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71.
D S Narayan 《Pramana》1979,12(4):391-395
The production of prompt neutrinos in the beam dump experiment is explained in a cluster model, by postulating the emission of strange clusters in hadron collisions, besides the usual non-strange clusters. The low mass strange clusters can decay only by the weak interaction. The leptonic and semi-leptonic decay modes of these clusters give rise to prompt neutrinos. A prediction of the model is that the ratios <v e>/π + at PS energies would be the same as SPS energies.  相似文献   
72.
The parity violating non-leptonic decays of hyperons and of charmed baryons are discussed in the framework of SU (8) symmetry. Several relations in addition to the ones obtained earlier by using SU (4) symmetry and20″-dominance, are obtained. The assumption of20″-dominance at the SU (4) level is no longer required for explaining the non-leptonic decays of 1/2+ baryons.  相似文献   
73.
The formalisms of helicity coupling amplitudes for J/ψ→π^+π^-π^0 are presented. A detailed discussion is also given on the barrier factor, Breit Wigner, and density matrix. A Monte Carlo simulation of J/ψ→ρ(770)π→π^+π^-π^0 is carried out. The results show that the p(770) resonance is well reproduced compared with experimental data.  相似文献   
74.
A role of the axial-vector mesons, such as K1 and a1, on the emitted-photon spectrum in hot hadronic matter is studied through the channels πρ→a 1→πγ and Kρ→K 1Kγ. Both channels could be dominant over the region lower than E γ∼ 0.5 GeV, while the role of the K1 meson is diminished in the higher E γ region. This study is carried out with an SU L(3) ⊗SU R(3) effective chiral Lagrangian which includes vector and axial-vector mesons systematically and explains well their hadronic and radiative decays simultaneously. Received: 8 August 2001 / Accepted: 4 February 2002  相似文献   
75.
Recent exclusive coincidence measurements of non-mesonic weak decays (NMWD) reported for the ratio of the partial decay width of neutron-induced-to-proton-induced NMWD, Γnp , values of 0.45±0.11±0.03 and 0.51±0.13±0.04 for 5lam and 12 Λ C , respectively. These observations agree well with the improved theoretical Γnp ratios which are in the range of 0.3-0.7. It appears that the long-standing discrepancy between the experimental and theoretical values of Γnp has finally been solved. However, when compared to the results of intra-nuclear cascade (INC) calculations, the observed numbers of both single nucleons and coincident nucleon pairs are strongly quenched. The quenching of the proton yield observed previously has been interpreted as an increase of the Γnp ratio. On the other hand, significant contributions from the two-nucleon-induced three-body process ΛNNnNN are predicted. Indeed, the angular correlation of the emitted nucleon pairs in the NMWD of 12 Λ C showed not only decay events in back-to-back kinematics, but also events with non-back-to-back kinematics. In this paper we show that the difficulties to extract the correct Γnp ratio from the proton spectra is related to the three-body weak-interaction process which strongly quenches the nucleon yields.  相似文献   
76.
77.
We present the expected ALICE performance for the measurement of the p t-differential cross section of electrons from beauty decays in central Pb-Pb collisions at the LHC. for the ALICE Collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.  相似文献   
78.
Within the framework of perturbative QCD factorization, we investigate the nonfactorizable contributions to the factorization-forbidden quasi-two-body decays \begin{document}$ B_{(s)}\rightarrow h\chi_{c0}\rightarrow h\pi^+\pi^-(K^+K^-) $\end{document} with \begin{document}$ h=\pi, K $\end{document}. We compare our predicted branching ratios for the \begin{document}$ B_{(s)}\rightarrow K\chi_{c0}\rightarrow K\pi^+\pi^-(K^+K^-) $\end{document} decay with available experiment data as well as predictions by other theoretical studies. The branching ratios of these decays are consistent with data and other theoretical predictions. However, in the Cabibbo-suppressed decays \begin{document}$ B_{(s)}\rightarrow h\chi_{c0}\rightarrow h\pi^+\pi^-(K^+K^-) $\end{document} with \begin{document}$ h=\bar{K}^0,\pi $\end{document}, the values of the branching ratios are of the order of \begin{document}$ 10^{-7} $\end{document} and \begin{document}$ 10^{-8} $\end{document}. The ratio \begin{document}$ R_{\chi_{c0}} $\end{document} between the decays \begin{document}$B^+\rightarrow $\end{document}\begin{document}$ \pi^+\chi_{c0}\rightarrow \pi^+\pi^+\pi^-$\end{document} and \begin{document}$ B^+\rightarrow K^+\chi_{c0}\rightarrow K^+\pi^+\pi^- $\end{document} and the distribution of branching ratios for different decay modes in invariant mass are considered in this study.  相似文献   
79.
We study the CP-averaged branching fractions and the CP-violating asymmetries in the pure annihilation decays ofB _s~0→a_0~+a _0~-andB _d~0→K_0~(*+)K_0~(*-),where a_0[K_0~*]denotes the scalar a_0(980) and a_0(1450)[K_0~*(800)(ork)and K_0~*(1430)],with the perturbative QCD factorization approach under the assumption of two-quark structure for the a_0and K_0~*states.The numerical results show that the branching ratios of theB _d~0→K_0~(*+)K_0~(*-)decays are in the order of 10~(-6),while the decay rates of theB_s~0→a_0~+a _0~-modes are in the order of 10~(-5).In light of the measured modes with the same quark components in the pseudoscalar sector,namely,B _d~0→K~+K~-and B_s~0→p p~(+-),the predictions for the considered decay modes in this work are expected to be measured at the Large Hadron Collider beauty and/or Belle-Ⅱ experiments in the (near) future.Meanwhile,it is of great interest to find that the twist-3 distribution amplitudes φ~S and φ~T with inclusion of the Gegenbauer polynomials for the scalar a_0(1450) and K_0~*(1430)states in scenario2 contribute slightly to the branching ratios while significantly to the CP violations in the B_d~0→K_0~*(14 30)~+K_0*(14 30)~-and B_s~0→a_0(1450)~+a_0(1450)~-decays,which indicates that,compared to the asymptotic φ~Sand φ~T,these Gegenbauer polynomials could change the strong phases evidently in these pure annihilation decay channels.These predictions await for the future confirmation experimentally,which could further provide useful information to help explore the inner structure of the scalars and shed light on the annihilation decay mechanism.  相似文献   
80.
E.  Koorambas 《理论物理通讯》2013,(11):561-570
We investigate the nature of the dark matter by proposing a mechanism for the breaking of local rotational symmetry between ordinary third family leptons and proposed non-regular leptons at energy scales below 10 TeV. This symmetry breaking mechanism involves electric charge swap between ordinary families of leptons can and produces highly massive non-regular leptons of order 0 (1 TeV) mass unobservable at energy scales below 10 TeV (the scale of LEP Ⅰ, Ⅱ and neutrino oscillation experiments). Electric charge swap between ordinary families of leptons produces heavy neutral non-regular leptons with order 0 (1 TeV) masses, which may form cold dark matter. The existence of these proposed leptons can be tested once the Large Hadron Collider (LHC) becomes operative at 10 TeV energy-scales. This proposition may have far reaching applications in astrophysics and cosmology.  相似文献   
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