Roman Zwicky

B →Vℓ+ℓ− in the Standard Model from light-cone sum rules

A bstractWe present Bq → ρ, Bq → ω, Bq → K∗, Bs → K∗ and Bs → ϕ form factors from light-cone sum rules (LCSR) at Oαs

B_{d,s}->rho, omega, K*, phi Decay Form Factors from Light-Cone Sum Rules Revisited

\mathcal{O}\left({\alpha}_s\right)

SU(3) breaking of leading-twist K and K∗ distribution amplitudes—a reprise

for twist-2 and 3 and Oαs0

B → V γ beyond QCD factorization

\mathcal{O}\left({\alpha}_s^0\right)

Scaling relations for the entire spectrum in mass-deformed conformal gauge theories

for twist-4 with updated hadronic input parameters. Three asymptotic light-cone distribution amplitudes of twist-4 (and 5) are determined, necessary for the form factors to obey the equations of motion. It is argued that the latter constrain the uncertainty of tensor-to-vector form factor ratios thereby improving the prediction of zeros of helicity amplitudes of major importance for B → K∗ℓℓ angular observables. We provide easy-to-use fits to the LCSR results, including the full error correlation matrix, in all modes at low q2 as well as combined fits to LCSR and lattice results covering the entire kinematic range for Bq → K∗, Bs → K∗ and Bs → ϕ. The error correlation matrix avoids the problem of overestimating the uncertainty in phenomenological applications. Using the new form factors and recent computations of non-factorisable contributions we provide Standard Model predictions for B → K∗γ as well as B → K∗ℓ+ℓ− and Bs → ϕμ+μ− at low dilepton invariant mass. Employing our B → (ρ,ω) form factor results we extract the CKM element |Vub| from the semileptonic decays B → (ρ, ω)ℓν and find good agreement with other exclusive determinations.

Exploiting the width difference in Bs→ϕγ.

We present a number of analytical results which should guide the interpretation of lattice data in theories with an infrared fixed point (IRFP) deformed by a mass term ?L=-mq? q. From renormalization group (RG) arguments we obtain the leading scaling exponent, F?m?F, for all decay constants of the lowest lying states other than the ones affected by the chiral anomaly and the tensor ones. These scaling relations provide a clear cut way to distinguish a theory with an IRFP from a confining theory with heavy fermions. Moreover, we present a derivation relating the scaling of ?q? q??m?q? q to the scaling of the density of eigenvalues of the massless Dirac operator ?(?)???q? q. RG arguments yield ?q? q=(3-?*)/(1+?*) as a function of the mass anomalous dimension ?* at the IRFP. The arguments can be generalized to other condensates such as ?G2??m4/(1+?*). We describe a heuristic derivation of the result on the condensates, which provides interesting connections between different approaches. Our results are compared with existing data from numerical studies of SU(2) with two adjoint Dirac fermions