65 research outputs found

    Multiscale Technicolor and bsγb \to s \gamma

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    Correction to the bsγb\rightarrow s\gamma branching ratio in the multiscale walking technicolor model (MWTCM) is examined. For the original MWTCM, the correction is too large to explain the recent CLEO data. We show that if topcolor is further introduced, the branching ratio in the topcolor assisted MWTCM can be in agreement with the CLEO data for a certain range of the parameters.Comment: 11 pages, Latex, no macros, 3 figures, hard copy is available upon request. to appear in Z. Phys.

    Charmless decays B -> PP, PV, and effects of new strong and electroweak penguins in Topcolor-assisted Technicolor model

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    Based on the low energy effective Hamiltonian with generalized factorization, we calculate the new physics contributions to the branching ratios and CP-violating asymmetries of the two-body charmless hadronic decays BPP,PVB \to PP, PV from the new strong and electroweak penguin diagrams in the TC2 model. The top-pion penguins dominate the new physics corrections, and both new gluonic and electroweak penguins contribute effectively to most decay modes. For tree-dominated decay modes Bππ,ρπ,etc,B \to \pi \pi, \rho \pi, etc, the new physics corrections are less than 10%. For decays BK()πB \to K^{(*)} \pi, K()ηK^{(*)} \eta, etcetc, the new physics enhancements can be rather large (from 70- 70% to 200\sim 200%) and are insensitive to the variations of NceffN_c^{eff}, k2k^2, η\eta and mπ~m_{\tilde{\pi}} within the reasonable ranges. For decays B0ϕπB^0 \to \phi \pi, ϕη()\phi \eta^{(')}, KKˉ0K^* \bar{K}^0 and ρ+K0\rho^+ K^0, δB\delta {\cal B} is strongly NceffN_c^{eff}-dependent: varying from -90% to 1680\sim 1680% in the range of Nceff=2N_c^{eff}=2-\infty. The new physics corrections to the CP-violating asymmetries ACP{\cal A}_{CP} vary greatly for different B decay channels. For five measured CP asymmetries of BKπ,Kη,ωπB \to K \pi, K \eta', \omega \pi decays, δACP\delta {\cal A}_{CP} is only about 20% and will be masked by large theoretical uncertainties. The new physics enhancements to interesting BKηB \to K \eta' decays are significant in size (50\sim 50%), insensitive to the variations of input parameters and hence lead to a plausible interpretation for the unexpectedly large BKηB \to K \eta' decay rates. The TC2 model predictions for branching ratios and CP-violating asymmteries of all fifty seven BPP,PVB \to PP, PV decay modes are consistent with the available data within one or two standard deviations.Comment: Latex file, 56 pages with 11 ps and eps figures. to be published in Eur.Phys.J.

    The Υ(nS){\Upsilon}(nS) {\to} BcπB_{c}^{\ast}{\pi}, BcKB_{c}^{\ast}K decays with perturbative QCD approach

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    Besides the traditional strong and electromagnetic decay modes, Υ(nS){\Upsilon}(nS) meson can also decay through the weak interactions within the standard model of elementary particle. With anticipation of copious Υ(nS){\Upsilon}(nS) data samples at the running LHC and coming SuperKEKB experiments, the two-body nonleptonic bottom-changing Υ(nS){\Upsilon}(nS) {\to} BcπB_{c}^{\ast}{\pi}, BcKB_{c}^{\ast}K decays (nn == 1, 2, 3) are investigated with perturbative QCD approach firstly. The absolute branching ratios for Υ(nS){\Upsilon}(nS) {\to} BcπB_{c}^{\ast}{\pi} and BcKB_{c}^{\ast}K decays are estimated to reach up to about 101010^{-10} and 101110^{-11}, respectively, which might possibly be measured by the future experiments.Comment: 16 pages, 3 figure