Nonlinear and Quantum Origin of Doubly Infinite Family of Modified   Addition Laws for Fourmomenta
  We show that infinite variety of Poincar\'{e} bialgebras with nontrivial classical r-matrices generate nonsymmetric nonlinear composition laws for the fourmomenta. We also present the problem of lifting the Poincar\'{e} bialgebras to quantum Poincar\'{e} groups by using e.g. Drinfeld twist, what permits to provide the nonlinear composition law in any order of dimensionfull deformation parmeter $\lambda$ (from physical reasons we can put $\lambda = \lambda_{p}$ where $\lambda_{p}$ is the Planck lenght). The second infinite variety of composition laws for fourmomentum is obtained by nonlinear change of basis in Poincar\'{e} algebra, which can be performed for any choice of coalgebraic sector, with classical or quantum coproduct. In last Section we propose some modification of Hopf algebra scheme with Casimir-dependent deformation parameter, which can help to resolve the problem of consistent passage to macroscopic classical limit. 
J. Lukierski (Institute for Theoretical Physics, University of   Wroc{\l}aw, Poland) and A. Nowicki (Institute of Physics, U...