A quantum correction to the Brans-Dicke theory due to interactions among
matter fields is calculated, resulting in violation of WEP, hence giving a
constraint on the parameter $\omega$ far more stringent than accepted so far.
The tentative estimate gives the lower bounds $\gsim 10^{6}$ and $\gsim 10^{8}$
for the assumed force-range $\gsim 1$m and $\gsim 1$AU, respectively.Comment: 7 pages, LaTe

Fujii, Yasunori