Signatures of TeV Scale Gravity in High Energy Collisions

In TeV scale unification models, gravity propagates in 4+d dimensions while gauge and matter fields are confined to a four dimensional brane, with gravity becoming strong at the TeV scale. For a such scenario, we study strong gravitational interactions in a effective Schwarzschild geometry. Two regimes appear. For large impact parameters, the ratio rho=(Rs/ro)1+d, (with Rs the Schwarzschild radius and ro the closest approach to the black hole), is small and the deflection angle is proportional to rho (like Rutherford-type scattering).For small impact parameters, the deflection angle develops a logarithmic singularity and becomes infinite for rho=rho crit= 2/(3+d). This singularity is reflected into a strong enhancement of the backward scattering (like a glory-type effect). We suggest a distinctive signature of black hole formation in particle collisions at TeV energies, the observation of the backward scattering events and its associated diffractive effects.