The year 2024 marked the 50th anniversary of the discovery of the J/ψ particle, which unveiled the charm quark and the charmonium spectrum, instigating the “November Revolution” in particle physics. This discovery catalyzed the development of quenched potential models, most notably the Cornell model, which provided a foundational quantitative description of the hadronic spectrum. However, the landscape of hadron spectroscopy has been profoundly transformed since the turn of the 21st century with the observation of numerous charmonium-like states, such as X(3872), which exhibit properties starkly at odds with quenched model predictions. These discrepancies, exemplified by the “X(3872) low-mass puzzle” and the “Y problem” associated with vector states like Y(4260), underscore the critical limitations of the quenched approximation and signal the necessity for a new theoretical paradigm. This review synthesizes recent advances in hadronic spectroscopy, arguing that the unquenched picture, which incorporates coupled-channel effects such as hadronic loops, is essential for a unified description of these new states and associated anomalies. We demonstrate how unquenched effects provide compelling solutions to long-standing puzzles in charmonium decays (e.g., the “ρπ puzzle” and anomalous dipion transitions), predict and explain the existence of exotic charged states like Zc(3900) and Zb(10610) via mechanisms such as Initial Single Pion Emission, and offer a framework for understanding interactions between charmonia and with nucleons. Furthermore, we emphasize the universality of unquenched effects, extending their application to bottomonium and light-flavor sectors. As experimental precision continues to improve, we advocate for the systematic development of unquenched hadronic spectroscopy, which heralds a new era of high-precision theoretical and experimental studies, moving decisively beyond the quenched approximation to achieve a more complete understanding of non-perturbative behavior of the strong interaction.
This work concerns about stochastic Burgers type equations with reflection. First of all, by means of the equicontinuous uniform Laplace principle, we prove the Freidlin-Wentzell uniform large deviation principle for these equations uniformly on bounded sets. Then based on this result, we establish the Dembo-Zeitouni uniform large deviation principle for these equations uniformly on compact sets. Finally, an averaging principle result for these equations is obtained through the time discretization approach.
The stochastic generalized Burgers-Huxley equation (SgBHE) introduces a power law parameter in its nonlinear terms, offering a robust framework for modeling reaction-convection-diffusion processes under uncertainty. While existing research has mainly focused on theoretical aspects, this work represents the first attempt to study the strong convergence of an explicit full-discrete scheme for the SgBHE driven by an additive fractional Gaussian noise. To approximate the continuous problem, we propose a temporal nonlinear-tamed exponential integrator combined with the spatial spectral Galerkin method. We derive strong error estimates and examine convergence rates for the fully discrete scheme, depending on the regularity of both time and spatial variables. In contrast to the stochastic Burgers-Huxley equation (SBHE), we develop a progressive technique to overcome the challenges posed by the generalized nonlinear terms, ensuring the boundedness of moments for the numerical solution. A numerical experiment is conducted to validate the theoretical results.
This study develops an event-driven simulation framework to analyze congestion-induced service degradation in timetable-based urban rail transit systems (URTSs) under time-dependent demand. Rather than representing service deterioration as a static outcome or an isolated disturbance, service degradation is represented as an operational process that emerges from passenger accumulation, extended dwell times, and headway constraints. Using the Shenzhen URTS as a case study, the model is evaluated against smart-card observations and then used to characterize baseline congestion regimes and system responses to controlled operational perturbations. Results show that congestion-induced service degradation is strongly localized in both time and space, with impacts remaining largely confined even under severe service gaps. Reduced-model comparisons further show that simplified settings can reproduce the broad timing of degradation onset and buildup, but systematically underestimate degradation intensity, persistence, and recovery lag when endogenous feedback becomes important. The proposed framework provides an operationally explicit basis for analyzing how service degradation forms, persists, and is absorbed in timetable-based URTSs.
The fluidized-bed combustion of sludge was investigated to examine the effects of NaCl and montmorillonite on the migration of heavy metals. The addition of NaCl caused severe slagging and chlorination, increasing the yields of bottom slag and fly ash. It also promoted the formation of finer particles, as the fraction of PM2.5 increased, especially PM1-0.1. Elements such as Cr, Ni, Zn, and Na/K were more enriched in the cyclone fly ash and the PM2.5 of fly ash due to the chlorination, evaporation, and condensation effect, whereas volatile Pb was predominantly transported to cyclone fly ash and PM5. The addition of montmorillonite with or without NaCl both enhanced the formation of bottom slag via interactions with sludge components or gaseous alkali species, while reducing the yield of fly ash. The migration of heavy metals to bottom slag and cyclone fly ash was promoted, with the concentration of heavy metals in fly ash slightly decreased. The combined use of montmorillonite and NaCl effectively reduced the leaching ratio of heavy metals in bottom slag and cyclone fly ash. Furthermore, the contents of fine/ultrafine particles PM2.5-1, PM1-0.1, and PM0.1 were all reduced, along with the associated heavy metal proportions. This study aimed to help control the mobility of heavy metals during sludge combustion with the intervention of inorganic chlorine.
