1,827 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

    Bad Religion: How Ex-Mormon Fiction Reinforces Normative Views of American Religion

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    This project examines recent fiction by ex-Mormon authors and highlights how these novels reinforce an American ideal of “good religion.” These texts reveal the boundaries of American religious freedom by illustrating examples of “bad religion” and providing favorable alternatives. The paper looks at scholarship on 19th century anti-Mormon literature, which provides a foundation for the more modern literature at hand. Through the recent narratives, authors point to an abstract concept of benign, acceptable religion, marking as harmful that which does not share these key characteristics. While these fictional sects appear differently in each work, they comment on similar themes, such as the threat of rigid authority structures and figures, community isolation and insulation, coercive proselytizing and manipulation, and an emphasis on escaping the sect. These themes highlight the existence of a particular brand of American “good religion,” which is antithetical to such groups illustrated in these texts

    The Impact of a 4th Generation on Mixing and CP Violation in the Charm System

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    We study D0-D0 mixing in the presence of a fourth generation of quarks. In particular, we calculate the size of the allowed CP violation which is found at the observable level well beyond anything possible with CKM dynamics. We calculate the semileptonic asymmetry a_SL and the mixing induced CP asymmetry eta_fS_f which are correlated with each other. We also investigate the correlation of eta_fS_f with a number of prominent observables in other mesonic systems like epsilon'/epsilon, Br(K_L -> pi0 nu nu), Br(K+ -> pi+ nu nu), Br(B_s ->mu+ mu-), Br(B_d -> mu+ mu-) and finally S_psi phi in the B_s system. We identify a clear pattern of flavour and CP violation predicted by the SM4 model: While simultaneous large 4G effects in the K and D systems are possible, accompanying large NP effects in the B_d system are disfavoured. However this behaviour is not as pronounced as found for the LHT and RSc models. In contrast to this, sizeable CP violating effects in the B_s system are possible unless extreme effects in eta_fS_f are found, and Br(B_s ->mu+ mu-) can be strongly enhanced regardless of the situation in the D system. We find that, on the other hand, S_psi phi > 0.2 combined with the measured epsilon'/epsilon significantly diminishes 4G effects within the D system.Comment: 22 pages, 23 figures, v2 (references added

    Indirect tests of the Randall-Sundrum model

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    I present phenomenological implications of the Randall-Sundrum model for indirect searches, specifically a selection of flavor observables and Higgs-related collider searches. I review the interplay of constraints from CP violation in flavor physics, possible effects in rare decays, and model-specific protection mechanisms. Deviations in the Higgs couplings to fermions and, at one-loop, to gluons are unexpectedly strong and lead to strong modifications in Higgs searches.Comment: 8 pages, 6 figures; Talk given at Discrete '10: Symposium on Prospects in the Physics of Discrete Symmetries, Rome, Italy, 6-11 Dec 201

    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

    Patterns of Flavour Violation in a Warped Extra Dimensional Model with Custodial Protection

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    We present a particular warped extra dimensional model, where the flavour diagonal and flavour non-diagonal Z boson couplings to left-handed down quarks are protected by the custodial symmetry P_LR. After a brief introduction of the model and of its main theoretical motivations, we present a complete study of rare K and B meson decays, including K+ --> pi+ nu anti-nu, K_L --> pi0 nu anti-nu, B_{s,d} --> mu+ mu- and B_{s,d} --> X_{s,d} nu anti-nu. In particular we restrict the parameter space of the model to the subspace which fits all quark masses, CKM mixing parameters and all the measured Delta F=2 observables, keeping the Kaluza-Klein scale in the reach of LHC (~(2-3)TeV). There we show that, in addition to the one loop contribution of the Standard Model (SM), the dominating new physics contribution to the rare decays of K and B_{s,d} mesons is the tree level exchange of the Z boson of the SM governed by right-handed couplings to down-type quarks. In order to reduce the parameter dependence, we study correlations between various branching ratios of B and K mesons and between Delta F=1 and Delta F=2 observables. The patterns that we find allow to distinguish this new physics scenario from the SM and can offer an opportunity to future experiments to confirm or rule out the model.Comment: 10 pages, 8 figures, To appear in the proceedings of DISCRETE '08, 11-16 December 2008, Valencia, Spai

    On CP Asymmetries in Two-, Three- and Four-Body D Decays

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    Indirect and direct CP violations have been established in K_L and B_d decays. They have been found in two-body decay channels -- with the exception of K_L to pi^+ pi^- e^+ e^- transitions. Evidence for direct CP asymmetry has just appeared in LHCb data on A_{CP}(D^0 to K^+ K^-) - A_{CP}(D^0 to pi^+ pi^-) with 3.5 sigma significance. Manifestations of New Dynamics (ND) can appear in CP asymmetries just below experimental bounds. We discuss D^{\pm}_{(s)}, D^0/\bar D^0 and D_L/D_S transitions to 2-, 3- and 4-body final states with a comment on predictions for inclusive vs. exclusive CP asymmetries. In particular we discuss T asymmetries in D to h_1 h_2 l^+ l^- in analogy with K_L to pi^+ pi^- e^+ e^- transitions due to interference between M1, internal bremsstrahlung and possible E1 amplitudes. Such an effect depends on the strength of CP violation originating from the ND -- as discussed here for Little Higgs Models with T parity and non-minimal Higgs sectors -- but also in the interferences between these amplitudes even in the Standard Model (SM). More general lessons can be learnt for T asymmetries in non-leptonic D decays like D to h_1h_2 h_3 h_4. Such manifestations of ND can be tested at LHCb and other Super-Flavour Factories like the projects at KEK near Tokyo and at Tor Vergata/Frascati near Rome.Comment: 27 pages, 6 figures. Revised with current results from LHCb and HFAG and further interpretation

    Inferior frontal oscillations reveal visuo-motor matching for actions and speech: evidence from human intracranial recordings.

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    The neural correspondence between the systems responsible for the execution and recognition of actions has been suggested both in humans and non-human primates. Apart from being a key region of this visuo-motor observation-execution matching (OEM) system, the human inferior frontal gyrus (IFG) is also important for speech production. The functional overlap of visuo-motor OEM and speech, together with the phylogenetic history of the IFG as a motor area, has led to the idea that speech function has evolved from pre-existing motor systems and to the hypothesis that an OEM system may exist also for speech. However, visuo-motor OEM and speech OEM have never been compared directly. We used electrocorticography to analyze oscillations recorded from intracranial electrodes in human fronto-parieto-temporal cortex during visuo-motor (executing or visually observing an action) and speech OEM tasks (verbally describing an action using the first or third person pronoun). The results show that neural activity related to visuo-motor OEM is widespread in the frontal, parietal, and temporal regions. Speech OEM also elicited widespread responses partly overlapping with visuo-motor OEM sites (bilaterally), including frontal, parietal, and temporal regions. Interestingly a more focal region, the inferior frontal gyrus (bilaterally), showed both visuo-motor OEM and speech OEM properties independent of orolingual speech-unrelated movements. Building on the methodological advantages in human invasive electrocorticography, the present findings provide highly precise spatial and temporal information to support the existence of a modality-independent action representation system in the human brain that is shared between systems for performing, interpreting and describing actions
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