[en] The purely leptonic decays D^±→e^±ν and D^±_s→e^±ν, for which no experimental limits exist, are highly suppressed in the Standard Model. Mere observation of these decays at the B factories Belle/BaBar or forthcoming CLEO-c would be a clear signal of physics beyond the SM. We show that R-parity violating slepton contributions can give rise to spectacular enhancements of the decay rates, resulting in branching ratios as large as 5x10^-3, which strongly motivates a search in these channels

[en] We extend the formalism based on perturbative QCD that was developed in our previous work, and compute the hyperfine splittings of the bottomonium spectrum as well as the fine and hyperfine splittings of the charmonium spectrum. All the corrections up to O(α_S⁵m) are included in the computations. We find agreement (with respect to theoretical uncertainties) with the experimental values whenever available and give predictions for not yet observed splittings

[en] We study the direct CP asymmetry of the decays b → sγ, and b → dγ, in the context of two models: i) a supersymmetric (SUSY) model with unconstrained SUSY phases, and ii) a model with a single generation of vector quarks. In both the above models we show that b → dγ can sizeably influence the combined asymmetry (i.e. that of a sample containing both b → sγ and b → dγ), and in case (ii) may in fact be the dominant contribution

[en] The extension of the Standard Model by a sequential fourth generation is one of the most obvious extensions but still an interesting and topical one. We present a concise study that uses both tree-level and loop constraints to determine the possible effects on various observables.

[en] The extension of the standard model by a sequential fourth generation is interesting and topical. We present a concise study that uses both tree-level and loop constraints to determine the possible effects on various observables and present a new way to study allowed regions in parameter space. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[en] We investigate the rare decay Λ_b→Λ_γ which receives both short and long distance contributions. We estimate the long distance contributions and find them very small. The form factors are obtained from Λ_c→Λlν_l using heavy quark symmetry and a pole model. The short distance piece opens a window to new physics and we discuss the sensitivity of Λ_b→Λ_γ to such effects. (author)

[en] The Littlest Higgs Model with T-parity (LHT) is an interesting alternative model for New Physics at the TeV scale. Although Flavour Physics was not the reason for creating the LHT model, significant effects (such as large CP violation where not predicted by the SM) can be created without violating existing experimental bounds. We study the B-, K- and especially the D-sector. (author)

[en] The Littlest Higgs Model with T parity (LHT) is an interesting alternative model for New Physics at the TeV scale. Although Flavour Physics was not the reason for creating the LHT model, significant effects (such as large CP violation where not predicted by the SM) can be created without violating existing experimental bounds. We study the B-, K- and especially the D-sector. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

[en] The CP asymmetries of the decay B_d⁰→K⁰ anti K⁰, which originates from anti b→ anti d s anti s flavor-changing neutral-current processes, and its CP-averaged branching ratio BR(B_d→K⁰ anti K⁰) offer interesting avenues to explore flavor physics. We show that we may characterize this channel, within the standard model, in a theoretically clean manner through a surface in observable space. In order to extract the relevant information from BR (B_d→K⁰ anti K⁰), further information is required, which is provided by the B→ππ system and the SU(3) flavor symmetry, where we include the leading factorizable SU(3)-breaking corrections and discuss how experimental insights into non-factorizable effects can be obtained. We point out that the standard model implies a lower bound for BR(B_d→K⁰ anti K⁰), which is very close to its current experimental upper bound, thereby suggesting that this decay should soon be observed. Moreover, we explore the implications for ''color suppression'' in the B→ππ system, and convert the data for these modes in a peculiar standard-model pattern for the CP-violating B_d⁰→K⁰ anti K⁰ observables. (orig.)

[en] High Luminosity upgrades of the KEK-B collider are being discussed. We consider the role of the purely leptonic decays B^± → l^±ν and B⁰ → l⁺l^- in motivating such an upgrade. These decays are very sensitive to R parity violating extensions of the MSSM, and we show that future runs of the KEK-B factory can be competitive with high energy colliders for probing such models. (author)