Limits on Low Scale Gravity from $e^{+}{e}^{-}\to W^{+}{W}^{-},ZZ$ and $\gamma \gamma$

Abstract

It has been proposed recently that the scale of quantum gravity (``the string scale'') can be $M_S\sim$ few TeV with $n\ge 2$ extra dimensions of size $R\stackrel{<}{\sim }$ mm so that, at distances greater than $R$, Newtonian gravity with $M_{Pl}\sim 10^{18}$ GeV is reproduced if $M_{Pl}^2\sim R^n{M}_S^{n+2}$. Exchange of virtual gravitons in this theory generates higher-dimensional operators involving SM fields, suppressed by powers of $M_S$. We discuss constraints on this scenario from the contribution of these operators to the processes $e^{+}{e}^{-}\to W^{+}{W}^{-},ZZ,\gamma \gamma$. We find that LEP2 can place a limit $M_S\approx 1$ TeV from $e^{+}{e}^{-}\to W^{+}{W}^{-},ZZ,\gamma \gamma$.

Comments: Replacing an earlier version. A discussion of using polarized electron beams and some minor comments have been added