Lattice Calculation of D- and B-meson Semileptonic Decays, using the Clover Action at beta=6.0 on APE

Abstract

We present the results of a high statistics lattice calculation of hadronic form factors relevant for $D-$ and $B-$meson semi-leptonic decays into light pseudoscalar and vector mesons. The results have been obtained by averaging over 170 gauge field configurations, generated in the quenched approximation, at ${\hat{I}}^2=6.0$, on a $18^3\times 64$ lattice, using the $O(a)$-improved SW-Clover action.From the study of the matrix element $<K^{-}|J_{\hat{I}}¼|D^0>$, we obtain $f_{+}(0)=0.78\pm 0.08$ and from the matrix element $<{\bar{K}}^{\ast 0}|J_{\hat{I}}¼|D^{+}>$ we obtain $V(0)=1.08\pm 0.22$, $A_1(0)=0.67\pm 0.11$ and $A_2(0)=0.49\pm 0.34$. We also obtain the ratios $V(0)/A_1(0)=1.6\pm 0.3$ and $A_2(0)/A_1(0)=0.7\pm 0.4$. Our predictions for the different form factors are in good agreement with the experimental data, although, in the case of $A_2(0)$, the errors are still too large to draw any firm conclusion. With the help of the Heavy Quark Effective Theory (HQET) we have also extrapolated the lattice results to $B$-meson decays. The form factors follow a behaviour compatible with the HQET predictions. Our results are in agreement with a previous lattice calculation, performed at ${\hat{I}}^2=6.4$, using the standard Wilson action.

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