184 research outputs found

    Top quark, heavy fermions and the composite Higgs boson

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    We study the properties of heavy fermions in the vector-like representation of the electro-weak gauge group SU(2)W×U(1)YSU(2)_W\times U(1)_Y with Yukawa couplings to the standard model Higgs boson. Applying the renormalization group analysis, we discuss the effects of heavy fermions to the vacuum stability bound and the triviality bound on the mass of the Higgs boson. We also discuss the interesting possibility that the Higgs particle is composed of the top quark and heavy fermions. The bound on the composite Higgs mass is estimated using the method of Bardeen, Hill and Lindner, 150GeVmH\leq m_H\leq 450GeV.Comment: 10 pages and 6 figures. This paper replaces and is an extended version of hep-ph/9602340 (published in Phys. Lett. B370(1996)201;Erratum B382(1996)448

    Some Remarks on Exotic Resonances

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    Using large NcN_c counting rule, it is argued that tetra-quark resonances do not exist. Also it is pointed out that there exists the violation of exchange degeneracy in the exotic KNKN scattering channel. It implies either the failure of resonance saturation assumption or it suggests the existence of exotic baryon resonances in such a channel.Comment: Talk given at 10th International Symposium on Meson-Nucleon Physics and the Structure of the Nucleon (MENU 2004), Beijing, China, 29 Aug - 4 Sep 200

    A Numerical Analysis to the {π\pi} and {K} Coupled--Channel Scalar Form-factor

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    A numerical analysis to the scalar form-factor in the ππ\pi\pi and KK coupled--channel system is made by solving the coupled-channel dispersive integral equations, using the iteration method. The solutions are found not unique. Physical application to the ππ\pi\pi central production in the ppppππpp\to pp\pi\pi process is discussed based upon the numerical solutions we found.Comment: 8 pages, Latex, 3 figures. Minor changes and one reference adde

    Some Remarks on the Final State Interactions in BπKB\to \pi K Decays

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    Careful discussions are made on some points which are met in studying B decay final state interactions, taking the B0π+KB^0\to \pi^+ K^- process as an example. We point out that π\pi--exchange rescatterings are not important, whereas for DD^* and DD^{**} exchanges, since the B0D+DsB^0\to D^+D_s^- decay has a large branching ratio their contributions may be large enough to enhance the BπKB\to \pi K branching ratio significantly. However our estimates fail to predict a large enhancement.Comment: 5 pages, use elsart.sty; The previous version is erroneous in explaining the "charm peguin" effects. No large enhancement to BπKB\to \pi K is found through D+DsD^+D_s^- intermediate stat

    FINAL STATE INTERACTIONS OF BDKB\to DK DECAYS

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    We study the final state strong interactions of the BDKB\rightarrow DK decay processes, using the Regge model. We conclude that the final state interaction phases are very small, typically a few degrees. Neglecting final state interactions in obtaining the weak decay amplitudes is a good approximation.Comment: 10 pages, standard latex without figure

    A Renormalization Group Analysis of the Higgs Boson with Heavy Fermions and Compositeness

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    We study the properties of heavy fermions in the vector-like representation of the electro-weak gauge group SU(2)W×U(1)YSU(2)_W\times U(1)_Y with Yukawa couplings to the standard model (SM) Higgs boson. Using the renormalization group analysis, we discuss their effects on the vacuum stability and the triviality bound on the Higgs self-coupling, within the context of the standard model (i.e., the Higgs particle is elementary). Contrary to the low energy case where the decoupling theorem dictates their behavior, the inclusion of heavy fermions drastically change the SM structure at high scale. We also discuss the interesting possibility of compositeness, i.e., the Higgs particle is composed of the heavy fermions using the method of Bardeen, Hill and Lindner~\cite{BHL91}. Finally we briefly comment on their possible role in explaining RbR_b and RcR_c.Comment: Some typographic errors are corrected and title is changed. Version to appear in Physics Letter B. 9 pages 6 Postscript figures, use epsf.st
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