Multi-particle systems in quantum spacetime and a novel challenge for center-of-mass motion

In recent times, there has been considerable interest in scenarios for quantum gravity in which particle kinematics is affected nonlinearly by the Planck scale, with encouraging results for the phenomenological prospects, but also some concerns that the nonlinearities might produce pathological properties for composite/multiparticle systems. We here focus on kinematics in the [Formula: see text]-Minkowski noncommutative spacetime, the quantum spacetime which has been most studied from this perspective and compare the implications of the alternative descriptions of the total momentum of a multiparticle system which have been so far proposed. We provide evidence suggesting that priority should be given to defining the total momentum as the standard linear sum of the momenta of the particles composing the system. We also uncover a previously unnoticed feature concerning some (minute but conceptually important) effects on center-of-mass motion due to properties of the motion of the constituents relative to the center of mass.

Energy Dissipation Analysis of Composite Frame Structure with Supplemental Viscous Dampers

With a 10 layer of concrete filled square steel tubular column beam frame structure as the object of study ,discrete structure into multiparticle system and establish a dynamic differential equation,solve this dynamic equation by Newmark -β method .Establish thefinite element model of the structure is based on Sap2000 ,then dynamic elastic-plastic time history analysis are carried out, the research results show that the dynamic characteristics of structure,s story drifts,story shear and acceleration with energy dissipating devices are smaller than the model without energy dissipating devices under different earthquake intensities. the damped effect is considered obvious.

Entropy Analysis in Relativistic Heavy-Ion Collisions

Entropy creation in multiparticle system is investigated by analysing the experimental data on ion-ion collisions at AGS and SPS energies and the results thus obtained are compared with those predicted by multiphase transport and correlation-free Monte Carlo models. Entropies produced in limited- and full-phase space are observed to increase with increasing beam energy. The entropy values, normalized to the maximum rapidity and plotted against pseudorapidity (bin width also normalized to the maximum rapidity), are found to be energy independent, exhibiting a kind of entropy scaling. Such scaling is observed in the full phase space as well as in the regions confined to the forward or backward hemispheres. The findings also reveal that there exist strong correlations amongst the particles produced in the forward and backward hemispheres around the midrapidity. These correlations are found to be of short range in nature, and the contributions from the long-range correlations seem to be absent. PACS numbers: 25.75-q, 25.75.Gz.