共查询到20条相似文献,搜索用时 31 毫秒
1.
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
2.
L. Adiels G. Backenstoss I. Bergström S. Carius S. Charalambous M. D. Cooper Ch. Findeisen D. Hatzifotiadou M. Hugi A. Kerek H. O. Meyer P. Pavlopoulos J. Repond L. Tauscher D. Troester M. C. S. Williams K. Zioutas 《Zeitschrift fur Physik C Particles and Fields》1989,42(1):49-58
The inclusive η-momentum spectrum from \(\bar p\) annihilations at rest in liquid hydrogen was measured at LEAR. Branching ratios were obtained for $$\begin{gathered} p\bar p \to \eta \omega \left( {1.04_{ - 0.10}^{ + 0.09} } \right)\% ,\eta \rho ^0 \left( {0.53_{ - 0.08}^{ + 0.20} } \right)\% , \hfill \\ \pi a_2 \left( {8.49_{ - 1.10}^{ + 1.05} } \right)\% ,\eta \pi ^0 \left( {1.33 \pm 0.27} \right) \times 10^{ - 4} , \hfill \\ \end{gathered} $$ , and ηη(8.1±3.1)×10?5. An upper limit for \(p\bar p \to \eta \eta '\) of 1.8×10?4 at 95% CL was found. The ratio of the branching ratios is BR(η?)/BR(ηω)=0.51 ?0.06 +0.20 . For the ratio of branching ratios into two pseudoscalar mesons, we have BR(ηπ0)/BR(π0π0)=0.65±0.14, BR(ηη)/BR(π0π0), BR(η η ′ )/BR(π0π0) at 95% CL, and BR(ηη)/BR(ηπ0). 相似文献
3.
O. I. Piskounova 《Physics of Atomic Nuclei》2001,64(1):98-102
The asymmetry between the spectra of leading and nonleading charmed mesons that was measured in Σ? A interactions at p L=340 GeV/c in the WA89 experiment is described within the Model of Quark-Gluon Strings (QGS model also known as QGSM) under the assumption that there is a fraction of charmed sea quark-antiquark pairs (intrinsic charm) in an interacting hyperon. It is shown that the asymmetries between D ?-and D +-meson spectra and between D s ? -and D s + -meson spectra can be approximated by QGSM curves obtained with the same string-fragmentation parameter, a 1=10, and the same intrinsic-charm fraction, $\delta _{c,\bar c} = 0.01$ , as those that were used in describing D s ? /D s + -meson asymmetry of π? A experiments in previous studies. The asymmetry between the spectra of Λc and $\bar \Lambda _c $ that was measured in Σ? A collisions at p L=600 GeV/c in the E781 experiment is also described within this scheme. The QGSM results are compared with the results of the calculations in the next-to-leading approximation of perturbative QCD that were performed by other authors. 相似文献
4.
J. Chrin 《Zeitschrift fur Physik C Particles and Fields》1987,36(1):163-171
Results on the fragmentation of heavy quarks from analyses of inclusive lepton production ine + e ? annihilation are studied. The use of various fragmentation variables is closely examined and their differences resolved, providing a common basis for comparison of experimental results. The mean value of the fraction of available energy-momentum carried by the primary heavy hadron, defined as $$z = \frac{{(E + p_\parallel )_{hadron} }}{{(E + p)_{quark} }},$$ is determined to be 〈z〉=0.67±0.02±0.02 and 〈z〉b=0.83±0.01±0.02 for an unknown mixture of charmed and bottom flavoured hadrons respectively. The corresponding values of the parameter? Q of the Peterson fragmentation function are $$\varepsilon _c = 0.06_{ + 0.02 + 0.02}^{ - 0.01 - 0.01} and \varepsilon _b = 0.06_{ + 0.001 + 0.02}^{ - 0.001 - 0.02} .$$ The ratio? c /? b can be approximately related toM b 2 /M c 2 giving a value of 10 ?2?4 +4+5 , in agreement with an expectation of ~10. Measurements of the charged multiplicity of hadronic events containing heavy quark jets are investigated in terms of the mean value ofz. 相似文献
5.
6.
S. Dvořák 《Czechoslovak Journal of Physics》1968,18(7):840-846
The identity $$\sum\limits_{v = 0} {\left( {\begin{array}{*{20}c} {n + 1} \\ v \\ \end{array} } \right)\left[ {\left( {\begin{array}{*{20}c} {n - v} \\ v \\ \end{array} } \right) - \left( {\begin{array}{*{20}c} {n - v} \\ {v - 1} \\ \end{array} } \right)} \right] = ( - 1)^n } $$ is proved and, by means of it, the coefficients of the decomposition ofD 1 n into irreducible representations are found. It holds: ifD 1 n \(\mathop {\sum ^n }\limits_{m = 0} A_{nm} D_m \) , then $$A_{nm} = \mathop \sum \limits_{\lambda = 0} \left( {\begin{array}{*{20}c} n \\ \lambda \\ \end{array} } \right)\left[ {\left( {\begin{array}{*{20}c} \lambda \\ {n - m - \lambda } \\ \end{array} } \right) - \left( {\begin{array}{*{20}c} \lambda \\ {n - m - \lambda - 1} \\ \end{array} } \right)} \right].$$ 相似文献
7.
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
8.
A. E. Asratyan M. Aderholz V. V. Ammosov W. Burkot E. F. Clayton T. Coghen O. Erriquez G. S. Gapienko V. A. Gapienko J. Guy D. Hantke G. T. Jones V. S. Kaftanov U. F. Katz J. Kern V. A. Korotkov S. P. Krutchinin M. A. Kubantsev P. Marage D. B. Miller M. M. Mobayyen D. R. O. Morrison M. Neveu J. Sacton N. Schmitz K. Varvell W. Venus W. Wittek V. G. Zaetz 《Zeitschrift fur Physik C Particles and Fields》1993,58(1):55-60
The diffractive production of charmed strangeD s * and possiblyD s mesons by neutrinos and antineutrinos on nucleons in hydrogen, deuterium and neon targets is observed. The slope parameter of thet distribution is 3.3±0.8 (GeV)?2. The production rate per charged current neutrino interaction with an isoscalar target times the D s + →φτ+ branching fraction is (1.03±0.27)×10?4. 相似文献
9.
V. A. Uvarov S. A. Akimenko V. N. Bolotov G. I. Britvich V. A. Duk A. P. Filin A. V. Inyakin S. A. Kholodenko A. A. Khudyakov A. S. Konstantinov V. F. Konstantinov V. M. Leontiev A. I. Makarov V. F. Obraztsov V. A. Polyakov A. Yu. Polyarush A. V. Popov V. I. Romanovsky O. V. Stenyakin O. G. Tchikilev O. P. Yushchenko 《Physics of Atomic Nuclei》2014,77(6):725-732
The ratio of branching fractions for \(K^ - \to e^ - \bar \nu _e \pi ^0\) andK ? → π?π0 decays has been measured using the ISTRA+ spectrometer. The result of our measurement is the following: $$\mathcal{R}_{Ke_3 /K_{2\pi } } = 0.2423 \pm 0.0015(stat.) \pm 0.0037(syst.).$$ Using the current PDG value for the K 2π branching fraction, this result leads to the measured K e3 branching fraction of Br(K e3) = 0.0501 ± 0.0009 and to the value of |V us |f +(0) = 0.2115 ± 0.0021. 相似文献
10.
The general theory of inhomogeneous mean-field systems of Raggio and Werner provides a variational expression for the (almost sure) limiting free energy density of the Hopfield model $$H_{N,p}^{\{ \xi \} } (S) = - \frac{1}{{2N}}\sum\limits_{i,j = 1}^N {\sum\limits_{\mu = 1}^N {\xi _i^\mu \xi _j^\mu S_i S_j } } $$ for Ising spinsS i andp random patterns ξμ=(ξ 1 μ ,ξ 2 μ ,...,ξ N μ ) under the assumption that $$\mathop {\lim }\limits_{N \to \gamma } N^{ - 1} \sum\limits_{i = 1}^N {\delta _{\xi _i } = \lambda ,} \xi _i = (\xi _i^1 ,\xi _i^2 ,...,\xi _i^p )$$ exists (almost surely) in the space of probability measures overp copies of {?1, 1}. Including an “external field” term ?ξ μ p hμμξ i=1 N ξ i μ Si, we give a number of general properties of the free-energy density and compute it for (a)p=2 in general and (b)p arbitrary when λ is uniform and at most the two componentsh μ1 andh μ2 are nonzero, obtaining the (almost sure) formula $$f(\beta ,h) = \tfrac{1}{2}f^{ew} (\beta ,h^{\mu _1 } + h^{\mu _2 } ) + \tfrac{1}{2}f^{ew} (\beta ,h^{\mu _1 } - h^{\mu _2 } )$$ for the free energy, wheref cw denotes the limiting free energy density of the Curie-Weiss model with unit interaction constant. In both cases, we obtain explicit formulas for the limiting (almost sure) values of the so-called overlap parameters $$m_N^\mu (\beta ,h) = N^{ - 1} \sum\limits_{i = 1}^N {\xi _i^\mu \left\langle {S_i } \right\rangle } $$ in terms of the Curie-Weiss magnetizations. For the general i.i.d. case with Prob {ξ i μ =±1}=(1/2)±?, we obtain the lower bound 1+4?2(p?1) for the temperatureT c separating the trivial free regime where the overlap vector is zero from the nontrivial regime where it is nonzero. This lower bound is exact forp=2, or ε=0, or ε=±1/2. Forp=2 we identify an intermediate temperature region between T*=1?4?2 and Tc=1+4?2 where the overlap vector is homogeneous (i.e., all its components are equal) and nonzero.T * marks the transition to the nonhomogeneous regime where the components of the overlap vector are distinct. We conjecture that the homogeneous nonzero regime exists forp≥3 and that T*=max{1?4?2(p?1),0}. 相似文献
11.
For a large class of generalizedN-body-Schrödinger operators,H, we show that ifE<Σ=infσess(H) and ψ is an eigenfunction ofH with eigenvalueE, then $$\begin{array}{*{20}c} {\lim } \\ {R \to \infty } \\ \end{array} R^{ - 1} \ln \left( {\int\limits_{S^{n - 1} } {|\psi (R\omega )|} ^2 d\omega } \right)^{1/2} = - \alpha _0 ,$$ with α 0 2 +E a threshold. Similar results are given forE≧Σ. 相似文献
12.
We investigate the effects of final state interactions (FSI) contributions in the nonleptonic two body $B^ + \to D_S^ + \bar K^0$ decay, however the hadronic decay of $B^ + \to D_S^ + \bar K^0$ is analyzed by using “QCD factorization” (QCDF) method and final state interaction (FSI). First, the $B^ + \to D_S^ + \bar K^0$ decay is calculated via QCDF method and only the annihilation graphs exist in that method. Hence, the FSI must be seriously considered to solve the $B^ + \to D_S^ + \bar K^0$ decay and the D 0π+(D 0*ρ+), D +π0(D +*ρ0) and D +η c (D +*J/ψ) via the exchange of K +(*), K 0(*) and D s +(*) mesones are chosen for the intermediate states. To estimate the intermediate states amplitudes, the QCDF method is again used. These amplitudes are used in the absorptive part of the diagrams. The experimental branching ratio of $B^ + \to D_S^ + \bar K^0$ decay is less than 8 × 10?4 and the predicted branching ratio is 0.23 × 10?9 in the absence of FSI effects and it becomes 6.74 × 10?4 when FSI contributions are taken into account. 相似文献
13.
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
14.
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
15.
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. 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》1990,48(1):29-45
In the CERN NA 32 experiment a high-resolution silicon vertex detector and a purely topological approach have been used to investigate various decays of charmed particles. We observe ~620 fully reconstructed decays ofD 0 in 12 channels and determine the branching ratios. For fourD 0 decay modes involving a single (unseen) π0 the small and narrowD *+?D 0 mass difference is used to measure their branching ratios. We also observe ~280 fully reconstructedD + decays in 10 channels, ~90D s + decays in 11 channels as well as 160Λ s c and 18 decay channels ofD +. For theD s + , we measure the branching fractions within a subset of 16 three- and five-prong decay channels. For theΛ s c , we determine the branching fractions within a sample of 11 three- and five-prong decay channels, nearly all involving a proton. 相似文献
16.
Thomas S. Ullrich 《Acta Physica Hungarica A》2004,21(2-4):143-150
Inclusive spectra of charged particles at midrapidity in Au+Au collisions at $\sqrt {s_{NN} } = 130$ GeV and 200 GeV were measured with the STAR detector at RHIC. The measured mean transverse momentum 〈p T 〉 shows a characteristic dependence on charged particle multiplicity and beam energy in Au+Au collisions that is distinctly different from pp, $p\bar p$ and e+e? collisions. A 32%±3%(syst) increase in 〈p T 〉 from pp to Au+Au collisions was observed at 200 GeV. While the charged multiplicity was found to increase by 19%±5%(syst) from $\sqrt {s_{NN} } = 130$ GeV to 200 GeV, no significant difference in 〈p T 〉 was found between the two energies. A comparison with model predictions is discussed. 相似文献
17.
I. Alfter E. Bodenstedt W. Knichel J. Schüth R. Vianden 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):363-376
g-factors of rotational states in176Hf and180Hf were measured with the twelve detector IPAC-apparatus of our laboratory [1]. The natural radioactivity 3.78·1010y176Lu and the 5.5 h isomer180mHf were used which populate the ground-state rotational bands of176Hf and180Hf. The integral rotations ofγ-γ directional correlations in strong external magnetic fields and in static hyperfine fields of (Lu→Hf)Fe2 and HfFe2 were observed. The following results were obtained: $$\begin{array}{l} ^{176} Hf: g\left( {4_1^ + } \right) = + 0.334\left( {38} \right) \\ ^{180} Hf: g\left( {2_1^ + } \right) = + 0.305\left( {14} \right) \\ g\left( {4_1^ + } \right) = + 0.358\left( {43} \right) \\ {{ g\left( {6_1^ + } \right)} \mathord{\left/ {\vphantom {{ g\left( {6_1^ + } \right)} {g\left( {4_1^ + } \right)}}} \right. \kern-\nulldelimiterspace} {g\left( {4_1^ + } \right)}} = + 0.95\left( {12} \right) \\ \end{array}$$ . The hyperfine field in (Lu→Hf)Fe2 was calibrated by observing the integral rotation of the 9/2? first excited state of177Hf populated in the decay of 6.7d177Lu. Theg-factor of this state was redetermined in an external magnetic field as $$^{177} Hf: g\left( {{9 \mathord{\left/ {\vphantom {9 {2^ - }}} \right. \kern-\nulldelimiterspace} {2^ - }}} \right) = + 0.228\left( 7 \right)$$ . Finally theg-factor of the 2 1 + state of176Hf was derived from the measuredg(2 1 + ) of180Hf by use of the precisely known ratiog(2 1 + ,176Hf)/g(2 1 + ,180Hf) [2] as $$^{176} Hf: g\left( {2_1^ + } \right) = + 0.315\left( {30} \right)$$ . 相似文献
18.
P. Weidenauer K. D. Duch M. Heel H. Kalinowsky F. Kayser E. Klempt B. May J. Reifenröther O. Schreiber M. Ziegler D. Bailey S. Barlag J. M. Butler U. Gastaldi R. Landua C. Sabev W. Dahme F. Feld-Dahme U. Schaefer W. R. Wodrich J. C. Bizot B. Delcourt J. Jeanjean H. Nguyen E. G. Auld D. A. Axen K. L. Erdman B. Howard R. Howard B. L. White S. Ahmad M. Comyn G. M. Marshall G. Beer L. P. Robertson M. Botlo C. Laa H. Vonach C. Amsler M. Doser J. Riedlberger U. Straumann P. Truöl ASTERIX Collaboration 《Zeitschrift fur Physik C Particles and Fields》1990,47(3):353-365
We have measured the branching ratios for \(\bar pp\) annihilation at rest intoπ + π ? η andπ + π ? η′ in hydrogen gas in two data samples that have different fractions ofS-wave andP-wave initial states. The branching ratios are derived from a comparison with the topological branching ratio for \(\bar pp\) annihilations into four charged pions of (49±4)% and the branching ratio intoπ + π ? π + π ? π 0 of (18.7±1.6)%. We find a significant reduction of the branching ratios fromP-states for \(\bar pp \to \pi ^ + \pi ^ - \eta \) andπ + π ? η′ in comparison toS-state annihilation. $$\begin{gathered} BR(S - wave \to \pi ^ + \pi ^ - \eta ) = (13.7 \pm 1.46) \cdot 10^{ - 3} \hfill \\ BR(P - wave \to \pi ^ + \pi ^ - \eta ) = (3.35 \pm 0.84) \cdot 10^{ - 3} \hfill \\ BR(S - wave \to \pi ^ + \pi ^ - \eta ') = (3.46 \pm 0.67) \cdot 10^{ - 3} \hfill \\ BR(P - wave \to \pi ^ + \pi ^ - \eta ') = (0.61 \pm 0.33) \cdot 10^{ - 3} . \hfill \\ \end{gathered} $$ In a partial wave analysis of theπ + π ? η Dalitz plot we find the following contributions: Phase space, \(a_2^ + (1320)\pi ^ \mp \) ,ηρ0 andf 2(1270)η: $$\begin{gathered} BR(S - wave \to \pi ^ + \pi ^ - \eta PS) = (6.31 \pm 1.22) \cdot 10^{ - 3} \hfill \\ BR(P - wave \to \pi ^ + \pi ^ - \eta PS) = (0.47 \pm 0.26) \cdot 10^{ - 3} \hfill \\ BR(^1 S_0 \to a_2^ \pm (1320)\pi ^ \mp ) = (2.59 \pm 0.73) \cdot 10^{ - 3} \hfill \\ BR(^3 S_1 \to a_2^ \pm (1320)\pi ^ \mp ) = (1.31 \pm 0.48) \cdot 10^{ - 3} \hfill \\ BR(P - wave \to a_2^ \pm (1320)\pi ^ \mp ) = (1.31 \pm 0.69) \cdot 10^{ - 3} \hfill \\ BR(^3 S_1 \to \rho \eta ) = (3.29 \pm 0.90) \cdot 10^{ - 3} \hfill \\ BR(^1 P_1 \to \rho \eta ) = (0.94 \pm 0.53) \cdot 10^{ - 3} \hfill \\ BR(^1 S_0 \to f_2 (1270)\eta ) = (0.083 \pm 0.086) \cdot 10^{ - 3} \hfill \\ BR(P - wave \to f_2 (1270)\eta ) = (0.64 \pm 0.26) \cdot 10^{ - 3} . \hfill \\ \end{gathered} $$ We find a 2 σ effect for the reaction \(\bar pp \to a_0^ \pm (980)\pi ^ \mp \) , \(a_0^ \pm \to \eta \pi ^ \pm \) , with a branching ratio of (0.13±0.07)·10?3. For η' production we give a branching ratio of \(\bar pp \to \rho \eta '\) of (1.81±0.44)·10?3 from3 S 1. We estmate a contribution of about 0.3·10?3 for ρη' fromP-states. The ratio of ρη and ρη' rpoduction is used to test the validity of the quark line rule. In theπ + π ? π + π ? γ final state we do not observe the reaction \(\bar pp \to \pi ^ + \pi ^ - \omega \) , ω→π + π ? λ and derive an upper limit of 3·10?3 for decay modeω→π + π ? λ. 相似文献
19.
Munemi Miyamoto 《Communications in Mathematical Physics》1985,98(2):253-258
Consider the 1/2-Ising model inZ 2. Let σ j be the spin at the site (j, 0)∈Z 2 (j=0, ±1, ±2, ...). Let \(\{ X_n \} _{n = 0}^{ + \infty } \) be a random walk with the random transition probabilities such that $$P(X_{n + 1} = j \pm 1|X_n = j) = p_j^ \pm \equiv 1/2 \pm v(\sigma _j - \mu )/2$$ We show a case whereE[p j + ≧E[p j ? ], but \(\mathop {\lim }\limits_{n \to \infty } X_n = - \infty \) is recurrent a.s. 相似文献
20.
H. Abramowicz J. G. H. de Groot J. T. He J. Knobloch J. May P. Palazzi A. Para F. Ranjard T. Z. Ruan A. Savoy-Navarro D. Schlatter J. Steinberger H. Taureg W. von Rüden H. Wahl J. Wotschack W. M. Wu F. Eisele H. P. Klasen K. Kleinknecht H. Lierl B. Pszola B. Renk H. J. Willutzki G. Conforto F. Dydak T. Flottmann C. Geweniger V. Hepp J. Królikowski K. Tittel P. Bloch C. Guyot S. Loucatos J. P. Merlo B. Peyaud J. Rander J. Rothberg J. P. Schuller R. Turlay 《Zeitschrift fur Physik C Particles and Fields》1982,13(3):179-189
In the interactions of 400 GeV/c protons with copper nuclei, a flux of prompt neutrinos is observed. The reactions produced by these neutrinos in our apparatus appear consistent with those of electron- and muon-neutrinos. The prompt neutrino fluxes are interpreted as being due to associated production and subsequent semileptonic decay of charmed hadrons. The prompt flux ratio \(\bar v_\mu /v_\mu = 0.46_{ - 0.16}^{ + 0.21} \) suggests a sizeable production of charmed baryons near the forward direction. The ratio of prompte ?+e + toµ ?+µ + event rates is 0.64 ?0.15 +0.22 , where unity is expected frome-μ universality. 相似文献