Jet Transport Research Articles

Hard Probes: After the dust has settled!

A lot has been learnt in the 15 years since the first data on jet modification at the Relativistic Heavy Ion Collider (RHIC). This proceeding will describe the portion of the theory that is unassailable, and attempt to chart a course for the next period of precision measurements and related calculations. In particular, we will focus on the emerging series of higher order calculations, which may reveal the scale, energy and temperature dependence of jet transport coefficients, as well as develop ingredients for a future NLO calculation of jet modification. Connections with the underlying degrees of freedom in the Quark Gluon Plasma (QGP) will be explored. We will discuss the challenges faced by Monte-Carlo event generators and their comparison with a broad spectrum of jet modification data. First principles calculations of transport coefficients, and the determination of new transport coefficients which encapsulate the transition of energy momentum from the jet scale to the medium scale will also be discussed.

Drag induced radiative energy loss of semi-hard heavy quarks

We revisited gluon bremsstrahlung off a heavy quark in nuclear matter within higher twist formalism. In this work, we demonstrate that, in addition to transverse momentum diffusion parameter (qˆ), the gluon emission spectrum for a heavy quark is quite sensitive to eˆ, which quantify the amount of light-cone drag experienced by a parton. This effect leads to an additional energy loss term for heavy-quarks. From heavy flavor suppression data in ultra-relativistic heavy-ion collisions one can now estimate the value of this sub-leading non-perturbative jet transport parameter (eˆ) from our results.

Laboratory experiments on the formation and recoil jet transport of aerosol by laser ablation

In a high-repetition rate inertial fusion reactor, the first wall will be subjected to repeated ablation along with pellet implosions, which then leads to the formation of aerosol to scatter and/or deflect laser beams for the subsequent implosion, affecting the overall reactor performance. Proposed in the present work is a method of in-situ directed transport of aerosol particles by the use of laser ablation-induced jet recoil momenta. Lithium and carbon are used as the primary ablation targets, the former of which is known to form aerosol in the form of droplet, and the latter of which tends to form carbon nanotubes. Laboratory-scale experiments have been conducted to irradiate airborne aerosol particles with high-intensity laser to produce ablation-induced jet. Data have indicated a change in aerosol flow direction, but only in the case of lithium.

Structural design methodology of electro-optical system installation on special mission jet transport aircraft

The research reported in this paper investigated the structural design methodology of equipping a jet aircraft modified for maritime patrol with any type of observation system. The study includes installation feasibility, definition of mounting types (fix/retractable), installation location, airworthiness requirements, design considerations, structural design requirements, and static/dynamic analysis considerations. Due to lack of design publication in this field, this study focuses on methodology of electro-optical sensor installation as a flowchart leading to a road map to equip an aircraft with any type of maritime sensor. For validation of above methodology, a case study for installation of an electro-optical system on a particular jet aircraft with new mission is presented. By comparison of system and aircraft specification based on methodology flowchart, a retractable mounting was chosen. To accomplish a safe installation, an optimal mechanism suitable with aircraft fuselage and required backup structure was designed using reinforced cut out. The design was then analyzed for static and dynamic critical load cases using MSC/NASTRAN software.

Quantifying jet transport properties via large $$p_T$$ p T hadron production

Nuclear modification factor $R_{AA}$ for large $p_T$ single hadron is studied in a next-to-leading order (NLO) perturbative QCD (pQCD) parton model with medium-modified fragmentation functions (mFFs) due to jet quenching in high-energy heavy-ion collisions. The energy loss of the hard partons in the QGP is incorporated in the mFFs which utilize two most important parameters to characterize the transport properties of the hard parton jets: the jet transport parameter $\hat q_{0}$ and the mean free path $\lambda_{0}$, both at the initial time $\tau_0$. A phenomenological study of the experimental data for $R_{AA}(p_{T})$ is performed to constrain the two parameters with simultaneous $\chi^2/{\rm d.o.f}$ fits to RHIC as well as LHC data. We obtain for energetic quarks $\hat q_{0}\approx 1.1 \pm 0.2$ GeV$^2$/fm and $\lambda_{0}\approx 0.4 \pm 0.03$ fm in central $Au+Au$ collisions at $\sqrt{s_{NN}}=200$ GeV, while $\hat q_{0}\approx 1.7 \pm 0.3$ GeV$^2$/fm, and $\lambda_{0}\approx 0.5 \pm 0.05$ fm in central $Pb+Pb$ collisions at $\sqrt{s_{NN}}=2.76$ TeV. Numerical analysis shows that the best fit favors a multiple scattering picture for the energetic jets propagating through the bulk medium, with a moderate averaged number of gluon emissions. Based on the best constraints for $\lambda_{0}$ and $\tau_0$, the estimated value for the mean-squared transverse momentum broadening is moderate which implies that the hard jets go through the medium with small reflection.

Power-free water pump based on a superhydrophobic surface: generation of a mushroom-like jet and anti-gravity long-distance transport

A self-capturing phenomenon was investigated to design an integrated antigravity transport system based on a superhydrophobic surface.

Using Fuzzy Set as a Controller on the Lateral Dynamic of Autopilot to Reducing the Effect of the Atmospheric Disturbance

In this paper, used fuzzy set as a controller to control roll and yaw angles in lateral dynamic of the autopilot system for jet transport using MATLAB/SIMULINK. Autopilot systems are complex devices that demand exact control and stability. In this paper explained the lateral dynamic on automatic pilot and studied the effect of atmospheric disturbances on the stability then designed the fuzzy set controller to reduce three type of disturbance which faced the pilot during the flight.

Reducing the Effect of the Atmospheric Disturbance on Longitudinal Fight Control System Usage PID Controller

Autopilot systems have been vital to flight control for several years and have been making flight easier and more effective. Nevertheless, these autopilot systems are complex devices that demand exact control and stability. In this paper, design PID controller to control pitch angle in longitudinal dynamic of the autopilot system for jet transport using MATLAB/SIMULINK. In this paper designed on automatic pilot with Multi Input Multi Output (MIMO) system. Also, we studied the effect of atmospheric disturbances when a PID controller has been applied the results shown how this controller with good tuning reducing the effect of atmospheric disturbance on the consistency of the autopilot.

Trapped electron mode driven electron heat transport in JET: experimental investigation and gyro-kinetic theory validation

The main purpose of this work is to study the dependence of trapped electron modes (TEM) threshold and of electron stiffness on the most relevant plasma parameters. Dedicated transport experiments based on heat flux scans and Te modulation have been performed in JET in TEM dominated plasmas with pure ICRH electron heating and a numerical study using gyrokinetic simulations has been performed with the code GKW. Using multilinear regressions on the experimental data, the stabilizing effect of magnetic shear predicted by theory for our plasma parameters is confirmed while no significant effect of safety factor was found. Good quantitative agreement is found between the TEM thresholds found in the experiments and calculated with linear GKW simulations. Non-linear simulations have given further confirmation of the threshold values and allowed comparison with the values of stiffness found experimentally. Perturbative studies using RF power modulation indicate the existence of an inward convective term for the electron heat flux. Adding NBI power, ion temperature gradient (ITG) modes become dominant and a reduction of with respect to pure ICRH, TEM dominant discharges has been experimentally observed, in spite of increased total electron power. Possible explanations are discussed.

Tools to detect structures in dynamical systems using Jet Transport

This paper is devoted to the development of some dynamical indicators that allow the determination of regions and structures that separate different dynamic regimes in autonomous and non-autonomous dynamical systems. The underlying idea is closely related to the Lagrangian coherent structures concept introduced by Haller. In the present paper, instead of using the Cauchy–Green tensor, that determines the domains where the flow associated to a differential equation is expanding in the normal direction, the Jet Transport methodology is used. This is a semi-numerical tool, that has as basic ingredients a polynomial algebra package and a numerical integration method, allowing, at each integration step, the propagation under a flow of a neighbourhood U instead of a single initial condition. The output of the procedure is a polynomial in several variables that represents the image of U up to a selected order, containing high order terms of the variational equations. Using these high order representation, the places where the normal direction expands can be easily detected, in a similar manner as the procedures for calculating the Lagrangian coherent structures do. In order to illustrate the methodology, first the results obtained in the determination of the separatrices of the simple and the periodically perturbed pendulum are given. Later, the applications to the circular restricted three body problem are considered, where the aim is the detection of invariant manifolds of libration point orbits, as well as in the non-autonomous vector field defined by the elliptic restricted three body problem.

Consistency of Perfect Fluidity and Jet Quenching in Semi-Quark-Gluon Monopole Plasmas**Supported by the USA DOE Nuclear Science under Grant No DE-FG02-93ER40764, the National Science Foundation under Grant No PHY-1352368, and the RIKEN BNL Research Center.

We utilize a new framework, CUJET3.0, to deduce the energy and temperature dependence of the jet transport parameter, q̂(E > 10 GeV, T), from a combined analysis of available data on nuclear modification factor and azimuthal asymmetries from high energy nuclear collisions at RHIC/BNL and LHC/CERN. Extending a previous perturbative-QCD based jet energy loss model (known as CUJET2.0) with (2+1)D viscous hydrodynamic bulk evolution, this new framework includes three novel features of nonperturbative physics origin: (i) the Polyakov loop suppression of color-electric scattering (aka ‘semi-QGP’ of Pisarski et al.), (ii) the enhancement of jet scattering due to emergent magnetic monopoles near Tc (aka ‘magnetic scenario’ of Liao and Shuryak), and (iii) thermodynamic properties constrained by lattice QCD data. CUJET3.0 reduces to v2.0 at high temperatures T >400 MeV, while greatly enhances q̂ near the QCD deconfinement transition temperature range. This enhancement accounts well for the observed elliptic harmonics of jets with pT > 10 GeV. Extrapolating our data-constrained q̂ down to thermal energy scales, E∼2 GeV, we find for the first time a remarkable consistency between high energy jet quenching and bulk perfect fluidity with η/s ∼ T3/q̂ ∼ 0.1 near Tc.

Parametric Exploration of Wing–Body Junction Flow Using Computational Fluid Dynamics

The wing–body junction flow is investigated parametrically using computational fluid dynamics in an attempt to understand the effects of junction flow on aircraft drag, with a focus on application to large business jet or commercial transport aircraft. A Reynolds-averaged Navier–Stokes computational fluid dynamics methodology is validated against detailed experimental data for a junction flow. Computational fluid dynamics results for a wing with a leading-edge strake (an aerodynamic surface designed to reduce flow separation, thereby reducing aircraft drag) are presented, and the effects of scaling this strake are explored. The effectiveness of the strake on a swept wing is compared to the same for a straight wing. Finally, the results from this parametric study are successfully applied to sizing a leading-edge strake for a commercial transport aircraft. It is demonstrated that a systematic approach, starting with a simple, validated model and building up to a realistic aircraft application, can build confidence in computational fluid dynamics results.

Capturing the Transport Variability of a Western Boundary Jet: Results from the Agulhas Current Time-Series Experiment (ACT)

AbstractThe volume transport of the Agulhas Current was measured over a 3-yr period by an array of seven current meter moorings and four current- and pressure-recording inverted echo sounders (CPIES) deployed at 34°S. CPIES extended the array farther offshore in order to capture, for the first time, the full Agulhas Current during meander events. Transports derived from CPIES are well correlated with overlapping current meter transports (0.89). The Eulerian mean current is 219 km wide and 3000 m deep, with peak surface speeds of 1.8 m s−1 and a weak northward undercurrent on the continental slope below 1200 m. A new algorithm to capture the western boundary jet transport at each time step T is defined as the poleward transport out to the first maximum of the vertically integrated velocity beyond the half-width of the mean jet. The mean transport of the Agulhas Current jet, so defined, is −84 Sverdrups (Sv; 1 Sv ≡ 106 m3 s−1) with a standard error of 2 Sv. Sampling and instrumental errors are explicitly estimated and amount to an additional 9 Sv. A more traditional estimate, based on net transport integrated to a fixed distance offshore Tbox, gives a mean transport of −77 ± 5 Sv. This transport is 10 Sv greater than an equivalent transport at 32°S, corresponding to a latitudinal increase equal to that predicted by Sverdrup dynamics. The time series of T and Tbox show important differences during solitary meander events and at longer time scales. In terms of an annual cycle, the Agulhas Current appears strongest during austral summer, a similar phase to the Gulf Stream and Kuroshio.

Jet modification in the next decade: A pedestrian outlook

In this review, we recount the current status of the theory of jet modification in dense matter. We commence with an outline of the ‘traditional’ observables which may be calculated without recourse to event generators. These include single- and double-hadron suppression, nuclear modification factor vs. reaction plane etc. All these measurements are used to justify both the required underlying physical picture of jet modification as well as the final obtained values of jet transport coefficients. This is followed by a review of the more modern observables which have arisen with the ability to reconstruct full jets, and the challenges faced therein. This is followed by a preview of upcoming theoretical developments in the field and an outlook on how the interface between these developments, phenomenological improvements, and upcoming data will allow us to quantitatively determine properties of the medium which effect the modification of hard jets.

Numerical Simulation and Stratification Structure Analysis of Freezing Rain Event in Guizhou in January 2008

Severe freezing rain disaster has happened in Guizhou Province early 2008. The meso-scale maintenance mechanism of the stationary front related to the event is analyzed from the aspects of circulation,low er jet and moisture transportation. And as typical case,the third process which is the most devastating one in the event has been simulated through WRF model. The results consist with observations in circulation pattern,precipitation distribution and intensity. High resolution simulation clearly reflects stratification structure of stationary front and distribution characteristics of cloud substances over freezing rain area in Guizhou. The research shows that except the general three-layer structure(includes ice layer,warm layer and cold layer),the typical two-layer structure of freezing rain also appeared in central region of Guizhou. This means freezing rain may develop merely when a deep warm moist layer that has temperature exceed 0℃ in middle altitude overruns a colder layer,while solid particles in upper air hardly exist. Abundant liquid drops contain in warm layer fall through shallow colder layer forming supercooling raindrops,and freeze on contact with surface.

Unsteady High-Angle-of-Attack Aerodynamic Models of a Generic Jet Transport

Accurate simulation of flight beyond normal conditions requires models of the aircraft aerodynamics at high angles of attack, for which the flow over the wing and control surfaces may be rapidly changing and massively separated. This study focuses on large-amplitude forced oscillations of a benchmark commercial aircraft configuration. Existing models are modified to describe the unsteady aerodynamic forces on the aircraft up to stall range. Steady-state and periodically forced unsteady Reynolds-averaged Navier–Stokes simulation data are employed to calibrate the model parameters. The results of the reduced-order models are in good overall agreement with those observed in the unsteady Reynolds-averaged Navier–Stokes simulations.

Higher-twist contributions to the transverse momentum broadening in semi-inclusive deep inelastic scattering off large nuclei

Multiple scattering leads to transverse momentum broadening of the struck quark in semi-inclusive deeply inelastic scatterings (SIDIS). Nuclear broadening of the transverse momentum squared at the leading twist is determined by the twist-four collinear quark-gluon correlation function of the target nucleus that is in turn related to the jet transport parameter inside the nuclear medium. The twist-six contributions to the transverse momentum broadening are calculated as power corrections $\sim 1/Q^2$. Such power corrections are found to have no extra nuclear enhancement beyond the twist-four matrix elements and are determined by the nuclear modification of collinear parton distribution and correlation functions. They become important for an accurate extraction of the jet transport parameter inside large nuclei and its scale evolution at intermediate values of the hard scale $Q^2$.

QCD Evolution of Nuclear Quark-Gluon Correlation Function

We summarize the results on the next-to-leading order (NLO) calculations of transverse momentum broadening in semi-inclusive deeply inelastic e + A scattering (SIDIS) and Drell-Yan dilepton production (DY) in p + A collisions. The corresponding transverse momentum weighted differential cross sections are shown to factorize at NLO. Our calculations identify the QCD evolution equation for the quark-gluon correlation function, and also confirm the universality of the associated quark-gluon correlation function in SIDIS and DY. The evolution equation can be further applied to determine the QCD factorization scale and the energy dependence of the jet transport parameter [Formula: see text].

Variability of zonal currents in the eastern equatorial Indian Ocean on seasonal to interannual time scales

This study examines equatorial zonal current variations in the upper layers of eastern Indian Ocean in relation to variations in the Indian Ocean Dipole (IOD). The analysis utilizes data from the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) and the European Centre for Medium-Range Weather Forecasts-Ocean Reanalysis System 4 (ECMWF-ORAS4). Surface currents are characterized by semiannual eastward flowing Wyrtki jets along the equator in boreal spring and fall, forced by westerly monsoon transition winds. The fall jet intensifies during negative IOD (NIOD) events when westerlies are anomalously strong but significantly weakens during positive IOD (PIOD) events when westerlies are anomalously weak. As zonal wind stress weakens during PIOD events, sea surface height becomes unusually low in the eastern basin and high in the west, setting up an anomalous pressure force that drives increased eastward transport in the thermocline. Opposite tendencies are evident during NIOD events in response to intensified equatorial westerlies. Current transport adjustments to anomalous zonal wind forcing during IOD events extend into the following year, consistent with the cycling of equatorial wave energy around the basin. A surface layer mass budget calculation for the eastern sea surface temperature (SST) pole of the IOD indicates upwelling of ∼2.9±0.7 Sv during normal periods, increasing by 40–50% during PIOD events and reducing effectively to zero during NIOD events. IOD-related variations in Wyrtki jet and thermocline transports are major influences on these upwelling rates and associated water mass transformations, which vary consistently with SST changes.

Transverse momentum broadening at NLO and QCD evolution of qˆ

Within the framework of a high-twist approach, we show the first complete next-to-leading order calculation of transverse momentum broadening in semi-inclusive deeply inelastic $e+A$ scattering and Drell-Yan dilepton production in $p+A$ collisions. We demonstrate at one-loop level how QCD factorization holds for multiple scattering in nuclear medium, and the university of the associated quark-gluon correlation function. Our calculation also identifies QCD evolution equation for the quark-gluon correlation function, which determines the QCD factorization scale and energy dependence of jet transport parameter $\hat q$.