yu. D. Prokoshkin S. A. Sadovsky A. V. Sarantsev 《Physics of Atomic Nuclei》2000,63(8):1410-1427
We perform a K-matrix analysis of IJ PC =00++, 10++, 02++, and 12++ meson partial waves using GAMS data on π? p → π0π0 n, ηηn, ηη'n that are supplemented with BNL data on π? p → K $\bar K$ n and Crystal Barrel data on p $\bar p$ (at rest) → π0π0π0, π0ηη, π0π0η. The positions of the amplitude poles (physical resonances) are determined, together with the positions of the K-matrix poles (bare states) and the values of barestate couplings to two-meson channels. The nonet classification of the bare states found in the present analysis is discussed. 相似文献
13.
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 V. Lüth G. Lutz J. Malos W. Männer E. Neugebauer H. Palka M. Pepe 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 ACCMOR Collaboration 《Zeitschrift fur Physik C Particles and Fields》1990,46(4):563-567
We present the final results on the measurement of the masses and lifetimes of the mesonsD 0,D + andD s + in the NA32 experiment at the CERN SPS, using silicon microstrip detectors and charge-coupled devices for vertex reconstruction. We measure the following lifetimes: \(\tau _{D^0 } = 3.88 \pm _{0.21}^{0.23} \cdot 10^{ - 13} s\) using a sample of 479D°→K ?π+π?π+ and 162D°→K ?π+ decays; \(\tau _{D^ + } = 10.5 \pm _{0.72}^{0.77} \cdot 10^{ - 13} s\) with a sample of 317D +→K ?π+π+ decays; \(\tau _{D_s^ + } = 4.69 \pm _{0.86}^{1.02} \cdot 10^{ - 13} s\) with a sample of 54D s + →K + K ?π+ decays. We measure the following masses:m D 0=1864.6±0.3±1.0 MeV,m D +=1870.0±0.5±1.0 MeV and \(m_{D_s^ + } \) =1967.0±1.0±1.0 MeV. 相似文献
14.
W. Fetscher P. Kokkas P. Pavlopoulos Th. Ruf Th. Schietinger 《Zeitschrift fur Physik C Particles and Fields》1996,72(4):543-547
We propose a new method for measuring the difference $\Delta f = f(0) - \bar f(0)$ of the forward scattering amplitudes for K0 and $\bar K^0 $ by use of decay rates of initially pure strangeness states after passage through a regenerator. The phenomenology of coherent kaon regeneration is presented for arbitrary mixtures of K0 and $\bar K^0 $ . 相似文献
15.
Effects of a nonzero mass for the tau neutrinov τ as well as a right-handed charged-current contribution to the τ?v τ coupling are discussed. Angular correlations of the decay products of τ+τ? ine + e ? annihilation are calculated as functions of \(m_{v_\tau } \) and the relative amount of right-handed τ?v τ coupling. 相似文献
16.
The branching ratios for the exclusive decays of the heavy quarkonia Ψ(3770) and ?(10580) to a pair of light mesons [π + π -, $K\bar K$ , ρ(ω)π, ρ(ω)η, ρ(ω)η’, $K^* \bar K$ +c.c, ρ + ρ -, and $K^* \bar K^* $ ] and the branching ratios for the decays Ψ(3770) → J/Ψ + P(P = π 0, η) and ?(10580) → ?(1S) + P(P = π 0,η,η′), which involve a heavy quarkonium in the final state, are calculated with allowance for new data on the width of the D*±(2010) meson and the mass differences between the charged and neutral beauty mesons (B ±, on one hand, and B 0 and $\bar B^0 $ , on the other hand). The calculations are based on the model where the Okubo-Zweig-Iizuka rule is dynamically violated owing to the intermediate state $D\bar D (B\bar B)$ in the case of the Ψ(3770) [?(10580)] meson. The inclusive annihilation of Ψ(3770) and ?(10580) mesons to light hadrons is discussed. 相似文献
17.
A. V. Anisovich V. V. Anisovich V. N. Markov N. A. Nikonov 《Physics of Atomic Nuclei》2002,65(3):497-512
The quark structure of φ(1020) and f 0(980) is studied on the basis of data on the radiative decays φ(1020) → γπ 0, γη, γη′, γ a 0(980), γ f 0(980) and f 0(980) → γγ. The partial widths are calculated under the assumption that all the mesons under consideration are $\bar qq$ states: φ(1020) is a dominantly $s\bar s$ state ( $\eta ' = n\bar nsin\theta + s\bar scos\theta $ component contributes not more than 1%); η, η′, and π 0 are standard $q\bar q$ states, $\eta = n\bar ncos\theta - s\bar ssin\theta $ and $\eta ' = n\bar nsin\theta + s\bar scos\theta $ with θ?37°; and f 0(980) is a e5 meson with the flavor wave function $n\bar ncos\varphi + s\bar ssin\varphi $ . The transition φ → γπ 0 specifies the admixture of the $n\bar n$ component in the φ meson: it is on the order of 0.5%. We argue that this order of $n\bar n$ value does not contradict data on the decay φ(1020) → γ a 0(980). The partial widths calculated for the decays φ → γη, γη? are in reasonable agreement with experimental data. The measured branching-ratio value Br(φ→γf 0(980))=(3.4±0.4 ?0.5 +1.5 ×10?4) requires 25°≤|?|≤90°. For the decay f 0(980) → γγ, the agreement with data, Γ(f 0(980) → γγ)=0.28 ?0.13 +0.09 keV, is attained at either ?=85°±8° or ?=?46°±8°. A simultaneous analysis of the decays φ(1020) → γ f 0(980) and f 0(980) → γγ favors the solution with the negative mixing angle of ?=?48°±6°, setting f 0(980) very close to the flavor octet (? octet=±54.7°). 相似文献
18.
J. C. Pati 《Physics of Atomic Nuclei》2000,63(6):1058-1077
Following recent joint works with K. Babu and F. Wilczek, I stress here that supersymmetric unification, based on symmetries like SO(10) or a string-derived G(224)=SU(2) L ×SU(2) R ×SU(4) C possesses some crucial features that are intimately linked to each other. They are (a) gauge-coupling unification; (b) the masses and mixings of all fermions, including especially the neutrinos; and last but not least (c) proton decay. In this context, it is noted that the value of $m_{v_L^\tau } \sim 1/20{\text{ }}eV$ , suggested by the Super-Kamiokande result, goes extremely well with the unification-hypothesis, based on the ideas of (i) SU(4)-color, (ii) left-right symmetry, and (iii) supersymmetry. A concrete proposal is presented within an economical SO(10)-framework that makes five successful predictions for the masses and mixings of the quarks and the charged leptons. The same framework explains why the νπ?ντ oscillation angle is so large $(\sin ^2 2\theta _{\nu _\mu \nu _\tau }^{osc} \approx 0.82 - 0.96)$ and yet V bc is so small (≈0.04), both in accord with observation. The influence of the masses of the neutrinos and of the charged fermions on proton decay is discussed concretely, within this framework. The $\bar \nu K^ + $ mode is expected to be dominant for SUSY SO(10) as well as SU(5). A distinctive feature of the SO(10) model, however, is the likely prominence of the μ+ K 0 mode, which, for SU(5), is highly suppressed. Our study shows that while current limits on the rate of proton decaying into $\bar \nu K^ + $ are compatible with theoretical expectations, improvements in these limits by a factor of 5–10 should either turn up events, or else the SO(10)-framework described here, which is otherwise so successful, will be in jeopardy. Prominence of theμ+ K 0 mode, if observed, will be most significant in that it will reveal the intriguing link that exists between neutrino masses and proton decay in the context of supersymmetric unification. 相似文献
19.
We estimate $BR(K \to \pi \nu \bar \nu )$ in the context of the Standard Model by fitting for λ t≡V tdV ts * of the “kaon unitarity triangle” relation. To find the vertex of this triangle, we fit data from |? K|, the CP-violating parameter describing K mixing, and a ψ,K , the CP-violating asymmetry in B d 0 → J/ψK 0 decays, and obtain the values $\left. {BR(K \to \pi \nu \bar \nu )} \right|_{SM} = (7.07 \pm 1.03) \times 10^{ - 11} $ and $\left. {BR(K_L^0 \to \pi ^0 \nu \bar \nu )} \right|_{SM} = (2.60 \pm 0.52) \times 10^{ - 11} $ . Our estimate is independent of the CKM matrix element V cb and of the ratio of B-mixing frequencies ${{\Delta m_{B_s } } \mathord{\left/ {\vphantom {{\Delta m_{B_s } } {\Delta m_{B_d } }}} \right. \kern-0em} {\Delta m_{B_d } }}$ . We also use the constraint estimation of λ t with additional data from $\Delta m_{B_d } $ and |V ub|. This combined analysis slightly increases the precision of the rate estimation of $K^ + \to \pi ^ + \nu \bar \nu $ and $K_L^0 \to \pi ^0 \nu \bar \nu $ (by ?10 and ?20%, respectively). The measured value of $BR(K^ + \to \pi ^ + \nu \bar \nu )$ can be compared both to this estimate and to predictions made from ${{\Delta m_{B_s } } \mathord{\left/ {\vphantom {{\Delta m_{B_s } } {\Delta m_{B_d } }}} \right. \kern-0em} {\Delta m_{B_d } }}$ . 相似文献
20.
Patricia Fachini 《Acta Physica Hungarica A》2002,15(3-4):195-204
Preliminary results from measurements of resonances (K *0(892), $\overline {K*^0 } (892)$ , Φ(1020), and ρ(770)) and weakly decaying particles (Λ(1116), $\bar \Lambda (1116)$ , and K S 0 (498)) are presented. The measurements are performed at mid-rapidity by the STAR detector in $\sqrt {s_{NN} } = 130$ GeV Au?Au collisions at RHIC. The ratios K *0/h?, $\overline {K*^0 } /K$ , and $\bar \Lambda /\Lambda $ are compared to measurements at different energies and colliding systems. Estimates of thermal parameters, such as temperature and baryon chemical potential, are also presented. 相似文献