Bulletin of the Lebedev Physics Institute

, Volume 42, Issue 1, pp 21–25 | Cite as

Torus or black disk?

  • I. M. DreminEmail author


It is shown that the interaction region of colliding protons appears almost totally absorbing (black) at impact parameters to 0.4–0.5 fm and LHC energy of 7 TeV. The blackness of the proton interaction region for central interactions is completely defined by the ratio of the diffraction cone slope B in elastic scattering to the total cross section. The corresponding parameter is close to unity at LHC energies. The behavior of this ratio at higher energies will determine whether the interaction region structure will remind a torus or a black disk. Recent phenomenological fittings of experimental data at 7 TeV give no way of distinguishing these cases due to inaccuracies of experiments and uncertainties of the extrapolation to unmeasured regions of transferred momenta.


proton interaction region impact parameter torus black disk 


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Copyright information

© Allerton Press, Inc. 2015

Authors and Affiliations

  1. 1.Lebedev Physical InstituteRussian Academy of SciencesMoscowRussia
  2. 2.National Research Nuclear University “MEPhI”MoscowRussia

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