Sciences Et Techniques

Casimir scaling in glueballs in SU(��) and Sp(2��) gauge theories: Hints from constituent approaches

Sat, 10 Jan 2026 00:00:00 GMT

Casimir scaling in glueballs in SU(��) and Sp(2��) gauge theories: Hints from constituent approaches Buisseret, Fabien; Semay, Claude; Mathieu, Vincent; Chevalier, Cyrille Xe have shown that the ratio of the glueball masses on their large N mass in SU(N) and Sp(2N) gauge theories dominantly scales according to the Casimir scaling hypothesis. This result is in agreement with previous findings in the mesonic sector. Such scaling laws may help to put constraints on effective models parameters, as we have shown in the case of constituent gluons approaches, where the observed scaling law favours adjoint strings as the best candidate to model interactions between constituent gluons. A simple two-body spinless Salpeter Hamiltonian with funnel potential is able to model the SU(∞) and Sp(∞) ��=+ low-lying spectrum provided constituent gluons are seen as transverse particles. A three-body Y-junction generalization of this Hamiltonian leads to a ��=− low-lying spectrum with the expected global features but show-ing extra states with respect to the lattice QCD spectrum.

Boson stars and black holes with complex and real scalar hair

Tue, 08 Apr 2025 00:00:00 GMT

Boson stars and black holes with complex and real scalar hair Brihaye, Yves; Buisseret, Fabien; Hartmann, Betti; Layfield, Oliver We discuss boson stars and black holes with scalar hair in a model where the complex scalar field forming the boson star and the hair on the black hole, respectively, interacts with a real scalar field via a H´enon-Heiles-type potential. We demonstrate that black holes and boson stars carrying only a real scalar field with cubic self-interaction are possible and that black holes with both real and complex scalar field branch off from these solutions for sufficiently large interaction between the two fields and/or sufficiently large horizon radius rh. The latter possess lower mass for the same choice of coupling constants than the former, however seem to be thermodynamically preferred only for high enough temperature.

Q-balls and charged Q-balls in a two-scalar field theory with generalized Henon-Heiles potential

Tue, 30 Apr 2024 00:00:00 GMT

Q-balls and charged Q-balls in a two-scalar field theory with generalized Henon-Heiles potential Buisseret, Fabien; Brihaye, Yves We construct Q-ball solutions from a model consisting of one massive scalar field ξ and one massive complex scalar field ϕ interacting via the cubic couplings g1ξϕ ϕ þ g2ξ3, typical of Henon-Heiles-like potentials. Although being formally simple, these couplings allow for Q-balls. In one spatial dimension, analytical solutions exist, either with vanishing or nonvanishing ϕ. In three spatial dimensions, we numerically build Q-ball solutions and investigate their behaviors when changing the relatives values of g1 and g2. For g1 < g2, two Q-balls with the same frequency exist, while ω ¼ 0 can be reached when g1 > g2. We then extend the former solutions by gauging the U(1) symmetry of ϕ and show that charged Q-balls exist.

Diffusion in Phase Space as a Tool to Assess Variability of Vertical Centre-of-Mass Motion during Long-Range Walking

Mon, 06 Feb 2023 00:00:00 GMT

Diffusion in Phase Space as a Tool to Assess Variability of Vertical Centre-of-Mass Motion during Long-Range Walking Boulanger, Nicolas; BUISSERET, Fabien; Dehouck, Victor; DIERICK, Frédéric; White, Olivier When a Hamiltonian system undergoes a stochastic, time-dependent anharmonic perturbation, the values of its adiabatic invariants as a function of time follow a distribution whose shape obeys a Fokker–Planck equation. The effective dynamics of the body’s centre-of-mass during human walking is expected to represent such a stochastically perturbed dynamical system. By studying, in phase space, the vertical motion of the body’s centre-of-mass of 25 healthy participants walking for 10 min at spontaneous speed, we show that the distribution of the adiabatic invariant is compatible with the solution of a Fokker–Planck equation with a constant diffusion coefficient. The latter distribution appears to be a promising new tool for studying the long-range kinematic variability of walking.