2,446 research outputs found

    A Geometric Parametrization of the Cabibbo-Kobayashi-Maskawa Matrix and the Jarlskog Invariant

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    In this paper we give a geometric parametrization to the Cabibbo-Kobayashi-Maskawa (CKM) mixing matrix and the Jarlskog invariant, which is based on two flag manifolds SU(3)/U(1)2SU(3)/U(1)^{2}. To treat a fourth generation of quarks on CP violation we generalize the parametrization to one based on two flag manifolds SU(4)/U(1)3SU(4)/U(1)^{3}.Comment: Latex ; 14 pages ; 2 figures ; minor change

    Factorization fits to charmless strangeless B decays

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    We present fits to charmless strangeless hadronic B decay data for mean branching ratios and CP-violating asymmetries using the QCD factorization model of Beneke et al. Apart from one CP-violating parameter, the model gives a very good representation of 26 measured data. We find the CKM angle alpha = (93.5 +/- 8.4 -1.3) degrees and to be quite stable to plausible "charming penguin" corrections.Comment: 4 pages, LaTeX, Minor changes to text, references adde

    Gluon and gluino penguin diagrams and the charmless decays of the b quark

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    Gluon mediated exclusive hadronic decays of b quarks are studied within the standard model (SM) and the constrained minimally supersymmetric standard model (MSSM). For all allowed regions of the MSSM parameter space (A, tan beta, m_0, m_{1/2}) the penguin magnetic dipole form factor F^R_2 is dominant over the electric dipole and can be larger than the magnetic dipole form factor of the SM. However, overall the SM electric dipole decay amplitude F^L_1 dominates the decay rate. The MSSM penguin contributions to the free quark decay rate approach the 10% level for those regions of parameter space close to the highest allowed values of tan beta (~55) for which the gluino is light (m_{\tilde{g}} \approx 360 GeV) and lies within the range of the six d-squark masses. In these regions the supersymmetric box amplitudes are negligible. The MSSM phases change very little over the allowed parameter space and can lead to significant interference with the SM amplitudes

    Cosmological implications of conformal field theory

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    Requiring all massless elementary fields to have conformal scaling symmetry removes a conflict between gravitational theory and the quantum theory of elementary particles and fields. Extending this postulate to the scalar field of the Higgs model, dynamical breaking of both gauge and conformal symmetries determines parameters for the interacting fields. In uniform isotropic geometry a modified Friedmann cosmic evolution equation is derived with nonvanishing cosmological constant. Parameters determined by numerical solution are consistent with empirical data for redshifts z≤z∗=1090z\leq z_*=1090, including luminosity distances for observed type Ia supernovae and peak structure ratios in the cosmic microwave background (CMB). The theory does not require dark matter.Comment: 8 pages Conclusions about the early universe which must be reexamined have been removed. Manuscript revised and reformatted. Accepted for publication in Modern Physics Letters A (2011

    Possible Cosmological Implications of the Quark-Hadron Phase Transition

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    We study the quark-hadron phase transition within an effective model of QCD, and find that in a reasonable range of the main parameters of the model, bodies with quark content between 10−210^{-2} and 10 solar masses can have been formed in the early universe. In addition, we show that a significant amount of entropy is released during the transition. This may imply the existence of a higher baryon number density than what is usually expected at temperatures above the QCD scale. The cosmological QCD transition may then provide a natural way for decreasing the high baryon asymmetry created by an Affleck-Dine like mechanism down to the value required by primordial nucleosynthesis.Comment: 19 pages, LaTeX, 5 Postscript figures included. Submitted to Journal of Physics

    LHCb's Potential to Measure Flavour-Specific CP-Asymmetry in Semileptonic and Hadronic Bs0B^0_s Decays

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    "The CP asymmetry in Bs-Bsbar mixing, denoted as a^s_{fs}, is sensitive to new weak phases in the presence of physics beyond the Standard Model. This can be probed through a measurement of the time-dependent charge asymmetry A^s_{fs}(t) in flavour-specific decays. This note describes the LHCb strategy to measure a^s_{fs} using a time-dependent method, in flavour untagged decays of Bs->Ds mu nu and Bs->Ds pi. We also investigate a measurement of the difference of a^s_{fs} and a^d_{fs} in Bs->Ds mu nu and Bd->Dmu nu decays which allows to control the systematic uncertainty that arise from detection asymmetries.

    Stability of the Zagreb Carnegie-Mellon-Berkeley model

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    In ref. [1] we have used the Zagreb realization of Carnegie-Melon-Berkeley coupled-channel, unitary model as a tool for extracting pole positions from the world collection of partial wave data, with the aim of eliminating model dependence in pole-search procedures. In order that the method is sensible, we in this paper discuss the stability of the method with respect to the strong variation of different model ingredients. We show that the Zagreb CMB procedure is very stable with strong variation of the model assumptions, and that it can reliably predict the pole positions of the fitted partial wave amplitudes.Comment: 25 pages, 12 figures, 19 table

    Three-pion exchange: a gap in the nucleon-nucleon potential

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    The leading contribution to the three-pion exchange nucleon-nucleon potential is calculated in the framework of chiral symmetry. It has pseudoscalar and axial components and is dominated by the former, which has a range of about 1.5 fm and tends to enhance the OPEP. The strength of this force does not depend on the pion mass and hence it survives in the chiral limit.Comment: 20 pages, 5 figures, 1 tabl
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