arXiv subjects

G. Siegert

Publications and source records attributed to G. Siegert.

24 records · Page 2Linked to original sources

arXiv1995

Semileptonic Decays of Heavy Mesons: A Status Report

We present intermediate results on our ongoing investigation concerning semileptonic decays of heavy pseudoscalar mesons into pseudoscalar and vector mesons. The corresponding formfactors are evaluated at several momenta and appropriate combinations of four light and four heavy quarks, which are chosen to allow for an extrapolation into the B Meson region. In order to obtain clear groundstate signals we apply gauge invariant ``Wuppertal'' smearing to the quarks. The analysis is based on 32 quenched gauge configurations of size $24^3 \times 64$ at $β=6.3$, with Wilson fermions.

hep-lat↗

arXiv1994

Heavy-light baryonic mass splittings from the lattice

We present lattice estimates of the mass of the heavy-light baryons $Λ_b$ and $Ξ_b$ obtained using propagating heavy quarks. For $Λ_b$ our result is $M_{Λ_b}=5.728 \pm 0.144 \pm 0.018$ GeV, after extrapolation to the continuum limit and in the quenched approximation.

hep-lat↗

arXiv1994

Beautiful Baryons from Lattice QCD

We perform a lattice study of heavy baryons, containing one ($Λ_b$) or two $b$-quarks ($Ξ_b$). Using the quenched approximation we obtain for the mass of $Λ_b$ $$ M_{Λ_b}= 5.728 \pm 0.144 \pm 0.018 {\rm GeV}.$$ The mass splitting between the $Λ_b$ and the B-meson is found to increase by about 20\% if the light quark mass is varied from the chiral limit to the strange quark mass.

hep-lat↗

arXiv1993

The Leptonic Decay Constants of $\bar{Q}q$ Mesons and the Lattice Resolution

We present a high statistics study of the leptonic decay constant $f_P$ of heavy pseudoscalar mesons using propagating heavy Wilson quarks within the quenched approximation, on lattices covering sizes from about 0.7~fm to 2~fm. Varying $β$ between 5.74 and 6.26 we observe a sizeable $a$ dependence of $f_P$ when one uses the quark field normalization that was suggested by Kronfeld and Mackenzie, compared with the weaker dependence observed for the standard relativistic norm. The two schemes come into agreement when one extrapolates to $a \rightarrow 0$. The extrapolations needed to reach the continuum quantity $f_B$ introduce large errors and lead to the value $f_B=0.18(5)$~GeV in the quenched approximation. This suggests that much more effort will be needed to obtain an accurate lattice prediction for $f_B$.

hep-lat↗

arXiv1993

Scaling Study of the Leptonic Decay Constants of Heavy-Light Mesons: A Consumers Report on Improvement Factors

A high statistics calculation, performed at $β=5.74,\;6.00$ and $6.26$, enables us to study the variation of the leptonic decay constants $f_P$ of heavy pseudoscalar mesons with the lattice spacing $a$. We observe only a weak $a$ dependence when the standard $\sqrt{2κ}$ normalization is used for the quark fields, whereas application of the Kronfeld-Mackenzie normalization induces a stronger variation with $a$. Increasing the meson mass from $1.1GeV$ to $2.3GeV$ this situation becomes even more pronounced.

hep-lat↗

arXiv1993

Semi-leptonic Decays of Heavy Flavours on a Fine Grained Lattice

We present the results of a numerical calculation of semi-leptonic form factors relevant for heavy flavour meson decays into light mesons, at $β=6.4$ on a $24^3 \times 60$ lattice, using the Wilson action in the quenched approximation. We obtain $f^+_K(0)=0.65\pm 0.18$, $V(0)=0.95\pm 0.34$, $A_1(0)=0.63\pm 0.14 $ and $A_2(0)=0.45\pm 0.33 $. We also obtain $A_1(q^2_{max})=0.62\pm 0.09$, $V(0)/A_1(0)=1.5\pm 0.28 $ and $A_2(0)/A_1(0)=0.7\pm 0.4$. The results for $f^+_K(0)$, $V(0)$ and $A_1(0)$ are consistent with the experimental data and with previous lattice determinations with larger lattice spacings. In the case of $A_2(0)$ the errors are too large to draw any firm conclusion. We have also extrapolated the form factors to the B meson, showing a behaviour compatible with the predictions by the heavy quark effective theory (HQET). Within large uncertainties, our results suggest that $A_2/A_1$ increases with the heavy quark mass. We also get very rough estimates for the partial decay widths $B \rightarrow πl ν_l)=\vert V_{ub} \vert^2 (12 \pm 8) 10^{12} s^{-1}$ and $Γ(B \rightarrow ρl ν_l)=\vert V_{ub} \vert^2 (13 \pm12) 10^{12} s^{-1}$, which can be used to give upper bounds on the rates

hep-lat↗