Black Holes in Many Dimensions at the CERN Large Hadron Collider: Testing Critical String Theory

We consider black hole production at the CERN Large Hadron Collider (LHC) in a generic scenario with many extra dimensions where the standard model fields are confined to a brane. With $\sim 20$ dimensions the hierarchy problem is shown to be naturally solved without the need for large compactification radii. We find that in such a scenario the properties of black holes can be used to determine the number of extra dimensions, $n$. In particular, we demonstrate that measurements of the decay distributions of such black holes at the LHC can determine if $n$ is significantly larger than 6 or 7 with high confidence and thus can probe one of the critical properties of string theory compactifications.

Figure 1

$M_{*}{R}_c$ as a function of $n$ for $M_{*}=1\mathrm{TeV}$ for a torus (solid line) and sphere (dashed line) compactifications.

Figure 2

Top panel: cross section for production of black holes with mass $M>M_{\mathrm{BH},\min }$ with $M_{*}=1.5\mathrm{TeV}$, for $n=2$ (bottom) to 25 (top) of the band. Also shown is the QCD dijet cross section for dijet invariant mass $M\ge M_{\mathrm{BH},\min }$, and $|\eta |<1$. Bottom panel: ${\mathrm{p̸}}_T$ distribution of BH events passing cuts described in the text for $M_{*}=1\mathrm{TeV}$ and $n=2,6,21$.

Figure 3

Exclusion curves in the $(n,M_{*})$ plane, assuming the data lie at the point $(21,1\mathrm{TeV})$. Points outside the curves are excluded at $3\sigma$, $5\sigma$, or $10\sigma$.