Discriminating supersymmetry and black holes at the CERN Large Hadron Collider

We show how to differentiate the minimal supersymmetric extension of the standard model from black hole events at the CERN Large Hadron Collider. Black holes are simulated with the CATFISH generator. Supersymmetry simulations use a combination of pythia and isajet. Our study, based on event-shape variables, visible and missing momenta, and analysis of dilepton events, demonstrates that supersymmetry and black hole events at the LHC can be easily discriminated.

Figure 1

Comparison of visible energy (left), missing transverse momentum ${\mathrm{P̸}}_T$ (middle) and sphericity (right) for 10 000 events for the five LHC points of Table  (A: filled circles, B: filled squares, C: filled triangles, D: open circles and E: open squares).

Figure 2

The top three SUSY decay chains and their branching ratios.

Figure 3

Comparison of 10 000 SUSY and BH benchmark events at the LHC. Visible energy and missing transverse momentum ${\mathrm{P̸}}_T$ (top panels) are comparable due to the presence of invisible channels in both models. Leptons with large transverse momentum provide instead an effective discriminator (bottom right panel).

Figure 4

Distribution of visible energy, ${\mathrm{P̸}}_T$ and transverse momenta of leptons and $\mathrm{\text{hadrons}}+\mathrm{\text{photons}}$. SUSY plots are shown as open squares. The four plots in the left panel show the effect of different decay modes in the Planck phase of ten-dimensional BHs: remnant formation ($n_p=0$, filled triangles), two-body decay ($n_p=2$, filled circles) and four-body decay ($n_p=4$, filled squares). The fundamental Planck scale is $M_{\star }=1\mathrm{TeV}$. The four plots in the right panel show the effect of varying the fundamental Planck scale: $M_{\star }=1\mathrm{TeV}$ (filled triangles), $M_{\star }=2\mathrm{TeV}$ (filled circles) and $M_{\star }=3\mathrm{TeV}$ (filled squares). The ten-dimensional BHs decay in two hard quanta at the end of the evaporation phase.

Figure 5

Sphericity (top panels) and 2nd Fox-Wolfram moment (bottom panels) for 10 000 BH and MSSM events (open squares). The left panels show the effect of different Planckian decay modes: BH remnant (filled triangles), two-body decay (filled circles) and four-body decay (filled squares). The fundamental scale is $M_{\star }=1\mathrm{TeV}$ and the number of extra dimensions is six. The right panels show the effect of different fundamental scales: $M_{\star }=1\mathrm{TeV}$ (filled triangles), 2 TeV (filled circles) and 3 TeV (filled squares). The ten-dimensional BHs decay in two quanta at the end of the Hawking phase.

Figure 6

Light and heavy jet masses (four leftmost panels) and number of jets (right panels) for 10 000 BH and MSSM events. Symbols are like in previous figures.

Figure 7

Invariant mass distribution (in GeV) for 1000 SUSY and BH OSSF dilepton events. The SUSY distribution (shaded histogram) shows the typical endpoint due to the presence of the LSP. The high-$P_T$ tail of the BH distribution is originated by uncorrelated lepton pairs emitted during the Hawking evaporation phase. The final BH decay is in two-quanta (left panel) or four-quanta (right panel).

Figure 8

Left panel: Histogram of the number of events with high-$P_T$ leptons for 10 000 MSSM (filled squares) and BH interactions (open triangles). The number of BH events with three isolated leptons is smaller than the number of SUSY events by a factor of $\sim 20$. The probability of producing BH events with four or more leptons is virtually zero. Right panel: $P_T$ scatter plot for $\sim 1000$ isolated opposite-flavor dilepton events for SUSY (filled squares) and BHs (open triangles). BH leptons are harder than SUSY leptons and show a larger spread in $P_T$.