3,039 research outputs found

    Phenomenological discriminations of the Yukawa interactions in two-Higgs doublet models with Z2Z_2 symmetry

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    There are four types of two-Higgs doublet models under a discrete Z2Z_2 symmetry imposed to avoid tree-level flavour-changing neutral current, i.e. type-I, type-II, type-X and type-Y models. We investigate the possibility to discriminate the four models in the light of the flavour physics data, including BsBˉsB_s-\bar B_s mixing, Bs,dμ+μB_{s,d} \to \mu^+ \mu^-, BτνB\to \tau\nu and BˉXsγ\bar B \to X_s \gamma decays, the recent LHC Higgs data, the direct search for charged Higgs at LEP, and the constraints from perturbative unitarity and vacuum stability. After deriving the combined constraints on the Yukawa interaction parameters, we have shown that the correlation between the mass eigenstate rate asymmetry AΔΓA_{\Delta\Gamma} of Bsμ+μB_{s} \to \mu^+ \mu^- and the ratio R=B(Bsμ+μ)exp/B(Bsμ+μ)SMR={\cal B}(B_{s} \to \mu^+ \mu^-)_{exp}/ {\cal B}(B_{s} \to \mu^+ \mu^-)_{SM} could be sensitive probe to discriminate the four models with future precise measurements of the observables in the Bsμ+μB_{s} \to \mu^+ \mu^- decay at LHCb.Comment: 29 pages, 4 tables, 11 figures. v3: minor corrections included, matches published version in EPJ

    Deflation and Monetary Policy in Taiwan

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    From 1999 to 2003, Taiwan faced a deflationary situation. The reasons for this deflation can be attributed to both domestic and global factors. Domestic changes including local political unrest, tensions with China, outbound investment to China, a weakened financial system, and a deteriorating government financial situation, provided the backdrop for the economic slowdown and corresponding deflation. A number of global factors, especially the bursting of the Internet and IT bubbles in late 2000 and the rise of China's economy, also heavily influenced both global and Taiwanese prices. This paper adopts a simplified aggregate demand and aggregate supply model to derive a deterministic equation of the GDP deflator (PGDP), and then applies quarterly data covering the period from 1982 to 2003 to estimate the PGDP equation using 2SLS. The empirical results are used to identify the sources of PGDP deflation in Taiwan. In addition, the phenomenon of price divergence appears since 2002 where the WPI increased and the CPI decreased. The causes of the WPI-CPI divergence are also investigated in this paper.

    The puzzles in BππB\to \pi\pi and πK \pi K decays: possible implications for R-parity violating supersymmetry

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    Recent experiments suggest that certain data of Bππ,πKB \to \pi\pi,\pi K decays are inconsistent with the standard model expectations. We try to explain the discrepancies with R-parity violating suppersymmetry. By employing the QCD factorization approach, we study these decays in the minimal supersymmetric standard model with R-parity violation. We show that R-parity violation can resolve the discrepancies in both BππB \to \pi\pi and BπKB \to \pi K decays, and find that in some regions of parameter spaces all these requirements, including the CP averaged branching ratios and the direct CP asymmetries, can be satisfied. Furthermore, we have derived stringent bounds on relevant R-parity violating couplings from the latest experimental data, and some of these constraints are stronger than the existing bounds.Comment: 24 pages, 6 figures and 5 tables. Text revised. Final version to appear in PR

    Revisiting B\to\pi K, \pi K^{\ast} and \rho K decays: CP violations and implication for New Physics

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    Combining the up-to-date experimental information on BπK,πKB\to\pi K, \pi K^{\ast} and ρK\rho K decays, we revisit the decay rates and CP asymmetries of these decays within the framework of QCD factorization. Using an infrared finite gluon propagator of Cornwall prescription, we find that the time-like annihilation amplitude could contribute a large strong phase, while the space-like hard spectator scattering amplitude is real. Numerically, we find that all the branching ratios and most of the direct CP violations, except ACP(B±K±π0)A_{CP}(B^{\pm}\to K^{\pm}\pi^{0}), agree with the current experimental data with an effective gluon mass mg0.5GeVm_g\simeq0.5 {\rm GeV}. Taking the unmatched difference in direct CP violations between Bπ0K±B\to\pi^{0} K^{\pm} and πK±\pi^{\mp}K^{\pm} decays as a hint of new physics, we perform a model-independent analysis of new physics contributions with a set of sˉ(1+γ5)bqˉ(1+γ5)q\bar{s}(1+\gamma_{5})b\otimes\bar{q}(1+\gamma_{5})q (q=u,d) operators. Detail analyses of the relative impacts of the operators are presented in five cases. Fitting the twelve decay modes, parameter spaces are found generally with nontrivial weak phases. Our results may indicate that both strong phase from annihilation amplitude and new weak phase from new physics are needed to resolve the πK\pi K puzzle. To further test the new physics hypothesis, the mixing-induced CP violations in Bπ0KSB\to\pi^{0}K_{S} and ρ0KS\rho^{0}K_{S} are discussed and good agreements with the recent experimental data are found.Comment: Version published in JHE