Light-Cone Sum Rules for the Form Factors of the NγΔN\gamma\Delta transition at Q^2=0

The radiative $\Delta \to \gamma N$ transition is examined at the real photon point $Q^2=0$ using the framework of light-cone QCD sum rules. In particular, we determine the sum rules for the transition form factors $G_M(0)$ and $R_{EM}$ up to twist 4.Comment: Talk given at the Workshop on Exclusive Reactions at High Momentum Transfer 200

g-2 In the custodially protected RS model

We study leptonic operators of dimension six in the custodially protected Randall-Sundrum model. Their contribution to the anomalous magnetic moment of the muon is evaluated. We find that the contribution to g-2 due to diagrams with an internal gauge boson exchange is given by approximately 2.72*10^-10 (1 TeV/T)^2 basically independent of the model parameters except for the KK mass scale T---a factor of more than 3 larger than in a scenario without custodial protection. We also investigate the impact of contributions to the dipole operators due to an internal Higgs exchange, which can provide sizable albeit model-dependent corrections.Comment: 21 pages, 8 figure

Bˉ→Xsγ\bar B\to X_s \gamma with a warped bulk Higgs

We study the decay $\bar B\to X_s\gamma$ in Randall-Sundrum models with an IR-localised bulk Higgs. The two models under consideration are a minimal model as well as a model with a custodial protection mechanism. We include the effects of tree- and one-loop diagrams involving 5D gluon and Higgs exchanges as well as QCD corrections arising from the evolution from the Kaluza-Klein scale to the typical scale of the decay. We find the RS corrections to the branching fraction can be sizeable for large Yukawas and moderate KK scales $T$; for small Yukawas the RS contribution is small enough to be invisible in current experimental data.Comment: 20 pages, 5 figures(V2: references added, matches version published in Nuclear Physics B

Lepton flavour violation in RS models with a brane- or nearly brane-localized Higgs

We perform a comprehensive study of charged lepton flavour violation in Randall-Sundrum (RS) models in a fully 5D quantum-field-theoretical framework. We consider the RS model with minimal field content and a "custodially protected" extension as well as three implementations of the IR-brane localized Higgs field, including the non-decoupling effect of the Kaluza-Klein (KK) excitations of a narrow bulk Higgs. Our calculation provides the first complete result for the flavour-violating electromagnetic dipole operator in Randall-Sundrum models. It contains three contributions with different dependence on the magnitude of the anarchic 5D Yukawa matrix, which can all be important in certain parameter regions. We study the typical range for the branching fractions of mu -> e gamma, mu -> 3e, mu N -> e N as well as tau -> mu gamma, tau -> 3 mu and the electron electric dipole moment by a numerical scan in both the minimal and the custodial RS model. The combination of mu -> e gamma and mu N -> e N currently provides the most stringent constraint on the parameter space of the model. A typical lower limit on the KK scale T is around 2 TeV in the minimal model (up to 4 TeV in the bulk Higgs case with large Yukawa couplings), and around 4 TeV in the custodially protected model, which corresponds to a mass of about 10 TeV for the first KK excitations, far beyond the lower limit from the non-observation of direct production at the LHC.Comment: 64 pages, 21 figures, LaTeX, v2: electron EDM analysis added, matches published versio

B meson distribution amplitude from B --> \gamma l \nu

We reconsider the utility of the radiative decay $B \to \gamma \ell \nu$ with an energetic photon in the final state for determining parameters of the $B$-meson light-cone distribution amplitude. Including $1/m_b$ power corrections and radiative corrections at next-to-leading logarithmic order, we perform an improved analysis of the existing BABAR data. We find a provisional lower limit on the inverse moment of the $B$ meson distribution amplitude, $\lambda_B$, which, due to the inclusion of radiative and power corrections, is significantly lower than the previous result. More data with large photon energy is, however, required to obtain reliable results, as should become available in the future from SuperB factories.Comment: 15 pages, 5 figure

Determination of the magnetic susceptibility of the quark condensate using radiative heavy meson decays

We use a light-cone sum rule (LCSR) analysis of the branching ratios of radiative meson decays to contrain the value of the magnetic susceptibility of the quark condensate $\chi(\mu)$. For the first time, we use a complete set of three-particle distribution amplitudes that enables us to give a consistent prediction for the branching ratios. Furthermore we will make use of a very recent update of several non-perturbative parameters. Our final result for $\chi(\mu= 1 {\rm GeV})= 2.85 \pm 0.5 {\rm GeV}^{-2}$ (assuming asymptotic wave functions) agrees with the currently used value of $3.15 \pm 0.3 {\rm GeV}^{-2}$.Comment: 21 pages, 4 figures, references adde

Light-cone sum rules for the NγΔN\gamma\Delta transitions for real photons

We examine the radiative $\Delta \to \gamma N$ transition at the real photon point $Q^2=0$ using the framework of light-cone QCD sum rules. In particular, the sum rules for the transition form factors $G_M(0)$ and $R_{EM}$ are determined up to twist 4. The result for $G_M(0)$ agrees with experiment within 10% accuracy. The agreement for $R_{EM}$ is also reasonable. In addition, we derive new light-cone sum rules for the magnetic moments of nucleons, with a complete account of twist-4 corrections based on a recent reanalysis of photon distribution amplitudes.Comment: 34 pages, 9 figures, revised version, published in Phys. Rev. D, one misplaced reference correcte

Phenomenology of the Heavy Flavored spin 3/2 Baryons in Light Cone QCD

Motivated by the results of the recent experimental discoveries for charm and bottom baryons, the masses and magnetic moments of the heavy baryons with $J^P=3/2^+$ containing a single heavy quark are studied within light cone QCD sum rules method. Our results on the masses of heavy baryons are in good agreement with predictions of other approaches, as well as with the existing experimental data.Comment: 12 Pages, 18 Figures and 3 Tables. Based on: arXiv:0807.3481v2 [hep-ph](Nucl.Phys.B808:137-154,2009). To be Published in the Proceeding of the International Conference on New Trends in High Energy Physics, 27 Sept.-4 Oct. 2008, Yalta, Crimea, Ukrain