In this work we revisit the famous Fermi two-atom problem, which concerns how relativistic causality impacts atomic transition probabilities, using the tools from relativistic quantum information and algebraic quantum field theory. The problem has sparked different analyses from many directions and angles since the proposed solution by Buchholz and Yngvason [Phys. Rev. Lett. 73, 613 (1994)]. Some of

A number of popular extensions of the Standard Model of particle physics predict the existence of doubly charged scalar particles X±±. Such particles may be long lived or even stable. If they exist, X−− could form atomic bound states with light nuclei and catalyze their fusion by essentially eliminating the Coulomb barrier between them. Such an X-catalyzed fusion (XCF) process does not require high

’t Hooft anomalies of quantum field theories (QFTs) with an invertible global symmetry G (including spacetime and internal symmetries) in a dd spacetime are known to be classified by a d+1d cobordism group TPd+1(G), whose group generator is a d+1d cobordism invariant written as an invertible topological field theory (iTFT) with a partition function Zd+1. It has recently been proposed that the deformation

f(Q) gravity is an extension of the symmetric teleparallel equivalent to general relativity. We demonstrate the Hamiltonian analysis of f(Q) gravity with fixing the coincident gauge condition. Using the standard Dirac-Bergmann algorithm, we show that f(Q) gravity has 8 physical degrees of freedom. This result reflects that the diffeomorphism symmetry of f(Q) gravity is completely broken due to the

The effective approach in loop quantum cosmology (LQC) has provided means to obtain predictions for observable quantities in LQC models. While an effective dynamics in LQC has been extensively considered in different scenarios, a robust demonstration of the validity of effective descriptions for the perturbative level still requires further attention. The consistency of the description adopted in most

We derive multicomponent relativistic second-order dissipative fluid dynamics from the Boltzmann equations for a reactive mixture of Nspec particle species with Nq intrinsic quantum numbers (e.g., electric charge, baryon number, and strangeness) using the method of moments. We obtain the continuity equations for multiple conserved charges as well as the conservation equations for the total energy and

While the ground-state tensor (JPC=2++) mesons a2(1320), K2*(1430), f2(1270), and f2′(1525) are well known experimentally and form an almost ideal nonet of quark-antiquark states, their chiral partners, the ground-states axial-tensor (JPC=2−−) mesons are poorly settled: only the kaonic member K2(1820) of the nonet has been experimentally found, whereas the isovector state ρ2 and two isoscalar states