Using the relation of a set of nonlinear Langevin equations with reaction-diffusion processes, we note the existence of a maximal strength of the noise for the stochastic traveling wave solutions of these equations. Its determination is obtained using the field-theoretical analysis of branching-annihilation random walks near the directed percolation transition. We study its consequence for the stochastic Fisher-Kolmogorov-Petrovsky-Piscounov equation. For the related Langevin equation modeling the Quantum Chromodynamic nonlinear evolution of the gluon density with rapidity, the physical maximal-noise limit may appear before the directed percolation transition, due to a shift in the traveling-wave speed. In this regime, an exact solution is known from a coalescence process. Universality and other open problems and applications are discussed in the outlook
In this paper we review and update the Amaral-Gay Ducati-Betemps-Soyez saturation model, by testing it against the recent H1-ZEUS combined data on deep inelastic scattering, including heavy quarks in the dipole amplitude. We obtain that this model, which is based on traveling wave solutions of the Balitsky-Kovchegov equation and built in the momentum space framework, yields very accurate descriptions of the reduced cross section, $σ_{r}(x,y,Q^{2})$, as well as DIS structure functions such as $F_{2}(x,Q^{2})$ and $F_{L}(x,Q^{2})$, all measured at HERA. Additionally, it provides good description…
Cross-fertilization of QCD and statistical physics: high energy scattering, reaction-diffusion, selective evolution, spin glasses and their connections
We report the first lattice QCD study of the heavy dibaryons in which all six quarks have the bottom (beauty) flavor. Performing a state-of-the-art lattice QCD calculation we find clear evidence for a deeply bound $Ω_{bbb}$-$Ω_{bbb}$ dibaryon in the $^1S_0$ channel, as a pole singularity in the $S$-wave $Ω_{bbb}$-$Ω_{bbb}$ scattering amplitude with a binding energy $-81(_{-16}^{+14})$ MeV. With such a deep binding, Coulomb repulsion serves only as a perturbation on the ground state wave function of the parameterized strong potential and may shift the strong binding only by a few percent. Consi…
We present the first direct $N_f=2$ lattice QCD computation of two- and three-$π^+$ scattering quantities that includes an ensemble at the physical point. We study the quark mass dependence of the two-pion phase shift, and the three-particle interaction parameters. We also compare to phenomenology and chiral perturbation theory (ChPT). In the two-particle sector, we observe good agreement to the phenomenological fits in $s$- and $d$-wave, and obtain $M_πa_0 = -0.0481(86)$ at the physical point from a direct computation. In the three-particle sector, we observe reasonable agreement at threshold…
Small $x$ behavior in QCD from maximal entanglement and conformal invariance
Stony Brook University（石溪大学）；Co-design Center for Quantum Advantage (C2QA), Stony Brook University（石溪大学量子优势协同设计中心）；Peng Huanwu Center for Fundamental Theory, Xi’an（西安庞焕武基础理论中心）；Institute of Modern Physics, Northwest University（西北大学现代物理研究所）；Energy and Photon Sciences Directorate, Condensed Matter and Materials Sciences Division, Brookhaven National Laboratory（布鲁克海文国家实验室凝聚态与材料科学部能源与光子科学局）；C.N. Yang Institute for Theoretical Physics, Stony Brook University（石溪大学杨振宁理论物理研究所）
The QCD axion is one of the best motivated dark matter candidates. The misalignment mechanism is well known to produce an abundance of the QCD axion consistent with dark matter for an axion decay constant of order $10^{12}$ GeV. For a smaller decay constant, the QCD axion, with Peccei-Quinn symmetry broken during inflation, makes up only a fraction of dark matter unless the axion field starts oscillating very close to the top of its potential, in a scenario called "large-misalignment". In this scenario, QCD axion dark matter with a small axion decay constant is partially comprised of very dens…
