0000000001011221
AUTHOR
Hugh P. Shanahan
Lattice study of the decay (B)over-bar(0)->p(+)l(-)(v)over-bar(l): Model-independent determination of vertical bar V-ub vertical bar
We present results of a lattice computation of the vector and axial-vector current matrix elements relevant for the semileptonic decay (B) over bar(0) --> rho(+)l(-)(l). The computations are performed in the quenched approximation of lattice QCD on a 24(3) x 48 lattice at beta = 6.2, using an O(a) improved fermionic action. Our principal result is for the differential decay rate, d Gamma/dq(2), for the decay (B) over bar(0) --> rho(+)l(-)(l), in a region beyond the charm endpoint, allowing a model-independent extraction of \V-ub\ from experimental measurements. Heavy quark symmetry relations between radiative and semileptonic decays of (B) over bar mesons into light vector mesons are also d…
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 $24^3\times48$ lattice at $\beta=6.2$, using an $O(a)$-improved fermion action. Fitting the resulting chirally-extrapolated Isgur-Wise function to Stech's relativistic-oscillator parametrization, we obtain a slope parameter $\rho^2=1.2+7-3. We then use this result, in conjunction with heavy-quark symmetry, to extract $V_{cb}$\ from the experimentally measured $\bar B\to D^*l\bar\nu\,$\ differential decay width. We find $|V_{cb}|\sqrt{\tau_B/1.48{\mathrm ps}}= 0.038 +2-2 +8-3, where the first set of errors is due to experimental uncertainties, while the second …
Form Factors for B -> pi l nu-bar_l and B -> K* gamma Decays on the Lattice
We present a unified method for analysing form factors in B --> pi l ($) over bar nu(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 ($) over bar nu(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 exclusiv…