Real-Time Nonperturbative Dynamics of Jet Production in Schwinger Model: Quantum Entanglement and Vacuum Modification.

The production of jets should allow testing the real-time response of the QCD vacuum disturbed by the propagation of high-momentum color charges. Addressing this problem theoretically requires a real-time, nonperturbative method. It is well known that the Schwinger model [QED in (1+1) dimensions] shares many common properties with QCD, including confinement, chiral symmetry breaking, and the existence of vacuum fermion condensate. As a step in developing such an approach, we report here on fully quantum simulations of a massive Schwinger model coupled to external sources representing quark and antiquark jets as produced in e^{+}e^{-} annihilation. We study, for the first time, the modification of the vacuum chiral condensate by the propagating jets and the quantum entanglement between the fragmenting jets. Our results indicate strong entanglement between the fragmentation products of the two jets at rapidity separations Δη≤2, which can potentially exist also in QCD and can be studied in experiments.

Experimental and Simulation Studies on the Slug Flow in Curve Pipes.

This work focuses on the two-phase slug flow in the curve pipe, which is very common in oil/gas wells. In terms of oil and gas production, the unstable slug flow may cause several problems and reduce production. In the present work, slug flow experiments were conducted in several curve pipes for varying inflow angles and gas-liquid velocity ratios. The real-time pressure was measured at the curve pipe using the Rosemount pressure gauges, and the liquid holdup was measured using the conductivity sensors, which were used to calculate the slug length. Then, we define the dimensionless slug length φD = L S/D (the ratio of slug length L to pipe diameter D), which can make the slug analysis free from the influence of different pipe diameters; φD is also used to analyze the change in the slug flow state. The experimental results show that the dimensionless slug length φD increases with the increase in the pipe curvature; φD first decreases and then increases with the increase in the inflow angle; φD also increases with the increase in the gas-liquid velocity ratio. This study adopts a dynamic slug flow model to simulate the well completion and the throttle cases under field conditions based on the hydraulic similarity principle. The pressure and liquid holdup results show that the large-scale segregated completion will lead to decreasing flow instability and the decrease in throttle opening will also lead to the decrease in flow instability.

Signatures of Chiral Magnetic Effect in the Collisions of Isobars.

Quantum anomaly is a fundamental feature of chiral fermions. In chiral materials, the microscopic anomaly leads to nontrivial macroscopic transport processes such as the chiral magnetic effect (CME), which has been in the spotlight lately across disciplines of physics. The quark-gluon plasma (QGP) created in relativistic nuclear collisions provides the unique example of a chiral material consisting of intrinsically relativistic chiral fermions. Potential discovery of CME in QGP is of utmost significance, with extensive experimental searches carried out over the past decade. A decisive new collider experiment, dedicated to detecting CME in the collisions of isobars, was performed in 2018 with analysis now underway. In this Letter, we develop the state-of-the-art theoretical tool for describing CME phenomena in these collisions and propose an appropriate isobar subtraction strategy for best background removal. Based on that, we make quantitative predictions for signatures of CME in the collisions of isobars. A new and robust observable that is independent of axial charge uncertainty-the ratio between isobar-subtracted γ- and δ- correlators-is found to be -(0.41±0.27) for event-plane measurement and -(0.90±0.45) for reaction-plane measurement.

Transient Pressure Analysis of Volume-Fractured Horizontal Wells Considering Complex Fracture Networks and Stress Sensitivity in Tight Reservoirs.

Tight reservoirs, as an important alternative for conventional energy resources, have been successfully exploited with the aid of hydraulic fracturing technologies. Because of the inherent ultralow permeability and porosity, tight oil reservoirs generally suffer from the effects of stress sensitivity. Both hydraulic fractures with complex geometries and a high-permeability area known as stimulated reservoir volume (SRV) may be generated by the massive hydraulic fracturing operations. All these bring huge challenges in transient pressure analysis of tight reservoirs. Up till now, although many research studies have been carried out on the transient pressure analysis of volume-fractured horizontal wells in tight reservoirs, unfortunately, there is still a lack of research studies that have taken stress sensitivity, complex fracture networks, and the SRV into consideration, simultaneously. To fill up this gap, this paper first idealizes the reservoir after hydraulic fracturing as two radial composite regions, that is, the unstimulated outer region and the inner SRV. The stress sensitivity is characterized by the variable permeability depending on the pore pressure. A linear source with consideration of the stress sensitivity in the composite reservoir is obtained by the perturbation technique, Laplace transformation, and the flow coupling of two regions. Second, the complex fracture networks are discretized into segments to capture their geometries. A semi-analytical model is finally established and validated by the comparison with previous models. On the basis of our model, six flow stages of volume-fractured horizontal well are identified and special features of each regime are analyzed. The stress sensitivity has a great impact on the later stage of production. The mobility ratio and the SRV radius mainly affect SRV pseudo-steady-state flow period and interporosity flow period in the outer region. Fracture number mainly affects the linear flow in the SRV. Fracture geometries mainly affect linear flow and interporosity flow in the SRV. This study has some significance for well test interpretation and production performance analysis of tight reservoirs.

Numerical Slug Flow Model of Curved Pipes with Experimental Validation.

The research for gas-liquid two-phase flow is very important for flow assurance and flow stability of chemical transportation. In terms of transportation pipelines, the curved section is a very significant part. Therefore, the present work proposes a transient slug flow model for the curve pipes, and we conducted some experiments to validate it. This slug flow model is a four-equation model that contains mass and momentum balances with the closure relations. The normal two-dimensional rectangular coordinate system is simplified to the one-dimensional polar coordinate system, which will make the simulation faster and easier. The common flow parameters, such as the pressure profile along the pipeline, real-time pressure, and liquid holdup, are calculated in this model. Three groups of experiments with three different pipe curvatures were carried out to validate this model; the experiments were under the same conditions as those of the model calculations. The transient pressure and liquid holdup were measured at the middle of the curved pipe. The experimental data are compared to the calculated results, and there are error analyses of pressure and liquid holdup that are made to review the model's performance. The analyses show that a large proportion of the pressure errors is within 10%, and most of the liquid holdup errors are within 0.1. The comparisons between the model and experiments show good agreement.