This work utilizes the novel approach of the strongly intensive quantity $\Sigma _{\mathrm {FB}}$ to investigate the forward-backward multiplicity correlation in UrQMD simulated pp collisions $\mathrm {at} \sqrt {{s}}=13$ TeV. Evidence of forward-backward correlation has been noted in UrQMD simulated pp collisions at different separation between the forward and backward pseudo-rapidity zones. The strongly intensive quantity $\Sigma _{\mathrm {FB}}$ has been found to increase slowly with increasing separation ($\eta _{\mathrm {gap}})$ between the forward and backward pseudo-rapidity zones. Comparisons of this analysis with PYTHIA tuned with Monash 2013 simulated values, EPOS3 simulated values and ALICE Collaboration values (for minimum bias events) have also been presented.

As is known to all, it is extraordinarily difficult to construct the variational principles of the nonlinear partial differential equations (NPDEs) for fluid mechanics. In this work, we focus on the Burgers-Korteweg-de Vries equation and attempt to establish its generalized variational principle by employing the semi-inverse method (SIM). Two different generalized variational principles (GVPs) are extracted and the detailed derivation process is presented. The GVPs can present some new inspiration for the study and application of the variational method.

The effective dynamics of loop quantum gravity for marginally bound Lemaître-Tolman-Bondi spacetimes predict that the big-bang singularity is resolved and replaced by a cosmic bounce. Numerics show that these effective dynamics also homogenize small regions soon after the bounce when inhomogeneities before the bounce are sufficiently large. These homogeneous regions typically have a width of a few Planck lengths where relative perturbations in the energy density remain less than 15%. If the bounce is followed by an inflationary period, the homogeneous region can reach cosmic scales and the amplitude of relative perturbations can be suppressed to a value compatible with observations.

The dispersion relation of surface plasmon polaritons (SPPs) is investigated as a function of the volume fraction of silver nanoparticles at the interface between nanocomposite and atomic media. The increase in silver nanoparticle content significantly influences SPP propagation, which is crucial for advancing plasmonic technologies. As the volume fraction of silver nanoparticles increases from 0% to 60%, the real part of the SPP wave vector rises from $2.5k_{0}$ to $5.5k_{0}$, and the SPP wavelength decreases from $\lambda _{sp} = 0.7\,\lambda$ to $\lambda _{sp} = 0.3\,\lambda$. This also modifies the propagation length from $40\,\lambda$ to $20\,\lambda$ and reduces the penetration depth in the nanocomposite from 0.125 nm to 0.005 nm.

Binding and unbinding of vortices drives Kosterlitz-Thouless phase transition in two-dimensional XY model. Here we investigate whether similar mechanism works in two-dimensional Heisenberg model, by using the fluctuation of skyrmion number inside a loop to characterize the nature of binding vs. unbinding of defects. Through Monte Carlo simulations, we find that the fluctuation is proportional to the perimeter of the loop at low temperatures while it is proportional to the area of the loop at high temperatures, implying binding of the defects at low temperatures and unbinding at high temperatures.

: In this article, the two-temperature model and the mechanism of effective interaction potentials are used to study the thermal relaxation of hot and dense non-isothermal plasma fuels such as DT, D3He, and P11B. In this work, we do not consider the ion and electron temperatures to be the same because the temperature inside the electron and ion subsystems reaches equilibrium much faster than the temperature between electrons and ions. This is due to the difference between the masses of ion and electron. Simulations and calculations for fusion by confinement are very complex because many different physical processes occur and it takes a lot of time to do these calculations. Therefore, we used the method of effective interaction potentials for the first time in this work because this method can provide accurate and fast calculations for dense plasmas. The effective interaction potentials include two parts: (a) charge overlap effects at long distances and (b) quantum effects at short distances. We calculate the stopping power, energy absorption, transfer coefficients, deceleration time, and temperature relaxation related to non-isothermal dense hot plasma of DT, D3He and P11B fuels and select

This study investigates two-dimensional atomic microscopy via surface plasmon polariton (SPP) waves at the interface of sodium metal and multi-walled carbon nanotubes (MWCNTs). The SPP damping spectrum encodes key information about atomic localization, achieving subwavelength precision with resolutions of $\lambda/2$ along spatial axes (x, y, z). By dynamically tuning the SPP dispersion relation through control fields and MWCNT parameters, we control the number, position, and shape of localized peaks within a single wavelength domain ($-\pi \leq k_x, k_y \leq \pi$). Remarkably, localization is achieved at scales below $\lambda/1000$ in x- and y-directions. We manipulate peak profiles into loop-like, wall-like, crater-like, and Gaussian shapes. These advancements offer significant potential in high-precision atomic positioning, nano-lithography, and Bose-Einstein condensation, opening new frontiers for atomic-scale control and imaging.

In this study, we present a model for the behavior of Dirac particles under the tensor interaction in the spherical core/shell regime. We examine the change of energy levels corresponding to the particles localized in a space of approximately 1.0 fm in the core region of the quantum sphere, with the well width. It is obtained that the analytical solutions occur when the two different levels accompany particle states of the same mass. Additionally, the solutions exhibiting anomalous behavior, giving rise to antiparticle-type states, exist at heavier mass.

In numerous scientific domains, a significant challenge lies in identifying causal relationships among the various components of a system solely based on observational data. Recently, the convergent cross mapping(namely, CCM) method proposed by Sugihara et al. has demonstrated substantial potential for causal inference in the absence of models. By varying the coupling strength of the coupled Logistic model, we found that for asymmetrically strongly coupled time series, the CCM method fails in inferring both the direction and strength of causal relationships. In this paper, we propose an improved version of CCM method, termed effective mutual information convergent cross mapping(namely, EMICCM) method, by considering inherent characteristics of time series such as nonlinearity and non-normal distribution features. As most real systems exhibit nonlinear and non-normally distributed characteristics, our method offers a more accurate measure for inferring causal relationships within them.

We investigate a hydrogen sensor based on Palladium (Pd) in a plasmonic structure, where a Pd layer is deposited on a gold substrate with an elliptical hole array. The Pd will transform to Pd-Hx in a hydrogen-rich gas environment, it will change with the concentration of hydrogen. To ensure safety, the concentration of H2 in air must lower 4%. We calculate the absorption spectra (ΔA) of the sensor by Finite-difference time-domain method (FDTD). The results show That the difference between absorptions in air of H2-less(0%) and H2-rich(4%) environment ΔA can reach to 0.136. The major influence factor is the size of the hole. We also discuss influence of the period of the array. For a large period, the long-range interaction will appear, which is tuned by the period and the incident wavelength. The long-range interaction may have a little effect on the maximum value of ΔA. Our proposed structure shows an excellent ability to sense H2.

The effective dynamics of loop quantum gravity for marginally bound Lemaître-Tolman-Bondi spacetimes predict that the big-bang singularity is resolved and replaced by a cosmic bounce. Numerics show that these effective dynamics also homogenize small regions soon after the bounce when inhomogeneities before the bounce are sufficiently large. These homogeneous regions typically have a width of a few Planck lengths where relative perturbations in the energy density remain less than 15%. If the bounce is followed by an inflationary period, the homogeneous region can reach cosmic scales and the amplitude of relative perturbations can be suppressed to a value compatible with observations.

Lubrication flows between two solid surfaces can be found in a variety of biological and engineering settings. In many of these systems, the lubricant exhibits viscoelastic properties, which modify the associated lubrication forces. Here, we experimentally study viscoelastic lubrication by considering the motion of a submerged cylinder sliding down an incline. We demonstrate that cylinders move faster when released in a viscoelastic Boger liquid compared to a Newtonian liquid with similar viscosity. Cylinders exhibit pure sliding motion in viscoelastic liquids, in contrast to the stick-slip motion observed in Newtonian liquids. We rationalize our results by using the second-order fluid model, which predicts a lift force on the cylinder arising from the normal-stress differences provided by the dissolved polymers. The interplay between viscoelastic lift, viscous friction, and gravity leads to a prediction for the sliding speed, which is consistent with our experimental results for weakly viscoelastic flows. Finally, we identify a remarkable difference between the lubrication of cylindrical and spherical contacts, as the latter does not exhibit any lift for weak viscoelasticity.

Effective loop quantum gravity dynamics are derived for spherically symmetric spacetimes with a perfect fluid matter content. For homogeneous spacetimes, the effective dynamics agree with the standard results of loop quantum cosmology, while the equations for static solutions give an effective Tolman-Oppenheimer-Volkoff equation. There exist solutions to the effective Tolman-Oppenheimer-Volkoff equation that have a mass of the order of the Planck mass, a Planckian radius, and no horizon; these miniature stars could potentially contribute to dark matter, and could be an end state for an evaporating black hole.

Intrinsic decoherence models (IDMs) have been proposed in order to solve the measurement problem in quantum mechanics. In this work, we assess the status of two of these models as physical theories by establishing the ultimate bounds on the estimability of their parameters. Our results show that dephasing and dissipative IDMs are amenable to falsification and should be considered physical theories worthy of experimental study.

The motility of living things and synthetic self-propelled objects is often described using active Brownian particles. To capture the interaction of these particles with their often complex environment, this model can be augmented with empirical forces or torques, for example, to describe their alignment with an obstacle or wall after a collision. Here, we assess the quality of these empirical models by comparing their output predictions with trajectories of rod-shaped active particles that scatter sterically at a flat wall. We employ a classical least-squares method to evaluate the instantaneous torque. In addition, we lay out a Bayesian inference procedure to construct the posterior distribution of plausible model parameters. In contrast to the least-squares fit, the Bayesian approach does not require orientational data of the active particle and can readily be applied to experimental tracking data.

For ensembles of spatially extended ions, electrostatic interaction energies can be calculated more accurately using a capped Coulomb potential, which remains constant within a fixed distance and then decays inversely with distance. When this fixed distance is small, the capped Coulomb potential transitions into a composite Coulomb-Yukawa potential, widely used in modeling dense electrolytes and ionic liquids and associated with a fourth-order derivative in Poisson's equation. To go beyond the fourth order, we develop a theoretical framework for continuum electrostatics based on the capped Coulomb potential. We derive and solve a modified Poisson equation and calculate corresponding electrostatic interaction energies. Solutions of the modified Poisson equation are shown to emerge from applying a differential operator to the potential predicted by the unmodified Poisson equation. We demonstrate that the electrostatic potential satisfying the modified Poisson equation can exhibit discontinuities at interfaces.

We investigate the dynamic behavior of spin reversal events in the dilute Ising model, focusing on the influence of static disorder introduced by pinned spins. Our Monte Carlo simulations reveal that in a homogeneous, defect-free system, the inter-event time (IET) between local spin flips follows an exponential distribution, characteristic of Poissonian processes. However, in heterogeneous systems where defects are present, we observe a significant departure from this behavior. At high temperatures, the IET exhibits a power-law distribution resulting from the interplay of spins located in varying potential environments, where defect density influences reversal probabilities. At low temperatures, all site classes converge to a unique power-law distribution, regardless of their potential, leading to distinct critical exponents for the high- and low-temperature regimes. This transition from exponential to power-law behavior underscores the critical response features of magnetic systems with defects, suggesting analogies to glassy dynamics. Our findings highlight the complex mechanisms governing spin dynamics in disordered systems, with implications for understanding the universal aspects of relaxation in glassy materials.

Gathering information about a system enables greater control over it. This principle lies at the core of information engines, which use measurement-based feedback to rectify thermal noise and convert information into work. Originating from Maxwell's and Szilárd's thought experiments, the thermodynamics of information engines has steadily advanced, with recent experimental realizations pushing the field forward. Coupled with technological advances and developments in nonequilibrium thermodynamics, novel implementations of information engines continue to challenge theoretical understanding. In this perspective, we discuss recent progress and highlight new opportunities, such as applying information engines to active, many-body, and inertial systems and leveraging tools like optimal control to design their driving protocols.

Modelling fluid turbulence using a 'skeleton' of coherent structures has traditionally progressed by focusing on a few canonical laboratory experiments such as pipe flow and Taylor-Couette flow. We here consider the stratified inclined duct, a sustained shear flow whose density stratification allows for the exploration of a wealth of new coherent and intermittent states at significantly higher Reynolds numbers than in unstratified flows. We automatically identify the underlying turbulent skeleton of this experiment with a data-driven method combining dimensionality reduction and unsupervised clustering of shadowgraph visualisations. We demonstrate the existence of multiple types of turbulence across parameter space and intermittent cycling between them, revealing distinct transition pathways. With a cluster-based network model of intermittency we uncover patterns in the transition probabilities and residence times under increasing levels of turbulent dissipation. Our method and results pave the way for new reduced-order models of multi-physics turbulence.

Attosecond microscopy aims to record electron movement on its natural length and time scale. It is a gateway to understanding the interaction of matter and light, the coupling between excitations in solids, and the resulting energy flow and decoherence behavior, but it demands simultaneous temporal and spatial resolution. Modern science has conquered these scales independently, with ultrafast light sources providing sub-femtosecond pulses and advanced microscopes achieving sub-nanometer resolving power. In this perspective, we inspect the challenges raised by combining extreme temporal and spatial resolution and then highlight how upcoming experimental techniques overcome them to realize laboratory-scale attosecond microscopes. Referencing proof-of-principle experiments, we delineate the techniques' strengths and their applicability to observing various ultrafast phenomena, materials, and sample geometries.