In the present work, relativistic quantum motion of massless fermions in a helicoidal graphene nanoribbon under influence uniform magnetic field is investigated. Considering ($B$) aligned along axis helicoid, this problem explored context Dirac equation curved space-time. As system does not support exact solutions due to considered background, bound-state and local density state (LDOS) are obta...

We study the topological susceptibility and fourth cumulant of QCD vacuum in a background magnetic field (H) using three-flavor chiral perturbation theory (χPT) for arbitrary quark masses n-flavor χPT with degenerate masses. find that enhancement by relative to H=0 value is larger compared two-flavor χPT. Additionally, comparing cumulant, we its suppression comparable fields, eH≲0.8mπ2, weaker ...