N. M. Hazel

Form factors for B → πlνl and B → K∗γ decays on the lattice

We present a unified method for analysing form factors in B -> pi l nu-bar_l and B -> K* gamma decays. The analysis provides consistency checks on the q^2 and 1/M extrapolations necessary to obtain the physical decay rates. For the first time the q^2 dependence of the form factors is obtained at the B scale. In the B -> pi l nu-bar_l case, we show that pole fits to f^+ may not be consistent with the q^2 behaviour of f^0, leading to a possible factor of two uncertainty in the decay rate and hence in the value of |V_{ub}|^2 deduced from it. For B -> K* gamma, from the combined analysis of form factors T_1 and T_2, we find the hadronisation ratio R_{K^*} of the exclusive B -> K* gamma to the inclusive b -> s gamma rates is of order 35% or 15% for constant and pole-type behaviour of T_2 respectively.

The Isgur-Wise function from the lattice

We calculate the Isgur-Wise function by measuring the elastic scattering amplitude of a D meson in the quenched approximation on a

‘‘Improved’’ lattice study of semileptonic decays of D mesons

{24}^{3}

Lattice study of the decay B0 → ϱ+l−vl: model-independent determination of |Vub |

\ifmmode\times\else\texttimes\fi{}48 lattice at \ensuremath{\beta}=6.2, using an O(a)-improved fermion action. Fitting the resulting chirally extrapolated Isgur-Wise function to Stechs relativistic-oscillator parametrization, we obtain a slope parameter

``Improved`` lattice study of semileptonic decays of {ital D} mesons

{\mathrm{\ensuremath{\rho}}}^{2}

Lattice calculation of the penguin diagram decay B-->K* gamma.

=1.

Lattice calculation of the branching ratio for some of the exclusive modes of b-->s gamma.

{2}_{\mathrm{\ensuremath{-}}3}^{+7}

Lattice calculation of the penguin diagram decay [ital B][r arrow][ital K][sup *][gamma]

. We then use this result, in conjunction with heavy-quark symmetry, to extract

Lattice study of the decay model-independent determination of |Vub |

{\mathit{V}}_{\mathit{c}\mathit{b}}

Probing with penguins: A lattice calculation of the branching ratio for some of the exclusive modes of

from the measured B\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}