High Energy Jets Research Articles

Measurements of sub-jet fragmentation with ALICE

High-energy jets offer rich opportunities to study quantum chromodynamics, from investigating the limits of perturbative calculability to constraining the emergent properties of the quark-gluon plasma (QGP). In these proceedings, we present new measurements of the fragmentation properties of jets. We report distributions of the sub-jet momentum fraction z_rzr measured in pp and Pb–Pb collisions with ALICE at the Large Hadron Collider. These measurements serve as input to test the universality of jet fragmentation in the QGP, and offer a path to elucidate jet quenching effects in the large-zz region.

Non-Gaussianities in collider energy flux

The microscopic dynamics of particle collisions is imprinted into the statistical properties of asymptotic energy flux, much like the dynamics of inflation is imprinted into the cosmic microwave background. This energy flux is characterized by correlation functions leftlangle mathcal{E}left({overrightarrow{n}}_1right)cdots mathcal{E}left({overrightarrow{n}}_kright)rightrangle of energy flow operators mathcal{E}left(overrightarrow{n}right) . There has been significant recent progress in studying energy flux, including the calculation of multi-point correlation functions and their direct measurement inside high-energy jets at the Large Hadron Collider (LHC). In this paper, we build on these advances by defining a notion of “celestial non-gaussianity” as a ratio of the three-point function to a product of two-point functions. We show that this celestial non-gaussianity is under perturbative control within jets at the LHC, allowing us to cleanly access the non-gaussian interactions of quarks and gluons. We find good agreement between perturbative calculations of the non-gaussianity and a charged-particle-based analysis using CMS Open Data, and we observe a strong non-gaussianity peaked in the “flattened triangle” regime. The ability to robustly study three-point correlations is a significant step in advancing our understanding of jet substructure at the LHC. We anticipate that the celestial non-gaussianity, and its generalizations, will play an important role in the development of higher-order parton showers simulations and in the hunt for ever more subtle signals of potential new physics within jets.

Ar/HMDS Plasma Jet as a Tool for Superhydrophobic Coatings on Epoxy Resin

During actual operation, the superhydrophobic surface provides excellent resistance to condensation and icing due to its low wettability. This study used an Ar/HMDS mixture as the working gas and a low-temperature plasma jet induced in an atmospheric pressure environment to create a superhydrophobic coating with a water contact angle of up to 172.6°, utilized a typical epoxy resin plate as the substrate. XPS analysis indicated the presence of a significant number of low surface energy functional groups containing Si and O on the epoxy resin surface. Scanning electron microscope (SEM) revealed the presence of dense microstructure and nanostructure on the surface. The process of plasma jet water-repellent modification of epoxy resin surface was further analyzed from two perspectives: particle collision in the electric field, molecular bond breaking and reorganization reaction of monomer, and grafting reaction of free radicals formed on the surface of epoxy resin by high-energy jet bombardment, combined with XPS test of high-purity discharge products in the jet tube. The results indicate that the epoxy resin surface modified by plasma jets achieves superhydrophobicity. The modification time is extended to 180 s, and the static water contact angle is increased from 72.4° to 172.6°. Dense microparticle and nanoparticle are formed on the surface. For the secondary binary composite rough structure, the percentage of Si and O elements increased to 41.3% and 27.8%, respectively. The Si(CH₃)O_3/2 system contributed the most, accounting for 40.5%.

HEJ 2.1: High-energy resummation with vector bosons and next-to-leading logarithms

We present version 2.1 of the High Energy Jets (HEJ) event generator for hadron colliders. HEJ is a Monte Carlo generator for processes at high energies with multiple well-separated jets in the final state. To achieve accurate predictions, conventional fixed-order perturbative QCD is supplemented with an all-order resummation of large high-energy logarithms. The new version 2.1 now supports processes with final-state leptons originating from a charged or neutral vector boson together with multiple jets, in addition to processes available in earlier versions. Furthermore, the all-order resummation is extended to include an additional gauge-invariant class of subdominant logarithmic corrections. HEJ 2.1 can be obtained from https://hej.hepforge.org. New version program summaryProgram Title:HEJ.CPC Library link to program files:https://doi.org/10.17632/24c9mb6pf9.2Licensing provisions: GPLv2 or later.Programming language: C++.Journal reference of previous version: Comput. Phys. Commun. 245 (2019) 106832.Does the new version supersede the previous version?: YesReasons for the new version: Support for further scattering processes and inclusion of additional corrections.Summary of revisions: This release adds support for the production of two final-state leptons originating from a charged or neutral vector boson together with multiple jets. Resummation is extended to include next-to-leading logarithmic corrections connected to the emission of additional quark-antiquark pairs.Nature of problem: Conventional event generators for high-energy colliders are based on fixed-order perturbation theory, which converges poorly in regions of phase space with large invariant masses between jets. Reliable predictions in these regions are of general interest, and particularly important whenever cuts relevant to weak-boson fusion or weak-boson scattering are applied.Solution method: The perturbative description can be amended by resumming the high-energy logarithms associated with large invariant masses to all orders in perturbation theory. HEJ 2 implements this resummation following the High Energy Jets framework. Using HEJ 2 in conjunction with a conventional event generator allows one to obtain reliable predictions for processes involving multiple jets in high-energy regions of phase space.Additional comments including restrictions and unusual features: The current version implements multi-jet processes with at most a single lepton pair or Higgs boson in the final state. Matching to fixed-order perturbation theory is currently restricted to leading order.

Neural conditional reweighting

There is a growing use of neural network classifiers as unbinned, high-dimensional (and variable-dimensional) reweighting functions. To date, the focus has been on marginal reweighting, where a subset of features are used for reweighting while all other features are integrated over. There are some situations, though, where it is preferable to condition on auxiliary features instead of marginalizing over them. In this paper, we introduce neural conditional reweighting, which extends neural marginal reweighting to the conditional case. This approach is particularly relevant in high-energy physics experiments for reweighting detector effects conditioned on particle-level truth information. We leverage a custom loss function that not only allows us to achieve neural conditional reweighting through a single training procedure, but also yields sensible interpolation even in the presence of phase space holes. As a specific example, we apply neural conditional reweighting to the energy response of high-energy jets, which could be used to improve the modeling of physics objects in parametrized fast simulation packages.

深度学习在喷注淬火中的应用

Deep learning techniques have broad applications in studying jet quenching phenomena. This paper reviews the works in recent years from several scholars employing different data representations of jet samples and architectures of neural network in terms of reconstructing the momentum of jets in a hot and dense QCD medium, distinguishing the vacuum jets and medium jets, and, in particular, identifying the energy loss of jets as well as distinguishing quark- and gluon-initiated jets in a QCD medium. In the study of jet energy loss prediction, we demonstrate that deep learning techniques can identify the degree of energy loss of high-energy jets traversing hot QCD matter on a jet-by-jet basis and show that our method advances the jet tomographic study of hot QCD matter. In the study of distinguishing quark-jets and gluon-jets in the medium, we find that the classification accuracy gradually decreases as the jets lose energy. Lastly, we discuss the medium modifications of quark and gluon jet substructures in a perspective view.

Jet Tomography in Heavy-Ion Collisions with Deep Learning

Deep learning techniques have the power to identify the degree of modification of high energy jets traversing deconfined QCD matter on a jet-by-jet basis. Such knowledge allows us to study jets based on their initial, rather than final, energy. We show how this new technique provides unique access to the genuine configuration profile of jets over the transverse plane of the nuclear collision, both with respect to their production point and their orientation. By effectively removing the selection biases induced by final-state interactions, one can analyze the potential azimuthal anisotropies of jet production associated to initial-state effects. Additionally, we demonstrate the capability of our new method to locate with precision the production point of a dijet pair in the nuclear overlap region, in what constitutes an important step forward toward the long term quest of using jets as tomographic probes of the quark-gluon plasma.

Principles and Developments in Soil Grouting: a Historical Review

Grouting includes a range of processes that involve the injection of wet or dry materials into the ground to provide improved engineering properties. Common aims are to increase strength or stiffness or to reduce permeability within the mass of ground treated. The simplest process in concept is the permeation of the pore spaces with a fluid grout which then sets, and provides the desired properties. Jet grouting employs erosion and mixing using high energy jets, to attack a wide-ranging set of soils and applications. This paper, mainly, addresses permeation grouting for the improvement of soils, in terms of strengthening or reduction of permeability, and compensation grouting for the displacement of structures during subsurface exploration. The historical evolution of these two grouting processes is described leading up to present-day practice. Reference is made to grouting materials, methods of injection, equipment, limitations and verification for each type of grouting. The grouts used to make permeation grouting are mainly suspensions and chemical solutions. The suspensions penetrate well into soils with granulometry up to coarse sand. On the contrary, the chemical solutions penetrate satisfactorily in finer formations up to fine sands or coarse sludges. Because some chemical solutions are toxic or generally harmful to the environment and humans, an effort has been made internationally in recent years to replace them with inorganic fine-grained suspensions.

Combined subleading high-energy logarithms and NLO accuracy for W production in association with multiple jets

Large logarithmic corrections in hat{s}/{p}_t^2 lead to substantial variations in the perturbative predictions for inclusive W-plus-dijet processes at the Large Hadron Collider. This instability can be cured by summing the leading-logarithmic contributions in hat{s}/{p}_t^2 to all orders in αs. As expected though, leading logarithmic accuracy is insufficient to guarantee a suitable description in regions of phase space away from the high energy limit.We present (i) the first calculation of all partonic channels contributing at next-to-leading logarithmic order in W-boson production in association with at least two jets, and (ii) bin-by-bin matching to next-to-leading fixed-order accuracy. This new perturbative input is implemented in High Energy Jets, and systematically improves the description of available experimental data in regions of phase space which are formally subleading with respect to hat{s}/{p}_t^2 .

Express ultra-jet diagnostics of defect resistance for surface layer of a material

In the manufacture of products of modern technology, such technologies of waterjet processing as water jet cutting are successfully used for cutting materials. However, the physical and energy basis of ultrajet technology predetermines a much broader scope of its practical applications. Most of modern technical products are made of composite materials. Moreover, some of them were obtained by innovative methods, for instance, selective laser fusion, which complicates their diagnostics. This article proposes an innovative method for determining a new informative parameter characterizing the defect resistance of various materials. This technique is based on the process of hydro-erosive destruction in the process of ultrajet exposure to a high-energy jet on the surface of the material being diagnosed. Ultra-jet diagnostics (UJD) is based on the analysis of the dependence of the characteristics of local hydro-erosion of the diagnosed area of the surface of the object under analysis (OA) on the parameters of its quality. Surface quality parameters include physical and mechanical properties (PMP) and the degree of operational and technological damage. In this article a new formula has been developed that numerically determines the degree of defect resistance of materials. Experimental testing of this technique on some types of modern materials confirms its reliability. The directions of the future development of the research results are formulated.

УСТАНОВКА ДЛЯ РЕЗАНИЯ МЯКОТНОГО И МЯСОКОСТНОГО СЫРЬЯ ВЫСОКОЭНЕРГЕТИЧЕКОЙ СТРУЕЙ ВОДЫ

В работе предлагается установка устройства и для обвалки и жиловки мясного сырья высокоэнергетической струей воды для улучшения качественных показателей, повышения производительности и снижения трудоемкости производственного процесса. При осуществлении способа на мясное сырье воздействуют высокоэнергетической струей воды под сверхзвуковым давлением.

Conversion of poplar biomass into high-energy density tricyclic sesquiterpene jet fuel blendstocks

BackgroundIn an effort to ensure future energy security, reduce greenhouse gas emissions and create domestic jobs, the US has invested in technologies to develop sustainable biofuels and bioproducts from renewable carbon sources such as lignocellulosic biomass. Bio-derived jet fuel is of particular interest as aviation is less amenable to electrification compared to other modes of transportation and synthetic biology provides the ability to tailor fuel properties to enhance performance. Specific energy and energy density are important properties in determining the attractiveness of potential bio-derived jet fuels. For example, increased energy content can give the industry options such as longer range, higher load or reduced takeoff weight. Energy-dense sesquiterpenes have been identified as potential next-generation jet fuels that can be renewably produced from lignocellulosic biomass.ResultsWe developed a biomass deconstruction and conversion process that enabled the production of two tricyclic sesquiterpenes, epi-isozizaene and prespatane, from the woody biomass poplar using the versatile basidiomycete Rhodosporidium toruloides. We demonstrated terpene production at both bench and bioreactor scales, with prespatane titers reaching 1173.6 mg/L when grown in poplar hydrolysate in a 2 L bioreactor. Additionally, we examined the theoretical fuel properties of prespatane and epi-isozizaene in their hydrogenated states as blending options for jet fuel, and compared them to aviation fuel, Jet A.ConclusionOur findings indicate that prespatane and epi-isozizaene in their hydrogenated states would be attractive blending options in Jet A or other lower density renewable jet fuels as they would improve viscosity and increase their energy density. Saturated epi-isozizaene and saturated prespatane have energy densities that are 16.6 and 18.8% higher than Jet A, respectively. These results highlight the potential of R. toruloides as a production host for the sustainable and scalable production of bio-derived jet fuel blends, and this is the first report of prespatane as an alternative jet fuel.

Rapid compact jet quenching in the Galactic black hole candidate X-ray binary MAXI J1535−571

ABSTRACTWe present results from six epochs of quasi-simultaneous radio, (sub-)millimetre, infrared, optical, and X-ray observations of the black hole X-ray binary MAXI J1535−571. These observations show that as the source transitioned through the hard–intermediate X-ray state towards the soft–intermediate X-ray state, the jet underwent dramatic and rapid changes. We observed the frequency of the jet spectral break, which corresponds to the most compact region in the jet where particle acceleration begins (higher frequencies indicate closer to the black hole), evolves from the infrared band into the radio band (decreasing by ≈3 orders of magnitude) in less than a day. During one observational epoch, we found evidence of the jet spectral break evolving in frequency through the radio band. Estimating the magnetic field and size of the particle acceleration region shows that the rapid fading of the high-energy jet emission was not consistent with radiative cooling; instead, the particle acceleration region seems to be moving away from the black hole on approximately dynamical time-scales. This result suggests that the compact jet quenching is not caused by local changes to the particle acceleration, rather we are observing the acceleration region of the jet travelling away from the black hole with the jet flow. Spectral analysis of the X-ray emission shows a gradual softening in the few days before the dramatic jet changes, followed by a more rapid softening ∼1–2 d after the onset of the jet quenching.

Application of ANFIS–PSO Hybrid Algorithm for Predicting the Dimensions of the Downstream Scour Hole of Ski-Jump Spillways

Ski-jump spillway (SJS) is one of the energy-dissipating structures, passing the flood through the dams. In these structures, the downstream bed is scoured due to the collision of the high energy jet. It is essential to obtain information on the scour-hole dimensions to enhance the safety of the dam and related structures. The machine learning and data mining methods are efficient in predicting hydraulic phenomena. In this study, the geometric properties of the scour-hole including the hole expansion (width), maximum depth of the scour and its distance from the end edge of the spillway were predicted using a model by combining the adaptive neuro-fuzzy inference system (ANFIS) and the particle swarm optimization (PSO) algorithm. The results showed that the developed ANFIS–PSO model obtained maximum scour depth with a precision of R2 = 0.94 and RMSE = 0.565, scour hole width with precision of R2 = 0.95 and RMSE = 1.153 and its distance from the end edge of the SJS with an accuracy of R2 = 0.96 and RMSE = 1.809. The evaluation and comparison of the simulation results indicated the superiority of the proposed model over other methods.

Jet Suppression From a Small to Intermediate to Large Radius.

We present predictions for jet suppression from small to intermediate to very large radius, for high energy jets created in heavy ion collisions at the LHC. We find that jet suppression is surprisingly independent of the anti-kT radius R, first slightly increasing as one increases R, then at larger values of Rvery slowly decreasing. This behavior arises from two competing effects, namely the larger energy loss of the hard jet components, which tends to increase suppression, versus the partial recovery of the lost energy due to medium response, reducing suppression.

Parametrizing the detector response with neural networks

In high energy physics, characterizing the response of a detector to radiation is one of the most important and fundamental experimental tasks. In many cases, this task is accomplished by parameterizing summary statistics of the full detector response probability density. The parameterized detector response can then be used for calibration as well as for directly improving physics analysis sensitivity. This paper discusses how to parameterize summary statistics of the detector response using neural networks. In particular, neural networks are powerful tools for incorporating multidimensional data and the loss function used during training determines which summary statistic is learned. One common summary statistic that has not been combined with deep learning (as far as the authors are aware) is the mode. A neural network-based approach to mode learning is proposed and empirically demonstrated in the context of high energy jet calibrations. Altogether, the neural network-based toolkit for detector response parameterization can enhance the utility of data collected at high energy physics experiments and beyond.

HEJ 2: High energy resummation for hadron colliders

We present HEJ 2, a new implementation of the High Energy Jets formalism for high-energy resummation in hadron-collider processes as a flexible Monte Carlo event generator. In combination with a conventional fixed-order event generator, HEJ 2 can be used to obtain greatly improved predictions for a number of phenomenologically important processes by adding all-order logarithmic corrections in sˆ∕p⊥2. A prime example for such a process is the gluon-fusion production of a Higgs boson in association with widely separated jets, which constitutes the dominant background to Higgs boson production in weak-boson fusion. Program summaryProgram Title: HEJ 2Program Files doi:http://dx.doi.org/10.17632/24c9mb6pf9.1Licensing provisions: GPLv2 or laterProgramming language: C++Nature of problem: Conventional event generators for high-energy colliders are based on fixed-order perturbation theory, which converges poorly in regions of phase space with large invariant masses between jets. However, reliable predictions in these regions are of particular importance whenever cuts relevant to weak-boson fusion or weak-boson scattering are applied. One highly relevant example is the separation of gluon fusion and weak-boson fusion contributions to the production of a Higgs boson in association with two or more jets.Solution method: The perturbative description can be amended by resumming the high-energy logarithms associated with large invariant masses to all orders in perturbation theory. HEJ 2 implements this resummation following the High Energy Jets framework. Using HEJ 2 in conjunction with a conventional event generator allows one to obtain reliable predictions for processes involving multiple jets in high-energy regions of phase space.Additional comments including restrictions and unusual features: The current version of HEJ 2 implements multi-jet processes with at most a single Higgs boson in the final state. Matching to fixed-order perturbation theory is currently restricted to leading order.

Simultaneous description of hadron and jet suppression in heavy-ion collisions

We present a global fit to all data on the suppression of high-energy jets and high-energy hadrons in the most central heavy-ion collisions at the CERN Large Hadron Collider (LHC) for two different collision energies, within a hybrid strong-weak coupling quenching model. Even though the measured suppression factors for hadrons and jets differ significantly from one another and appear to asymptote to different values in the high-energy limit, we obtain a simultaneous description of all these data after constraining the value of a single model parameter. We use our model to investigate the origin of the difference between the observed suppression of jets and hadrons and relate it, quantitatively, to the observed modification of the jet fragmentation function in jets that have been modified by passage through the medium produced in heavy-ion collisions. In particular, the observed increase in the fraction of hard fragments in medium-modified jets, which indicates that jets with the fewest hardest fragments lose the least energy, corresponds quantitatively to the observed difference between the suppression of hadrons and jets. We argue that a harder fragmentation pattern for jets with a given energy after quenching is a generic feature of any mechanism for the interaction between jets and the medium that they traverse that yields a larger suppression for wider jets. We also compare the results of our global fit to LHC data to measurements of the suppression of high-energy hadrons in BNL Relativistic Heavy Ion Collider (RHIC) collisions, and find that with its parameter chosen to fit the LHC data, our model is inconsistent with the RHIC data at the $3\ensuremath{\sigma}$ level, suggesting that hard probes interact more strongly with the less hot quark-gluon plasma produced at RHIC.

Effect of microstructure characterization on penetration performance and penetration mechanism of Fe-Al-Bi alloy shaped charge liner

Nowadays, an increasing number of new materials are used in shaped charge liner (SCL). However, most current work is focused on the density and high acoustic velocity of the SCL raw materials in order to improve the penetration depth of the SCL. This paper is going to introduce a Fe-Al-Bi alloy used for the SCL starting from new consideration of by importing the concept of 9 pressed sintering. The alloy’s matrix is Al. Core-shell structure particles which have ductile and tough Fe cores and hard Fe3Al shells evenly distribute on the matrix. This paper analyzes the SCL’s continuous high-energy jet which is the core-shell structure particles covered by plasma state Al. The interaction between the jet and targets improve SCL’s penetration diameter and depth. It has been improved, compared with traditional SCL, the Fe-Al-Bi alloy SCL has better penetration performance.

Mixing enhancement for supersonic mixing layer by using plasma synthetic jet

Mixing enhancement for supersonic mixing layer is of great importance for developing scramjet engine. The growth rate of supersonic mixing layer is smaller than that of subsonic mixing layer. As the compressibility increases, the mixing enhancement becomes more difficult. Plasma synthetic jet is regarded as a promising flow control technology. The plasma synthetic jet generator can produce high energy jet. This generator has no moving parts and does not need additional gas source. It is the first time that plasma synthetic jet has been used to enhance the mixing in supersonic mixing layers. The influence of plasma synthetic jet on the supersonic mixing layer is investigated experimentally and numerically. The experiments are conducted in the low noise supersonic mixing layer wind tunnel. The Mach number of upper stream and lower stream are 1.37 and 2.39 respectively. The convective Mach number of this wind tunnel is 0.32. The plasma synthetic jet actuators are installed in the splitter plate. The distance between the jet hole and the splitter plate end is 15 mm. The nanoparticle-based planar laser scattering (NPLS), particle image velocimetry (PIV) and schlieren are used to obtain the response of the supersonic mixing layer to single pulse plasma synthetic jet perturbation. The NPLS successfully captures the large-scaled vortex structures induced by the plasma synthetic jet in the supersonic mixing layers. The effect of plasma synthetic jet is remarkable. The schlieren images show the process of the perturbation. An oblique shock wave is generated when the jet is ejected. The PIV is employed to obtain the influence of plasma synthetic jet on the velocity field. The <i>y</i>-velocity standard deviation increases due to the perturbation. The actuators’ mixing enhancement effects and actuators’ performances at three locations are investigated by two-dimensional numerical simulation. The three actuators are located on the upper, bottom and end surface of splitter plate respectively. The numerical simulation results show that the mixing layer thickness is increased by the plasma synthetic jet perturbation. There are two mechanisms of perturbations while actuators are located at different positions. The actuators installed on the upper and bottom surface of splitter plate influence the mixing layer through perturbing the upper and lower stream respectively. The actuator installed at the end of splitter plate affects the mixing layer directly. The response time of supersonic mixing layers to the perturbation of the actuator installed at the end of splitter plate is shorter than those of the others. The performance of each actuator is sensitive to the location.