CAN BLACK HOLES BE PRODUCED at HIGH-ENERGY COLLIDERS?

• The present boom of interest to the black holes is very much substantiated by accumulation of astrophysical observations, which can be interpreted in terms of black holes [1]. This, certainly, refers to very large-mass systems that are to be described in the framework of classical (non-quantum) field theory (General Relativity or other classical theories of gravitation). Quantum properties of the black holes (BH in the following) were addressed some 30 years ago [2] with a conclusion that quantum effects lead to the thermal radiation from the BH with an effective “temperature” inversely proportional to the BH mass. Quick evaporation of the BH with small masses caused some hopes that the “mini-BH” may be relevant in the high-energy collisions of subnuclear particles, and the corresponding events could be observable due to the characteristic event shapes. However expected sizes of such effects are negligible at present or near (LHC) energies because of the small value of the Newton constant ∼ M PL. It is of interest to note that one of the most fervent prophets of the black holes, S.W. Hawking, has recently expressed his deep doubts that the true event horizon ever forms at all (S. Hawking’s talk at GR 17, Dublin, 2004). • New prospects for exploration of the BH effects were opened by the theories with extradimensions [3] in which gravitational interactions at small distances could get very strong at the scales of order 1 TeV−1. The mechanism of the BH production in high-energy collisions is usually presented as follows. Two energetic partons from the colliding hadrons (protons) with the c.m.s. energy √ s — considered as a component of the energy-momentum tensor in the r.h.s. of the Hilbert–Einstein equation — produce the metric perturbation corresponding to a BH of the mass √ s. This configuration having the Hawking temperature 1/ √ s quickly evaporates giving rise to a specific final multiparticle state. The cross-section of such elementary process is assumed to be purely geometric