2,430 research outputs found

    CP Violation in D0 - anti-D0 Oscillations: General Considerations and Applications to the Littlest Higgs Model with T-Parity

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    The observed D0 - anti-D0 oscillations provide a new stage in our search for New Physics in heavy flavour dynamics. The theoretical verdict on the observed values of x_D and y_D remains ambiguous: while they could be totally generated by Standard Model dynamics, they could also contain a sizable or even leading contribution from New Physics. Those oscillations are likely to enhance the observability of CP violation as clear manifestations of New Physics. We present general formulae for D0 - anti-D0 oscillations, concentrating on the case of negligible direct CP violation. In particular we derive a general formula for the time-dependent mixing-induced CP asymmetry in decays to a CP eigenstate and its correlation with the semileptonic CP asymmetry a_SL(D0) in D0(t) -> l nu K. We apply our formalism to the Littlest Higgs model with T-parity, using the time-dependent CP asymmetry in D -> K_S phi as an example. We find observable effects at a level well beyond anything possible with CKM dynamics. Comparisons with CP violation in the K and B systems offer an excellent test of this scenario and reveal the specific pattern of flavour and CP violation in the D0 - anti-D0 system predicted by this model. We discuss a number of charm decays that could potentially offer an insight in the dynamics of CP violation in D decays. We also apply our formalism to B_s - anti-B_s mixing.Comment: 26 pages, 9 png figures, 1 table. v2: eq. (A.1) corrected, minor clarifying comments and few references added. v3: typos corrected, matches published versio

    Rare K and B Decays in a Warped Extra Dimension with Custodial Protection

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    We present a complete study of rare K and B meson decays in a warped extra dimensional model with a custodial protection of (both diagonal and non-diagonal) Z d_L^i \bar d_L^j couplings, including K^+ -> pi^+ nu anti-nu, K_L -> pi^0 nu anti-nu, K_L -> pi^0 l^+ l^-, K_L -> mu^+ mu^-, B_{s,d} -> mu^+ mu^-, B -> K nu anti-nu, B -> K^* nu anti-nu and B -> X_{s,d} nu anti-nu. In this model in addition to Standard Model one loop contributions these processes receive tree level contributions from the Z boson and the new heavy electroweak gauge bosons. We analyse all these contributions that turn out to be dominated by tree level Z boson exchanges governed by right-handed couplings to down-type quarks. Imposing all existing constraints from Delta F=2 transitions analysed by us recently and fitting all quark masses and CKM mixing parameters we find that a number of branching ratios for rare K decays can differ significantly from the SM predictions, while the corresponding effects in rare B decays are modest, dominantly due to the custodial protection being more effective in B decays than in K decays. In order to reduce the parameter dependence we study correlations between various observables within the K system, within the B system and in particular between K and B systems, and also between Delta F=2 and Delta F=1 observables. These correlations allow for a clear distinction between this new physics scenario and models with minimal flavour violation or the Littlest Higgs Model with T-parity, and could give an opportunity to future experiments to confirm or rule out the model. We show how our results would change if the custodial protection of Z d_L^i bar d^j_L couplings was absent. In the case of rare B decays the modifications are spectacular.Comment: 50 pages, 17 figures. v2: minor clarifying comments and references added. v3: few clarifying comments added, matches published versio

    Top quark chromomagnetic dipole moment in the littlest Higgs model with T-parity

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    The littlest Higgs model with T-parity, which is called LHTLHT model, predicts the existence of the new particles, such as heavy top quark, heavy gauge bosons, and mirror fermions. We calculate the one-loop contributions of these new particles to the top quark chromomagnetic dipole moment (CMDM)(CMDM) ΔK\Delta K. We find that the contribution of the LHTLHT model is one order of magnitude smaller than the standard model prediction value.Comment: latex files, 12 pages, 3 figure

    Constraints on New Physics from B mesons

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    Brief review of the searches for the rare decays Bs0μ+μB^0_s \rightarrow \mu^+ \mu^- and B0μ+μB^0 \rightarrow \mu^+ \mu^-

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    The current experimental status of the searches for the very rare decays Bs0μ+μB^0_s \rightarrow \mu^+ \mu^- and B0μ+μB^0 \rightarrow \mu^+ \mu^- is discussed. These channels are highly sensitive to various extensions of the Standard Model, specially in the scalar and pseudoscalar sector. The recent, most sensitive measurements from the CDF, ATLAS, CMS and LHCb collaborations are discussed and the combined upper exclusion limit on the branching fractions determined by the LHC experiments is shown to be 4.2×1094.2\times 10^{-9} for Bs0μ+μB^0_s \rightarrow \mu^+ \mu^- and 0.8×1090.8\times 10^{-9} for B0μ+μB^0 \rightarrow \mu^+ \mu^-. The implications of these tight bounds on a selected set of New Physics models is sketched.Comment: 20 pages, 15 figures, invited review for Modern Physics Letters

    bsb \to s Transitions in Family-dependent U(1)U(1)^\prime Models

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    We analyze flavor-changing-neutral-current (FCNC) effects in the bsb\to s transitions that are induced by family non-universal U(1)U(1)' gauge symmetries. After systematically developing the necessary formalism, we present a correlated analysis for the ΔB=1,2\Delta B =1, 2 processes. We adopt a model-independent approach in which we only require family-universal charges for the first and second generations and small fermion mixing angles. We analyze the constraints on the resulting parameter space from BsBˉsB_s - \bar B_s mixing and the time-dependent CP asymmetries of the penguin-dominated Bd(π,ϕ,η,ρ,ω,f0)KSB_d \to (\pi, \phi, \eta', \rho, \omega, f_0)K_S decays. Our results indicate that the currently observed discrepancies in some of these modes with respect to the Standard Model predictions can be consistently accommodated within this general class of models.Comment: 36 pages, 11 figure

    Frank Miller’s Sin City College Football: A Game to Die For And Other Lessons About the Right of Publicity and Video Games

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    The challenge of finding a workable solution for applying the right of publicity is a formidable one because it implicates not only a delicate balance between First Amendment rights and the rights of publicity, but also the complications of varying state laws. The best of the tests developed by the courts so far—the transformative use test—was borrowed from copyright law and itself reflects a careful balance between First Amendment and copyright interests. Additionally, because of dramatic progress in technology, it is likely that in the near future this balancing will often involve not only the rights of publicity and the First Amendment but also copyright law as well

    Privacy and Outrage

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    It is not an understatement that technology has dramatically altered virtually every aspect of our life in recent years. While technology has always driven change, these changes are occurring more rapidly and more extensively than ever before. We are fully entrenched in the world of Big Data, the Internet of Things, and Smart Cities – and we are never going back. As always, society and its laws must evolve, but it is not always an easy process. The notion of privacy has certainly changed in our data-driven world and continues to change daily. While it has always been difficult to define exactly what privacy is, it is even more difficult to propose what privacy should become. Technology and its uses – or abuses – are altering the notion of privacy into something that may be unrecognizable in the near future. Studies show that people say they are still concerned about privacy, but their behavior does not reflect that.1 Like any value, the importance of privacy varies from person to person. This makes it even more difficult to establish a one-sizefits-all concept of privacy. This paper explores some of the historical, legal, and ethical development of privacy; discusses how some of the normative values of privacy may survive or change; and examines how outrage has been – and will continue to be – a driver of such change

    Minimal Flavour Violation and Beyond

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    Starting from the effective-theory framework for Minimal Flavour Violation, we give a systematic definition of next-to-minimal (quark) flavour violation in terms of a set of spurion fields exhibiting a particular hierarchy with respect to a small (Wolfenstein-like) parameter. A few illustrative examples and their consequences for charged and neutral decays with different quark chiralities are worked out in some detail. Our framework can be used as a model-independent classification scheme for the parameterization of flavour structure from physics beyond the Standard Model.Comment: 17 pages, no figures, phenomenological discussion extended, references adde

    Electroweak and Flavour Structure of a Warped Extra Dimension with Custodial Protection

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    We present the electroweak and flavour structure of a model with a warped extra dimension and the bulk gauge group SU(3) x SU(2)_L x SU(2)_R x P_LR x U(1)_X. The presence of SU(2)_R implies an unbroken custodial symmetry in the Higgs system allowing to eliminate large contributions to the T parameter, whereas the P_LR symmetry and the enlarged fermion representations provide a custodial symmetry for flavour diagonal and flavour changing couplings of the SM Z boson to left-handed down-type quarks. We diagonalise analytically the mass matrices of charged and neutral gauge bosons including the first KK modes. We present the mass matrices for quarks including heavy KK modes and discuss the neutral and charged currents involving light and heavy fields. We give the corresponding complete set of Feynman rules in the unitary gauge.Comment: 74 pages, 2 figures. clarifying comments and references added, version to be published in JHE
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